In vitro release of diclofenac sodium from multiple emulsions; Effect of location of drug and pH of the aqueous phase

Multiple w/o/w and o/w/o emulsions of diclofenac sodium were prepared and studied to see the effect of location of drug in one or more phases along with change of pH of the external aqueous phase of the w/o/w and aqueous phase of o/w/o emulsion. The rate and extent of drug release were affected by pH of the aqueous phase and also by the location of the drug in w/o/w and o/w/o emulsions. Among all the multiple emulsions evaluated, the maximum rate and extent of drug release were observed from a w/o/w emulsion containing equal amounts of drug in both the aqueous phases with pH 8 of the external aqueous phase, and a control o/w/o emulsion which contained total amounts of drug only in the internal oil phase without any pH adjustment of the aqueous phase.