The blood level profile and urinary excretion of meclomen (MCM) and its metabolites after single and repeated oral administrations to healthy human volunteers have been investigated. When MCM was orally administered in single doses of 75, 150 and 300mg to human volunteers, the blood level of MCM and its main metabolite, M-1, reached the maximum at 1-1.5 and 1.5-2 hr and then decreased with half lives of 0.9-1.1 and 5.3-12.1 hr, respectively. The area under time-concentration curve (AUC) and

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... mal plasma concentration of MCM were closely correlated with doses in the range of 75-300 mg. In 24 hr after the administration of MCM in the three doses, the total urinary excretions of MCM and its metabolites including M-1, M-2, M-3 and M-4, were 31, 28 and 27%, respectively. The excretion ratio of the metabolites was almost the same in each dose. When MCM was given three times per day in doses of 50, 100 and 200'mg for 5 days to healthy human volunteers, the maximal blood levels of MCM were nearly equal in the respective doses and in 14-15 hr after the third administration in each day. The blood concentrations of MCM and M-1 decreased to 1/15-1/100 and 1/20 1/40 of the corresponding maximum in the 6th day while the maximal level of M-1 gradually increased depending on the dose. On the other hand, the total urinary excretion of MCM and its four metabolites during 6 days after the admini stration appeared to correlate closely in the three doses as well as in the case of a single administration but the excretion ratio of M-1 increased slightly in all doses. These results imply that no significant amounts of MCM and M-1 would be accumulated in human beings.