The most serious drug interaction with Tadalafil occurs with:
Most serious drug interaction with Tadalafil occurs with Nitrates. Administration of Tadalafil to patients using anu form of organic nitrate is contraindicated as it can cause potentially fatal hypotension. This is thought to result from the combined effects of nitrates and Tadafanil on the nitric oxide/cGMP pathway. Phosphodiesterase inhibitors (sildenafil, vardenafil, tadalafil) used to treat erectile dysfunction enhance nitric oxide production and can cause potentially fatal hypotension when used in combination of nitrates. These two drugs should not be used together within 24 hours (sildenafil) or 48 hours (vardenafil, tadafanil) due to this. Tadafanil drug Interactions (FDA Prescribing Information) Contraindicated Use with Caution Nitrates (Potentiates Hypotensive effect. May cause fatal Hypotension) Alpha-Blocker (Potentiates hypotensive Effect) Anti-hypeensives (Potentiates Hypotensive Effect) Alcohol (Potentiates Hypotensive Effect) CYP3A4 inhibitors (eg., Ketoconazole, Ritonavir) may increase levels of tadafanil CYP3A4 inducers (eg., Rifampicin) may decrease levels of Tadafanil When Tadafanil is co-adminstered with an alpha blocker; patients should be stable on alpha-blocker therapy prior to initiating treatment with Tadafanil and tadafanil should be initiated at the lowest recommeded dose. For patients taking Tadafanil (for use as needed) , concominant potent inhibitors of CYP3A4, such as ketoconazole or ritonavir, the maximum recommended dose of Tadafanil is 10 mg, not to exceed once every 72 hours. For patients taking Tadafanil (once daily), concomitant potent inhibitors of CYP3A4; such as ketoconazole or ritonavir, the dose should not exceed 2.5mg. Ref: The second Princeton consensus on sexual dysfunction and cardiac risk; new guidelines for sexual medicine
NItrates
Alpha-Blockers
Ketoconazole
Rifampicin
Other topics and Adverse effects