Distribution, metabolism and excretion of 14C-MT-141 in rats. II. Distribution and excretion after multiple intravenous administration in male rats and after single intravenous administration in female rats

The distribution and tissue accumulation of the radioactivity were studied in male rats after the multiple intravenous administration of 14C-MT-141. The distribution and the placental transfer were also studied using pregnant rats or lactating rats after the single intravenous administration of 14C-MT-141. The radioactive concentration in the fetus was low and the radioactivity was distributed almost uniformly through the fetus body. The peak time of the milk level was 2 hours after the administration and the radioactivity in milk decreased gradually thereafter. The milk levels decreased more slowly than the blood levels did. The blood level after the last dose administered daily for 7 days tended to decrease more slowly, when compared with the single administration. However the blood concentration at 48 hours after the last administration was less than 3 times as high as that after the single administration.