Serum gastrin after 12 months' continuous cimetidine therapy for duodenal ulcer.

Serum immunoreactive gastrin was measured in 14 patients with duodenal ulcer before and during a 12-month course of cimetidine 400 mg bd. All patients were symptomatically well during the cimetidine therapy and both basal gastrin and that in response to a protein rich meal were assessed before, at six months and at 12 months during therapy. The basal and post-prandial gastrin were significantly higher at six and 12 months on cimetidine than before cimetidine but the six and 12 month levels were similar. This study thus shows that the progressive increase in serum gastrin during six months of continuous cimetidine therapy does not occur beyond this time period.