Studies on the Metabolic Fate of Loprinone Hydrochloride. (2): Transfer into Fetus and Milk.

Abstract

Transfer of radioactivity into the fetus and milk after a single intravenous administration of 14C-Loprinone hydrochloride to pregnant or lactating rats were investigated. 1. On day 12 and 19 of gestation, the tissue levels of radioactivity in the fetus at 5 min after dosing were lower than the plasma levels of radioactivity in the maternal rat. But the elimination of radioactivity in the fetus was slower than that in the maternal plasma. 2. In the fetus on day 19 of gestation, the levels of radioactivity in the kidney, liver and gut were higher than those in the other tissues. 3. The elimination of radioactivity from maternal tissues except liver, kidney, uterus and placenta, was rapid. But 24 hr after dosing, the levels of radioactivity in all tissues were very low. 4. In the fetus on day 12 and 19 of gestation, almost all of radioactivity corresponded to the unchanged form. 5. The milk-to-plasma co ncentration ratio reached the maximum value of 97.1 at 4 hr after dosing. The disappearance of the radioactivity from the milk was slower than that from the maternal plasma. And small amount of radioactivity was detected in the milk at 48 hr after dosing. 6. The radioactivity in the milk consisted mainly from the unchanged form.