Preparation and characterization of multiple emulsion based systems for controlled diclofenac sodium release.

Multiple w/o/w type emulsions were prepared and stabilized through interfacial complex films formation as a result of interaction of macromolecules like gelatin, bovine serum albumin (BSA), polyvinyl alcohol (PVA) and polyacrylic acid (PAA) (each present in internal aqueous phase separately) with sorbitan monostearate (Span 60) present in the middle oil phase. The stability of prepared emulsions was assessed using microscopic analysis which showed no significant changes in the average size of globule and number of droplets counted per cubic mm on storage. Viscosity and zeta potential studies revealed appreciable stability of the multiple emulsions. The multiple emulsion containing macromolecules in their internal phase demonstrated better entrapment efficiency. Intramuscular injection of drug in a w/o/w emulsion formulation provided a protracted drug plasma profile for diclofenac sodium.