Dispersion system

The suspension dosage form has long been used for poorly soluble active ingredients for various therapeutic indications. Development of stable suspensions over the shelf life of the drug product continues to be a challenge on many fronts.

1. TOPIC : DISPERSION SYSTEM Prepared & Presented by : Prof. Vedanshu R. Malviya ( M.pharm ) P. R. POTE PATIL COLLEGE OF PHARMACY, AMRAVATI.

2. Topics to be covered… Basic introduction of dispersion system. Classification of dispersion system. Coarse dispersion and types. Colloids (intro, advantage, disadvantage, classification, stability ). Emulsion (intro, advantage, disadvantage , classification, types, mechanism ). Suspension (intro, types, stability). Reference.

3. Dispersion system: Dispersed system is a biphasic system, consist of two phases, one is known as dispersed phase, which is dispersed throughout in a continuous phase called as dispersion medium. The volume of dispersion medium or continuous phase is greater than the dispersed phase. Example of dispersed phase includes; dust in the air, whereas that of dispersion medium includes water in milk.

4. Classification of dispersed system on the basis of particle size:

5. Classification of dispersion system according to state:

6. Coarse dispersion Colloids Emulsion Suspension

7. COLLOIDS: A disperse system consists essentially of one component, the disperse phase, dispersed as particles or droplets throughout another component, the continuous phase. Therefore, dispersions in which the size of the dispersed particles is within the range of 1 nm to about 0.5 µm are termed as colloid.

8. C lassification O f C olloids : On the basis of interaction of dispersed particles with molecules of the dispersion medium, colloidal dispersions are classified into following categories: Lyophilic colloids : System containing colloidal particles that interact to an appreciable extent with the dispersion medium are referred to as lyophilic colloids.

9. Lyophobic colloids: The second class of colloids is composed of materials that have little attraction, if any, for the dispersion medium. These are lyophobic colloids.

10. Association colloid : Association or amphiphiles are molecules or ions which have certain affinity for both polar and nonpolar solvents. In water, at low concentrations, surface active agents exist individually as monomers.

11. Stability of colloids:

12. EMULSIONS: An emulsion is a biphasic liquid preparation containing two immiscible liquids, one of which is dispersed as minute globules into the other. The liquid which is converted into minute globules is called the dispersed phase and the liquid in which the globules are dispersed is called the continuous phase. Normally, two immiscible liquid cannot be dispersed for a long period . So, an emulsifying agent is added to the system. It forms a film around the globules in-order to scatter them indefinitely in the continuous phase, so that a stable emulsion is formed. The globule size in emulsion varies from 0.25-25µm. Example; milk, rubber, latex, crude oil etc….. Also emulsions themselves have medicinal properties like for example; liquid paraffin is used as purgative and laxative.

13. Advantages: Mask the unpleasant taste. Economical. Improved bioavailability. Sustained release medication. Nutritional supplement. Diagnostic purposes. Topical use. Disadvantages: P roblem of creaming and sedimentation. Phase inversion. P roblem of handling.

14. Classification of emulsions: Based on the nature of dispersed phase, emulsions are classified as: Oil-in-water (o/w) Water-in-oil (w/o)

15. Determination of type of emulsion:

16. Mechanism of emulsion instability: Breaking

17. Suspensions: It is a biphasic liquid dosage form of medicament. It is a coarse dispersion in which internal phase (therapeutically active ingredient) is dispersed uniformly throughout the external phase. The solid particles act as disperse phase where as liquid vehicle acts as the continuous phase. The particle size of disperse phase is very important in the formulation of suspension.

18. Advantages : Stability. Choice of solvent. Mask the taste. Bioavailability Ease of administration. Prolonged action dosage forms. Disadvantages: Sedimentation. Compaction. Uniform drug delivery cannot be achieved sometimes. Bulky, handling require care.

19. Types of suspension:

20. Stability of suspension: Sedimentation volume: F= Vu/Vo where , Vu=ultimate volume of sediment Vo = initial volume of the suspension

21. Degree of flocculation: It is the ratio of the sedimentation volume of the flocculated suspension ,F , to the sedimentation volume of the deflocculated suspension, F ∞ ß = F / F ∞ ß = (Vu/Vo) flocculated ---------------------------- (Vu/Vo) deflocculated The minimum value of ß is 1,when flocculated suspension sedimentation volume is equal to the sedimentation volume of deflocculated suspension.

22. Reference: Martin’s physical pharmacy & pharmaceutical sciences . https:// www.slideshare.net/bknanjwade/disperse-systems-52487067 https:// www.slideshare.net/Soft-Learners/disperse-systempharmaceutics Menkhaus TJ, Fong H. Electrospun Nanofibers for Protein Adsorption. InElectrospinning : Nanofabrication and Applications 2019 Jan 1 (pp. 517-542). William Andrew Publishing.

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