2001 Volume 16 Issue 4 Pages 314-324
Tissue distribution and the transfer of radioactivity into the fetus or milk were studied following a single intravenous administration of [14C]M17055 to rats at a dose of 0.3 mg/kg.
1. Tissue levels of radioactivity in male rats showed maximum level in most tissues at 5 minutes after administration. The concentrations in kidney and liver showed respectively 11.7 and 8.1 fold greater levels than that in plasma, while the levels in other tissues were lower than those in plasma. Then the levels of radioactivity in most tissues decreased to undetectable levels within 168 hours after administration.
2. Although higher kidney/plasma ratio of radioactivity was observed in female rats, the distribution of radioactivity in female rats showed similar pattern when compared with that in male rats.
3. After administration to pregnant rats on 12th and 19th day of gestation, a little radioactivity was transferred into the fetus and eliminated slowly in the rats on 19th day of gestation. Although temporary rising of radioactivity was observed in the intestine and its contents of the fetus, the radioactivity decreased to undetectable level in newborn rats at 168 hours after administration to the maternal rats. The distribution of radioactivity in pregnant rats showed similar pattern compared with that in non-pregnant female rats, which suggested that the influence of pregnancy on the distribution seems to have minimal effect in female rat.
4. The level of radioactivity in the milk reached a maximum level (63 ng eq./mL) at 2 hours and exceeded the plasma level within 2 ?? 12 hours after administration. Then the radioactivity decreased rapidly and reached lower level than that in plasma at 48 hours after administration.
