Selective Serotonin Reuptake Inhibitor Pharmacokinetics During Pregnancy: Clinical and Research Implications

Pharmacotherapy of Chronic Neuropsychiatric Conditions During Pregnancy

Many pregnant persons will experience neuropsychiatric conditions during pregnancy, including migraine, attention deficit disorder, depression, and anxiety. Treatment of each of these conditions requires shared decision-making among the individual, family, and health care team. Although medications may include risk, the benefits often outweigh the potential fetal risks. In this article, we review pharmacologic treatment options for each of these conditions and appropriate use in pregnancy to maintain the stability of conditions and to optimize maternal and fetal outcomes.

Concentrations of Fluoxetine Enantiomers Decline During Pregnancy and Increase After Birth

RATIONALE

Few studies of the effect of the dynamic physiologic changes during pregnancy on plasma concentrations of fluoxetine (FLX) have been published.

OBJECTIVES

We determined the change in concentration to dose (C/D) ratios of R- and S-FLX and R- and S-norfluoxetine monthly during pregnancy and postpartum, assessed their relationships to cytochrome P450 (CYP) 2D6 and CYP2C9 metabolizer phenotypes, and evaluated the course of their depressive and anxiety symptoms.

METHODS

In this observational study, 10 FLX-treated pregnant individuals provided blood samples at steady state every 4 weeks during pregnancy and once postpartum for measurement of plasma FLX and norfluoxetine enantiomer concentrations. Participants were genotyped for variants in CYP2C9 and CYP2D6 using commercial assays with Taqman probes. At each assessment, depressive and anxiety symptoms were quantified.

RESULTS

The C/D ratios of all FLX and norfluoxetine enantiomers, and the active moiety, decreased steadily through pregnancy and rose after birth. In the final trimester, the mean C/D ratio of the active moiety was 24.9% lower compared with the mean nonpregnant, 12-week postpartum C/D ratio. One individual with CYP2D6 ultrarapid metabolizer status was prescribed the highest FLX dose among participants. In these treated individuals, the mean depressive and anxiety symptoms remained in the mild range across the perinatal period.

CONCLUSIONS

These data do not support a recommendation for routine plasma concentration monitoring or CYP2D6 pharmacogenetic testing for pregnant people treated with FLX; however, monitoring for symptom relapse is recommended because of declining plasma drug concentrations.

The Effect of SSRI Exposure in Pregnancy on Early Respiratory and Metabolic Adaptation in Infants Born Preterm

Selective serotonin reuptake inhibitors (SSRIs) are increasingly used for maternal depression during pregnancy; however, their use has been linked to adverse effects in newborns. Respiratory and feeding problems, jaundice, metabolic and temperature dysregulation and hypoglycemia have been described in term infants. However, scarce data exists on early neonatal adaptation in exposed infants born prematurely. We aimed to assess the effects of SSRI exposure on early neonatal adaptation measures in infants born prematurely. Data from preterm infants exposed to maternal SSRIs during pregnancy and from matched controls were retrospectively collected. Forty-two infants comprised the final cohort: 21 infants with SSRI exposure and 21 matched controls. 1 min Apgar score was significantly lower in the exposed group compared to the non-exposed group (p = 0.043). No differences were found in 5 min Apgar scores, cord pH, need for delivery room resuscitation, rate of hypoglycemia, hyponatremia, hyperbilirubinemia, need for phototherapy, temperature stability and maximal oxygen requirements. No differences were found in the total time of respiratory support, time to reaching full enteral feeds, length of stay and complications of prematurity. Unlike studies in term infants, no significant differences were found in adaptation and short-term outcomes between preterm infants with and without SSRI exposure in pregnancy.

Population pharmacokinetics of esomeprazole in patients with preterm preeclampsia

Esomeprazole is a proton pump inhibitor being investigated for treatment of preeclampsia. Esomeprazole pharmacokinetics during pregnancy are unknown. We used data from 10 pregnant participants with preterm preeclampsia, and 49 non-pregnant participants to develop a population pharmacokinetic model of esomeprazole. A two-compartment model described the data well. In pregnant participants after single dose, clearance was 42.2% (14.9% - 61.6%) lower compared to non-pregnant, most likely due to inhibition of CYP2C19. In non-pregnant after repeated dosing, clearance was 54.9% (48.2% - 63.5%) lower in extensive metabolizers and bioavailability was 33% (10.0% - 52.0%) higher compared to single dosing, which could be due to autoinhibition of CYP2C19. During pregnancy, the CYP2C19 autoinhibition effect with repeated dosing is expected to lead to much lower increase in exposure compared to non-pregnant, since CYP2C19 is already inhibited due to pregnancy.