Emulsion and suspensions

Emulsion and suspensions

1. Emulsions and Suspensions Created by:- Abhishek Dhiman 16pph002

2. Emulsions An emulsion is a biphasic liquid preparation containing two immiscible liquid , one of which is dispersed as a minute globule into the others. The liquid which is converted into minute globules is called dispersed phase and liquid in which the globules are dispersed is called the continuous phase

3. Type of Emulsions The emulsions are of two types :- Oil in water type (o/w) Water in oil type (w/o) In oil-in-water type emulsion,the oil is in dispersed phase where as water is in continuous phase. The o/w type emulsions are preferred for internal use In water-in-oil type emulsion,the water is in the dispersed phase whereas oil is in continuous phase.

4. Dilution test Dye test Conductivity test Fluorescence test Tests for identification of type of emulsion

5. Classification of emulsions in accordance to the type of emulsifying agents used in the preparation of an emulsion :- Emulsion containing natural gum e.g:- gum acacia, tragacanth Emulsion containing gum substitute e.g:- Cellulose Emulsion containing saponins Emulsion containing starch Emulsion containing natural waxes e.g :- woolfat and bees wax Emulsion containing synthetic wax e.g:-emulsifying wax Emulsion containing other emulsifying agents such as pectin. Classification of Emulsions

6. Emulsions for oral administration :- These are usually o/w type of emulsions. E.g:- cod liver oil Emulsions for external use :- These may be either o/w type or w/o type. E.g:- oily calamine lotion Emulsions for parenteral use:- These are used to administer fat soluble vitamins such as A,D,E and oil soluble sex hormones ,because there absorption in this form is very rapid. E.g:- cleviprex B. Classification of emulsions in accordance to their mode of administration

7. Emulsions for rectal use:-These are used in the form of enema for the evacuation of bowl. starch mucilage is generally used in the preparation of enema. E.g:- Micralex citrato

8. The emulsifying agents reduce the interfacial tensions between two phase i.e, oil phase and aqueous phase and then make them miscible with each other and form stable emulsion . Emulsifying agents are also known as emulgents or emulsifier No. of the emulsifying agents are : Acacia Polysorbate 20 Polysorbate 60 Polysorbate 80 Tragacanth Formulation of Emulsion A. Emulsifying Agents

9. Emulsifying Agents

10. B. Preservation of emulsions :- Emulsions which are prepared by using emulsifying agents such as carbohydrates, proteins may lead to the growth of bacteria, fungi in the presence of water. In order to preserve emulsion properly:- Benzoic acid (0.1-0.2%) Methyl paraben and propyl paraben (0.1-0.2%) Chloroform (0.25%) Cetrimide (0.002-0.01%) c. Antioxidants :- During storage of emulsions the fats and emulsifying agents under go oxidation by atmospheric oxygen. T his can be avoided by using antioxidants such as Gallic acid and Ascorbic etc .

11. D . Flavours :- vanillin is a good flavouring agent for liquid paraffin emulsions. Benzaldehyde is generally used as a flavouring agent for cod liver oil emulsions. Stability of emulsions An emulsion remain to be sable if it remains as such after its preparation. An emulsion is a heterogeneous system consisting of at least one immiscible liquid  dispersed in another in the form of droplets. Emulsions are widely used in various fields  such as the pharmaceutical, agricultural, cosmetic, paint and food industries .

12. A second corollary of the positive free energy change of emulsions is that most emulsions are thermodynamically unstable. In order to prepare emulsions with shelf life stability required for a pharmaceutical product is about 1-3 years, it depends upon the correct choice of emulsifiers be made, polymeric stabilizers must be added. The most common emulsifiers and emulsion stabilizers are amphiphilic molecule with a pollar group attached to an non- pollar group they may be anionic cationic or non-ionic

13. Modernist thickeners and gelling ingredients can make emulsions more stable. Besides giving emulsions more texture, thickeners also help to slow down the rate at which emulsions separate. As the liquid is more viscous, the suspended droplets can't move around so easily to eventually combine in a specific area. This is important for everything from a sauce, which needs to stay emulsified for as long as it would take a diner to eat it, to ice cream, which needs to stay emulsified to prevent the growth or ice crystals. Agar,  gellan, gelatin, guar gum,  sodium alginate  and xanthan gum can all be used as emulsion stabilizers. You can learn more about each of these ingredients in our Hydrocolloid Guide.

14. SUSPENSIONS

15. Suspensions Suspensions are the biphasic liquid dosage form of medicament in which the finely divided solids particles ranging from 0.5 to 5.0 micron are dispersed in a liquid or semisolid vehicles. The particle size of disperse phase is very important in the formulation of suspensions. Qualities of a Good suspension It s hould settle slowly and should be readily re-dispersed on gentle shaking of the container It should be chemically inert. The suspension particle should not make a cake The suspension should pour readily and evenly from its container

16. Classification of suspensions Suspensions are classified into four main parts according to there pharmaceutical use:- Oral Suspensions e.g :- Tetracycline HCL Parenteral Suspensions e.g:- procaine pencilline G Ophthalmic Suspensions e.g:- 2-amino butanol Suspensions for external use e.g;- calamine lotion

17. Formulation of suspension :- Flocculating agents :- In suspensions the solids particles are well dispersed medium i.e vehicle. The dispersion can be improved by adding a surfactant or protective collides which acts as flocculating agents . The flocculating agents acts by reducing the surface tensions and thereby improving the dispersions of solids and minimise flocculation E.g:- sodium lauryl sulphate, tweens, spans etc. Thickening agents :- These are hydrophilic colloids which form colloidal dispersions with water and increase the viscosity of the continuous phase, so that the solid particle remains suspended in it for a sufficient long time to measure a uniform accurate dose.

18. The thickening agents used to stabilise suspensions are classified into three major groups Polysaccharides Inorganic agents Synthetic compounds Wetting agents:- These are the substances which reduce the interfacial tensions between the solid particles and liquid medium, thus producing a suspension of required quality. This may be achieved by adding a suitable wetting agent which is absorbed at solid or liquid interface in such a way that the affinity of the particles for the surrounding medium is increased and the interparticular forces are decreased

19. Preservativ e:- A suitable preservative is needed to preserve suspensions against bacterial growth. Preservative selected should be effective against a wide range of microorganism. Benzoic acid, sodium benzoate, methyl paraben Organoleptic additives :- Colouring agents, sweetening agents and flavouring agents are generally incorporated in oral suspensions.

20. Some theoretic consideration are :- Particle size control Wetting Sedimentation Brownian movement Electro kinetics or zeta potential

21. Evaluation of the stability of suspensions Sedimentation method :- The measurement of sedimentation volume is the most important parameter in the evaluation of the stability of suspensions. The suspension formulation (50ml) was made separately into 100ml measuring cylinder and sedimentation volume was read after At weakly intervals for 12 weeks Rheological methods :- It provides information about settling behaviour. The arrangement of the vehicle and the particle structural features.

22. Electro kinetic methods:- Measurement of Zeta potential using micro electrophoresis apparatus and zetaplus it shows the stability of dispersed system. Micrometric method :- The stability of suspension depends on the particle size of the dispersed phase change in the particle size with reference to time will provide useful information regarding the stability of a suspensions

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