MECHANISMS OF DRUG TRANSFER ACROSS THE HUMAN PLACENTA

In this review we summarized literature data on the mechanisms of huma n placental drug transport studied in the isolated perfused placental cotyledon, placental membrane vesicles or trophoblastic cell cultures. Overall human placental drug transport rarely exceeds the transfer of flow-dependent and membrane-limited marker compounds. Interestingly, relatively often placental drug transfer appeared to be much smaller, indicating impaired trans-placental transport, depending on the physic o-chemical characteristics of the drug or placental factors such as ti ssue binding or metabolism. Although in perfusion studies overall huma n placental drug transport occurs by simple diffusion, at the membrane level several drug transport systems have been found, mainly for drug s structurally related to endogenous compounds.