Tadalafil Erythromycin

Sildenafil doses should be decreased when any potent cytochrome P450 3A4 inhibitor is used (e g., cimetidine, erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and saquinavir). Vardenafil doses vary accordingto which agent is used (2.5 mg q 72 h for ritonavir, 2.5 mg q 24 h for indinavir, ketoconazole 400 mg daily, and itraconazole 400 mg daily and 5 mg q 24 h for ketoconazole 200 mg daily, itraconazole200 mg daily, and erythromycin). Tadalafil doses are reduced only when it is used with the most potent cytochrome P450 3A4 inhibitors (e g., ketoconazole or ritonavir). 

Others Acetaminophen, amiodarone, carbamazepine, delavirdine, efavirenz, nevirapine, quinidine, repaglinide, sildenafil, tadalafil, trazodone, vardenafil Amiodarone, amprenavir, atazanavir, ciprofloxacin, cisapride, clarithromycin, diltiozem, erythromycin, fluconazole, fluvoxamine, grapefruit juice (in high ingestion), indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, norfloxacin, ritonavir, telithromycin, troleandomycin, verapamil, voriconazole Carbamazepine, efavirenz, glucocorticoids, macrolide antibiotics, nevirapine, phenytoin, phenobarbital, rifabutin, rifapentine, rifampin, St. John s wort... 

Ketoconazole (400 mg daily), a selective and potent inhibitor of CYP3A4, increased tadalafil 20-mg single-dose exposure (AUC) by 312%. Other CYP inhibitors—Although specific interactions have not been studied, other CYP3A4 inhibitors, such as erythromycin, itraconazole, and grapefruit juice, would likely increase tadalafil exposure. 

Erythromycin raises sildenafil levels almost threefold and raises vardenafil levels fourfold. Clarithromycin raises sildenafil levels about twofold. Erythromycin is predicted to similarly raise tadalafil levels. Azithromycin does not interact with sildenafil. 

Ketoconazole , (p.l270), doubles tadalafil levels. The manufacturers therefore predict that other CYP3A4 inhibitors such as erythromycin will interact similarly. 

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