Evaluation of side effects of ondansetron in pregnancy: a descriptive case-series study

Ondansetron is a 5-hydroxytryptamine receptor antagonist which is a highly effective antiemetic for postoperative and chemotherapy induced nausea and vomiting. It is an off-label drug to treat nausea and vomiting of pregnancy but availa-ble data about its safety is limited. In this study our purpose was to evaluate neonatal outcomes in women who received this treatment. This study is a descriptive retrospective case series study, included 22 preg-nant women who treated with ondansetron due to repeated nausea and vomiting unre-sponsive to our center's protocol, at Mahdiyeh Hospital, Tehran, Iran from May 2006 to September 2014. We investigated neonatal factors including: gestational age at birth, stillbirth, neonatal birth weight, apgar score, need to NICU admission and major birth defects. The outcomes of 22 pregnancies and 22 newborns are presented here. We had two twin pregnancies and two abortions. Ondansetron was initiated in 18 cases (72%) on average gestational age of 9 weeks, during organogenesis. In 8 cases (32%) on-dansetron continued till third trimester of pregnancy. In primary evaluation, all the pa-tients had ketonuria, 15 cases (60%) had hypokalmia (K< 3.5), 3 cases (12%) had ab-normal TSH that all of them were hyperthyroidism and 5 cases (20%) had abnormal liver function test (LFT) Three patients (12%) had positive urine culture, one patient had hypercalcemia and one patient who was known a case of hypocalcemia had low serum calcium. The mean time of admission due to hyperemesis gravidarum (HG) was 5 days (2-10 sd=1.92). In this study we had only one preterm birth and the mean neo-natal birth weight was 3110 gram, one newborn was low birth weight due to preterm birth. Finally none of newborns had low apgar score, no one needed to NICU admis-sion and no congenital anomaly was seen in neonates. Ondansetron taken during pregnancy was not associated with increased risk of adverse fetal outcomes.