[Absorption, distribution, metabolism and excretion of bacmecillinam. III. Absorption, metabolism and excretion of 14C-bacmecillinam following oral administration to dogs].

The pharmacokinetics (i.e., blood level, biological half-lives and excretion) of bacmecillinam (KW-1100) was investigated. KW-1100 was orally administered to dogs at the dose of 20 mg/kg (as mecillinam). Biological half-lives (radioactivity) of 14C-KW-1100 in plasma were 1.2 hours (T1/2 alpha) and 52 hours (T1/2 beta). The Cmax and Tmax were 8.4 micrograms/ml and 2 hours. The biological half-life (microbiological activity) of KW-1100 in plasma was 0.9 hour. The Cmax and Tmax were 5.6 micrograms/ml and 1 hour. The urinary and fecal excretion of 14C-KW-1100 were approximately 46% and 49% (0 approximately 72 hours), respectively. The major metabolites in the urine (0 approximately 8 hours) were mecillinam, 5,5-dimethyl-2-(1'-formamidomethyl)-thiazolidine-1',4-dicarboxy lat e (M-1) and 6-beta-[(hexahydro-1 H-azepin-1-yl)-methyleneamino]penicilloic acid (M-6), each distribution ratio of which was 57.2, 24.2 and 12.0% of the total radioactivity in the sample, respectively. The major metabolite in the plasma at peak time (2 hours) was mecillinam (56.2%).