[Preliminary in vitro study of the transplacental passage of spiramycin].

Spiramycin, a true macrolide antibiotic, is the only agent which can be used for the preventive treatment of congenital toxoplasmosis. It gives very high levels in the human placenta, but its transplacental transfer is likely to be very poor, so that it may not cure an already infected foetus. We studied the human placental transfer of spiramycin by an in vitro perfusion model of placentas obtained at term of uncomplicated pregnancies. The transfer rate of spiramycin was found to be close to 9% of the maternal circulating concentrations and 23% of the antipyrine transfer rate, which is only flow-limited. Possible therapeutic implications of these results are discussed.