Emulsion SB

Pharmaceutical Emulsion, Method of Preparation, Instabilities in emulsion, Emulsifying agents, Droplet stabilization, HLB, Davis method, Griffin method, Phase inversion temperature, PIT, Micellization, Cloud Point, Method of preparation, Dry Gum method, Wet Gum, Bottle method

Theories of emulsion Video
https://youtu.be/exKWtDyuj9c

1. Pharmaceutical Emulsions
Version 2.0
(Dr.) Mirza Salman Baig
Assistant Professor (Pharmaceutics)
AIKTC, School of Pharmacy,New Panvel
Affiliated to University of Mumbai (INDIA)

2. 2
An Emulsion is a mixture of two or more
Immiscible liquids.
•Emulsion, is a mixture of two or more liquids
in which one is present as droplets distributed
throughout the other.OilOil
Water
Water
Oil
Water
Agitation
Separate rapidly into two
clear defined layers
OilOil
Water
Water
Oil
Water
Agitation
Separate rapidly into two
clear defined layers

4. Internal Phase or External Phase in
Emulsions:
➢The dispersed liquid is known as theInternal or
Discontinuous phase.
➢Whereas the dispersion medium is known as
theExternal or Continuous phase

5. Types Of Emulsions
Based on dispersed phase:
➢Oil in Water (O/W): Oil droplets dispersed in
water.
➢Water in Oil (W/O): Water droplets dispersed in
oil.
➢Water in Oil in water (W/O/W): Water in Oil
emulsion dispersed in water –multiple emulsion.
Based on size of liquid droplets:
➢ 0.2 –50 mm Macroemulsions
➢ 0.01 –0.2 mm Microemulsions

6. Instabilities in Emulsion:
➢Emulsions are, by nature, physically unstable; that is, they
tend to separate into two distinct phases or layers over
time.
➢Creamingoccurs when dispersed oil droplets merge and
rise to the top of an o/w emulsion or settle to the bottom in
w/o emulsions. In both cases, the emulsion can be easily
redispersed by shaking.
➢Coalescence (breaking or cracking)is the complete
and irreversible separation and fusion of the dispersed
phase.
➢Phase inversionor a change from w/o to o/w (or vice
versa) may occur. This is considered a type of instability by
some.

7. Identification test for Emulsions:
By using Naked eye, it is very difficult to
differentiate between o/w or w/o
emulsions. Thus, the following methods
have been used to identify the type of
emulsions.
1)Dye Test
2)Dilution Test
3)Electrical conductivity Test
4)Fluorescence Test.
5)Cobalt Chloride Test.

8. Formulation of Emulsion
•Drug (medicament)
•Oil Phase
•Aqueous phase
•Emulsifying agent (emulsifier)
•Antioxidants
•Preservatives
•Organoleptic additives
–Flavouringagents
–Colouringagent

9. Emulsifying Agent:
➢Emulsions are stabilized by adding an emulsifying
agent.
➢These agents have both a hydrophilic and
Lipophilicpart in their chemical structure.
➢All emulsifying agents get adsorbedat the Oil :
Water interface to provide a protective barrier
around the dispersed droplets.
➢In addition to this protective barrier, emulsifiers
stabilize the emulsion by reducing the interfacial
tensionof the system.

10. Water
Oil

11. Classification Of Emulsifying Agents:
Emulsifying agents can be classified according to
1) Chemical nature:
➢Synthetic Emulsifying Agents
➢Natural Emulsifying Agents
➢Finely Dispersed Solids
➢Other emulsifying Agents
2) Mechanism of action:
✓Monomolecular
✓Multi-molecular
✓Solid particle films.

12. Synthetic Emulsifying Agents
1) (pH > 8))
✓Sodium or potassium oleate
✓Triethanolamine stearate
✓sodium lauryl sulfate.
2) Cationic: (pH 3-7)
✓Benzalkonium chloride,
✓Benzethoniumchloride
✓Quaternary ammonium salts.
3) Non Ionic(pH 3-10)
✓Polyglycol,
✓Fatty acid esters,
✓Lecithin.
✓Sorbitanesters (Spans).
✓Polyoxyethylenederivatives of sorbitanesters (Tweens),
✓Glyceryl esters.
Cationic and Anionic surfactants are generally limited to use in topical, o/w emulsion

13. Natural Emulsifying Agents
Derived from Plants and Animals:
Vegetable derivatives:
•Acacia
•Tragacanth
•Agar
•Pectin
•Carrageenan
•Lecithin (egg)
Animal derivatives:
•Gelatin
•Lanolin
•Cholesterol

14. Finely Divided or Finely Dispersed
Solid Particle Emulsifiers
These agents form a particulate layeraround
dispersed particles. Most will swell in the
dispersion medium to increase viscosityand
reduce the interaction between dispersed droplets.
Most commonly they support the formation of o/w
emulsions,
E.g.
•Bentonite
•Veegum,
•Hectorite,
•Magnesium Hydroxide,
•Aluminum Hydroxide

15. Other Emulsifying Agents
A variety of fatty acids (e.g., stearic acid),
fatty alcohols (e.g., stearyl or cetyl alcohol), and
fatty esters (e.g., glyceryl monostearate) serve to
stabilize emulsions through their ability as
thickening agent the emulsion..

16. Droplet Stabilization
1)Interfacial tension theory
2)Interfacial film
3)Electric repulsion

17. 1) Interfacial tension
•Loweringinterfacialtensionisimportant
waytodecreasethefreesurfaceenergy
associatedwiththeformationofdroplets.
•Thermodynamicstabilization

18. 2) Interfacial film
•Surface active agents tends to concentrate
at interface
•Emulsifier adsorb at oil-water interface to
form monomolecular layer which prevents
coalescence of internal phase

19. 3) Electric repulsion
•If the emulsifier is ionized, the presence of
strong charge may lead to repulsion in
droplets and hence increasing stability.

20. 3) Electric repulsion
•The oilglobules in a pure oil and pure water
emulsion carry a negative charge.
•The water ionizes so that both hydrogen and
hydroxyl ions are present.
•The negative charge on the oil may come
from adsorptionof the OH ions. These
adsorbed hydroxyl ions form a layer around the
oil globules.
•A second layer of oppositely charged ions forms
a layer in the liquid outside the layer of negative
ions.
•The electric charge is a factor in all emulsions,
even those stabilized with emulsifying agents

21. HLB
•A system was developed to assist in making
systemic decisions about the amounts and types
of surfactants needed in stable products.
•The system is called the HLB (hydrophile-
lipophile balance) systemand has an arbitrary
scale of 1 -18.
•HLB numbers are experimentally determined for
the different emulsifiers. .

22. ✓Low number of hydrophilic groups on the Molecule
thus imparting Lipophilic character:
✓Spanshave low HLB numbers, Because of their
oil soluble character, Spans will cause the oil phase
to predominate and form an w/oemulsion.
High HLB indicates ?
Emulsifier has many hydrophilic groups on the
molecule thus imparting hydrophilic Character.
Tweenshave higher HLB numbers, because of their
water-soluble character, Tweens will cause the
water phase to predominate and form an o/w
emulsion.
HLB

23. HLB range Role
1-3 Anti-foaming agent
3-6 W/O emulsifying agents
7-9 Wetting agents
8-13 O/W emulsifying agents
13-15 Detergents
15-18 Solubilizing Agents
HLB

24. Selection of emulsifying Agent
•Types of Emulsifying agents
–Surfactant
–Hydrophilic colloids
–Finely divided solids
•Selection basis
–Shelf life (Stability)
–Type of emulsion
–Cost

25. •Definition:Thehydrophile-lipophilebalance
(HLB)systemisanarbitraryscalefor
expressingthehydrophilicandlipophilic
characteristicsofanemulsifyingagent.
•AgentswithHLBvalueof1-8arelipophilicand
suitableforpreparationofw/oemulsion,and
thosewithHLBvalueof8-18arehydrophilic
andgoodforo/wemulsion.
25
HLB System

26. HLBSystem
Theoilphaseofano/wemulsionrequiresaspecificHLB,called
therequiredhydrophile–lipophilebalance(RHLB).
26

27. HLB method (Griffin)
•Griffin defined HLB
•HLB= mol% Hydrophilic group/5
•Range 0-20
•Therefore, completely hydrophilic
molecule without non-polar group has HLB
value 20
•It is applicable to polyoxyethyleneether
derivatives

28. •HLB
mix= f ×HLB
A+ (1-f) ×HLB
B
•Where,
f is fraction of surfactant A in surfactant mixture
HLB method (Griffin)
Required HLB

29. HLB method (Davis)
•Davies suggested a method based on
calculating a value based on the chemical
groups of the molecules

30. HLBSystem
30
Calculations
Example
Calculate the amounts (ml) of each of the emulsifiers (tween
80 and span 80) that are required to prepare the emulsion:
Ingredient Amount RHLB(O/W)
1.Beeswax 15g 9
2.Lanolin 10g 12
3. Paraffinwax 20g 10
4. Cetylalcohol 5g 15
5. Emulsifiers (Tween 80 + Span80) 5ml
6.Preservative Asrequired
7.Color 0.2g
8. Water,purified q.s. 100ml

31. HLBSystem
Calculations
Example
First,calculatetheoverallRHLBoftheemulsionby
multiplyingtheRHLBofeachoil-likecomponent(items1-
4)bytheirweightfractionfromtheoilphase.Thetotal
weightoftheoilphaseis50g.Therefore:
Beeswax 15/50 ×9=2.70
Lanolin 10/50×12=2.40
Paraffin 20/50×10=4.00
Cetyl alcohol 5/50×15= 1.50
Total RHLB for the emulsion =10.60

32. HLBSystem
Calculations
Example
Next,ablendoftwoemulsifyingagentsischosen,onewithanHLB
abovetheRHLBoftheemulsion(Tween80,HLB=15)andthe
otherwithanHLBbelowtheRHLB(Span80,HLB
=4.3)
Calculatethepercentagesoftheemulsifiersusingtheformula:
% Surfactant with High HLB=
RHLB-HLB Low
HLB High-RHLB
% Tween=
10.6−4.3
15−4.3
=0.59
Therefore, 5 ml ×0.59 = 2.95 ml of Tween80
and the remainder, 2.05 ml, must be supplied by Span80

33. Phase Inversion Temperature
•o/w emulsion stabilized by non-ionic emulgent,
on heating undergoes inversion to w/o
•Reason: at high temperature emulgent become
more hydrophobic
•The temperature at which emulgent has equal
hydrophilicity and hydrophobicity, phase
inversion takes place
•PIT could also be related to stability of emulsion

34. Micellisation
•Micellesareformedwhenthe
concentrationofasurfactant
reachesagivenconcentration
calledcriticalmicelle
concentration(CMC)in
whichthesurfaceissaturated
withsurfactantmolecules.
•Themainreasonformicelle
formationistoobtaina
minimumfreeenergystate.
•Inamicelle,polarorionic
headsformanoutershellin
contactwithwater,whilenon-
polartailsaresequesteredin
theinteriortoavoidwater.
Concentration
Surface
Tension

35. Cloud point
•Fornon-ionicsurfactants,Increasingtemperature
increasesmicellarsizeanddecreaseCMC.
•Theeffectoftemperaturestopsatacharacteristic
temperaturecalledthecloudpointwherethe
solutionbecometurbidduetotheseparationofthe
solutionintotwophases.
Temperature has a comparatively small effect on the
micellar properties of ionic surfactants.

36. Methods of Preparation Of
Emulsions:
Commercially, emulsions are prepared in large
volume mixing tanks and refined and stabilized by
passage through a colloid mill or homogenizer.
Extemporaneous production is more concerned
with small scale methods.
•Dry Gum Methods
•Wet Gum Methods
•Bottle Method
•Beaker Method.
•In situ Soap Method.

37. DRY GUM Method for Preparation of
Emulsions:
Dry gum method is used to prepare the initial
or primary emulsion by mixing Oil and Gum
then slowly adding water

38. Procedure:
•Take mortar, 1 partgumis levigated with the 4
parts oiluntil the powder is thoroughly wetted;
then the 2 parts water are added all at once,
and the mixture is vigorously triturated until the
primary emulsion formed is creamy white and
produces a "cliking" sound as it is triturated.
•Active ingredients, preservatives, color, flavors
are added as a solution to the primary
emulsion.
•When all agents have been incorporated, the
emulsion should be transferred to a calibrated
vessel, brought to final volume with water.

40. Wet Gum Method
Fixed Oil : Water : Emulsifier (gum) … 4:2:1
MineralOil : Water : Emulsifier (gum) … 3:2:1
VolatileOil : Water : Emulsifier (gum) … 2:2:1
Procedure:
•In this method, the proportions of (fixed) oil, water, and
emulsifier are the same (4:2:1), but the order and
techniques of mixing are different.
•The 1 partgumis triturated with 2 parts waterto form a
mucilage; then the 4 parts oil is added slowly, in portions,
while triturating.
•After all the oil is added, the mixture is triturated for
several minutes to form the primary emulsion.
•Then other ingredients may be added as in the
continental method.

41. Bottle Method
➢This method may be used to prepare emulsions of
volatile oils, Oleaginous substances of very low
viscosities.
➢This method is a variation of the dry gum method.
➢One partpowdered acacia (or other gum) is
placed in a dry bottle and four parts oil are added.
➢The bottle is capped and thoroughly shaken.
➢To this, the required volume of water is added all
at once, and the mixture is shaken thoroughly until
the primary emulsion forms.

42. Beaker Method
➢Dividing components into water soluble and oil soluble
components.
➢All oil soluble components are dissolved in the oily phase
in one beaker and all water solublecomponents are
dissolved in the water in a separate beaker.
➢Oleaginous components are meltedand both phases are
heated to approximately 70°C over a water bath.
➢The internal phase is then added to theexternal phase
with stirring until the product reaches room temperature.

43. Liquid Paraffin Emulsion
Ingredients Qty Category
Liqiuid Paraffin 50ml Luxative
Gaum Acacia 12.5gm Emulgent
Gum Tracaganth 0.5gm Emulgent
Sodium Benzoate 0.5gm Preservative
Vanillin 0.05gm Flavour
Glycerin 12.5gm Humectant/Viscocity builder
Chloroform 0.25ml Preservative
Purified Water 100ml (q.s.) Vehicle

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