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)

摘要

The effects of a penetration enhancer, 1-dodecylazacycloheptan-2-one (Azone) and a sunscreen, the 2-ethylhexyl ester of 4-(dimethylamino)-benzoic-acid (Escalol 507) on the percutaneous absorption of hydroquinone (123319) were studied. Volunteers each received a single 100 microliter dose of a carbon-14 labeled hydroquinone preparation (module) by topical application to forehead skin. Module 1 contained Azone and Escalol-507, module 2 contained Azone, module 3 contained Escalol-507 and module 4 contained no Azone or Escalol-507. Average percutaneous absorption of hydroquinone as estimated from the urinary elimination data was 35, 66, 26, and 57 percent for modules 1, 2, 3, and 4, respectively. Peak elimination was noted within the first 12 hours and elimination was complete within 5 days from application. Escalol-507 (3 percent by weight) significantly inhibited the absorption. Azone (0.5 percent by weight) did not significantly increase absorption either alone or with Escalol-507 present. The authors suggest that if Azone were used at higher concentrations or in a different vehicle system, the findings might be different.