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