Pharmacokinetic studies of minoxidil

This document summarizes two studies on the pharmacokinetics of minoxidil, a new antihypertensive drug, in hypertensive patients. The studies found that minoxidil was rapidly removed from plasma with a half-life of 4.2 hours and was excreted predominantly in the urine as metabolites. The glucuronide conjugate was the predominant metabolite in the urine in the earlier collection periods, whereas the other metabolites of minoxidil were predominant in later periods. The studies suggest a dissociation between the drug in circulating blood and its pharmacologic activity, and that the prolonged hypotensive response to the drug may reflect the fate of the drug at tissue receptor sites.