Transdermal delivery of glibenclamide and glipizide: in vitro permeation studies through mouse skin

The purpose of this investigation was to study the feasibility of transdermal delivery of glibenclamide and glipizide. In vitro permeation of these drugs was studied through mouse skin using various penetration enhancers like Tween -20, polyethyleneglycol-400, ethanol and d-limonene by simultaneous application of drug and enhancer solution or by pretreatment of the skin with neat enhancer. The partition coefficient values indicated that both drugs partition well into the skin. Glipizide did not show any skin metabolism, while glibenclamide showed a minimal metabolism during in vitro skin metabolism studies. The flux values (microgram/cm2/h) of both drugs significantly (p < 0.05) increased in the presence of penetration enhancers. The glibenclamide flux values ranged from 1.39 +/- 0.13 without enhancer, to 19.01 +/- 2.14 in a combination of 50% ethanol and 5% d-limonene. Glipizide flux values ranged from 3.01 +/- 0.74 without enhancer, to 62.97 +/- 7.10 in a combination of 50% ethanol and 5% d-limonene. Skin retention and solubility of both drugs increased with all penetration enhancers compared to control. The target permeation rates for glibenclamide and glipizide were calculated to be 193.8 and 184.8 micrograms/h respectively. The present study showed that the target permeation rates for both drugs could be achieved with the aid of enhancers by increasing the area of application in an appreciable range.