pharmaceutical dosage form suspensions.ppt
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About This Presentation
Suspension formulations and manufacturer information
Slide Content
Pharmaceutical Suspensions
Prof. Ibrahim Alsarra
Department of PharmaceuticsDepartment of Pharmaceutics
College of PharmacyCollege of Pharmacy
King Saud UniversityKing Saud University
PHT 312: Pharmaceutics II
Prof. Ibrahim Alsarra
Department of PharmaceuticsDepartment of Pharmaceutics
College of PharmacyCollege of Pharmacy
King Saud UniversityKing Saud University
PHT 312: Pharmaceutics II
SuspensionsSuspensions and and emulsionsemulsions form an important class form an important class
of pharmaceutical dosage forms, but they also present of pharmaceutical dosage forms, but they also present
many formulation, stability, manufacturing and many formulation, stability, manufacturing and
packaging challenges. packaging challenges.
The principal objectives of this part of this course are to The principal objectives of this part of this course are to
provide some practical considerations that apply to provide some practical considerations that apply to
these systems, and then relate those considerations to these systems, and then relate those considerations to
formulation methods, evaluation procedures and formulation methods, evaluation procedures and
manufacturing techniques. manufacturing techniques.
IntroductionIntroduction
SuspensionsSuspensions and and emulsionsemulsions form an important class form an important class
of pharmaceutical dosage forms, but they also present of pharmaceutical dosage forms, but they also present
many formulation, stability, manufacturing and many formulation, stability, manufacturing and
packaging challenges. packaging challenges.
The principal objectives of this part of this course are to The principal objectives of this part of this course are to
provide some practical considerations that apply to provide some practical considerations that apply to
these systems, and then relate those considerations to these systems, and then relate those considerations to
formulation methods, evaluation procedures and formulation methods, evaluation procedures and
manufacturing techniques. manufacturing techniques.
IntroductionIntroduction
We are talking about two-phase systems. The We are talking about two-phase systems. The
substance that is distributed is referred to as the substance that is distributed is referred to as the
suspensoidsuspensoid (if a suspension) the dispersed (if a suspension) the dispersed
phase or the internal phase and the vehicle is phase or the internal phase and the vehicle is
termed the termed the dispersing phasedispersing phase, the dispersion , the dispersion
medium, the dispersive medium, the external medium, the dispersive medium, the external
phase or the continuous phase. phase or the continuous phase.
The particles of the dispersed phase can vary The particles of the dispersed phase can vary
widely in size, even within one formulation, widely in size, even within one formulation,
ranging from particles or droplets large enough ranging from particles or droplets large enough
to be visible to the naked eye down to as small to be visible to the naked eye down to as small
as colloidal dimensions. as colloidal dimensions.
IntroductionIntroduction
We are talking about two-phase systems. The We are talking about two-phase systems. The
substance that is distributed is referred to as the substance that is distributed is referred to as the
suspensoidsuspensoid (if a suspension) the dispersed (if a suspension) the dispersed
phase or the internal phase and the vehicle is phase or the internal phase and the vehicle is
termed the termed the dispersing phasedispersing phase, the dispersion , the dispersion
medium, the dispersive medium, the external medium, the dispersive medium, the external
phase or the continuous phase. phase or the continuous phase.
The particles of the dispersed phase can vary The particles of the dispersed phase can vary
widely in size, even within one formulation, widely in size, even within one formulation,
ranging from particles or droplets large enough ranging from particles or droplets large enough
to be visible to the naked eye down to as small to be visible to the naked eye down to as small
as colloidal dimensions. as colloidal dimensions.
IntroductionIntroduction
The manufacturer will usually want the dispersed The manufacturer will usually want the dispersed
phase particle size to fall in a narrow range to phase particle size to fall in a narrow range to
maintain uniformity within each product and from maintain uniformity within each product and from
package to package. Most good oral suspensions package to package. Most good oral suspensions
have a particle size in the diameter range 1 to 50 have a particle size in the diameter range 1 to 50
µµm. m.
Coarse Dispersion: Coarse Dispersion:
- - SuspensionSuspension: solid drug in liquid vehicle: solid drug in liquid vehicle
- - EmulsionEmulsion: Liquid drug in liquid vehicle : Liquid drug in liquid vehicle
1)- 1)- Oil-in-water emulsionsOil-in-water emulsions (o/w) (o/w)
2)- 2)- Water-in-oil emulsionsWater-in-oil emulsions (w/o) (w/o)
IntroductionIntroduction
The manufacturer will usually want the dispersed The manufacturer will usually want the dispersed
phase particle size to fall in a narrow range to phase particle size to fall in a narrow range to
maintain uniformity within each product and from maintain uniformity within each product and from
package to package. Most good oral suspensions package to package. Most good oral suspensions
have a particle size in the diameter range 1 to 50 have a particle size in the diameter range 1 to 50
µµm. m.
Coarse Dispersion: Coarse Dispersion:
- - SuspensionSuspension: solid drug in liquid vehicle: solid drug in liquid vehicle
- - EmulsionEmulsion: Liquid drug in liquid vehicle : Liquid drug in liquid vehicle
1)- 1)- Oil-in-water emulsionsOil-in-water emulsions (o/w) (o/w)
2)- 2)- Water-in-oil emulsionsWater-in-oil emulsions (w/o) (w/o)
IntroductionIntroduction
Solutions
♦ Have small particles
♦ Are transparent
♦ Do not separate
♦ Cannot be filtered
Colloids
♦ Have medium size particles
♦ Cannot be filtered
♦ Separated with semipermeable membranes
Suspensios
♦ Have very large particles
♦ Settle out
♦ Can be filtered
♦ Must stir to stay suspended
♦ Have small particles
♦ Are transparent
♦ Do not separate
♦ Cannot be filtered
Colloids
♦ Have medium size particles
♦ Cannot be filtered
♦ Separated with semipermeable membranes
Suspensios
♦ Have very large particles
♦ Settle out
♦ Can be filtered
♦ Must stir to stay suspended
Because of their larger particle size range, Because of their larger particle size range,
suspensions and emulsions are more likely to separate suspensions and emulsions are more likely to separate
from the dispersion medium by settling from the dispersion medium by settling
(sedimentation)(sedimentation) or creaming or creaming (rising)(rising), respectively. , respectively.
This presents a dosing uniformity problem since the This presents a dosing uniformity problem since the
drug is contained in these dispersed particles. If the drug is contained in these dispersed particles. If the
product has separated, the patient may be overdosing product has separated, the patient may be overdosing
or underdosing, depending on whether the sampled or underdosing, depending on whether the sampled
product was high in dispersed phase or low in product was high in dispersed phase or low in
dispersed phase. dispersed phase.
What the manufacturer will aim for is a product that What the manufacturer will aim for is a product that
possesses random but reasonably uniform possesses random but reasonably uniform
redistribution of the dispersed phase when the redistribution of the dispersed phase when the
container is shaken.container is shaken.
IntroductionIntroduction
Because of their larger particle size range, Because of their larger particle size range,
suspensions and emulsions are more likely to separate suspensions and emulsions are more likely to separate
from the dispersion medium by settling from the dispersion medium by settling
(sedimentation)(sedimentation) or creaming or creaming (rising)(rising), respectively. , respectively.
This presents a dosing uniformity problem since the This presents a dosing uniformity problem since the
drug is contained in these dispersed particles. If the drug is contained in these dispersed particles. If the
product has separated, the patient may be overdosing product has separated, the patient may be overdosing
or underdosing, depending on whether the sampled or underdosing, depending on whether the sampled
product was high in dispersed phase or low in product was high in dispersed phase or low in
dispersed phase. dispersed phase.
What the manufacturer will aim for is a product that What the manufacturer will aim for is a product that
possesses random but reasonably uniform possesses random but reasonably uniform
redistribution of the dispersed phase when the redistribution of the dispersed phase when the
container is shaken.container is shaken.
IntroductionIntroduction
SUSPENSIONSSUSPENSIONS
Heterogeneous systems consisting of two phasesHeterogeneous systems consisting of two phases. The continuous . The continuous
or or external phaseexternal phase is generally is generally a liquid or semisolida liquid or semisolid, and the , and the
dispersed or the internal phasedispersed or the internal phase is made up of particulate matter is made up of particulate matter
which is essentially insoluble in, but dispersed throughout, the which is essentially insoluble in, but dispersed throughout, the
continuous phase. Almost all suspension systems separate on continuous phase. Almost all suspension systems separate on
standing. standing.
The formulator’s main concern, therefore, is not necessarily to try The formulator’s main concern, therefore, is not necessarily to try
to eliminate separation, but rather to decrease the rate of settling to eliminate separation, but rather to decrease the rate of settling
and to permit easy resuspendability of any settled particulate and to permit easy resuspendability of any settled particulate
matter.matter.
A satisfactory suspension must remain sufficiently homogeneous A satisfactory suspension must remain sufficiently homogeneous
for at least the period of time necessary to remove and administer for at least the period of time necessary to remove and administer
the required dose after shaking its container. the required dose after shaking its container.
Heterogeneous systems consisting of two phasesHeterogeneous systems consisting of two phases. The continuous . The continuous
or or external phaseexternal phase is generally is generally a liquid or semisolida liquid or semisolid, and the , and the
dispersed or the internal phasedispersed or the internal phase is made up of particulate matter is made up of particulate matter
which is essentially insoluble in, but dispersed throughout, the which is essentially insoluble in, but dispersed throughout, the
continuous phase. Almost all suspension systems separate on continuous phase. Almost all suspension systems separate on
standing. standing.
The formulator’s main concern, therefore, is not necessarily to try The formulator’s main concern, therefore, is not necessarily to try
to eliminate separation, but rather to decrease the rate of settling to eliminate separation, but rather to decrease the rate of settling
and to permit easy resuspendability of any settled particulate and to permit easy resuspendability of any settled particulate
matter.matter.
A satisfactory suspension must remain sufficiently homogeneous A satisfactory suspension must remain sufficiently homogeneous
for at least the period of time necessary to remove and administer for at least the period of time necessary to remove and administer
the required dose after shaking its container. the required dose after shaking its container.
SUSPENSIONSSUSPENSIONS
Advantages to Oral Suspensions:Advantages to Oral Suspensions:
There are several reasons for using oral suspensions to deliver a There are several reasons for using oral suspensions to deliver a
drug: drug:
Pharmacokinetic modification Pharmacokinetic modification
Palatability Palatability
A liquid dosage form vs. a solid dosage formA liquid dosage form vs. a solid dosage form
Solubility and Stability Solubility and Stability
Advantages to Oral Suspensions:Advantages to Oral Suspensions:
There are several reasons for using oral suspensions to deliver a There are several reasons for using oral suspensions to deliver a
drug: drug:
Pharmacokinetic modification Pharmacokinetic modification
Palatability Palatability
A liquid dosage form vs. a solid dosage formA liquid dosage form vs. a solid dosage form
Solubility and Stability Solubility and Stability
SUSPENSIONSSUSPENSIONS
Pharmacokinetic modification achievable with suspension Pharmacokinetic modification achievable with suspension
forms relates essentially to improved absorption properties. forms relates essentially to improved absorption properties.
Suspension forms of drugs may be more readily Suspension forms of drugs may be more readily
bioavailable than comparable capsule or tablet solid dosage bioavailable than comparable capsule or tablet solid dosage
forms because the initial disintegration step is bypassed. forms because the initial disintegration step is bypassed.
On the other hand, significant bioavailability differences On the other hand, significant bioavailability differences
among generically equivalent brands of oral suspensions among generically equivalent brands of oral suspensions
have been occasionally observed. have been occasionally observed.
The fact that in aqueous suspensions the relatively The fact that in aqueous suspensions the relatively
insoluble drug greatly reduces or eliminates taste sensation insoluble drug greatly reduces or eliminates taste sensation
permits the formulation of palatable oral liquids which permits the formulation of palatable oral liquids which
would otherwise not be possible due to the bad taste of would otherwise not be possible due to the bad taste of
certain drugs. certain drugs.
Pharmacokinetic modification achievable with suspension Pharmacokinetic modification achievable with suspension
forms relates essentially to improved absorption properties. forms relates essentially to improved absorption properties.
Suspension forms of drugs may be more readily Suspension forms of drugs may be more readily
bioavailable than comparable capsule or tablet solid dosage bioavailable than comparable capsule or tablet solid dosage
forms because the initial disintegration step is bypassed. forms because the initial disintegration step is bypassed.
On the other hand, significant bioavailability differences On the other hand, significant bioavailability differences
among generically equivalent brands of oral suspensions among generically equivalent brands of oral suspensions
have been occasionally observed. have been occasionally observed.
The fact that in aqueous suspensions the relatively The fact that in aqueous suspensions the relatively
insoluble drug greatly reduces or eliminates taste sensation insoluble drug greatly reduces or eliminates taste sensation
permits the formulation of palatable oral liquids which permits the formulation of palatable oral liquids which
would otherwise not be possible due to the bad taste of would otherwise not be possible due to the bad taste of
certain drugs. certain drugs.
SUSPENSIONSSUSPENSIONS
Not infrequently a liquid form is preferred over the solid form Not infrequently a liquid form is preferred over the solid form
of a drug:of a drug:
(i) ease of swallowing issue with infants and geriatric patients.(i) ease of swallowing issue with infants and geriatric patients.
(ii) the flexibility in the range of doses (not locked into a (ii) the flexibility in the range of doses (not locked into a
particular dose by a tablet formulation). particular dose by a tablet formulation).
Since oral suspensions can be prepared by a pharmacist using Since oral suspensions can be prepared by a pharmacist using
commonly available suspending agents, the pharmacist must commonly available suspending agents, the pharmacist must
recommend that the extemporaneous product be used within a recommend that the extemporaneous product be used within a
relatively short time since there is usually no evidence to relatively short time since there is usually no evidence to
justify the assumption that long-term stability exists.justify the assumption that long-term stability exists.
Not infrequently a liquid form is preferred over the solid form Not infrequently a liquid form is preferred over the solid form
of a drug:of a drug:
(i) ease of swallowing issue with infants and geriatric patients.(i) ease of swallowing issue with infants and geriatric patients.
(ii) the flexibility in the range of doses (not locked into a (ii) the flexibility in the range of doses (not locked into a
particular dose by a tablet formulation). particular dose by a tablet formulation).
Since oral suspensions can be prepared by a pharmacist using Since oral suspensions can be prepared by a pharmacist using
commonly available suspending agents, the pharmacist must commonly available suspending agents, the pharmacist must
recommend that the extemporaneous product be used within a recommend that the extemporaneous product be used within a
relatively short time since there is usually no evidence to relatively short time since there is usually no evidence to
justify the assumption that long-term stability exists.justify the assumption that long-term stability exists.
SUSPENSIONSSUSPENSIONS
Some drugs are not sufficiently soluble in conventional, safe and Some drugs are not sufficiently soluble in conventional, safe and
legally permissible vehicles (e.g., water, syrup, hydroalcoholic legally permissible vehicles (e.g., water, syrup, hydroalcoholic
mixtures, and water/glycerin blends) to provide the desired dose mixtures, and water/glycerin blends) to provide the desired dose
in a 5 to 15 ml volume. in a 5 to 15 ml volume.
Chemical stability is often improved if the drug is insoluble in Chemical stability is often improved if the drug is insoluble in
the liquid medium. For this reason, suspensions may be prepared the liquid medium. For this reason, suspensions may be prepared
with a water-insoluble derivative of the parent drug. The with a water-insoluble derivative of the parent drug. The
insoluble derivative may be an ester, as in the case of acetyl insoluble derivative may be an ester, as in the case of acetyl
sulfisoxazole, or an insoluble salt, as in the case of propoxyphene sulfisoxazole, or an insoluble salt, as in the case of propoxyphene
napsylate. Sometimes the drug itself is sufficiently insoluble so napsylate. Sometimes the drug itself is sufficiently insoluble so
that a suspension may be prepared without derivatization, as is that a suspension may be prepared without derivatization, as is
the case of phenytoin in which the free-acid form of the drug (as the case of phenytoin in which the free-acid form of the drug (as
opposed to the sodium salt) is sufficiently insoluble so that an opposed to the sodium salt) is sufficiently insoluble so that an
aqueous suspension may be prepared.aqueous suspension may be prepared.
Some drugs are not sufficiently soluble in conventional, safe and Some drugs are not sufficiently soluble in conventional, safe and
legally permissible vehicles (e.g., water, syrup, hydroalcoholic legally permissible vehicles (e.g., water, syrup, hydroalcoholic
mixtures, and water/glycerin blends) to provide the desired dose mixtures, and water/glycerin blends) to provide the desired dose
in a 5 to 15 ml volume. in a 5 to 15 ml volume.
Chemical stability is often improved if the drug is insoluble in Chemical stability is often improved if the drug is insoluble in
the liquid medium. For this reason, suspensions may be prepared the liquid medium. For this reason, suspensions may be prepared
with a water-insoluble derivative of the parent drug. The with a water-insoluble derivative of the parent drug. The
insoluble derivative may be an ester, as in the case of acetyl insoluble derivative may be an ester, as in the case of acetyl
sulfisoxazole, or an insoluble salt, as in the case of propoxyphene sulfisoxazole, or an insoluble salt, as in the case of propoxyphene
napsylate. Sometimes the drug itself is sufficiently insoluble so napsylate. Sometimes the drug itself is sufficiently insoluble so
that a suspension may be prepared without derivatization, as is that a suspension may be prepared without derivatization, as is
the case of phenytoin in which the free-acid form of the drug (as the case of phenytoin in which the free-acid form of the drug (as
opposed to the sodium salt) is sufficiently insoluble so that an opposed to the sodium salt) is sufficiently insoluble so that an
aqueous suspension may be prepared.aqueous suspension may be prepared.
Desired features in a Desired features in a
pharmaceutical suspensionpharmaceutical suspension
1. Therapeutic efficacy - if the drug does not exert 1. Therapeutic efficacy - if the drug does not exert
pharmacological activity after administration, it has failed in its pharmacological activity after administration, it has failed in its
purpose.purpose.
2. Chemical stability - no degradation or decomposition of vital 2. Chemical stability - no degradation or decomposition of vital
components within the formulation during processing, storage, components within the formulation during processing, storage,
handling or administration.handling or administration.
3. Physical stability - the suspension should not settle too quickly 3. Physical stability - the suspension should not settle too quickly
and should be readily redispersed on gentle shaking.and should be readily redispersed on gentle shaking.
4. The particle size should remain fairly constant throughout the 4. The particle size should remain fairly constant throughout the
shelf-life of the product. You don't want dissolution or shelf-life of the product. You don't want dissolution or
aggregation of the particles within the suspension.aggregation of the particles within the suspension.
pharmaceutical suspensionpharmaceutical suspension
1. Therapeutic efficacy - if the drug does not exert 1. Therapeutic efficacy - if the drug does not exert
pharmacological activity after administration, it has failed in its pharmacological activity after administration, it has failed in its
purpose.purpose.
2. Chemical stability - no degradation or decomposition of vital 2. Chemical stability - no degradation or decomposition of vital
components within the formulation during processing, storage, components within the formulation during processing, storage,
handling or administration.handling or administration.
3. Physical stability - the suspension should not settle too quickly 3. Physical stability - the suspension should not settle too quickly
and should be readily redispersed on gentle shaking.and should be readily redispersed on gentle shaking.
4. The particle size should remain fairly constant throughout the 4. The particle size should remain fairly constant throughout the
shelf-life of the product. You don't want dissolution or shelf-life of the product. You don't want dissolution or
aggregation of the particles within the suspension.aggregation of the particles within the suspension.
Desired features in a Desired features in a
pharmaceutical suspensionpharmaceutical suspension
5. The suspension should pour easily and evenly from the 5. The suspension should pour easily and evenly from the
container.container.
6. The formulation should be aesthetically pleasing to the eye, 6. The formulation should be aesthetically pleasing to the eye,
nose and mouth. The appearance, viscosity, texture and any nose and mouth. The appearance, viscosity, texture and any
other properties detected by the senses must be considered.other properties detected by the senses must be considered.
pharmaceutical suspensionpharmaceutical suspension
5. The suspension should pour easily and evenly from the 5. The suspension should pour easily and evenly from the
container.container.
6. The formulation should be aesthetically pleasing to the eye, 6. The formulation should be aesthetically pleasing to the eye,
nose and mouth. The appearance, viscosity, texture and any nose and mouth. The appearance, viscosity, texture and any
other properties detected by the senses must be considered.other properties detected by the senses must be considered.
Available Suspension FormulationsAvailable Suspension Formulations
1. Ready-to-use Oral Suspension:1. Ready-to-use Oral Suspension:
If that is the case, the formulation requires addition of a If that is the case, the formulation requires addition of a
wetting or spreading agent prior to introduction of the solid wetting or spreading agent prior to introduction of the solid
particles to the continuous phase. The wetting agent is even particles to the continuous phase. The wetting agent is even
expected to enter the pores of the solid particles which expected to enter the pores of the solid particles which
allows the continuous phase to penetrate. Keep in mind allows the continuous phase to penetrate. Keep in mind
that that
only minimum amount of wetting agent should be used, only minimum amount of wetting agent should be used,
compatible with producing an adequate dispersion of the compatible with producing an adequate dispersion of the
particles. Excessive amount may lead to foaming or impart particles. Excessive amount may lead to foaming or impart
undesirable taste or odor to the product. Alcohol, glycerin undesirable taste or odor to the product. Alcohol, glycerin
and propylene glycol would qualify as wetting agents for and propylene glycol would qualify as wetting agents for
oral products. oral products.
1. Ready-to-use Oral Suspension:1. Ready-to-use Oral Suspension:
If that is the case, the formulation requires addition of a If that is the case, the formulation requires addition of a
wetting or spreading agent prior to introduction of the solid wetting or spreading agent prior to introduction of the solid
particles to the continuous phase. The wetting agent is even particles to the continuous phase. The wetting agent is even
expected to enter the pores of the solid particles which expected to enter the pores of the solid particles which
allows the continuous phase to penetrate. Keep in mind allows the continuous phase to penetrate. Keep in mind
that that
only minimum amount of wetting agent should be used, only minimum amount of wetting agent should be used,
compatible with producing an adequate dispersion of the compatible with producing an adequate dispersion of the
particles. Excessive amount may lead to foaming or impart particles. Excessive amount may lead to foaming or impart
undesirable taste or odor to the product. Alcohol, glycerin undesirable taste or odor to the product. Alcohol, glycerin
and propylene glycol would qualify as wetting agents for and propylene glycol would qualify as wetting agents for
oral products. oral products.
Available Suspension FormulationsAvailable Suspension Formulations
1. Ready-to-use Oral Suspension:1. Ready-to-use Oral Suspension:
In large scale production, the wetting agent would probably In large scale production, the wetting agent would probably
be added at the same time that the solid is reduced in size be added at the same time that the solid is reduced in size
in a colloid mill. In this way the surfaces of the particles are in a colloid mill. In this way the surfaces of the particles are
coated with the surfactant material prior to its introduction coated with the surfactant material prior to its introduction
Into the vehicle. The solid is added to a portion of the Into the vehicle. The solid is added to a portion of the
vehicle which already contains all the soluble components, vehicle which already contains all the soluble components,
including color, flavor and preservative. After thorough including color, flavor and preservative. After thorough
mixing, more vehicle is added sequentially with blending mixing, more vehicle is added sequentially with blending
after each addition. The final product is passed through a after each addition. The final product is passed through a
colloid mill or other blender to ensure uniformity.colloid mill or other blender to ensure uniformity.
1. Ready-to-use Oral Suspension:1. Ready-to-use Oral Suspension:
In large scale production, the wetting agent would probably In large scale production, the wetting agent would probably
be added at the same time that the solid is reduced in size be added at the same time that the solid is reduced in size
in a colloid mill. In this way the surfaces of the particles are in a colloid mill. In this way the surfaces of the particles are
coated with the surfactant material prior to its introduction coated with the surfactant material prior to its introduction
Into the vehicle. The solid is added to a portion of the Into the vehicle. The solid is added to a portion of the
vehicle which already contains all the soluble components, vehicle which already contains all the soluble components,
including color, flavor and preservative. After thorough including color, flavor and preservative. After thorough
mixing, more vehicle is added sequentially with blending mixing, more vehicle is added sequentially with blending
after each addition. The final product is passed through a after each addition. The final product is passed through a
colloid mill or other blender to ensure uniformity.colloid mill or other blender to ensure uniformity.
Available Suspension FormulationsAvailable Suspension Formulations
2. Extemporaneous Preparation:2. Extemporaneous Preparation:
As a pharmacist, you may be called upon to prepare an As a pharmacist, you may be called upon to prepare an
extemporaneous liquid form of a drug that is available in a extemporaneous liquid form of a drug that is available in a
solid dosage form, usually as a tablet or capsule. Place the solid dosage form, usually as a tablet or capsule. Place the
contents of the capsule or the whole tablet into a mortar contents of the capsule or the whole tablet into a mortar
and crush the material with your pestle. Slowly add a small and crush the material with your pestle. Slowly add a small
amount of the vehicle and mix the two to form a paste. amount of the vehicle and mix the two to form a paste.
Dilute the paste with more vehicle until all of the vehicle has Dilute the paste with more vehicle until all of the vehicle has
been added to the mortar. been added to the mortar.
2. Extemporaneous Preparation:2. Extemporaneous Preparation:
As a pharmacist, you may be called upon to prepare an As a pharmacist, you may be called upon to prepare an
extemporaneous liquid form of a drug that is available in a extemporaneous liquid form of a drug that is available in a
solid dosage form, usually as a tablet or capsule. Place the solid dosage form, usually as a tablet or capsule. Place the
contents of the capsule or the whole tablet into a mortar contents of the capsule or the whole tablet into a mortar
and crush the material with your pestle. Slowly add a small and crush the material with your pestle. Slowly add a small
amount of the vehicle and mix the two to form a paste. amount of the vehicle and mix the two to form a paste.
Dilute the paste with more vehicle until all of the vehicle has Dilute the paste with more vehicle until all of the vehicle has
been added to the mortar. been added to the mortar.
Available Suspension FormulationsAvailable Suspension Formulations
3. Dry Powders for Oral Suspension:3. Dry Powders for Oral Suspension:
The products that are available as ready-to-use suspensions The products that are available as ready-to-use suspensions
are labeled "Oral Suspension.are labeled "Oral Suspension.”” There are dry powder There are dry powder
mixtures or granules intended for suspension in an mixtures or granules intended for suspension in an
appropriate vehicle prior to administration as a suspension; appropriate vehicle prior to administration as a suspension;
they bear the title "... for Oral Suspension" to distinguish they bear the title "... for Oral Suspension" to distinguish
them from already prepared oral suspensions. The powder them from already prepared oral suspensions. The powder
mixture must contain any coloring agent, flavoring, mixture must contain any coloring agent, flavoring,
sweetener, stabilizing agent, suspending agent (viscosity sweetener, stabilizing agent, suspending agent (viscosity
modifier) and preservative intended for the final formulation modifier) and preservative intended for the final formulation
that is administered. By including all of these agents in the that is administered. By including all of these agents in the
powder mixture, the vehicle for reconstituting the product powder mixture, the vehicle for reconstituting the product
can be purified water. can be purified water.
3. Dry Powders for Oral Suspension:3. Dry Powders for Oral Suspension:
The products that are available as ready-to-use suspensions The products that are available as ready-to-use suspensions
are labeled "Oral Suspension.are labeled "Oral Suspension.”” There are dry powder There are dry powder
mixtures or granules intended for suspension in an mixtures or granules intended for suspension in an
appropriate vehicle prior to administration as a suspension; appropriate vehicle prior to administration as a suspension;
they bear the title "... for Oral Suspension" to distinguish they bear the title "... for Oral Suspension" to distinguish
them from already prepared oral suspensions. The powder them from already prepared oral suspensions. The powder
mixture must contain any coloring agent, flavoring, mixture must contain any coloring agent, flavoring,
sweetener, stabilizing agent, suspending agent (viscosity sweetener, stabilizing agent, suspending agent (viscosity
modifier) and preservative intended for the final formulation modifier) and preservative intended for the final formulation
that is administered. By including all of these agents in the that is administered. By including all of these agents in the
powder mixture, the vehicle for reconstituting the product powder mixture, the vehicle for reconstituting the product
can be purified water. can be purified water.
Available Suspension FormulationsAvailable Suspension Formulations
3. Dry Powders for Oral Suspension:3. Dry Powders for Oral Suspension:
When you as the pharmacist are called upon to reconstitute When you as the pharmacist are called upon to reconstitute
and dispense such a product:and dispense such a product:
1.1.Loosen the powder at the bottom of the container by gently Loosen the powder at the bottom of the container by gently
tapping it against a hard surface.tapping it against a hard surface.
2.2.Add a small portion of the label-designated amount of Add a small portion of the label-designated amount of
purified water and shake until the powder is wetted. purified water and shake until the powder is wetted.
3.3.Add the remainder of the water in several aliquots. Add the remainder of the water in several aliquots.
4.4.Shake the container to confirm that all of the particles are Shake the container to confirm that all of the particles are
wetted and suspended. wetted and suspended.
3. Dry Powders for Oral Suspension:3. Dry Powders for Oral Suspension:
When you as the pharmacist are called upon to reconstitute When you as the pharmacist are called upon to reconstitute
and dispense such a product:and dispense such a product:
1.1.Loosen the powder at the bottom of the container by gently Loosen the powder at the bottom of the container by gently
tapping it against a hard surface.tapping it against a hard surface.
2.2.Add a small portion of the label-designated amount of Add a small portion of the label-designated amount of
purified water and shake until the powder is wetted. purified water and shake until the powder is wetted.
3.3.Add the remainder of the water in several aliquots. Add the remainder of the water in several aliquots.
4.4.Shake the container to confirm that all of the particles are Shake the container to confirm that all of the particles are
wetted and suspended. wetted and suspended.
Routes of administration of Routes of administration of
suspensionsuspension
Suspensions are used to administer insoluble Suspensions are used to administer insoluble
and distasteful substances in a form that is and distasteful substances in a form that is
pleasant to taste by providing a suitable pleasant to taste by providing a suitable
form, for the application of dermatological form, for the application of dermatological
materials to the skin and mucous membrane materials to the skin and mucous membrane
and for parenteral usage. Thus suspensions and for parenteral usage. Thus suspensions
can be administered by can be administered by oraloral, , topicaltopical, ,
parenteralparenteral and and ophthalmicophthalmic application application
suspensionsuspension
Suspensions are used to administer insoluble Suspensions are used to administer insoluble
and distasteful substances in a form that is and distasteful substances in a form that is
pleasant to taste by providing a suitable pleasant to taste by providing a suitable
form, for the application of dermatological form, for the application of dermatological
materials to the skin and mucous membrane materials to the skin and mucous membrane
and for parenteral usage. Thus suspensions and for parenteral usage. Thus suspensions
can be administered by can be administered by oraloral, , topicaltopical, ,
parenteralparenteral and and ophthalmicophthalmic application application
Oral suspensionsOral suspensions
Patients who have problems in swallowing solid Patients who have problems in swallowing solid
dosage forms require drugs to be dispersed in a dosage forms require drugs to be dispersed in a
liquid. Oral suspensions permit the formulation of liquid. Oral suspensions permit the formulation of
poorly soluble drugs in the form of liquid dosage poorly soluble drugs in the form of liquid dosage
form. As these suspensions are to be taken by oral form. As these suspensions are to be taken by oral
route therefore they must contain suitable flavoring route therefore they must contain suitable flavoring
and sweetening agents. Drugs, which possess and sweetening agents. Drugs, which possess
unpleasant taste in solution dosage form like unpleasant taste in solution dosage form like
paracetamol, chloramphenicol palmitateparacetamol, chloramphenicol palmitate can be can be
formulated as palatable suspension as they are formulated as palatable suspension as they are
suitable for administration to peadiatric patients. suitable for administration to peadiatric patients.
Patients who have problems in swallowing solid Patients who have problems in swallowing solid
dosage forms require drugs to be dispersed in a dosage forms require drugs to be dispersed in a
liquid. Oral suspensions permit the formulation of liquid. Oral suspensions permit the formulation of
poorly soluble drugs in the form of liquid dosage poorly soluble drugs in the form of liquid dosage
form. As these suspensions are to be taken by oral form. As these suspensions are to be taken by oral
route therefore they must contain suitable flavoring route therefore they must contain suitable flavoring
and sweetening agents. Drugs, which possess and sweetening agents. Drugs, which possess
unpleasant taste in solution dosage form like unpleasant taste in solution dosage form like
paracetamol, chloramphenicol palmitateparacetamol, chloramphenicol palmitate can be can be
formulated as palatable suspension as they are formulated as palatable suspension as they are
suitable for administration to peadiatric patients. suitable for administration to peadiatric patients.
Topical suspensionsTopical suspensions
These suspensions are meant for external These suspensions are meant for external
application and therefore should be free from gritty application and therefore should be free from gritty
particles. Example of fluid suspension includes particles. Example of fluid suspension includes
calamine lotioncalamine lotion, which leave a deposit of calamine , which leave a deposit of calamine
on the skin after evaporation of the aqueous on the skin after evaporation of the aqueous
dispersion phase. dispersion phase. Zinc creamZinc cream has a consistency of has a consistency of
semisolid. Zinc cream consists of high percentage semisolid. Zinc cream consists of high percentage
of powders dispersed in an oily (paraffin) phase.of powders dispersed in an oily (paraffin) phase.
These suspensions are meant for external These suspensions are meant for external
application and therefore should be free from gritty application and therefore should be free from gritty
particles. Example of fluid suspension includes particles. Example of fluid suspension includes
calamine lotioncalamine lotion, which leave a deposit of calamine , which leave a deposit of calamine
on the skin after evaporation of the aqueous on the skin after evaporation of the aqueous
dispersion phase. dispersion phase. Zinc creamZinc cream has a consistency of has a consistency of
semisolid. Zinc cream consists of high percentage semisolid. Zinc cream consists of high percentage
of powders dispersed in an oily (paraffin) phase.of powders dispersed in an oily (paraffin) phase.
Parenteral suspensionsParenteral suspensions
These suspensions should be sterile and should These suspensions should be sterile and should
possess property of syringability. Vaccines are also possess property of syringability. Vaccines are also
formulated as dispersions of killed microorganisms formulated as dispersions of killed microorganisms
for example infor example in Cholera vaccineCholera vaccine or as toxoid or as toxoid
adsorbed on toadsorbed on to substrate like aluminium hydroxide substrate like aluminium hydroxide
or phosphate for prolonged antigenic stimulus. For or phosphate for prolonged antigenic stimulus. For
ExampleExample adsorbed adsorbed Diphtheria and Tetanus toxoidDiphtheria and Tetanus toxoid..
These suspensions should be sterile and should These suspensions should be sterile and should
possess property of syringability. Vaccines are also possess property of syringability. Vaccines are also
formulated as dispersions of killed microorganisms formulated as dispersions of killed microorganisms
for example infor example in Cholera vaccineCholera vaccine or as toxoid or as toxoid
adsorbed on toadsorbed on to substrate like aluminium hydroxide substrate like aluminium hydroxide
or phosphate for prolonged antigenic stimulus. For or phosphate for prolonged antigenic stimulus. For
ExampleExample adsorbed adsorbed Diphtheria and Tetanus toxoidDiphtheria and Tetanus toxoid..
Ophthalmic suspensionsOphthalmic suspensions
These should also be sterile and should possess These should also be sterile and should possess
very fine particles. Drugs, which are unstable in very fine particles. Drugs, which are unstable in
aqueous solution, are formulated as stable aqueous solution, are formulated as stable
suspensions using non-aqueous solvents. For suspensions using non-aqueous solvents. For
example fractioned coconut oil is used for example fractioned coconut oil is used for
dispersing tetracycline hydrochloride for ophthalmic dispersing tetracycline hydrochloride for ophthalmic
use.use.
These should also be sterile and should possess These should also be sterile and should possess
very fine particles. Drugs, which are unstable in very fine particles. Drugs, which are unstable in
aqueous solution, are formulated as stable aqueous solution, are formulated as stable
suspensions using non-aqueous solvents. For suspensions using non-aqueous solvents. For
example fractioned coconut oil is used for example fractioned coconut oil is used for
dispersing tetracycline hydrochloride for ophthalmic dispersing tetracycline hydrochloride for ophthalmic
use.use.
Theoretical considerationsTheoretical considerations
The basic concern involves the fact that suspensions The basic concern involves the fact that suspensions
settle, and it is necessary to redistribute it before using settle, and it is necessary to redistribute it before using
or dispensing the product. or dispensing the product.
A desirable suspension should be easily redispersed byA desirable suspension should be easily redispersed by
shaking, should remain suspended long enough to shaking, should remain suspended long enough to
withdraw an accurate dosage, and should have the withdraw an accurate dosage, and should have the
desired flow properties. desired flow properties.
Before we start discussing the formulation of Before we start discussing the formulation of
suspensions, suspensions,
it is of great importance to explain some concepts it is of great importance to explain some concepts
pertaining to the formulation.pertaining to the formulation.
The basic concern involves the fact that suspensions The basic concern involves the fact that suspensions
settle, and it is necessary to redistribute it before using settle, and it is necessary to redistribute it before using
or dispensing the product. or dispensing the product.
A desirable suspension should be easily redispersed byA desirable suspension should be easily redispersed by
shaking, should remain suspended long enough to shaking, should remain suspended long enough to
withdraw an accurate dosage, and should have the withdraw an accurate dosage, and should have the
desired flow properties. desired flow properties.
Before we start discussing the formulation of Before we start discussing the formulation of
suspensions, suspensions,
it is of great importance to explain some concepts it is of great importance to explain some concepts
pertaining to the formulation.pertaining to the formulation.
((11 -) -)Interfacial phenomenonInterfacial phenomenon
Smaller particle size and large surface area is Smaller particle size and large surface area is
associated with a surface free energy making it associated with a surface free energy making it
thermodynamically unstable. thermodynamically unstable.
Thus the particles possess high energy which leads to Thus the particles possess high energy which leads to
grouping together to reduce surface free energy thus grouping together to reduce surface free energy thus
leading to formation of floccules. These floccules are leading to formation of floccules. These floccules are
held together among themselves and within by weak held together among themselves and within by weak
van der waals forces. However in cases where particles van der waals forces. However in cases where particles
are adhered by stronger forces to form aggregates are adhered by stronger forces to form aggregates
forming hard cake. These phenomena occur in order forming hard cake. These phenomena occur in order
to make system more thermodynamically stable. to make system more thermodynamically stable.
In order to achieve a state of stability the system tend In order to achieve a state of stability the system tend
to reduce the surface free energy, which may be to reduce the surface free energy, which may be
accomplished by reduction of interfacial tension that is accomplished by reduction of interfacial tension that is
achieved by use of surfactants. achieved by use of surfactants.
Smaller particle size and large surface area is Smaller particle size and large surface area is
associated with a surface free energy making it associated with a surface free energy making it
thermodynamically unstable. thermodynamically unstable.
Thus the particles possess high energy which leads to Thus the particles possess high energy which leads to
grouping together to reduce surface free energy thus grouping together to reduce surface free energy thus
leading to formation of floccules. These floccules are leading to formation of floccules. These floccules are
held together among themselves and within by weak held together among themselves and within by weak
van der waals forces. However in cases where particles van der waals forces. However in cases where particles
are adhered by stronger forces to form aggregates are adhered by stronger forces to form aggregates
forming hard cake. These phenomena occur in order forming hard cake. These phenomena occur in order
to make system more thermodynamically stable. to make system more thermodynamically stable.
In order to achieve a state of stability the system tend In order to achieve a state of stability the system tend
to reduce the surface free energy, which may be to reduce the surface free energy, which may be
accomplished by reduction of interfacial tension that is accomplished by reduction of interfacial tension that is
achieved by use of surfactants. achieved by use of surfactants.
((22 -) -)WettingWetting
A difficulty that is frequently encountered and a factor of A difficulty that is frequently encountered and a factor of
prime importance in suspension formulation concerns prime importance in suspension formulation concerns
the wetting of the solid phase by the suspension medium. the wetting of the solid phase by the suspension medium.
By definition, a suspension is essentially an incompatible By definition, a suspension is essentially an incompatible
system, but to exist at all it requires some degree of system, but to exist at all it requires some degree of
compatibility, and good wetting of the suspended compatibility, and good wetting of the suspended
materials is important to achieve this end.materials is important to achieve this end.
When a strong affinity exists between a liquid and a solid, When a strong affinity exists between a liquid and a solid,
the liquid will easily form a thin film over the surface of the liquid will easily form a thin film over the surface of
the solid. When this affinity is nonexistent or weak, the solid. When this affinity is nonexistent or weak,
however, the liquid has difficulty displacing the air or however, the liquid has difficulty displacing the air or
other substances surrounding the solid, and there exists other substances surrounding the solid, and there exists
an angle of contact between the liquid and the solid. an angle of contact between the liquid and the solid.
A difficulty that is frequently encountered and a factor of A difficulty that is frequently encountered and a factor of
prime importance in suspension formulation concerns prime importance in suspension formulation concerns
the wetting of the solid phase by the suspension medium. the wetting of the solid phase by the suspension medium.
By definition, a suspension is essentially an incompatible By definition, a suspension is essentially an incompatible
system, but to exist at all it requires some degree of system, but to exist at all it requires some degree of
compatibility, and good wetting of the suspended compatibility, and good wetting of the suspended
materials is important to achieve this end.materials is important to achieve this end.
When a strong affinity exists between a liquid and a solid, When a strong affinity exists between a liquid and a solid,
the liquid will easily form a thin film over the surface of the liquid will easily form a thin film over the surface of
the solid. When this affinity is nonexistent or weak, the solid. When this affinity is nonexistent or weak,
however, the liquid has difficulty displacing the air or however, the liquid has difficulty displacing the air or
other substances surrounding the solid, and there exists other substances surrounding the solid, and there exists
an angle of contact between the liquid and the solid. an angle of contact between the liquid and the solid.
((22 -) -)WettingWetting……(cont.)(cont.)
This contact angle, This contact angle, , results from an equilibrium , results from an equilibrium
involving three interfacial tensions, specially, those involving three interfacial tensions, specially, those
acting at the interfaces between the liquid and vapor acting at the interfaces between the liquid and vapor
phase, at the solid and liquid phases, and at the solid phase, at the solid and liquid phases, and at the solid
and vapor phases. and vapor phases.
Certain solids are readily wet by liquid media whereas Certain solids are readily wet by liquid media whereas
others are not. In aqueous suspension terminology, others are not. In aqueous suspension terminology,
solids are said to be either solids are said to be either hydrophilichydrophilic (water loving) = (water loving) =
lyophobic (fat hating) or lyophobic (fat hating) or hydrophobichydrophobic (water hating) = (water hating) =
lypophilic (fat loving). lypophilic (fat loving).
Hydrophobic substances are easily wet by either water Hydrophobic substances are easily wet by either water
or other polar liquids; they may also greatly increase or other polar liquids; they may also greatly increase
the viscosity of water suspensions.the viscosity of water suspensions.
This contact angle, This contact angle, , results from an equilibrium , results from an equilibrium
involving three interfacial tensions, specially, those involving three interfacial tensions, specially, those
acting at the interfaces between the liquid and vapor acting at the interfaces between the liquid and vapor
phase, at the solid and liquid phases, and at the solid phase, at the solid and liquid phases, and at the solid
and vapor phases. and vapor phases.
Certain solids are readily wet by liquid media whereas Certain solids are readily wet by liquid media whereas
others are not. In aqueous suspension terminology, others are not. In aqueous suspension terminology,
solids are said to be either solids are said to be either hydrophilichydrophilic (water loving) = (water loving) =
lyophobic (fat hating) or lyophobic (fat hating) or hydrophobichydrophobic (water hating) = (water hating) =
lypophilic (fat loving). lypophilic (fat loving).
Hydrophobic substances are easily wet by either water Hydrophobic substances are easily wet by either water
or other polar liquids; they may also greatly increase or other polar liquids; they may also greatly increase
the viscosity of water suspensions.the viscosity of water suspensions.
((22 -) -)Wetting Wetting ……(cont.)(cont.)
Hydrophilic solids usually can be incorporated into Hydrophilic solids usually can be incorporated into
suspensions without the use of wetting agent, but suspensions without the use of wetting agent, but
hydrophobic materials are extremely difficult to hydrophobic materials are extremely difficult to
disperse and frequently float on the surface of the disperse and frequently float on the surface of the
fluid due to poor wetting of the particles or the fluid due to poor wetting of the particles or the
presence of tiny air pockets.presence of tiny air pockets.
A frequently helpful pharmaceutical technique for A frequently helpful pharmaceutical technique for
modifying the wetting characteristics of powders modifying the wetting characteristics of powders
involves the use of surfactants to decrease the solid-involves the use of surfactants to decrease the solid-
liquid interfacial tension. liquid interfacial tension.
Hydrophilic solids usually can be incorporated into Hydrophilic solids usually can be incorporated into
suspensions without the use of wetting agent, but suspensions without the use of wetting agent, but
hydrophobic materials are extremely difficult to hydrophobic materials are extremely difficult to
disperse and frequently float on the surface of the disperse and frequently float on the surface of the
fluid due to poor wetting of the particles or the fluid due to poor wetting of the particles or the
presence of tiny air pockets.presence of tiny air pockets.
A frequently helpful pharmaceutical technique for A frequently helpful pharmaceutical technique for
modifying the wetting characteristics of powders modifying the wetting characteristics of powders
involves the use of surfactants to decrease the solid-involves the use of surfactants to decrease the solid-
liquid interfacial tension. liquid interfacial tension.
((22 -) -)Wetting Wetting ……(cont.)(cont.)
Other materials that can be used to aid dispersion of Other materials that can be used to aid dispersion of
hydrophobic solids are hydrophilic polymers such as hydrophobic solids are hydrophilic polymers such as
sodium carboxymethylcellulose. sodium carboxymethylcellulose.
These hydrophilic agents may, if used at too high These hydrophilic agents may, if used at too high
concentration, cause undesirable gelling instead of concentration, cause undesirable gelling instead of
just the desired degree of viscosity or thixotropy; the just the desired degree of viscosity or thixotropy; the
latter term refers to the formation of a gel like latter term refers to the formation of a gel like
structure which is easily broken and becomes fluid structure which is easily broken and becomes fluid
upon agitation. upon agitation.
Other materials that can be used to aid dispersion of Other materials that can be used to aid dispersion of
hydrophobic solids are hydrophilic polymers such as hydrophobic solids are hydrophilic polymers such as
sodium carboxymethylcellulose. sodium carboxymethylcellulose.
These hydrophilic agents may, if used at too high These hydrophilic agents may, if used at too high
concentration, cause undesirable gelling instead of concentration, cause undesirable gelling instead of
just the desired degree of viscosity or thixotropy; the just the desired degree of viscosity or thixotropy; the
latter term refers to the formation of a gel like latter term refers to the formation of a gel like
structure which is easily broken and becomes fluid structure which is easily broken and becomes fluid
upon agitation. upon agitation.
((33 -) -)Sedimentation (Settling) ratesSedimentation (Settling) rates
Sedimentation and flocculation rates are properties of Sedimentation and flocculation rates are properties of
suspension systems governed by particles size, particle-suspension systems governed by particles size, particle-
particle interactions, densities of the particle and the particle interactions, densities of the particle and the
medium, and the viscosities of the continuous phase. medium, and the viscosities of the continuous phase.
In deflocculated polydispersed systemsIn deflocculated polydispersed systems (i.e. those (i.e. those
having many different particle sizes present). having many different particle sizes present).
In this case the large particles settle downward more In this case the large particles settle downward more
rapidly than the smaller particles, whereas in rapidly than the smaller particles, whereas in
concentrated deflocculated suspensions the larger concentrated deflocculated suspensions the larger
particles exhibit hindered settling and the smallest particles exhibit hindered settling and the smallest
settle more rapidly.settle more rapidly.
Sedimentation and flocculation rates are properties of Sedimentation and flocculation rates are properties of
suspension systems governed by particles size, particle-suspension systems governed by particles size, particle-
particle interactions, densities of the particle and the particle interactions, densities of the particle and the
medium, and the viscosities of the continuous phase. medium, and the viscosities of the continuous phase.
In deflocculated polydispersed systemsIn deflocculated polydispersed systems (i.e. those (i.e. those
having many different particle sizes present). having many different particle sizes present).
In this case the large particles settle downward more In this case the large particles settle downward more
rapidly than the smaller particles, whereas in rapidly than the smaller particles, whereas in
concentrated deflocculated suspensions the larger concentrated deflocculated suspensions the larger
particles exhibit hindered settling and the smallest particles exhibit hindered settling and the smallest
settle more rapidly.settle more rapidly.
((33 -) -)Sedimentation (Settling) ratesSedimentation (Settling) rates
In flocculated suspensionsIn flocculated suspensions, the particles are linked , the particles are linked
together into flocs which initially settle according to together into flocs which initially settle according to
the size of floc and the porosity of the aggregated the size of floc and the porosity of the aggregated
mass, and therefore, a clear supernatant is formed on mass, and therefore, a clear supernatant is formed on
settling. settling.
In flocculated suspensionsIn flocculated suspensions, the particles are linked , the particles are linked
together into flocs which initially settle according to together into flocs which initially settle according to
the size of floc and the porosity of the aggregated the size of floc and the porosity of the aggregated
mass, and therefore, a clear supernatant is formed on mass, and therefore, a clear supernatant is formed on
settling. settling.
((33 -) -)Sedimentation (Settling) ratesSedimentation (Settling) rates
The well known StokesThe well known Stokes’’ relation describes the relation describes the
sedimentation velocity of a particle in suspension:sedimentation velocity of a particle in suspension:
where v = velocity of the sedimentation or rate of where v = velocity of the sedimentation or rate of
settling in cm/sec; settling in cm/sec;
r = particle radius; r = particle radius;
D = particle diameter in cm; D = particle diameter in cm;
d1 and d2 = density of the particle and the liquid, d1 and d2 = density of the particle and the liquid,
respectively, in (g/cmrespectively, in (g/cm
33
); );
g = acceleration due to gravity (gravitational constant) g = acceleration due to gravity (gravitational constant)
= 980.7 cm/sec= 980.7 cm/sec
22
; ;
= the viscosity of the medium in poises.= the viscosity of the medium in poises.
18
)(
9
)(2
21
2
21
2
gddDgddr
v
The well known StokesThe well known Stokes’’ relation describes the relation describes the
sedimentation velocity of a particle in suspension:sedimentation velocity of a particle in suspension:
where v = velocity of the sedimentation or rate of where v = velocity of the sedimentation or rate of
settling in cm/sec; settling in cm/sec;
r = particle radius; r = particle radius;
D = particle diameter in cm; D = particle diameter in cm;
d1 and d2 = density of the particle and the liquid, d1 and d2 = density of the particle and the liquid,
respectively, in (g/cmrespectively, in (g/cm
33
); );
g = acceleration due to gravity (gravitational constant) g = acceleration due to gravity (gravitational constant)
= 980.7 cm/sec= 980.7 cm/sec
22
; ;
= the viscosity of the medium in poises.= the viscosity of the medium in poises.
18
)(
9
)(2
21
2
21
2
gddDgddr
v
((33 -) -)Sedimentation (Settling) ratesSedimentation (Settling) rates
The various parameters influencing the rate of settling are The various parameters influencing the rate of settling are
contained in the Stokescontained in the Stokes’’ equation. These parameters lead equation. These parameters lead
to several manufacturing considerations as well as to the to several manufacturing considerations as well as to the
inclusion of certain additives to oral suspension inclusion of certain additives to oral suspension
formulations:formulations:
Reduction of particle sizeReduction of particle size (Recall, however, that reducing (Recall, however, that reducing
the particle size may also promote caking.) the particle size may also promote caking.)
Solid contentSolid content - recall that Stokes - recall that Stokes’’ equation is based on a equation is based on a
dilute suspension because the presence of other particles dilute suspension because the presence of other particles
hinders settling hinders settling
Increasing the density of the vehicleIncreasing the density of the vehicle (additive) (additive)
Increasing the viscosity of the vehicleIncreasing the viscosity of the vehicle (within limits since (within limits since
the increase in viscosity also affects flow from the bottle) the increase in viscosity also affects flow from the bottle)
(additive: suspending agent or viscosity modifier) (additive: suspending agent or viscosity modifier)
Prevention of aggregation/cakingPrevention of aggregation/caking (additives: surfactants (additives: surfactants
and flocculating agents)and flocculating agents)
The various parameters influencing the rate of settling are The various parameters influencing the rate of settling are
contained in the Stokescontained in the Stokes’’ equation. These parameters lead equation. These parameters lead
to several manufacturing considerations as well as to the to several manufacturing considerations as well as to the
inclusion of certain additives to oral suspension inclusion of certain additives to oral suspension
formulations:formulations:
Reduction of particle sizeReduction of particle size (Recall, however, that reducing (Recall, however, that reducing
the particle size may also promote caking.) the particle size may also promote caking.)
Solid contentSolid content - recall that Stokes - recall that Stokes’’ equation is based on a equation is based on a
dilute suspension because the presence of other particles dilute suspension because the presence of other particles
hinders settling hinders settling
Increasing the density of the vehicleIncreasing the density of the vehicle (additive) (additive)
Increasing the viscosity of the vehicleIncreasing the viscosity of the vehicle (within limits since (within limits since
the increase in viscosity also affects flow from the bottle) the increase in viscosity also affects flow from the bottle)
(additive: suspending agent or viscosity modifier) (additive: suspending agent or viscosity modifier)
Prevention of aggregation/cakingPrevention of aggregation/caking (additives: surfactants (additives: surfactants
and flocculating agents)and flocculating agents)
((33 -) -)Sedimentation (Settling) ratesSedimentation (Settling) rates
This is usually accomplished by dry milling prior to This is usually accomplished by dry milling prior to
incorporating the dispersed phase into the vehicle:incorporating the dispersed phase into the vehicle:
1.1.Micropulverizers are the high-speed equipment that can Micropulverizers are the high-speed equipment that can
rapidly, conveniently and inexpensively produce fine rapidly, conveniently and inexpensively produce fine
powders in the diameter range 10 to 50 powders in the diameter range 10 to 50 µµm.m.
2.2.To achieve particles less than 10 To achieve particles less than 10 µµm in diameter requires a m in diameter requires a
process called jet-milling or micronizing. The particles are process called jet-milling or micronizing. The particles are
carried into compressed air streams where they collide with carried into compressed air streams where they collide with
one another due to the violent turbulence and high one another due to the violent turbulence and high
velocities present in these systems. These collisions result velocities present in these systems. These collisions result
in fragmentation and the resultant decrease in particle size.in fragmentation and the resultant decrease in particle size.
3.3.Particles of extremely small dimensions can be produced by Particles of extremely small dimensions can be produced by
spray drying.spray drying.
(A) -Particle size reduction:
This is usually accomplished by dry milling prior to This is usually accomplished by dry milling prior to
incorporating the dispersed phase into the vehicle:incorporating the dispersed phase into the vehicle:
1.1.Micropulverizers are the high-speed equipment that can Micropulverizers are the high-speed equipment that can
rapidly, conveniently and inexpensively produce fine rapidly, conveniently and inexpensively produce fine
powders in the diameter range 10 to 50 powders in the diameter range 10 to 50 µµm.m.
2.2.To achieve particles less than 10 To achieve particles less than 10 µµm in diameter requires a m in diameter requires a
process called jet-milling or micronizing. The particles are process called jet-milling or micronizing. The particles are
carried into compressed air streams where they collide with carried into compressed air streams where they collide with
one another due to the violent turbulence and high one another due to the violent turbulence and high
velocities present in these systems. These collisions result velocities present in these systems. These collisions result
in fragmentation and the resultant decrease in particle size.in fragmentation and the resultant decrease in particle size.
3.3.Particles of extremely small dimensions can be produced by Particles of extremely small dimensions can be produced by
spray drying.spray drying.
(A) -Particle size reduction:
((33 -) -)Sedimentation (Settling) ratesSedimentation (Settling) rates
Carboxymethylcellulose (CMC), methylcellulose, Carboxymethylcellulose (CMC), methylcellulose,
xanthan gum, and bentonite have been used to xanthan gum, and bentonite have been used to
thicken the continuous phase and help to support the thicken the continuous phase and help to support the
physical stability of the suspension. These agents are physical stability of the suspension. These agents are
poorly absorbed from the GI tract and essentially pass poorly absorbed from the GI tract and essentially pass
through unchanged. through unchanged.
When polymeric substances and hydrophilic colloids When polymeric substances and hydrophilic colloids
are used as suspending agents, appropriate testing are used as suspending agents, appropriate testing
must be performed to ascertain that the substance must be performed to ascertain that the substance
does not interfere with the absorption of the drug. does not interfere with the absorption of the drug.
The usual mechanism is adsorption or sequestering of The usual mechanism is adsorption or sequestering of
the drug which interferes with the rate and extent of the drug which interferes with the rate and extent of
absorption. absorption.
(A) -Viscosity Modifiers:
Carboxymethylcellulose (CMC), methylcellulose, Carboxymethylcellulose (CMC), methylcellulose,
xanthan gum, and bentonite have been used to xanthan gum, and bentonite have been used to
thicken the continuous phase and help to support the thicken the continuous phase and help to support the
physical stability of the suspension. These agents are physical stability of the suspension. These agents are
poorly absorbed from the GI tract and essentially pass poorly absorbed from the GI tract and essentially pass
through unchanged. through unchanged.
When polymeric substances and hydrophilic colloids When polymeric substances and hydrophilic colloids
are used as suspending agents, appropriate testing are used as suspending agents, appropriate testing
must be performed to ascertain that the substance must be performed to ascertain that the substance
does not interfere with the absorption of the drug. does not interfere with the absorption of the drug.
The usual mechanism is adsorption or sequestering of The usual mechanism is adsorption or sequestering of
the drug which interferes with the rate and extent of the drug which interferes with the rate and extent of
absorption. absorption.
(A) -Viscosity Modifiers:
((33 -) -)Sedimentation (Settling) ratesSedimentation (Settling) rates
To determine if the product is too viscous, the study of To determine if the product is too viscous, the study of
flow characteristics, or rheology, comes into play. flow characteristics, or rheology, comes into play.
Viscometers are employed which measure the relative Viscometers are employed which measure the relative
ease or difficulty in rotating spindles through the ease or difficulty in rotating spindles through the
sample medium.sample medium.
(A) -Viscosity Modifiers:
To determine if the product is too viscous, the study of To determine if the product is too viscous, the study of
flow characteristics, or rheology, comes into play. flow characteristics, or rheology, comes into play.
Viscometers are employed which measure the relative Viscometers are employed which measure the relative
ease or difficulty in rotating spindles through the ease or difficulty in rotating spindles through the
sample medium.sample medium.
(A) -Viscosity Modifiers:
((44 -) -)Surface potential at a surface of Surface potential at a surface of
particlesparticles
Both attractive and repulsive forces exist Both attractive and repulsive forces exist
between particles in a liquid medium. The between particles in a liquid medium. The
balance achieved between these opposing balance achieved between these opposing
forces determines whether or not particles forces determines whether or not particles
approaching each other actually make contact approaching each other actually make contact
or repulsed at a certain distance of separation.or repulsed at a certain distance of separation.
The attractive forces are van der WaalsThe attractive forces are van der Waals’’ forces forces
of London dispersion type. The repulsive of London dispersion type. The repulsive
forces arise from the presence of an electrical forces arise from the presence of an electrical
potential relative to the surrounding medium. potential relative to the surrounding medium.
particlesparticles
Both attractive and repulsive forces exist Both attractive and repulsive forces exist
between particles in a liquid medium. The between particles in a liquid medium. The
balance achieved between these opposing balance achieved between these opposing
forces determines whether or not particles forces determines whether or not particles
approaching each other actually make contact approaching each other actually make contact
or repulsed at a certain distance of separation.or repulsed at a certain distance of separation.
The attractive forces are van der WaalsThe attractive forces are van der Waals’’ forces forces
of London dispersion type. The repulsive of London dispersion type. The repulsive
forces arise from the presence of an electrical forces arise from the presence of an electrical
potential relative to the surrounding medium. potential relative to the surrounding medium.
((44 -) -)Surface potential at a surface of Surface potential at a surface of
particlesparticles
both attractive and repulsive forces exist between particles both attractive and repulsive forces exist between particles
in a liquid medium. The balance achieved between these in a liquid medium. The balance achieved between these
opposing forces determines whether or not particles opposing forces determines whether or not particles
approaching each other actually make contact or repulsed approaching each other actually make contact or repulsed
at a certain distance of separation.at a certain distance of separation.
The attractive forces are van der WaalsThe attractive forces are van der Waals’’ forces of London forces of London
dispersion type. The repulsive forces arise from the dispersion type. The repulsive forces arise from the
presence of an electrical potential relative to the presence of an electrical potential relative to the
surrounding medium. surrounding medium.
Usually particles acquire a charge as a result of (1) Usually particles acquire a charge as a result of (1)
ionization of the molecules at the surface, (2) adsorption of ionization of the molecules at the surface, (2) adsorption of
ions by the particles from the surrounding liquid, and (3) a ions by the particles from the surrounding liquid, and (3) a
difference in the dielectric constant of the continuous difference in the dielectric constant of the continuous
phase and the dispersed particles.phase and the dispersed particles.
particlesparticles
both attractive and repulsive forces exist between particles both attractive and repulsive forces exist between particles
in a liquid medium. The balance achieved between these in a liquid medium. The balance achieved between these
opposing forces determines whether or not particles opposing forces determines whether or not particles
approaching each other actually make contact or repulsed approaching each other actually make contact or repulsed
at a certain distance of separation.at a certain distance of separation.
The attractive forces are van der WaalsThe attractive forces are van der Waals’’ forces of London forces of London
dispersion type. The repulsive forces arise from the dispersion type. The repulsive forces arise from the
presence of an electrical potential relative to the presence of an electrical potential relative to the
surrounding medium. surrounding medium.
Usually particles acquire a charge as a result of (1) Usually particles acquire a charge as a result of (1)
ionization of the molecules at the surface, (2) adsorption of ionization of the molecules at the surface, (2) adsorption of
ions by the particles from the surrounding liquid, and (3) a ions by the particles from the surrounding liquid, and (3) a
difference in the dielectric constant of the continuous difference in the dielectric constant of the continuous
phase and the dispersed particles.phase and the dispersed particles.
((55 -) -)Zeta potentialZeta potential ( (
zz or or ))
A measurable indication of the potential existing at the A measurable indication of the potential existing at the
surface of a particle. When the zeta potential is relatively surface of a particle. When the zeta potential is relatively
high high (25 mV or more)(25 mV or more), the repulsive electrical forces , the repulsive electrical forces
between two particles exceed the attractive London forces. between two particles exceed the attractive London forces.
Accordingly, the particles are dispersed and said to be Accordingly, the particles are dispersed and said to be
deflocculated. Even when brought close together by deflocculated. Even when brought close together by
random motion or agitation, deflocculated particles resist random motion or agitation, deflocculated particles resist
collision due to their high surface potential. collision due to their high surface potential.
The addition of a preferentially adsorbed ion, whose The addition of a preferentially adsorbed ion, whose
charge is opposite in sign to that on the particle, tends charge is opposite in sign to that on the particle, tends
to neutralize the surface potential and leads to a to neutralize the surface potential and leads to a
progressive lowering of the zeta potential.progressive lowering of the zeta potential.
zz or or ))
A measurable indication of the potential existing at the A measurable indication of the potential existing at the
surface of a particle. When the zeta potential is relatively surface of a particle. When the zeta potential is relatively
high high (25 mV or more)(25 mV or more), the repulsive electrical forces , the repulsive electrical forces
between two particles exceed the attractive London forces. between two particles exceed the attractive London forces.
Accordingly, the particles are dispersed and said to be Accordingly, the particles are dispersed and said to be
deflocculated. Even when brought close together by deflocculated. Even when brought close together by
random motion or agitation, deflocculated particles resist random motion or agitation, deflocculated particles resist
collision due to their high surface potential. collision due to their high surface potential.
The addition of a preferentially adsorbed ion, whose The addition of a preferentially adsorbed ion, whose
charge is opposite in sign to that on the particle, tends charge is opposite in sign to that on the particle, tends
to neutralize the surface potential and leads to a to neutralize the surface potential and leads to a
progressive lowering of the zeta potential.progressive lowering of the zeta potential.
((55 -) -)Zeta potentialZeta potential ( (
zz or or ))
At some concentration of the added ions the electrical At some concentration of the added ions the electrical
forces of repulsion are lowered sufficiently that the forces of repulsion are lowered sufficiently that the
forces of attraction predominate. Under these forces of attraction predominate. Under these
conditions the particles may approach each other conditions the particles may approach each other
closely and form loose aggregates, termed closely and form loose aggregates, termed flocsflocs. .
Such a system is said to be flocculated. In order to Such a system is said to be flocculated. In order to
obtain a flocculated, non-caking suspension with the obtain a flocculated, non-caking suspension with the
maximum sedimentation volume, the zeta potential maximum sedimentation volume, the zeta potential
must be controlled so as to lie within a certain range must be controlled so as to lie within a certain range
(generally less than 25 mV)(generally less than 25 mV), which can be achieved by , which can be achieved by
the rational use of electrolyte.the rational use of electrolyte.
zz or or ))
At some concentration of the added ions the electrical At some concentration of the added ions the electrical
forces of repulsion are lowered sufficiently that the forces of repulsion are lowered sufficiently that the
forces of attraction predominate. Under these forces of attraction predominate. Under these
conditions the particles may approach each other conditions the particles may approach each other
closely and form loose aggregates, termed closely and form loose aggregates, termed flocsflocs. .
Such a system is said to be flocculated. In order to Such a system is said to be flocculated. In order to
obtain a flocculated, non-caking suspension with the obtain a flocculated, non-caking suspension with the
maximum sedimentation volume, the zeta potential maximum sedimentation volume, the zeta potential
must be controlled so as to lie within a certain range must be controlled so as to lie within a certain range
(generally less than 25 mV)(generally less than 25 mV), which can be achieved by , which can be achieved by
the rational use of electrolyte.the rational use of electrolyte.
((66-)-) Flocculated SystemsFlocculated Systems
When formulating suspensions, it When formulating suspensions, it
is most important to make sure is most important to make sure
that the particles are well that the particles are well
dispersed in the aqueous phase dispersed in the aqueous phase
or other vehicle. or other vehicle.
In this type the solid particles of In this type the solid particles of
dispersed phase aggregate dispersed phase aggregate
leading to network like structure leading to network like structure
of solid particles in dispersion of solid particles in dispersion
medium. The aggregates form no medium. The aggregates form no
hard cake. These aggregates hard cake. These aggregates
settle rapidly due to their size as settle rapidly due to their size as
rate of sedimentation is high and rate of sedimentation is high and
sediment formed is loose and sediment formed is loose and
easily redispersible. easily redispersible.
When formulating suspensions, it When formulating suspensions, it
is most important to make sure is most important to make sure
that the particles are well that the particles are well
dispersed in the aqueous phase dispersed in the aqueous phase
or other vehicle. or other vehicle.
In this type the solid particles of In this type the solid particles of
dispersed phase aggregate dispersed phase aggregate
leading to network like structure leading to network like structure
of solid particles in dispersion of solid particles in dispersion
medium. The aggregates form no medium. The aggregates form no
hard cake. These aggregates hard cake. These aggregates
settle rapidly due to their size as settle rapidly due to their size as
rate of sedimentation is high and rate of sedimentation is high and
sediment formed is loose and sediment formed is loose and
easily redispersible. easily redispersible.
((77-)-) Deflocculated SystemsDeflocculated Systems
These agents retard settling These agents retard settling
and agglomeration of the and agglomeration of the
particles by functioning as an particles by functioning as an
energy barrier, which energy barrier, which
minimizes interparticle minimizes interparticle
attraction and ultimate attraction and ultimate
flocculation. flocculation.
In deflocculated system the In deflocculated system the
particles are well dispersed and particles are well dispersed and
settle singly but more slowly settle singly but more slowly
than a flocculated system. The than a flocculated system. The
particles, however, have a particles, however, have a
tendency to form a sediment or tendency to form a sediment or
cake that is very difficult to cake that is very difficult to
redisperse.redisperse.
These agents retard settling These agents retard settling
and agglomeration of the and agglomeration of the
particles by functioning as an particles by functioning as an
energy barrier, which energy barrier, which
minimizes interparticle minimizes interparticle
attraction and ultimate attraction and ultimate
flocculation. flocculation.
In deflocculated system the In deflocculated system the
particles are well dispersed and particles are well dispersed and
settle singly but more slowly settle singly but more slowly
than a flocculated system. The than a flocculated system. The
particles, however, have a particles, however, have a
tendency to form a sediment or tendency to form a sediment or
cake that is very difficult to cake that is very difficult to
redisperse.redisperse.
Properties of Flocculated and Deflocculated Particles in Suspensions
Deflocculated Flocculated
Particles exist in suspension as separate
entities
Particles form loose aggregates
Rate of sedimentation is slow, since each
particle settles separately
Rate of sedimentation is high, since particles
settle as a floc, which is a collection of
particles
A sediment is formed slowly A sediment is formed rapidly
A hard cake is formed which is difficult, if
not possible, to redisperse
The sediment is easy to redisperse, so as to
reform the original suspension
Deflocculated Flocculated
Particles exist in suspension as separate
entities
Particles form loose aggregates
Rate of sedimentation is slow, since each
particle settles separately
Rate of sedimentation is high, since particles
settle as a floc, which is a collection of
particles
A sediment is formed slowly A sediment is formed rapidly
A hard cake is formed which is difficult, if
not possible, to redisperse
The sediment is easy to redisperse, so as to
reform the original suspension
((88 -) -)Quantitative Expressions of Quantitative Expressions of
SedimentationSedimentation
The sedimentation volume, FThe sedimentation volume, F,, is the ratio of the final, or is the ratio of the final, or
ultimate, volume of the sediment, Vultimate, volume of the sediment, V
uu, to the original , to the original
volume of the suspension, Vvolume of the suspension, V
00, before the settling. Thus,, before the settling. Thus,
As the volume of the suspension which appears occupied As the volume of the suspension which appears occupied
by the sediment increases, the value of F, which normally by the sediment increases, the value of F, which normally
ranges from nearly 0 to 1, increases. In the system where ranges from nearly 0 to 1, increases. In the system where
F = 0.75, for example, 75% of the total volume in the F = 0.75, for example, 75% of the total volume in the
container is apparently occupied by the loose, porous container is apparently occupied by the loose, porous
flocs forming the sediment. When F = 1, no sediment is flocs forming the sediment. When F = 1, no sediment is
apparent even though the system is flocculated. apparent even though the system is flocculated.
This is the ideal suspension for, under these conditions, This is the ideal suspension for, under these conditions,
no sedimentation will occur. Caking also will be absent.no sedimentation will occur. Caking also will be absent.
0V
V
F
u
SedimentationSedimentation
The sedimentation volume, FThe sedimentation volume, F,, is the ratio of the final, or is the ratio of the final, or
ultimate, volume of the sediment, Vultimate, volume of the sediment, V
uu, to the original , to the original
volume of the suspension, Vvolume of the suspension, V
00, before the settling. Thus,, before the settling. Thus,
As the volume of the suspension which appears occupied As the volume of the suspension which appears occupied
by the sediment increases, the value of F, which normally by the sediment increases, the value of F, which normally
ranges from nearly 0 to 1, increases. In the system where ranges from nearly 0 to 1, increases. In the system where
F = 0.75, for example, 75% of the total volume in the F = 0.75, for example, 75% of the total volume in the
container is apparently occupied by the loose, porous container is apparently occupied by the loose, porous
flocs forming the sediment. When F = 1, no sediment is flocs forming the sediment. When F = 1, no sediment is
apparent even though the system is flocculated. apparent even though the system is flocculated.
This is the ideal suspension for, under these conditions, This is the ideal suspension for, under these conditions,
no sedimentation will occur. Caking also will be absent.no sedimentation will occur. Caking also will be absent.
0V
V
F
u
((88 -) -)Quantitative Expressions of Quantitative Expressions of
SedimentationSedimentation
Degree of flocculation: a better parameter for comparing Degree of flocculation: a better parameter for comparing
flocculated systems is the degree of flocculation, flocculated systems is the degree of flocculation, , which , which
relates the sedimentation volume of the flocculated relates the sedimentation volume of the flocculated
suspension, F, to the sedimentation volume of the suspension, F, to the sedimentation volume of the
suspension when deflocculated, Fsuspension when deflocculated, F
..
The degree of flocculation is, therefore, an expression of The degree of flocculation is, therefore, an expression of
the increased sediment volume resulting from the increased sediment volume resulting from
flocculation. flocculation.
in which F is the sedimentation volume of the deflocculated in which F is the sedimentation volume of the deflocculated
suspension. suspension.
F
F
uV
V
F
SedimentationSedimentation
Degree of flocculation: a better parameter for comparing Degree of flocculation: a better parameter for comparing
flocculated systems is the degree of flocculation, flocculated systems is the degree of flocculation, , which , which
relates the sedimentation volume of the flocculated relates the sedimentation volume of the flocculated
suspension, F, to the sedimentation volume of the suspension, F, to the sedimentation volume of the
suspension when deflocculated, Fsuspension when deflocculated, F
..
The degree of flocculation is, therefore, an expression of The degree of flocculation is, therefore, an expression of
the increased sediment volume resulting from the increased sediment volume resulting from
flocculation. flocculation.
in which F is the sedimentation volume of the deflocculated in which F is the sedimentation volume of the deflocculated
suspension. suspension.
F
F
uV
V
F
Some Suspension Products Some Suspension Products
available in Marketavailable in Market
Product Product
namename
ManufactureManufacture Active Active
IngredientIngredient
IndicationsIndications
Tegretal Tegretal
(100mg/(100mg/
5ml.) 5ml.)
Novartis Novartis
PharmaceuticaPharmaceutica
ls Ltd.ls Ltd.
CarbamazepinCarbamazepin
ee
AnticonvulsanAnticonvulsan
ts ts
Naprosyn Naprosyn
(125mg/5ml)(125mg/5ml)
Roche LabRoche Lab NaproxenNaproxen NSAIDs NSAIDs
ArthritisArthritis
available in Marketavailable in Market
Product Product
namename
ManufactureManufacture Active Active
IngredientIngredient
IndicationsIndications
Tegretal Tegretal
(100mg/(100mg/
5ml.) 5ml.)
Novartis Novartis
PharmaceuticaPharmaceutica
ls Ltd.ls Ltd.
CarbamazepinCarbamazepin
ee
AnticonvulsanAnticonvulsan
ts ts
Naprosyn Naprosyn
(125mg/5ml)(125mg/5ml)
Roche LabRoche Lab NaproxenNaproxen NSAIDs NSAIDs
ArthritisArthritis
Important NotesImportant Notes
It is critical to add the proper amount of purified water to It is critical to add the proper amount of purified water to
the product as this determines the dose of the drug in the the product as this determines the dose of the drug in the
designated volume to be administered. By using purified designated volume to be administered. By using purified
water instead of tap water, you avoid the introduction of water instead of tap water, you avoid the introduction of
contaminants to the system which could adversely affect contaminants to the system which could adversely affect
the the
stability of the preparation. stability of the preparation.
One advantage to these dry powder formulations is the One advantage to these dry powder formulations is the
enhanced stability provided to water-sensitive drugs during enhanced stability provided to water-sensitive drugs during
storage.storage.
It is critical to add the proper amount of purified water to It is critical to add the proper amount of purified water to
the product as this determines the dose of the drug in the the product as this determines the dose of the drug in the
designated volume to be administered. By using purified designated volume to be administered. By using purified
water instead of tap water, you avoid the introduction of water instead of tap water, you avoid the introduction of
contaminants to the system which could adversely affect contaminants to the system which could adversely affect
the the
stability of the preparation. stability of the preparation.
One advantage to these dry powder formulations is the One advantage to these dry powder formulations is the
enhanced stability provided to water-sensitive drugs during enhanced stability provided to water-sensitive drugs during
storage.storage.
Administration and Counseling for Oral Administration and Counseling for Oral
SuspensionsSuspensions
Most oral suspensions are administered by teaspoon Most oral suspensions are administered by teaspoon
or tablespoon. Make certain that you counsel the or tablespoon. Make certain that you counsel the
patient regarding which to use.patient regarding which to use.
Reconstituted products are usually suspensions and Reconstituted products are usually suspensions and
an oversized bottle is necessary to allow a headspace an oversized bottle is necessary to allow a headspace
to shake the suspension into for adequate to shake the suspension into for adequate
redispersion. redispersion.
Make clear to the patient that the headspace is not Make clear to the patient that the headspace is not
because they have been cheated of drug, but rather to because they have been cheated of drug, but rather to
allow room to shake the mixture.allow room to shake the mixture.
SuspensionsSuspensions
Most oral suspensions are administered by teaspoon Most oral suspensions are administered by teaspoon
or tablespoon. Make certain that you counsel the or tablespoon. Make certain that you counsel the
patient regarding which to use.patient regarding which to use.
Reconstituted products are usually suspensions and Reconstituted products are usually suspensions and
an oversized bottle is necessary to allow a headspace an oversized bottle is necessary to allow a headspace
to shake the suspension into for adequate to shake the suspension into for adequate
redispersion. redispersion.
Make clear to the patient that the headspace is not Make clear to the patient that the headspace is not
because they have been cheated of drug, but rather to because they have been cheated of drug, but rather to
allow room to shake the mixture.allow room to shake the mixture.
Administration and Counseling for Oral Administration and Counseling for Oral
SuspensionsSuspensions
Some patients don't understand that the medication is Some patients don't understand that the medication is
for oral administration. For example, make clear to the for oral administration. For example, make clear to the
patient that the oral antibiotic suspension to treat a patient that the oral antibiotic suspension to treat a
middle ear infection is to be taken by mouth and not middle ear infection is to be taken by mouth and not
placed in the ear canal.placed in the ear canal.
If the medication states that the product should be If the medication states that the product should be
refrigerated, counsel the patient to store it in the refrigerated, counsel the patient to store it in the
refrigerator. Some suspension and emulsion products refrigerator. Some suspension and emulsion products
do not require refrigeration during storage. It do not require refrigeration during storage. It
probably is dependent on the level of preservative probably is dependent on the level of preservative
present in the formulation.present in the formulation.
SuspensionsSuspensions
Some patients don't understand that the medication is Some patients don't understand that the medication is
for oral administration. For example, make clear to the for oral administration. For example, make clear to the
patient that the oral antibiotic suspension to treat a patient that the oral antibiotic suspension to treat a
middle ear infection is to be taken by mouth and not middle ear infection is to be taken by mouth and not
placed in the ear canal.placed in the ear canal.
If the medication states that the product should be If the medication states that the product should be
refrigerated, counsel the patient to store it in the refrigerated, counsel the patient to store it in the
refrigerator. Some suspension and emulsion products refrigerator. Some suspension and emulsion products
do not require refrigeration during storage. It do not require refrigeration during storage. It
probably is dependent on the level of preservative probably is dependent on the level of preservative
present in the formulation.present in the formulation.
Administration and Counseling for Oral Administration and Counseling for Oral
SuspensionsSuspensions
Some suspensions can interfere with the Some suspensions can interfere with the
bioavailability of other oral drugs. bioavailability of other oral drugs.
Examples are: Cholestyramine suspension has been Examples are: Cholestyramine suspension has been
shown to decrease the bioavailability of warfarin, shown to decrease the bioavailability of warfarin,
digitoxin and thyroid hormones, probably by digitoxin and thyroid hormones, probably by
adsorption of the drug to the suspensoid particles. adsorption of the drug to the suspensoid particles.
Advise the patient to stagger the administration of Advise the patient to stagger the administration of
their oral drugs by several hours when interferences their oral drugs by several hours when interferences
have been reported.have been reported.
SuspensionsSuspensions
Some suspensions can interfere with the Some suspensions can interfere with the
bioavailability of other oral drugs. bioavailability of other oral drugs.
Examples are: Cholestyramine suspension has been Examples are: Cholestyramine suspension has been
shown to decrease the bioavailability of warfarin, shown to decrease the bioavailability of warfarin,
digitoxin and thyroid hormones, probably by digitoxin and thyroid hormones, probably by
adsorption of the drug to the suspensoid particles. adsorption of the drug to the suspensoid particles.
Advise the patient to stagger the administration of Advise the patient to stagger the administration of
their oral drugs by several hours when interferences their oral drugs by several hours when interferences
have been reported.have been reported.
Special Labels and Advices for Special Labels and Advices for
SuspensionsSuspensions
Shake well before use Shake well before use
Store in a cool place Store in a cool place
Extemporaneously prepared and reconstituted Extemporaneously prepared and reconstituted
suspensions will have a relatively short shelf suspensions will have a relatively short shelf
life. The are usually required to be recently or life. The are usually required to be recently or
freshly prepared, with a 1-4 week expiry date.freshly prepared, with a 1-4 week expiry date.
SuspensionsSuspensions
Shake well before use Shake well before use
Store in a cool place Store in a cool place
Extemporaneously prepared and reconstituted Extemporaneously prepared and reconstituted
suspensions will have a relatively short shelf suspensions will have a relatively short shelf
life. The are usually required to be recently or life. The are usually required to be recently or
freshly prepared, with a 1-4 week expiry date.freshly prepared, with a 1-4 week expiry date.
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