Atazanavir (Reyataz®)


Atazanavir is an HIV protease inhibitor.

Antiviral Activity

Atazanavir has activity against HIV-1.

Mechanism of Action

Atazanavir forms an inhibitor-enzyme complex with HIV protease preventing the normal maturation process of HIV and formation of mature infectious virions.

Mechanism of Resistance

Higher levels of protease inhibitor resistance result from the accumulation of multiple protease inhibitor-resistance mutations. The many mechanisms of resistance include reduced binding affinity between the inhibitor and the protease enzyme, alterations in enzyme catalysis, effects on dimer stability, alterations in inhibitor binding kinetics, and re-shaping of the active site.


By inhibiting the HIV protease enzyme, therapy with atazanavir decreases plasma HIV-1 RNA and increases CD4+ T cell counts in HIV infected individuals. In vitro studies have integrated plasma concentrations with antiviral activity.


Administration of atazanavir with food increases bioavailability and reduces intersubject variation in systemic exposure. Atazanavir is 86% bound to plasma proteins and is metabolized by CYP450 3A4 via monooxygenation and dioxygenation with subsequent glucuronidation.

Adverse Effects

Hyperbilirubinemia is the most common adverse effect. Diarrhea, nausea and abdominal pain can also be seen. Atazanavir does not appear to significantly alter lipid metabolism over the short term unlike other protease inhibitors.


Capsule 100mg, 150mg, 200mg

Adolescents and adults

Antiretroviral naïve patients – 400 mg once daily

Antiretroviral-experienced patients – 300 mg once daily in combination with ritonavir

100 mg once daily


the recommended dose has not yet been established.

Disease state based dosing

Renal Impairment: no dose adjustment necessary

Hepatic Impairment: no dose adjustment necessary but caution should be exercised.

Contraindications/Warnings/ Precautions

Atazanavir is contraindicated with:

midazolam, triazolam, dihydroergotamine, ergotamine, ergonovine, methylergonovine, cisapride (no longer marketed in the United States) and pimozide.

Drug Interactions

Atazanavir is a known substrate and inhibitor of CYP3A4 in vitro. Therefore, medications that are also metabolized by CYP3A4 may interact with atazanavir.


Category B: no evidence of risk in humans but studies inadequate.

Monitoring Requirements

HIV-RNA, bilirubin

Brand names/Manufacturer

Reyataz®/Bristol-Myers Squibb