Effect of natural penetration enhancers on dermal delivery of hydrocortisone acetate

The purpose of the research work was to develop microemulsion (ME) of hydrocortisone acetate (HCA) using natural penetration enhancers and to determine its possibility in effective dermal delivery. Eucalyptus oil, clove oil and lemon grass oil were selected as natural penetration enhancers and pseudo-ternary phase diagrams were plotted using Tween 80 as surfactant and ethanol as cosurfactant. ME of each penetration enhancer was optimized using three factors, three levels Box–Behnken design, with independent variables as penetration enhancer, Tween 80 and ethanol. Formulations were assessed for percentage drug release as dependent variable. Response of these formulations decreased as the concentration of oil ranged from high to low and the response showed positive effect with increase in concentration of Tween 80 and ethanol. The globule size of optimized batches of eucalyptus oil, clove oil and lemon grass oil were found to be 226.1, 129.04 and 818.9 nm respectively. Optimized batches of MEs were then incorporated in carbopol 940 to form ME based gel without affecting their structure. Ex vivo permeation studies showed that amount of drug permeated from ME based gels was less than ME formulation indicating greater retention of HCA into skin layers. Retention of drug in skin layers both dermis and epidermis was higher for all three natural penetration enhancer. Hence natural penetration enhancers can be used for effective delivery of topical corticosteroids to the skin for improved treatment of several skin diseases and can be a better choice over synthetic penetration enhancers in terms of safety. © 2014, The Korean Society of Pharmaceutical Sciences and Technology.