Can Ondansetron (Zofran) be given during pregnancy?

From the Guidelines

Ondansetron can be given in pregnancy, particularly for managing severe nausea and vomiting in pregnancy (NVP) or hyperemesis gravidarum that hasn't responded to first-line treatments, with careful consideration of the potential risks and benefits 1. When considering the use of ondansetron in pregnancy, it's essential to weigh the benefits against the risks. The medication is often prescribed when other treatments fail, and current evidence suggests no significant increase in major birth defects with ondansetron use, though some studies have shown a small increased risk of oral clefts when used in the first trimester 1. Some key points to consider when using ondansetron in pregnancy include:

• The typical dose is 4-8 mg intravenously or intramuscularly every 8 hours as needed 1.
• Ondansetron is not FDA-approved specifically for use during pregnancy, but it is often prescribed when other treatments fail 1.
• Healthcare providers typically recommend trying other safer options first, such as vitamin B6 with doxylamine, before considering ondansetron 1.
• Patients should always discuss the potential risks and benefits with their healthcare provider before using this medication during pregnancy 1. It's also important to note that the European Association for the Study of the Liver Clinical Practice Guidelines recommend ondansetron as a second-line therapy for the management of hyperemesis gravidarum, and the American College of Obstetricians and Gynecologists (ACOG) recommends using ondansetron on a case-by-case basis in patients with persistent symptoms before 10 weeks of pregnancy 1.

From the FDA Drug Label

Published epidemiological studies on the association between ondansetron use and major birth defects have reported inconsistent findings and have important methodological limitations that preclude conclusions about the safety of ondansetron use in pregnancy Available postmarketing data have not identified a drug associated risk of miscarriage or adverse maternal outcomes. Reproductive studies in rats and rabbits did not show evidence of harm to the fetus when ondansetron was administered during organogenesis at approximately 6 and 24 times the maximum recommended human oral dose of 24 mg/day, based on body surface area (BSA), respectively

The use of ondansetron in pregnancy is not directly supported by the FDA drug label as safe. Key points to consider:

• Inconsistent findings in epidemiological studies
• No identified drug-associated risk of miscarriage or adverse maternal outcomes
• Reproductive studies in animals showed no harm to the fetus However, due to the inconsistent findings and methodological limitations, no conclusion can be drawn about the safety of ondansetron use in pregnancy 2 2.

From the Research

Ondansetron Use in Pregnancy

• The use of ondansetron during pregnancy has been studied in several clinical trials, with some studies suggesting its efficacy in treating morning sickness and hyperemesis gravidarum 3, 4.
• However, there are also concerns about the potential risks and benefits associated with its use, particularly with regards to abnormal pregnancy outcomes 5.
• A systematic review and meta-analysis found that ondansetron was not associated with abnormal pregnancy outcomes, although the study noted that future research is needed to fully understand the potential risks and benefits 5.
• Another study found that ondansetron was effective in treating nausea and vomiting in pregnant women, but noted that the current data do not support a reluctance to treat women with ondansetron in clinical practice 4.

Safety and Efficacy

• Ondansetron has been shown to be effective in treating nausea and vomiting, including pregnancy-related morning sickness 3, 4.
• However, the safety of ondansetron during pregnancy is still a topic of debate, with some studies suggesting a potential increased risk of cardiac defects, neural tube defects, and chest cleft 5.
• Other studies have found no significant association between ondansetron and abnormal pregnancy outcomes, including orofacial clefts, spinal limb defects, urinary tract deformities, and stillbirth 5.
• The American College of Obstetricians and Gynecologists recommends early treatment of nausea and vomiting of pregnancy to stop progression to hyperemesis gravidarum, and ondansetron is a commonly used treatment for this condition 4.

Comparison with Other Treatments

• Ondansetron has been compared with other antiemetic treatments, including metoclopramide, in several studies 6, 7.
• One study found that ondansetron was more effective than metoclopramide in preventing nausea and vomiting induced by chemotherapy 6.
• Another study found that ondansetron and metoclopramide were similar in efficacy and safety for treating undifferentiated emergency department nausea and vomiting 7.