Studies on the influence of penetration enhancers on in vitro permeation of carvedilol across rat abdominal skin

The aim of the investigation was to study the effect of penetration enhancers on the in vitro permeation of carvedilol across excised rat abdominal skin and to select suitable penetration enhancer. Terpenes menthol, camphor, dlimonene and carvone; surfactants, Transcutol and Labrasol at 5% w/v, were used as penetration enhancers in the study. Skin permeation studies were conducted in Franz diffusion cells using excised rat abdominal skin. Solutions containing 5% w/v camphor showed maximum permeation (451.20 μg?) in 24 hr with a flux of 5.23 μg/hr/cm² and was significantly different (p<0.05) to flux obtained with other permeation enhancers. Control (phosphate buffer saline, pH 7.4 containing 40% v/v polyethylene glycol) sample showed lowest permeation (59.18 μg?), with a flux of 0.67 ìg?/hr/cm². The flux of carvedilol obtained from the solutions containing camphor, Transcutol, d-limonene, carvone, Labrasol and menthol (5% w/v) were 7.81, 7.26, 6.52, 5.91, 4.21 and 2.28 times higher than that observed with control, respectively. The flux obtained with camphor was significantly higher (p<0.05) than the fluxes obtained with other penetration enhancers. The present study suggests that camphor, Transcutol and d-limonene at 5% w/v level may be used as penetration enhancers in the development of transdermal drug delivery systems.