Stage of pregnancy-dependent transplacental passage of 195mPt after cis-platinum treatment.

The placental transfer of the clinically important cytostatic drug cis-diamminedichloroplatinum(II) (cis-platinum, DDP) was investigated by application of 195mPt-labelled DDP to pregnant NMRI mice on day 10, 11, 12, . . ., or 17 of gestation and by measurement of the radioactivity in the embryos or fetuses in intervals between 0.5 and 48 hr after application. Whereas on days 10, 11 and 12 after treatment only very small amounts of radioactivity could be detected in the embryos, from day 13 considerable and increasing amounts of radioactivity could be found; finally, within the fetal compartment on day 17 even an effect of enrichment of DDP over a uniform distribution between mother and embryos was observable. It is supposed that the ability of DDP to pass the placental barrier only after accomplished maturation of the placenta is due to active carrier-mediated transport processes.