Which drugs or supplements interact with atazanavir?

Atazanavir inhibits the enzymes that eliminate many drugs from the body. Administration of these drugs along with atazanavir may result in increased concentrations of these drugs and cause more side effects. Atazanavir also is eliminated by enzymes in the liver, and drugs that increase the activity of these enzymes may decrease the concentration of atazanavir in the blood and reduce the effect of atazanavir. Conversely, drugs that prevent the elimination of atazanavir may increase the concentration of atazanavir in the blood and cause increased atazanavir-related side effects. Some of the important potential or known interactions are mentioned below. Viewers should consult their health care professional before combining any drugs with atazanavir.

Rifampin (Rifadin), St. John’s Wort, tenofovir (Viread), and efavirenz (Sustiva) decrease the blood levels of atazanavir and this can reduce the effect of atazanavir. Dose modifications are necessary when atazanavir is combined with efavirenz or tenofovir. Rifampin and St. John’s Wort should not be combined with atazanavir.

Atazanavir decreases the elimination and, therefore, could increase the side effects of triazolam (Halcion), midazolam (Versed), bepridil (Vascor), verapamil (Isoptin) , diltiazem (Cardizem), lovastatin (Mevacor), simvastatin (Zocor), atorvastatin (Lipitor), pimozide (Orap), irinotecan (Camptosar), cyclosporine (Sandimmune), rifabutin (Mycobutin), amiodarone (Cordarone), clarithromycin (Biaxin), alfuzosin (Uroxatral), and ergot drugs (Migranal, Cafergot). Combining atazanavir with lovastatin, simvastatin, pimozide, triazolam, midazolam, irinotecan, ergot drugs, or alfuzosin is contraindicated.

Atazanavir is best absorbed under acidic conditions. Therefore, medications that decrease stomach acidity could reduce the absorption of atazanavir. Drugs that decrease stomach acidity include antacids, proton pump inhibitors such as omeprazole (Prilosec), lansoprazole (Prevacid), pantoprazole (Protonix), rabeprazole (Aciphex) esomeprazole (Nexium); H2-receptor antagonists such as cimetidine (Tagamet), ranitidine (Zantac), famotidine (Pepcid), nizatidine (Axid); and buffered drugs such as didanosine (Videx). Individuals who are taking antacids or didanosine should take their atazanavir two hours before or one hour after the didanosine or antacid. Proton pump inhibitors should not be combined with atazanavir in previously treated patients. For treatment naive patients the dose of proton pump inhibitor should not exceed the equivalent of omeprazole 20 mg and must be given 12 hours before administration of atazanavir. The dose of H2-antagonists should not exceed the equivalent of 40 mg famotidine twice daily and atazanavir should be administered 2 hours before or 10 hours after administration of the H2-antagonists.

Atazanavir increases the effect of warfarin (Coumadin). Therefore the effect of warfarin should be monitored more frequently and doses should be modified accordingly.

Combining amiodarone (Cordarone), lidocaine, quinidine, or bepridil (Vascor) with atazanavir may cause dangerous abnormal heart rhythms.

Atazanavir increases blood levels of PDE5 inhibitors such as sildenafil (Viagra, Revatio), tadalafil (Adcirca, Cialis), and vardenafil (Levitra). Atazanavir should not be combined with Revatio (sildenafil used for treating pulmonary hypertension). It should be used with caution with reduced doses of the other PDE5 inhibitors.

What else should I know about atazanavir?

What preparations of atazanavir are available?

Capsules: 100, 150, 200, and 300 mg

How should I keep atazanavir stored?

Atazanavir should be stored at room temperature, between 15 C to 30 C (59 F to 86 F).