Further evaluation of a new penetration enhancer, HPE-101

The penetration enhancer, 1-[2-(decylthio)ethyl]azacyclopentan-2-one (HPE-101), significantly enhanced the excretion of topically applied [14C]indomethacin when dissolved in dipropylene glycol, triethylene glycol, diethylene glycol, 1,3-butylene glycol, trimethylene glycol, glycerin, water, silicone or triethanolamine, but not when dissolved in ethanol, isopropyl alcohol, oleyl alcohol, olive oil, peppermint oil, isopropyl myristate or hexylene glycol. HPE-101 significantly enhanced the excrection of [14C]indomethacin, [14C]nicotinic acid, [14C]5-fluorouracil, [3H]oestradiol and [3H]triamcinolone acetonide, but not that of [3H]testosterone. HPE-101 also significantly enhanced the excretion of [14C]indomethacin applied to intact skin of rabbit, guinea-pig and rat, and to tape-stripped skin of guinea-pig, but did not enhance the excretion of [14C]indomethacin applied to tape-stripped skin of rat or rabbit.