The Sound of Evolution
Cimetidine
Mechanism of action:
Cimetidine is a first-generation histamine H₂ receptor antagonist. In gastric parietal cells, histamine binds to the H₂ receptor, activates adenylyl cyclase, and increases cAMP levels. This then promotes both the activity and membrane expression of the hydrogen potassium ATPase (H⁺/K⁺-ATPase), thereby stimulating gastric acid secretion. Cimetidine competitively antagonizes the H₂ receptor and blocks these effects.
Reference(s):
1. Michnovicz JJ et al. (1991). Cimetidine inhibits catechol estrogen metabolism in women. Metabolism.
2. Larsson R et al. (1982). The pharmacokinetics of cimetidine and its sulphoxide metabolite in patients with normal and impaired renal function. Br J Clin Pharmacol.
3. Lu X et al. (1998). Cimetidine sulfoxidation in small intestinal microsomes. Drug Metab Dispos.