1997 年 12 巻 2 号 p. 102-107
The absorption, metabolism and excretion of nucleoside analogue, lamivudine, were investigated after a single oral administration of 3H-lamivudine to male and female dogs at a dose of 2 mg/kg.
1. The total radioactivity in plasma reached the maximum at 0.9 hour after oral administration to male dogs and declined rapidly with a half-life of 2.9 hours. The concentrations of lamivudine in plasma reached the maximum at 0.8 hour after oral administration and declined with a half-life of 1.4 hours. Profiles of the plasma levels of total radioactivity or lamivudine in female dogs were similar to those in male dogs.
2. The ratio of plasma protein binding of radioactivity was below 17% and the ratio of distribution to erythrocytes of radioactivity was 35-38%, after oral administration to male dogs.
3. The excreted radioactivity in urine and feces was 85.3% and 9.5% of the dose in male dogs, respectively, 93.2% and 5.8% in female dogs within 168 hours after oral administration.
4. Lamivudine and two major metabolites, trans-sulphoxide of lamivudine and cytosine, were observed by the radio-HPLC analysis of urine collected from male and female dogs after oral administration.
