Objective: To compare ondansetron with metoclopramide in the treatment of hyperemesis gravidarum.

Methods: We enrolled 160 women with hyperemesis gravidarum in a double-blind randomized trial. Participants were randomized to intravenous 4 mg ondansetron or 10 mg metoclopramide every 8 hours for 24 hours. Participants kept an emesis diary for 24 hours; at 24 hours, they expressed their well-being using a 10-point visual numeric rating scale and answered an adverse effects questionnaire. Nausea intensity was evaluated using a 10-point visual numeric rating scale at enrollment and at 8, 16, and 24 hours. Primary analysis was on an intention-to-treat basis.

Results: Eighty women each were randomized to ondansetron or metoclopramide. Median well-being visual numeric rating scale scores were 9 (range, 5-10) compared with 9 (range, 4-10) (P=.33) and vomiting episodes in the first 24 hours were 1 (range, 0-9) compared with 2 (range, 0-23) (P=.38) for ondansetron compared with metoclopramide, respectively. Repeat-measures analysis of variance of nausea visual numeric rating scale showed no difference between study drugs (P=.22). Reported rates of drowsiness (12.5% compared with 30%; P=.01; number needed to treat to benefit, 6), xerostomia (10.0% compared with 23.8%; P<.01; number needed to treat to benefit, 8), and persistent ketonuria at 24 hours (12.5% compared with 30%; P=.01; number needed to treat to benefit, 6) were less frequent with ondansetron. Length of hospital stay was similar.

Conclusion: Ondansetron and metoclopramide demonstrated similar antiemetic and antinauseant effects in hyperemesis gravidarum. However, the overall profile, particularly regarding adverse effects, was better with ondansetron. In our setting, metoclopramide was significantly less expensive than ondansetron and remained a reasonable antiemetic choice.

Clinical trial registration: ISRCN Register, www.isrctn.org, ISRCTN00592566.

Level of evidence: I.