Effect of cimetidine on intrinsic factor secretion stimulated by different doses of pentagastrin in patients with impaired renal function.

Gastric intrinsic factor (IF) secretion was examined in five patients with impaired renal function during stepwise increasing doses (0.02, 0.2, and 2.0 micrograms/kg/h) of intravenous infusion of pentagastrin alone or in combination with continuous intravenous infusion of cimetidine (05 mg/kg/h) after and initial bolus of 1.5 mg/kg. Whereas cimetidine caused a moderate reduction of maximally stimulated IF output, the output during submaximal stimulation was reduced to basal levels by cimetidine. The results suggest that IF insufficiency may occur during cimetidine treatment in patients with impaired renal function on long-term treatment with H2-blockers.