Effect of gabapentin on hyperemesis gravidarum: a double-blind, randomized controlled trial.

Background: Hyperemesis gravidarum is a disabling disease of nausea, vomiting, and undernutrition in early pregnancy for which there are no effective outpatient therapies. Poor weight gain in hyperemesis gravidarum is associated with several adverse fetal outcomes including preterm delivery, low birthweight, small for gestational age, low 5-minute Apgar scores, and neurodevelopmental delay. Gabapentin is most commonly used clinically for treating neuropathic pain but also substantially reduces chemotherapy-induced and postoperative nausea and vomiting. Pregnancy registry data have shown maternal first-trimester gabapentin monotherapy to be associated with a 1.2% rate of major congenital malformations among 659 infants, which compares favorably with the 1.6% to 2.2% major congenital malformation rate in the general population. Open-label gabapentin treatment in hyperemesis gravidarum was associated with reduced nausea and vomiting and improved oral nutrition.

Objective: This study aimed to determine whether gabapentin is more effective than standard-of-care therapy for treating hyperemesis gravidarum.

Study Design: A double-blind, randomized, multicenter trial was conducted among patients with medically refractory hyperemesis gravidarum requiring intravenous hydration. Patients were randomized (1:1) to either oral gabapentin (1800-2400 mg/d) or an active comparator of either oral ondansetron (24-32 mg/d) or oral metoclopramide (45-60 mg/d) for 7 days. Differences in Motherisk-pregnancy-unique quantification of nausea and emesis total scores between treatment groups averaged over days 5 to 7, using intention-to-treat principle employing a linear mixed-effects model adjusted for baseline Motherisk-pregnancy-unique quantification of nausea and emesis scores, which served as the primary endpoint. Secondary outcomes included Motherisk-pregnancy-unique quantification of nausea and emesis nausea and vomit and retch subscores, oral nutrition, global satisfaction of treatment, relief, desire to continue therapy, Nausea and Vomiting of Pregnancy Quality of Life, and Hyperemesis Gravidarum Pregnancy Termination Consideration. Adjustments for multiple comparisons were made employing the false discovery rate.

Results: A total of 31 patients with hyperemesis gravidarum were enrolled from October 2014 to May 2019. Among the 21 patients providing primary outcome data (12 assigned to gabapentin and 9 to the active comparator arm), 18 were enrolled as outpatients and all 21 were outpatients from days 5 to 7. The study groups' baseline characteristics were well matched. Gabapentin treatment provided a 52% greater reduction in days 5 to 7 baseline adjusted Motherisk-pregnancy-unique quantification of nausea and emesis total scores than treatment with active comparator (95% confidence interval, 16-88; P=.01). Most secondary outcomes also favored gabapentin over active comparator treatment including 46% and 49% decreases in baseline adjusted Motherisk-pregnancy-unique quantification of nausea and emesis nausea (95% confidence interval, 19-72; P=.005) and vomit and retch subscores (95% confidence interval, 21-77; P=.005), respectively; a 96% increase in baseline adjusted oral nutrition scores (95% confidence interval, 27-165; P=.01); and a 254% difference in global satisfaction of treatment (95% confidence interval, 48-459; P=.03). Relief (P=.06) and desire to continue therapy (P=.06) both showed trends favoring gabapentin treatment but Nausea and Vomiting of Pregnancy Quality of Life (P=.68) and Hyperemesis Gravidarum Pregnancy Termination Consideration (P=.58) did not. Adverse events were roughly equivalent between the groups. There were no serious adverse events.

Conclusion: In this small trial, gabapentin was more effective than standard-of-care therapy for reducing nausea and vomiting and increasing oral nutrition and global satisfaction in outpatients with hyperemesis gravidarum. These data build on previous findings in other patient populations supporting gabapentin as a novel antinausea and antiemetic therapy and support further research on gabapentin for this challenging complication of pregnancy.