Rebound hypersecretion after H2-antagonist withdrawal--a comparative study with nizatidine, ranitidine and famotidine

Our previous study demonstrated rebound nocturnal acid hypersecretion after a 4-week course of nizatidine. Nocturnal acid output was increased by 77% two days after discontinuing treatment compared with pretreatment values. To confirm this effect with other H2-blockers we assessed daytime intragastric pH, fasting and meal-stimulated plasma gastrin and nocturnal acid output in 9 duodenal ulcer patients in remission before, during and two days after treatment with three different drugs. Each patient received 4-week courses of 300 mg ranitidine, 40 mg famotidine or 300 mg nizatidine, taken at 20.00 hours in randomized order with a 'washout' period of 4 weeks between each course of drug. Median nocturnal acid output (mmol/10 h) decreased during treatment with ranitidine to 3 (range 0-17), famotidine to 4 (1-12) and nizatidine 6 (0-40) compared with the respective pre-treatment values, 49 (20-126; P less than 0.01), 52 (22-105; P less than 0.01) and 32 (23-114; P less than 0.01). Two days after discontinuing treatment nocturnal acid output was increased after ranitidine at 77 (28-237; P less than 0.04) and after nizatidine at 64 (17-130; P less than 0.05) compared with pre-treatment values. There was no significant change in nocturnal acid output after famotidine at 57 (27-107) compared with the pre-treatment value. There was no change in daytime intragastric pH with any drug during or after treatment compared with the pre-treatment values. Fasting and meal-stimulated plasma gastrin concentrations were increased on the final treatment day with ranitidine and famotidine but had returned to pretreatment levels two days after treatment. The rebound acid hypersecretion may contribute to the high ulcer relapse rate after discontinuation of H2-receptor antagonists.