Antipsychotics in pregnancy – do we need Therapeutic Drug Monitoring?

Treating psychiatric disorders during pregnancy requires balancing of risks between minimal maternal–fetal drug exposure and a maximum maternal efficacy. Physiological changes in pregnancy are known to cause changes in drug disposition and may alter antipsychotic concentrations in serum and plasma. However, evidence regarding changes in antipsychotic disposition seen in pregnancy is scarce.

The English-language literature indexed on PubMed was searched for publications that evaluated pharmacokinetic changes or Therapeutic Drug Monitoring (TDM) of antipsychotic drugs during pregnancy.

CYP3A induction reduces plasma concentrations of antipsychotic drugs. Serum concentrations of quetiapine and aripiprazole decrease by more than 50% during pregnancy, whereas olanzapine concentrations seem to remain largely unchanged during pregnancy. Olanzapine, haloperidol, clozapine, and risperidone show the highest ratios of antipsychotic excretion into the umbilical cord blood.

The results warrant a reconsideration of the general advice of using the pre-pregnancy “minimum effective dose” of antipsychotics during pregnancy. As drug clearance increases, sub therapeutic drug levels may ensue, potentially exposing the mother and unborn child to both the medication and the illness. Due to the physiological changes of pregnancy and enhanced hepatic metabolism, drug doses may need to be adjusted during pregnancy to sustain efficacy.

Publication History

Article published online:
12 March 2024