Maternal & fetal drug effects
Fetal drug exposure
Teratogenic defects in an unborn child can occur from fetal drug exposure. The placenta is permeable to molecules smaller than 1000Da (most drugs). Other criteria for placental passage are lipid solubility (lipophilic agents pass easier than hydrophilic), extent of plasma binding and degree of ionisation. The effects of drugs in the fetus depend on the type of drug, the period of drug use
and the drug concentration in fetal tissues. Because the placental lining is permeable to most drugs, fetal drug exposure comes from and is almost equal to maternal drug exposure.
So it is important to note that maternal drug exposure is dynamic during the course of pregnancy. To better examine the effects on the fetus, we will explore the effects on the mother.
Which category of drugs has the best passage over the placenta ?