Enhancement effect of p-menthane-3,8-diol on in vitro permeation of antipyrine and indomethacin through Yucatan micropig skin

The enhancing effect of p-menthane-3,8-diol (MDO) on skin permeation of antipyrine (ANP) and indomethacin (IM) through Yucatan micropig skin in vitro was compared with l-menthol. p-menthane-3,8-diol is a metabolite of l-menthol and has little odor. It is easy to combine the vehicle because of lower lipophilicity than l-menthol. All formulations contained 40% (v/v) ethanol. The permeation of ANP increased with MDO about three times that without enhancer by increasing ANP concentration in the skin. However, the MDO effect was about a quarter that of l-menthol. The permeation of IM with MDO was about 15 times that with no enhancer and it was almost the same as that with l-menthol. The lag time of permeation was not significantly changed by MDO, which was not so in the case of l-menthol. Skin concentration of IM increased about 11 times and six times with MDO and l-menthol, respectively. MDO and l-menthol partitioned to the skin relatively high concentrations, 5.9 and 2.5 mg/cm³, respectively. The solubility of IM in the skin was improved by MDO, and consequently, the permeation of IM was enhanced.