Ondansetron in pregnancy revisited: Assessment and pregnancy labelling by the European Medicines Agency (EMA) & Pharmacovigilance Risk Assessment Committee (PRAC)

Risk of abnormal pregnancy outcomes after using ondansetron during pregnancy: A systematic review and meta-analysis

Background: Hyperemesis gravidarum is a serious pregnancy complication that affects approximately 1% of pregnancies worldwide.

Objective: To determine whether the use of ondansetron during pregnancy is associated with abnormal pregnancy outcomes.

Search strategy: PubMed, Cochrane Library, CINAHL, Embase, CNKI, CBM, WANFANG, and ClinicalTrials.gov were searched for citations published in any language from inception to 15 December 2021.

Selection criteria: Eligible studies included any observational study.

Data collection and analysis: Odds ratio (OR) and 95% confidence interval (CI) were used as indicators to examine the association between ondansetron and abnormal pregnancy outcomes.

Main results: Twenty articles from 1,558 citations were included. Our preliminary analysis showed that compared with the unexposed group, the use of ondansetron during pregnancy may be associated with an increased incidence of cardiac defects (OR = 1.06, 95% CI: 1.01–1.10), neural tube defects (OR = 1.12, 95% CI: 1.05–1.18), and chest cleft (OR = 1.21, 95% CI: 1.07–1.37). Further sensitivity analysis showed no significant association between ondansetron and cardiac defects (OR = 1.15,95% CI: 0.94–1.40) or neural tube defects (OR = 0.87,95% CI: 0.46–1.66). When controversial studies were eliminated, the results for the chest defects disappeared. Simultaneously, we found that the use of ondansetron was associated with a reduced incidence of miscarriage (OR = 0.53, 95% CI: 0.31–0.89). Ondansetron was not associated with orofacial clefts (OR = 1.09,95% CI: 0.95–1.25), spinal limb defects (OR = 1.14,95% CI: 0.89–1.46), urinary tract deformities (OR = 1.06,95% CI: 0.97–1.15), any congenital malformations (OR = 1.03,95% CI: 0.98–1.09), stillbirth (OR = 0.97,95% CI: 0.83–1.15), preterm birth (OR = 1.22,95% CI: 0.80–1.85), neonatal asphyxia (OR = 1.05,95% CI: 0.72–1.54), or neonatal development (OR = 1.18,95% CI: 0.96–1.44) in our primary analysis.

Conclusion: In our analysis, using ondansetron during pregnancy was not associated with abnormal pregnancy outcomes. Although our study did not find sufficient evidence of ondansetron and adverse pregnancy outcomes, future studies including the exposure period and dose of ondansetron, as well as controlling for disease status, may be useful to truly elucidate the potential risks and benefits of ondansetron.

The Role of Serotonin Neurotransmission in Gastrointestinal Tract and Pharmacotherapy

5-Hydroxytryptamine (5-HT, serotonin) is a neurotransmitter in both the central nervous system and peripheral structures, acting also as a hormone in platelets. Although its concentration in the gut covers >90% of all organism resources, serotonin is mainly known as a neurotransmitter that takes part in the pathology of mental diseases. Serotonin modulates not only CNS neurons, but also pain transmission and platelet aggregation. In the periphery, 5-HT influences muscle motility in the gut, bronchi, uterus, and vessels directly and through neurons. Serotonin synthesis starts from hydroxylation of orally delivered tryptophan, followed by decarboxylation. Serotonin acts via numerous types of receptors and clinically plays a role in several neural, mental, and other chronic disorders, such as migraine, carcinoid syndrome, and some dysfunctions of the alimentary system. 5-HT acts as a paracrine hormone and growth factor. 5-HT receptors in both the brain and gut are targets for drugs modifying serotonin neurotransmission. The aim of the present article is to review the 5-HT receptors in the gastrointestinal (GI) tract to determine the role of serotonin in GI physiology and pathology, including known GI diseases and the role of serotonin in GI pharmacotherapy.