Suspension.pptx

This ppt deals with a brief overview on suspension that is helpful for both D.Pharm & B.pharm students.

1. A BRIEF NOTE ON SUSPENSION By:- Diptee Gupta Assistant Professor Seth Vishambhar Nath Institue of Pharmacy, Lucknow 1

2. Suspension are biphasic liquid dosage form of medicament in which finely divided solid particles ranging from 0.5 to 5 micron are suspended or dispersed in a liquid or semi solid vehicle. The solid particles constitute the discontinuous phase whereas liquid vehicle constitute the continuous phase. 2

3. Ideal properties of suspension The sediment or creaming produced on storage if any, must be easily re-suspended by moderate agitation of the container. The product must remain sufficiently homogenous for at least the period between shaking the container & removing the desired amount. The product may be required to thickened in order to reduce the rate of settling of particles. Any suspended particles should be small & uniformly size in order to give a smooth elegant product free from gritty texture. The suspension must be aesthetically pleasant. The flow properties of suspension should enable the formulation to be easily poured from the container. 3

4. Advantage of suspension Used to mask the taste of therapeutic agent. Used to administer the drug to patients who have difficulty in swallowing solid dosage form. May be formulated to provide controlled drug delivery. Eg : IM injection 4

5. Dis -Advantage of suspension Fundamentally unstable preparation & require formulation skill to ensure the physical stability over the period of shelf life. Suspension may be bulky & therefore difficult for a patient to carry. The formulation of aesthetic suspension is difficult. 5

6. Difference between flocculated & deflocculated suspension Flocculated suspension Deflocculated suspension Particles form loose aggregate & form a network like structure Particle exist as separate entities Rate of sedimentation is very high Rate of sedimentation is very low Sediment is rapidly formed Sediment is slowly formed Sediment is loosely packed & does not form a hard cake Sediment is closely packed & a hard cake is formed. It is easy to redisperse Difficult to redisperse Not pleasing in appearance Pleasing in appearance Floccules stick to the side of bottle Floccules do not stick to the side of bottle Les s bioavailability High bioavailability High s helf life low shelf life 6

7. Method of preparation of suspension 1. Suspension containing diffusible solids : Diffusible solids do not dissolve in water but on shaking the powder can diffuse evenly throughout the liquid for sufficient long time & allow uniform distribution of drug in each dose. Eg – calcium carbonate, light kaolin, light magnesium carbonate Method of dispensing: Diffusible solids converted into powder in a mortar & mix with soluble drug. Add 3/4 th part of vehicle to form a smooth paste. Add volatile liquid if any, mix well & Make up the final volume by adding vehicle & transfer it to bottle. Label it “ SHAKE THE BOTTLE WELL BEFORE USE” & dispense. 7

8. 2. Suspension containing indiffusible solids : Indiffusible solids do not remain evenly distributed in a vehicle on shaking for sufficiently long time. Suspending agents used to correct this type of problem. The two commonly used suspending agents are: 1) Compound tragacanth powder: which is used in ratio of 2g/100ml of suspension 2) Tragacanth mucilage used in ration in 1/4 th volume of suspension to be preparaed . Indiffusible solids eg : aspirin, Phenobarbitone , calamine, hydrocartisone , zinc oxide. 8

9. Evaluation of suspension A number of procedures has been suggested for evaluating the physical stability of suspension. Physical stability means “the condition in which particles remain uniformly distributed throughout the dispersion without any signs of sedimentation.” Following methods used for evaluation of suspension: Sedimentation method Rheological method Electro kinetic method Micrometric method 9

10. 1. Sedimentation method: The formation of sediment & its redispersibility are the 2 features related to elegance of suspension. The extent of sedimentation can be expressed by 2 parameters ( applicable only for flocculated suspension):- a) Sedimentation volume (F): it is the ratio of the ultimate height ( Hu ) of the sediment to the initial height (Ho) of total suspension. It is dependent on time. If F=1, there is no sedimentation , suspension looks elegant & practically acceptable If F<1, rapid settling of dispersed phase If F>1, network of flocculation loose 10

11. b) Degree of flocculation: If β = 1, the extent of flocculation . The higher the value of β, the greater will be physical stability. It is the destructive method as flocculated system is converted to deflocculated system by adding the deflocculating agents. 11

12. Redispersibility : it is an important criteria of physical stability. 100 ml suspension is placed in a graduated cylinder- allowed to settle. After that cylinder is rotated at 20rpm through 360 & when base of cylinder is clear of sediment then the end point is noted. Lower the number of revolution or shorter time for redispersion - faster dispersibility . 12

13. 2. Rheological Method: These method used to help in predicting the settling pattern . Brookfield viscometer with T spindle is used to study the viscosity of suspension Consistency of suspension is evaluated by – cup& bob Viscometer and cone & plate viscometer. 13

14. 3. Electro kinetic method: Determination of surface electric charge or zeta potential of suspension is helpful to find out the stability of suspension. Certain zeta potential produce more stable suspension due to controlled flocculation. Zeta potential can be calculated from migration velocity of particles measured by electrophoretic method. 14

15. 4. Micrometric method: The stability of suspension depend on the particle size of dispersed phase. The size of suspended particles may grow & lead to formation of lumps or cake. So change in particle size with time provide useful information about stability of suspension. 15