Abstract

Diclofenac hydroxyethyl pyrrolidine (DHEP), a novel salt of a known non-steroidal antiinflammatory drug was formulated (1.32% w/w DHEP equivalent to 1% w/w diclofenac) in a hydrogel base using Carbopol of 940 and 941 grade separately and also in emulsion base. Formulations of DHEP with different penetration enhancers in the three bases mentioned above were prepared and evaluated for their physicochemical properties. In vitro drug permeation studies were carried out in Keshary-Chien glass diffusion cells using freshly isolated guinea pig skin for all the formulations in comparison with gels containing no penetration enhancer. The experimental study involved colorimetric estimation of the amount of diclofenac diffusing from a formulation across the skin. Our results indicated that the lag time for the drug diffusion was not altered after the addition of an enhancer to any type of formulation but addition of a penetration enhancer increased the rate of drug diffusion when compared to formulations containing drug alone. Cardamom oil (1% w/w) showed maximum enhancement of flux of diclofenac in vitro in comparison with other enhancers used in the formulations.