Methimazole: an alternative route of administration.

Methimazole was administered orally and rectally in a single dose of 60 mg to six euthyroid volunteers (three females and three males). Blood levels of methimazole were the same whether administered by the oral or rectal route, with peak levels of 1184 +/- 118 and 1163 +/- 150 (+/-SEM) ng/ml respectively. This study provides evidence that the rectal administration of methimazole may be an alternative to treating hyperthyroid patients who are unable to take this drug by mouth.