Larson and colleagues conducted a study to assess if ranitidine given once or twice a day has a role in relieving symptoms of gastroesophageal reflux among pregnant women who had not improved with conservative measures.

This double-blind, placebo-controlled, triple crossover trial included women with heartburn despite antacid use from among the obstetrics clinic population. Following a baseline week, 20 participants were randomly allocated to the three weekly regimens - ranitidine 150 mg twice a day, placebo in the morning and ranitidine 150 mg in the evening, or placebo twice a day. Eighteen patients completed the study. Investigators compared the daily scores on symptom diaries, global assessments, and number of antacids taken.

• Twice-daily ranitidine reduced heartburn symptoms in comparison with baseline (P < .001) or placebo (P < .01).
• In comparison with ranitidine once daily, the twice-daily regimen was associated with less requirement of antacids compared with placebo (P < .05 versus P > .05) and baseline (P < .001 versus P < .05).
• The average reduction in heartburn severity with twice-daily ranitidine was 55.6% when compared with baseline, and 44.2% when compared with placebo.

Clearly, twice-daily ranitidine 150 mg is effective for relieving gastroesophageal reflux symptoms in pregnant women.

Source: Larson JD, Patatanian E, Miner Jr PB, et al. Double-blind, placebo-controlled study of ranitidine for gastroesophageal reflux symptoms during pregnancy. Obstet Gynecol. 1997 Jul;90(1):83-7.