Over-the-counter H(2)-receptor antagonists do not compromise intragastric pH control with proton pump inhibitors

Proton pump inhibitors effectively suppress intragastric acid. Nocturnal acid breakthrough occurs on any dosing regimen of oral proton pump inhibitors. Histamine(2)-receptor antagonists (H(2)RA) suppress intragastric acidity independently of meals and help to control nocturnal acid breakthrough. Because proton pump inhibitors require an acid intragastric milieu for activation, nocturnal dosing of H(2)RA might decrease the effect of proton pump inhibitors taken in the morning by decreasing their gastric-acid-driven activation.

Assess intragastric acid control on omeprazole, 20 mg, taken every morning, after variable dosing of over-the-counter famotidine, 10 mg.

Twelve Helicobacter pylori-negative, healthy volunteers received omeprazole, 20 mg, every morning before breakfast for 15 days. Baseline studies on omeprazole, 20 mg, in the morning, were done on day 7. On nights between days 8-9, 11-12 and 14-15, famotidine, 10 mg at bedtime, and 10 mg at bedtime and/or at 05.30 h, was given in a three-way, crossover, double-blind randomized design. Intragastric pH monitoring was performed on days 9, 12 and 15, starting at 08.00 h.

Percentage times intragastric pH < 4 on omeprazole, 20 mg, in the morning of the day after receiving famotidine, 10 mg, at bedtime (58.6 +/- 4.8); at 05.30 h (54.1 +/- 5.1); or at bedtime and at 05.30 h (54.3 +/- 5.0) did not differ significantly (P=0.65) from percentage times intragastric pH on day 7 of omeprazole, 20 mg, in the morning (49.5 +/- 5.1).

Concerns over inhibition of next-day daytime proton-pump inhibitor effect should not preclude use of nocturnal H(2)RAs in patients with gastro-oesophageal reflux disease.