UPTAKE OF DRUG-CARRIER LIPOSOMES BY PLACENTA - TRANSPLACENTAL DELIVERY OF DRUGS AND NUTRIENTS

Liposomes with different charge, size and lipid composition were injec ted i.v. into pregnant rats and rabbits and their uptake and transport across the placenta were studied. Results show that the placenta is v ery efficient in removing liposomes from the maternal circulation and that it takes up more liposomes per gram of tissue than the liver. Lip osomes are degraded intracellularly in the placenta and the entrapped material is then transported across to the fetus as free molecules. Un der the experimental conditions described in this article, no intact l iposomes were found to be transported across the placenta. In comparis on to the i.v. injection, infusion of liposomes into pregnant rabbits had greater effect on the localization of liposomal drug in the placen ta and fetal blood. In summary, these results show that small unilamel lar vesicles enhance delivery of drugs and nutrients to the placenta. They also suggest the possible danger of toxicity to the fetus if the expectant female is undergoing liposomal drug treatment.