Cimetidine Overview Cimetidine is an H2 receptor antagonist. It’s a competitive, reversible inhibitor of the action of histamine at the histamine H2-receptors, including receptors on the gastric cells. Cimetidine does not lower serum Ca++ in hypercalcemic states. Also, it is not an anticholinergic agent. Cimetidine when given as an intravenous bolus, stimulates the secretion of … Read moreCimetidine