Percutaneous absorption, metabolism, and elimination of the penetration enhancer Azone in humans after prolonged application under occlusion

Azone was applied undiluted to an extended area of the forearm and left in place for 12 h under occlusion in 3 volunteers. Azone was found to be absorbed in very low amounts (0.419 ± 0.259% of the applied dose) and accumulation in the body did not occur. As compared to a previous study, the new application conditions gave an increase in amount and percentage absorbed, but a decrease in flux. Absorbed material was excreted rapidly and almost exclusively through the urine after extensive metabolism to at least 3 rather polar compounds. These findings and the absence of treatment-related side-effects in the 3 volunteers suggest azone to be safe for human use when topically applied under occlusion