Percutaneous absorption of hydroquinone in humans: effect of 1-dodecylazacycloheptan-2-one (azone) and the 2-ethylhexyl ester of 4-(dimethylamino)benzoic acid (Escalol 507).
Hydroquinone was found to penetrate readily human forehead skin in vivo following a single topical exposure, in an alcoholic vehicle, of 24 h duration. Percutaneous absorption was estimated using radiotracer methodology and 14C-labeled hydroquinone. The effects of a penetration enhancer, 1-dodecylazacycloheptan-2-one, and a sunscreen, the 2-ethylhexyl ester of 4-(dimethylamino)benzoic acid, on the percutaneous absorption of hydroquinone were investigated. In vivo penetration of hydroquinone was significantly decreased (a less than 0.05) by the addition of the 2-ethylhexyl ester of 4-(dimethylamino)benzoic acid (3% w/w) to the vehicle. The penetration enhancer, 1-dodecylazacycloheptan-2-one (0.5% w/w), did not significantly increase (a greater than 0.05) the absorption of hydroquinone. From all hydroquinone preparations, percutaneous absorption was rapid and peak elimination occurred within the first 12 h following application. Elimination was complete within 5 d.
Bucks
D A
DA
Department of Dermatology, School of Medicine, University of California, San Francisco 94143.
McMaster
J R
JR
Guy
R H
RH
Maibach
H I
HI
D010129:4-Aminobenzoic Acid / Q000494:pharmacology*; D062365:Aminobenzoates / Q000494:pharmacology*; D001381:Azepines / Q000494:pharmacology*; D006801:Humans; D006873:Hydroquinones / Q000493:pharmacokinetics*; D012869:Skin Absorption / Q000187:drug effects*; D013473:Sunscreening Agents / Q000494:pharmacology*; D062366:para-Aminobenzoates
D062365:Aminobenzoates; D001381:Azepines; D006873:Hydroquinones; D013473:Sunscreening Agents; D062366:para-Aminobenzoates; C035229:laurocapram; D010129:4-Aminobenzoic Acid; C031927:hydroquinone; C041981:padimate-O