PEBC: What You Should Know: H2 Receptor Antagonists

Examples: Ranitidine, Famotidine, Nizatidine, Cimetidine

Indications: dyspepsia, can also be used off-label for allergic reactions due to partial H1 blockade

Dosing: most can be dosed once to twice daily

Adverse Effects:

-usually well-tolerated

-occasional headache, diarrhea, constipation, fatigue

-may impair calcium, iron absorption

**Cimetidine: gynecomastia, impotence

Drug Interactions:

-affects absorption of acid-dependent drugs such as atazanavir, ketoconazole; may need to administer 2 hours before H2 receptor antagonist

-cimetidine is a CYP1A2, 2C19, 2D6 and 3A4 inhibitor; careful with substrates

-bisphosphonates: reduced absorption