atazanavir, Reyataz (cont.)
Omudhome Ogbru, PharmD
Omudhome Ogbru, PharmD
Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.
Medical and Pharmacy Editor:
GENERIC AVAILABLE: No
PREPARATIONS: Capsules: 100, 150, 200, and 300 mg
STORAGE: Atazanavir should be stored at room temperature, between 15 C to 30 C (59 F to 86 F).
PRESCRIBED FOR: Atazanavir is used in combination with other drugs for the treatment of HIV infections.
DOSING: The starting dose of atazanavir for treatment naive adults is 300 mg atazanavir plus 100 mg ritonavir (Norvir) once daily with food or 400 mg atazanavir once daily with food if unable to tolerate ritonavir.
Ritonavir increases the concentration of atazanavir in the blood. Efavirenz (Sustiva) decreases the concentration of atazanavir in the blood. Therefore, when patients are receiving both atazanavir and efavirenz, 100 mg ritonavir also should be added to 400 mg atazanavir in order to keep the levels of atazanavir in the blood at the desired levels.
Adults who have previously received treatment should not be treated with atazanavir alone. They should receive atazanavir 300 mg plus ritonavir 100 mg once daily or atazanavir 400 mg plus ritonavir 100 mg once daily if also receiving H2-antagonists and tenofovir (Viread) (see drug interactions).
DRUG INTERACTIONS: 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.
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