The Absorption, Distribution, Excretion and Metabolism of [2-14C]Methimazole in Rat

Publisher Website
Google Scholar
Abstract
1. [2-14C]-Methimazole has been synthesized and its absorption, distribution and metabolism studied in male and female rats, after intraperitoneal and oral administration.2. After a single intraperitoneal injection, radioactivity was concentrated in the thyroid rising to a max. at 24 h, whilst the radioactivity was decreasing in other tissues. Thyroid radioactivity appeared to be protein-bound.3. Urinary excretion of 14C accounted for 60% dose at 12 h and 73·4–89·5% within 5 days. On average, 6–7% of methimazole was excreted unchanged in urine after a single intraperitoneal injection. Methimazole was metabolized to a greater extent in rats receiving it by the oral route compared to the intraperitoneal route.4. Thin-layer chromatography suggested the presence of six metabolites, of which the major one was strongly polar. Hydrolysis with β-glucuronidase indicated that only a minor proportion of the activity excreted at 6 h in the urine was present as glucuronide.