FORMULATION, EVALUATION AND OPTIMIZATION OFDICLOFENAC MULTIPLE EMULSION DRUG

Bechlor in Pharmacy

Multiple emulsions are novel carrier systems which are complex, poly-dispersed, multiphase systems consisting of at least two immiscible liquids i.e., both w/o and o/w emulsions exists simultaneously in a single system. Lipophilic and hydrophilic surfactants are used for stabilizing these two emulsions respectively. The droplets of dispersed phase contain even smaller dispersed droplets themselves, thus also called as “emulsions of emulsions”. The inner dispersed droplets in multiple emulsions are separated from outer liquid phase by a layer of another phase (1). The solute has to transverse from inner miscible phase to outer miscible phase via middle immiscible organic phase, prior to release at absorption site, thus also known as liquid membrane system. Partition and diffusion coefficient of drug and strength of middle membrane phase, which is a multimolecular layer of oil, water and emulsifier at both the interfaces of multiple emulsion, controls the drug release from these systems. This extends the classical definition to include “liquid droplets and/or liquid crystals dispersed in liquid” [2]. These are heterogeneous preparation composed of two immiscible liquids, i.e. oil and water, one of which is dispersed as fine droplets uniformly throughout the other. The phase presented as small droplets are called dispersed, discontinuous or internal phase and the supporting liquid is known as continuous or external phase. Droplet diameter in multiple emulsions may range from 0.1 to 100 µm. It consists of large and poly dispersed droplets that are thermodynamically unstable with a strong tendency for coalescence, flocculation and creaming. This may lead emulsions to reverse back to separate oil and water phase by fusion or coalescence of droplets, thus it is required to add third component which kinetically stabilizes multiple emulsions, known as emulsifying agent/emulsifier.

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