Development and evaluation of a microemulsion formulation for transdermal delivery of Diclofenac diethylammonium

The aim of the present study was to prepare and evaluate different formulations of Diclofenac diethylammonium in microemulsion base with a view to enhance its permeability through the skin. Various o/w and w/o microemulsions of Diclofenac diethylammonium were prepared by the spontaneous emulsification methods. Isopropyl myristate was used as oil phase, Polyoxyethylenesorbitan monooleate and Sorbitanmonolaurate as surfactants and Isopropyl alcohol, Dioctylsodium sulfosuccinate (AOT) and polyoxyethylene (10) octyl phenol ether as co-surfactants. Microemulsion existence region was determined using the pseudo-ternary phase diagrams for preparing different formulations. The optimized o/w and w/o microemulsions consist of 1.16% w/w Diclofenac diethylammonium as the active ingredient. The microemulsions were characterized for different parameters. In-vitro permeation studies through rat skin showed that permeability parameters like flux (Jss) and permeability coefficient (P) were significantly higher for formulation then reference marketed product (Emulgel) (p<0.05). Primary skin irritation studies indicated that optimized formulations are safe for the application on the skin. Stability studies indicated that the physico-chemical parameters of the formulation remain unaffected at accelerated conditions of storage. All the percutaneous parameters as well as the pharmacodynamic anti-inflammatory study parameters were statistically calculated. The results indicated that the microemulsion system studied would be a promising tool for enhancing the percutaneous delivery of Diclofenac diethylammonium.