The Pharmacokinetics of DR-3355. (IV): Absorption, Distribution and Excretion after a Single Oral Administration to Monkeys.

The absorption and excretion of DR-3355 were studied in cynomolgus monkeys after an oral administration of 14C-DR-3355 at a dose of 20mg/kg. The distribution of radioactivity was also studied in squirrel monkeys by whole body autoradiography after an oral administration of 14C-DR-3355. The following results were obtained. 1. Blood levels of radioactivity reached the maximum value of 7.76μg/ml at 3hr after administration and was eliminated with a biological half life of 4.5hr until 24hr after administration. The concentration was below detection limit at 48hr after administration. 2. Blood cell binding rate of radioactivity was 37 ?? 48% between 30min and 24hr after administration. There was no time dependent change in the binding extent. 3. Serum protein binding of radioactivity was 14 ?? 24% throughout the measurement period and there was no tendency to increase binding during observation time. 4. Cumulative excretions of radioactivity within 168hr after administration were 86.1% and 5.0% of administered dose in urine and feces, respectively. 5. DR-3355 distributed into all tissues except central nervous system. Autoradiograms showed that radioactivity disappeared from most of tissues within 30 days after administration. The accumulation of radioactivity in the melanin containing tissues such as hair follicles and uveal tract was observed in the autoradiograms at 30 days after dosing.