6.Suspensions is a part of pharmaceutics.pptx

Suspension

1. Suspensions Mr.Chechare D.D. Lecturer PRES's College of Pharmacy (D.Pharm),Nashik.

2. Introduction Suspensions are the biphasic liquid dosage form of medicament in which finely divided solid particles are dispersed in a liquid. The solid particles acts as a disperse phase whereas liquid vehicle acts as the continuous phase. Suspensions are generally taken orally or by parenteral route. They are also used for external application.

3. Qualities of a Suspension 1) It should settle slowly, & readily re-dispersed on gentle shaking of the container . 2) It should pour readily and evenly from its container. 3) The suspended particles should not form a cake. 4) Suspended particles should be small and uniformly sized. 5) Viscosity must not so high. 6) It should be chemically inert.

4. Classification of Suspensions 1.Oral suspension. 2.Parentral suspension. 3.Ophthalmic suspension. 4. S uspension for External use.

5. Flocculated Suspension Non- flocculated Suspension 1)Particles exist as separate entities & form network like structure. 1)Particles fo r m loose aggregate 2) Rate of sedimentation is high. 2) Rate of sedimentation is slow. 3) Sediment is easy to redisperse 3) Sediment is difficult to redisperse 4) Sediment is loosely packed & does not form hard cake. 4) Sediment is very closely packed & hard cake is formed Difference between Flocculated & Non Flocculated Suspension

6. Flocculated Suspension Non- flocculated Suspension 5)Supernatant liquid is clear. 5)Supernatant liquid is not clear. 6) Floccules stick to the side of bottle 6)Floccules do not stick to the side of bottle . 7) Suspension is not pleasing in appearance. 7) Suspension is pleasing in appearance.

7. Formulation of Suspensions 1)Flocculating Agents: In Suspension solid particles are well dispersed in dispersion medium i.e., vehicle.Dispersion can be improved by adding a surfactant or protective colloid which acts as flocculating agent.The flocculating agent acts by 1. reducing the surface tension and 2. thereby improving the dispersion of solids and 3. minimise flocculation. E.g., sodium lauryl sulphate, tweens, spans, carbowaxes and electrolytes

8. Thickening Agents These are hydrophilic colloids which form colloidal dispersions with water and increases the viscosity of the continuous phase,so that the solid particles remain suspended in it for sufficient long time. Classification of Thickening agent: 1) Polysaccharides 2)Inorganic Agents 3) Synthetic Compounds

9. 1. Polysaccharide a. Natural polysaccharide: i. Gum acacia: Acts as protective collide and suspending agent. It contain resinous tincture. M ore effective when used with compound tragacanth powder. C ontain enzyme oxidase which will cause deterioration of medicament . Preservative is required to add.

10. ii. Tragacanth: It is a better thickening agent than acacia. It is used as Compound Tragacanth powder / mucilage suspend heavy indiffusible substances. k Tragacanth mucilage is used when the vehicle is water or chloroform water in proportion of 1/4th of the volume of the mixture. iii. Starch: Sometime used as suspending agent because it form viscous mucilage. It is a ingredient of compound tragacanth powder.

11. i v . Sodium alginate: It is v iscous solution in water. 1% concentration used as suspending agent. It should be soaked overnight before used.

12. b) Semi-synthetic: 1) Methyl cellulose: 0.5 to 2% concentration. Used for external and internal preparation. 2) Sodium carboxy methyl cellulose: 0.25 to 1% concentration. Used for oral external and Parenteral use. 3) Microcrystalline cellulose: Prepared from wood cellulose by acid hydrolysis. It produced colloidal dispersion.

13. 2. Inorganic agents a. Clay: commonly used thickening agent. i. Bentonite : Bentonite is pale, creamy hygroscopic powder. 2% used as suspending agent. ii. Aluminium magnesium silicate : I s creamy white, tasteless powder. Used in internal and external preparation

14. b . Aluminium hydroxide: It is used as suspending agent in suspension containing barium sulphate, sulphonamide and sulphur.

15. 3. Synthetic C ompound a. Carbomar (carboxy vinyl polymer): Used as thickening agent. Concentration 0.1 to 0.4%. Used for internal and external preparation. b . Colloidal silicon dioxide: It is white non-gritty powder. Used as suspending agent. Concentration 1.5 to 4%.

16. 3)Wetting Agents These are the sub.which reduce the interfacial tension between the solid particules and liquid medium,thus producing a suspension of required quality. Ex.Alcohol in Tragacanth mucilage, Glycerin in sodium alginate.

17. 4)Preservatives Suitable preservative is needed to preservesuspensions against bacterial growth. Preservatives selected should be effective against a wide range of microorganism. Benzoic acid, sodium benzoate, methyl paraben and propyl paraben are commonly u sed as a preservative in suspensions.

18. 5)Organoleptic Additives Colouring agents.sweeting agents & flavouring agents are incorporated in oral suspension.A suitable perfume and colour is added in suspension which are for external use.

19. Methods of Dispensing of Suspensions 1) Suspensions containing diffusible solids. 2) Suspensions containing indiffusible solids. 3) Suspensions containing precipitate-forming liquids. 4) Suspensions produce by chemical reactions.

20. 1) Suspensions containing diffusible solids. There are certain insoluble powdered substances which are light in weight and readily mix with water and remain suspended throughout the liquid for sufficient long time after shaking. Such substance are known as diffusible solids. Ex.:Calcium carbonate,Light magnesium carbonate.

21. General Method for Dispensing 1) Tare the container 2) Finely powder the solid ingredients. 3) Mix the insoluble powders in a mortar and add enough vehicle to make a smooth cream. 4)Add more vehicle to make it pourable. 5) Examine the suspension carefully & if it contains foreign particules ,strain through a muslin cloth .

22. 6) Rinse the mortar & pestle .Transfer the rinsings to the bottle. 7) Add any liquid ingredient. 8) Add more vehicle to produce the required volume and mix thoroughly by shaking the bottle.

23. 2) Suspensions containing indiffusible solids. This solids do not dissolve in water and do not remain uniformly distributed in the vehicle for sufficiently long time. General Method for Dispensing(Using compound tragacanth powder) 1)Finely powder the solid ingredients. 2) Mix them together in a mortar and add compound tragacanth powder. 3)Measure 3/4th of the vehicle and triturate to form a smooth cream.

24. 4) Examine the suspension carefully and ,if it contains any foreign particles,strain through a muslin piece into a bottle. 5) Rinse the mortar with small quantity of vehicle to clean it.Transfer the rinsings to the bottle. 6) Add any liquid ingredients. 7)Add more vehicle to produce the required volumne.

25. 3) Suspensions containing precipitate forming liquids. Certain liquid preparations contain resinous matter, when mixed with water , the resin is precipitated which may adhere to the sides of the bottle or form a clotted precipitate which will not re-diffuse upon shaking. To prevent this compound tragacanth powder or tragacanth mucilage are used.

26. General Method for Dispensing(Using compound tragacanth powder) 1) Finely powder indiffusible solids and diffusible solids and compound tragacanth powder. Mix them uniformly in mortar . 2) Measure the 1/2 of vehicle and incorporate a small amount of it to the powder & triturate till smooth cream is formed.Add remaining part of vehicle. 3) Measure the precipitate forming liquid in a dry measure and add it in a slow stream in the centre of the cream with rapid stirring

27. 4) Dissolve the soluble ingredient in sufficient amount of vehicle .Add it slowly with constant stirring to cream . 5)Add more vehicle to rinse the mortar and transfer the rinsing to the bottle. 6)Add any liquid ingredient. 7)Add more of the vehicle to produce the required volume.

28. General Method for Dispensing(Using tragacanth mucilage) Tragacanth mucilage is used when the vehicle is water or chloroform water. 1) Mix tragacanth mucilage with an equal volumne of vehicle. 2) Measure the precipitate forming liquid in a dry measure and add it in a slow stream in the centre of the mucilage with constant stirring . 3)Dissolve the solid substance if any ,in about 1/4th of the vehicle and mix it with above mixture.

29. 4)Add more vehicle to rinse the mortar and transfer the rinsing to the bottle. 5)Add any liquid ingredient. 6)Add more of the vehicle to produce the required volume.

30. 4) Suspensions produce by chemical reactions. In this type of suspensions, the highly diluted solutions of reactants are mixed together so as to form very finely divided precipitates that can be easily distributed throughout the liquid by shaking. The precipitates so formed are diffusible in nature. Hence, there is no need of adding any suspending agent

31. Containers Suspensions should be packed in containers which are having adequate air space above the liquid to permit adequate shaking. The oral suspensions should be packed in wide mouth bottle to permit prompt removal of the suspension.

32. Labelling The containers having liquid suspension must be labeled with a secondary label “ Shake well before use ”. In case of dry suspension powders, the specified amount of vehicle to be mixed may be indicated clearly on the label.

33. Storage Suspensions should be stored in a cool place but should not be kept in refrigerator. Freezing at a very low temperatures should be avoided which may lead to aggregation of suspended particles

34. Stability of Suspensions A stable suspension can be redisperse homoneneously with moderate shaking and can be easily poured throughout its shelf life.The most stable pharmaceutical suspension are flocculated . Evaluation of Stability of Suspension. 1) Sedimentation method. 2) Micromeritic method. 3) Rheological method. 4) Electrokinetic method.

35. 1) Sedimentation method The measurement of sedimentation is most imp.parameter.It is determined by keeping a measured volume of suspension in a cylinder in an undistrubed position for a definite period of time and note the ultimate height(Hu) of the sediment and initial height (Ho) of total suspension. The sedimentation volume F is the ratio of ultimate height(Hu) & initial height (Ho) F=Hu/Ho

36. The sedimentation volume (F) is plotted against time.The graph indicates the stability of suspension. The stable suspension shows a horizontal graph .

37. 2) Micromeritic method The stability of suspension depends on the particle size of the dispense phase.The size of particle in a suspension may grow and may lead to formation of lumps or caking.So any change in particle size with reference to time will provide useful information regarding the stability of suspension.

38. 3) Rheological method The viscosity of the suspension is studied at different time intervals by using good quality viscometer. 4) Electrokinetic method The determination of surface electric charge or zeta potential of suspension is helpful to find out the stability of suspension.