Bedtime cimetidine maintenance treatment: optimum dose and effect on subsequent natural history of duodenal ulcer.

Sixty patients, whose duodenal ulcers had healed endoscopically after six weeks of treatment with cimetidine 1 g/day in divided doses, were treated with maintenance cimetidine 800 mg at bedtime for six months. Eighteen relapsed endoscopically (30%). Of the 42 still in remission, 36 then completed a six month double-blind comparison of bedtime cimetidine 400 mg and placebo. Twelve of the 19 (63%) cimetidine-treated patients and 10 of 17 (59%) placebo-treated patients relapsed within six weeks (NS). This high relapse rate on cimetidine contrasts with our earlier trial, in which the six week relapse rate was only two out of 21 (10%) on bedtime cimetidine 800 mg and 16 out of 24 (66%) on placebo (P less than 0.0005). Apart from the difference in the dose of cimetidine, both our trials used the same experimental protocol during the double-blind part of the trial. In the earlier trial, however, there was no period of pretreatment with maintenance cimetidine as in the present trial. The pattern of placebo relapse was similar in both trials. We conclude that bedtime cimetidine maintenance treatment does not alter the long-term natural history of duodenal ulcer once it has been withdrawn; and that either tolerance to cimetidine develops during long-term maintenance treatment, or that bedtime cimetidine maintenance treatment in the conventional dose of 400 mg is not as effective as 800 mg in prevention of endoscopic relapse, although it does reduce symptoms.