Emulsions and microemulsions- computer in pharmaceutical formulatation

computer in pharmaceutical formulatation,development in pharmaceutical emulsion microemulsion as drug carriers

1. COMPUTERS IN PHARMACEUTICAL FORMULATIONS Presented By Sujitha Mary M Pharm St Joseph College Of Pharmacy 1

2. CONTENTS Computers in pharmaceutical formulations Development of pharmaceutical emulsions Microemulsions as drug carriers Reference 2

3. INTRODUCTION Formulation and development is a process of selection of component and processing Various technique such as design of experiments are implemented for optimization of formulation and processing parameter Traditionally optimization refers to changing one variable at a time Many times finding the correct answer is not simple . In such cases use of computer tools is the best way to solve problem 3

4. DEVELOPMENT OF PHARMACEUTICAL EMULSIONS Definition An emulsion is a thermodynamically unstable system containing mixture of two or more immiscible liquids which is stabilized by adding emulsifying agent. Phases of emulsion Discontinuous phase Continous phase 4

5. TYPES OF EMULSIONS Based on dispersed phase Oil in water(o/w) Water in oil (w/o) Water in oil in water(w/o/w) Based on size of liquids Macroemulsions Microemulsions 5

6. EMULSIFYING AGENTS An emulsifying agent is any material that enhances the stability of an emulsion Mainly 3 types Surfactants- Eg : SLS, Cetrimide Hydrocolloids- Eg : Acacia, Tragacanth Finely divided solids- Eg : Bentonite 6

7. THEORIES OF EMULSIFICATION Film theory : The added emulsifying agent forms a mechanical film by getting adsorption Viscosity theory : ↑in viscosity,↑in stability Wedge theory : Monovalent soap gives o/w emulsion,divalent soap gives w/o emulsion Interfacial theory : The added emulsifying agent reduces the interfacial tension 7

8. STABILITY OF EMULSIONS Most common stability problems are Creaming and sedimentation : As the droplets are subjected to gravity force,they tend to move upward (creaming) or downward(sedimentation) Cracking or coalescence : Is the fusion of 2 or more droplets of the disperse phase forming one droplet Phase inversion : Emulsion changes from one type to another 8

9. METHODS TO ENHANCE STABILITY Globule size : smaller particles have slower creaming or sedimentation Viscosity of continuous phase : ↑in viscosity ↑stability Using emulsifying agent : Enhance viscosity,reduce interfacial tension Storage of temperature : ↑ in temp,↓ stability 9

10. METHODS FOR EVALUATION OF STABILITY OF EMULSIONS Size frequency analysis by microscopy Velocity of craming Globule size analysis Turbidimetric analysis Conductivity testing 10

11. METHODS OF PREPARATION Dry gum method Triturate emulsifier+oil Add water Triturate and form primary emulsion Add remaining qty of water Wet gum method Triturate gum+water Add oil and form primary emulsion Add remaining qty of water 11

12. METHODS OF PREPARATION Bottle or Forbes bottle method Gum+oil ↓ shake ↓ Add water ↓ Shake to form primary emulsion ↓ Add remaining qty of water 12

13. APPLICATIONS OF EMULSIONS Oral administarion of water insoluble liquids IV administration of API as an emulsion( Taxol ) For external use( lotions,liniments ) Emulsions in aerosol can be used to produce foam 13

14. MICROEMULSIONS AS DRUG CARRIERS 14

15. MICROEMULSIONS Microemulsions are thermodynamically stable,optically transparent,isotropic dispersions of aquous and hydrocarbon liquids stabilized by an interfacial film of surfactants molecule 15

16. MICROEMULSION AS A DRUG CARRIER SYSTEM Improved drug solubilization Long shelf life Ease of preparation Improved bioavailability 16

17. DISADVANTAGES Stability is influenced by environmental parameters such as temperature and ph Limited solubilizing capacity for high melting substances 17

18. TYPES OF MICROEMULSIONS Direct microemulsion : Droplets are dispersed in the continuous aquous phase Reversed microemulsion : Water droplets are dispersed in the continuous oil phase Bicontinuous microemulsion : Micro domains of oil and water are interdispersed within the system 18

19. THEORIES OF MICROEMULSION Thermodynamic theory The free energy of microemulsion formation can be dependent on the extent to which surfactant lowers the surface tension of oil-water interface DGF= ˠDA -TDS Solubilization theory Formation of microemulsion by micelles gradually become larger and swells to a certain size range results Interfacial theory Microemulsion is capable of forming negative interfacial tension 19

20. COMPONENTS OF MICROEMULSION Oil – Eg:Isopropylmyristate,olive oil Surfactant –Eg:Tween80,Tween20 Cosurfactants-Eg:Propyleneglycol,Ethanol 20

21. PREPARATION Drug has to dissolve in to oil phase of microemulsion Water phase is combined with surfactant and cosurfactant The amount of surfactant and cosurfactant to be added in the oil phase is determined with the help of pseudoternary phase diagram Ultrasonicator can finally used to achieve the desired range for the dispersed phase It is then allow to equilibrate Gel may be prepared by the addition of gelling agent to above microemulsion 21

22. APPLICATIONS Dry cleaning process Pesticide formulation Floor polishers and cleaners Cutting oils In industry for the synthesis of polymers 22

23. REFERENCE www.slideshare .com Textbook of Industrial Pharmacy by Liebermann 23