Drug-Drug:
- ↑risk of hypotension with concurrent use of nitrates, nitric oxide donors (including amyl nitrate), specific PDE-5 inhibitors (including sildenafil, tadalafil, or vardenafil), and nonspecific PDE-5 inhibitors (including dipyridamole or theophylline); concurrent use contraindicated; do not administer within 24 hr of sildenafil; do not administer 24 hr before or within 48 hr after tadalafil.
- Concurrent use with soluble guanylate cyclase stimulators (including vericiguat) is contraindicated.
- Strong CYP and P-glycoprotein (P-gp)/breast cancer resistance protein (BCRP) inhibitors, including azole antifungals (ketoconazole and itraconazole) and protease inhibitors (ritonavir), ↑ levels and the risk of adverse reactions including hypotension; consider ↓ initial dose.
- Strong CYP3A inducers, including carbamazepine, phenobarbital, phenytoin, and rifampin, ↓ levels and may ↓ effectiveness.
- Concurrent use of antihypertensives, including diuretics, may ↑ risk of hypotension.
- Antacids↓ absorption; separate doses by
1 hr. - Cigarette smoking ↓levels and effectiveness; ↑ dose may be necessary and dose readjustment required after smoking cessation.
Drug-Natural Products:
- St. John's wort ↓levels and may ↓ effectiveness.