Rebound nocturnal hypersecretion after four weeks treatment with an H2 receptor antagonist.

Daytime intragastric pH, fasting and meal stimulated serum gastrin and nocturnal acid output were studied in eight male duodenal ulcer patients before, during and two days after completing nizatidine 300 mg nocte (20:00 h) for four weeks. Median nocturnal acid output (mmol/10 h) decreased during treatment to 11.6 (range 0.4-26.7) compared with pretreatment value of 39.4 (9.8-91.2); median acid inhibition 77% (p less than 0.01) which was strongest between 24:00 and 04:00 h. Two days after discontinuing treatment, nocturnal acid output increased to 74.1 (11-181). Compared with the pretreatment value this represents median rebound hypersecretion of 77% (p less than 0.05), caused by increased H+ concentration and volume of secretion. Overall median daytime intragastric pH (09:00-21:00 h) was unchanged on the final day of treatment and two days after completing therapy, compared with the pretreatment values. Fasting serum gastrin measured between 09:30 and 10:00 h and the integrated gastrin response to an OXO breakfast taken out at 10:00 h were also similar during and after treatment, compared with pretreatment values. The rebound nocturnal hypersecretion may be relevant to the high ulcer relapse rates after stopping H2 receptor antagonists.