, Blainville, Canada) was approved by the FDA in April 2013.2 The withdrawal of Bendectin from the US left American women without an FDA-approved drug for NVP and was associated with a 3-fold increased risk of hospitalization of women STI571 manufacturer for the severe forms of this condition.3 Presently, 97.7% of prescriptions for the treatment of NVP in the US are with medications

not labeled for use in pregnancy, not indicated for NVP, and not classified as safe in pregnancy (FDA category A). The use of inhibitors ondansetron for the treatment of NVP has steadily increased from 50,000 prescriptions per month in 2008 to 110,000 at the end of 2013 (Figure). This means that around 1 million pregnant American women are exposed to ondansetron out BMS-354825 chemical structure of 4 million pregnancies a year. Ondansetron (GlaxoSmithKlein Inc, Philadelphia, PA) is a serotonin 5-HT3 receptor antagonist, originally introduced to prevent nausea and vomiting induced by cancer chemotherapy, radiation therapy, and surgery. The fact that ondansetron became generic in 2007, and hence its price dropped, might have been an important cause for this increase,

with easier access to Medicaid and health maintenance organizations. Prescribing ondansetron as a first line option is not consistent with American Professors in Gynecology and Obstetrics and American College of Obstetricians and Gynecologists evidence-based recommendations for the management of NVP.4 and 5 It should be remembered that most drugs used in pregnancy, including steroids for the Astemizole prevention of respiratory distress syndrome, all tocolytic agents, and magnesium sulfate for the prevention of cerebral palsy,

to mention a few, have not been approved by the FDA. Yet, they are standard of care. In contrast, in the case of ondansetron there are unresolved issues surrounding the fetal and maternal safety, including recent warnings by the FDA on its potential to cause serious dysrhythmias.6 The fetal safety of the ondansetron was first investigated in humans by Einarson et al7 in 2004 through a prospective controlled cohort study of 176 women, in whom we could not detect an increased teratogenic risk. However, this sample size had the statistical power to rule out only a 5-fold increased risk of major malformations, and not any specific malformation. In February 2013, Pasternak et al8 reported that ondansetron was not associated with increased malformation rates when used for morning sickness. This was based on retrospective analysis of data from the Danish Birth Registry, collected between 2004 and 2011 and linked to the National Prescription Register. Each of the 1970 women exposed to ondansetron was matched to 4 unexposed controls.