Outline the factors influencing the transport of drugs across the placenta
The main points candidates were expected to know included the passive and active
mechanisms that regulate the transfer of drugs across placenta and the potential clinical
implications of drugs use in pregnancy in order to pass this question .
Good answers to this question included examples to all the possible mechanisms that can
affect the transport of drugs across placenta.
The common omissions were degree of ionisation, active transporters, placental metabolism,
explanation on the interaction between protein binding and ionisation of a drug in regulating
placenta transfer, and the expected molecular size or weight of a drug that affects passive
placental transfer of the drug.