ObjectiveTo determine whether ranitidine (Zantac) taken once or twice daily is effective for relieving symptoms of gastroesophageal reflux among pregnant women who had failed conservative measures.MethodsVolunteers with heartburn despite antacids were sought among our obstetric clinic population for this double-blind, placebo-controlled, triple crossover trial. After a baseline week, 20 patients were randomized to receive the three following weekly regimens: ranitidine 150 mg twice daily, placebo in the morning and ranitidine 150 mg in the evening, or placebo twice daily. Daily scores on symptom diaries, global assessments, and number of antacids taken were compared among the 18 patients completing the study.ResultsThe twice-daily dosage of ranitidine was the only regimen found to reduce heartburn symptoms when compared with the baseline (P< .001) or a placebo (P< .01). Compared with ranitidine taken once daily, the twice-daily dosing prompted less need for antacid tablets compared with the placebo (P< .05 versusP> .05) and to the baseline (P< .001 versusP< .05). The average reduction of heartburn severity using twice-daily ranitidine was 55.6% when compared with baseline (95% confidence interval [CI] 34.8%, 76.5%) and was 44.2% when compared with placebo (95% CI 15.4%, 72.9%).ConclusionThis study indicates the efficacy of ranitidine 150 mg taken twice daily, rather than once daily, for relief of gastroesophageal reflux symptoms during pregnancy.