PT - JOURNAL ARTICLE AU - JUHANA E. IDÄNPÄÄN-HEIKKILÄ AU - RONALD J. TASKA AU - H. ALTON ALLEN AU - JOSEPH C. SCHOOLAR TI - PLACENTAL TRANSFER OF DIAZEPAM-<sup>14</sup>C IN MICE, HAMSTERS AND MONKEYS DP - 1971 Mar 01 TA - Journal of Pharmacology and Experimental Therapeutics PG - 752--757 VI - 176 IP - 3 4099 - http://jpet.aspetjournals.org/content/176/3/752.short 4100 - http://jpet.aspetjournals.org/content/176/3/752.full SO - J Pharmacol Exp Ther1971 Mar 01; 176 AB - Twenty-five mice (13 in early pregnancy and 12 in late pregnancy), 8 hamsters in late pregnancy, and 4 third trimester pregnant Cynomolgus iris monkeys were injected with diazepam-14C and sacrificed at various time intervals. The maternal distribution, the placental transfer and the fetal distribution of diazepam-14C and its metabolites were studied by autoradiography and liquid scintillation counting. he unchanged diazepam-14C was distinguished from the diazepam metabolites by thinlayer chromatography. Diazepam-14C and its metabolites crossed the placental barrier and accumulated in the fetal tissue in all three of the tested species. In mice diazepam-14C and its metabolites accumulated in the fetuses more rapidly in late than in early pregnancy. Fetal monkeys had a high uptake of radioactivity in the peripheral nerves, liver, spinal cord, kidney, lung, fat, cerebellum and plasma. The pronounced uptake and long retention of diazepam and its metabolites in the fetal monkey cerebellum, spinal cord and peripheral nerves may explain the temporary hypoactivity and hypotonicity that has been reported to occur in human infants when their mothers receive diazepam during labor. © 1971 by The Williams &amp; Wilkins Co.