Drug-Drug

• Nevirapine induces the hepatic CYP3A4 enzyme system and can affect the behavior of drugs metabolized by this system.

• Significantly ↓ ketoconazole levels (concurrent use contraindicated).

• May induce methadone withdrawal within 2 weeks of starting therapy in patients physically dependent on methadone.

• May ↓ levels and effectiveness hormonal contraceptives (concurrent use of hormonal contraceptives should be avoided).

• Rifampin significantly ↓ levels and effectiveness of nevirapine (concurrent use contraindicated). ↓ Levels and effectiveness of clarithromycin (consider other agents). Also may ↓ levels and effectiveness of the following: lopinavir , fosamprenavir , saquinavir , nelfnavir , indinavir , efavirenz , amiodarone , disopyramide , lidocaine , itraconazole , carbamazepine , clonazepam , ethosuximide , diltiazem , nifedipine , verapamil , cyclosporine , tacrolimus , sirolimus , cyclophosphamide , ergotamine fentanyl rifabutin ; use together only with careful monitoring; ↑ dose of lopinavir/ritonavir to 500/125 mg twice daily.

• Fluconazole ↑ nevirapine levels and risk of toxcity.

• May ↑ risk of bleeding with warfarin .

• Use of prednisone during first 2 wk of therapy may ↑ risk of rash.

• Initiating other drugs that often cause rash , including trimethoprim/sulfamethoxazole and abacavir simultaneously with nevirapine may ↑ risk of rash.

• Concurrent use with atazanavir may ↓ atazanavir levels and ↑ nevirapine levels (concurrent use not recommended).

• May ↑ levels of darunavir/ritonavir and maraviroc .

Drug-Natural Products
St. John's wort may ↓ efficacy.