4-Methylpyrazole and the cutaneous vascular sensitivity to alcohol in Orientals.

Twelve healthy subjects of Oriental ancestry were challenged with topical applications of lower aliphatic alcohols and aldehydes after topical pretreatment consisting of 4-methylpyrazole in hydrophilic ointment on the volar aspect of one forearm and hydrophilic ointment alone on the contralateral volar forearm. Cutaneous blood flow was monitored by laser Doppler velocimetry. Pretreatment with 4-methylpyrazole, a specific inhibitor of alcohol dehydrogenase, led to a significant decrease in the cutaneous vascular response to the alcohols as a group, but did not lead to changes in the cutaneous vascular response to the aldehydes as a group. Among the individual alcohols, pretreatment with 4-methylpyrazole reduced the response significantly to all concentrations of 1-propanol and 1-butanol. The means of the vascular response to the different concentrations of ethanol decreased, but not significantly. Additionally, 4-methylpyrazole did not have an independent effect on cutaneous blood flow. These results are consistent with the view that the cutaneous vascular reaction to primary alcohols applied topically to the skin of Orientals is provoked, in large part, by the corresponding aldehyde.