Atazanavir

Atazanavir is an HIV-1 antiretroviral medicine always used as part of a combination treatment regimen — never on its own.

• Atazanavir capsules (brands: Atazanavir, Atazanavir Sulfate) treat HIV-1 infection in adults and in children 6 years and older weighing at least 15 kg
• Reyataz capsules treat HIV-1 infection in adults and in children 3 months and older weighing at least 5 kg
• Reyataz oral powder treats HIV-1 infection in adults and in children 3 months and older weighing at least 5 kg — and must always be taken with ritonavir
• None of these products are recommended for infants under 3 months of age due to the risk of kernicterus (a serious form of brain damage caused by very high bilirubin levels)
• Atazanavir capsules without ritonavir are not recommended for treatment-experienced adults or children who have had prior virologic failure (the virus stopped responding to therapy)

Atazanavir belongs to a class of HIV drugs called protease inhibitors. HIV uses an enzyme called protease to cut newly made viral proteins into the pieces it needs to build infectious copies of itself. Atazanavir blocks this enzyme, so the virus produces immature, non-infectious particles and cannot spread effectively through the body.

Different degrees of cross-resistance have been seen among protease inhibitors — meaning resistance to atazanavir does not necessarily rule out using a different protease inhibitor later, though this depends on the specific pattern of viral mutations.

Atazanavir capsules and Reyataz oral powder are taken by mouth once daily. Both must always be taken with food, which significantly improves how well the drug is absorbed and reduces variability in blood levels.

• Do not open atazanavir or Reyataz capsules
• Reyataz oral powder must be taken with ritonavir
• Pediatric doses of atazanavir and Reyataz capsules are based on body weight and must not exceed the adult dose
• Dose adjustments may be needed depending on other medications, kidney function, liver function, or pregnancy — always follow your prescriber's guidance

The most common side effects with atazanavir include:

• Nausea
• Yellowing of skin or eyes (jaundice/scleral icterus) from elevated bilirubin — very common but usually harmless
• Rash
• Headache
• Abdominal pain
• Vomiting
• Diarrhea
• Trouble sleeping (insomnia)

More serious reactions that require prompt medical attention include severe rash, signs of heart rhythm changes (palpitations, fainting), kidney stones or gallstones, liver problems, and — especially in pregnancy — symptoms of lactic acidosis such as unusual muscle pain, difficulty breathing, nausea, or feeling very cold.

• Heart conduction changes: Atazanavir can prolong the PR interval on an ECG (electrocardiogram — a heart tracing). This is usually asymptomatic but can rarely cause more serious heart rhythm problems. Patients with existing heart conduction disease need extra monitoring.
• Skin rash: Rash occurs in about 20% of patients. It is usually mild, but severe rashes require stopping atazanavir immediately.
• Elevated bilirubin (hyperbilirubinemia): Nearly all patients experience a rise in indirect bilirubin, causing yellowing of skin or eyes. This is reversible and generally harmless — do not lower your dose on your own.
• Kidney problems: Chronic kidney disease, kidney stones, and protein in the urine have been reported. Regular kidney lab testing is required for everyone taking atazanavir.
• Liver problems (hepatotoxicity): Patients with hepatitis B or C are at higher risk for serious liver complications. Liver tests must be monitored.
• Diabetes/high blood sugar: New or worsening diabetes and high blood sugar have been reported with protease inhibitor therapy.
• Immune reconstitution syndrome: When HIV treatment starts working, the recovering immune system can trigger inflammation against hidden infections. Symptoms may appear weeks to months after starting therapy.
• Fat redistribution: Body fat changes (such as belly fat accumulation or fat loss in the face/limbs) have been reported with antiretroviral therapy.
• Hemophilia: Increased bleeding episodes have been reported in people with hemophilia A and B taking protease inhibitors.

Atazanavir has a large number of significant drug interactions because it affects and is affected by key liver enzymes (CYP3A, UGT1A1). Always review all medications with your pharmacist or prescriber before starting.

• Contraindicated (never combine): Rifampin, St. John's wort, carbamazepine, phenobarbital, phenytoin — these lower atazanavir levels so much that HIV treatment can fail; lovastatin, simvastatin, lomitapide — dangerous muscle-level toxicity risk; alfuzosin — dangerous drop in blood pressure; pimozide, lurasidone (with ritonavir), orally administered midazolam, triazolam — life-threatening reactions; indinavir — both drugs raise bilirubin; nevirapine — loss of HIV control and increased nevirapine toxicity; certain hepatitis C antivirals (elbasvir/grazoprevir, glecaprevir/pibrentasvir) — serious liver enzyme elevations; ergot derivatives — severe constriction of blood vessels
• Acid-reducing drugs (antacids, proton-pump inhibitors, H2 blockers): Lower stomach acid reduces absorption of atazanavir — timing adjustments or dose changes are often needed
• Blood thinners (warfarin, rivaroxaban, apixaban, dabigatran): Atazanavir raises blood thinner levels, increasing bleeding risk — close monitoring required
• Tenofovir DF: Lowers atazanavir levels and raises tenofovir levels — ritonavir boosting and kidney monitoring are required when used together
• Trazodone and tricyclic antidepressants: Atazanavir raises their blood levels, increasing risk of side effects — use with caution and monitor closely
• Efavirenz: Lowers atazanavir levels — ritonavir boosting is required; not recommended in treatment-experienced patients

Not a complete list. The label covers the interactions the manufacturer studied or reported, and our own interaction database does not cover every medicine either. Bring your full medication list, including vitamins and herbal products, to your pharmacist.

• Tell every provider and pharmacist about all medications, vitamins, and supplements you take — this drug interacts with many common medicines
• Kidney function (creatinine, creatinine clearance, urinalysis) must be checked before starting and monitored throughout treatment
• If you have hepatitis B, hepatitis C, or any liver disease, liver function must be tested before and during treatment
• Atazanavir with ritonavir is not recommended if you have any degree of liver impairment; atazanavir alone is not recommended in severe liver impairment
• Atazanavir is not recommended for treatment-experienced patients with end-stage kidney disease on dialysis
• Pregnant patients must take atazanavir with ritonavir; discuss risks of lactic acidosis and elevated bilirubin — neonates should be monitored for high bilirubin in the first days of life
• Breastfeeding is generally not recommended due to risk of passing HIV to the infant and potential drug exposure
• Atazanavir capsules are not for children under 6 years of age (or under 3 months for Reyataz); Reyataz oral powder is not for infants under 3 months or weighing less than 5 kg
• Reyataz oral powder contains phenylalanine — do not use if you have phenylketonuria (PKU)
• Patients with hemophilia should know that protease inhibitors have been linked to increased bleeding episodes
• Older adults should be monitored carefully, given greater likelihood of kidney, liver, or heart concerns and other medications

Taking too much atazanavir can cause heart conduction changes — including a prolonged PR interval and, in one reported case of a very large accidental overdose, a type of heart block — as well as yellowing of the skin or eyes from high bilirubin. These effects resolved on their own in the reported case. There is no specific antidote; treatment focuses on supportive care, heart monitoring, and if appropriate, steps to remove unabsorbed drug (such as activated charcoal). Because atazanavir is heavily processed by the liver and tightly bound to proteins in the blood, dialysis is not expected to remove it effectively.

Atazanavir affects the heart's electrical system in a concentration- and dose-related way — it prolongs the PR interval (the time it takes for an electrical signal to travel from the top chambers of the heart to the bottom chambers). In studies, this prolongation was asymptomatic and mostly limited to first-degree AV block. Atazanavir does not appear to significantly affect the QTc interval (another heart rhythm measure) at recommended or even double the recommended doses, and no patients in clinical trials had dangerously prolonged QTc values above 500 milliseconds.

Atazanavir is absorbed relatively quickly after an oral dose — peak blood levels are typically reached within about 2.5 hours. Taking it with food meaningfully increases absorption (by up to 70% with a light meal for some regimens) and makes blood levels more consistent, which is why food is required. The drug is about 86% bound to proteins in the blood and is extensively broken down in the liver, mainly by an enzyme called CYP3A. Most of the drug (about 79%) leaves the body through the stool, with a smaller amount in the urine. The typical elimination half-life (the time it takes for half the drug to clear from the body) is roughly 7 hours in adults at steady state under some regimens, and longer when combined with ritonavir, which slows atazanavir's breakdown and keeps blood levels higher.

Store atazanavir capsules at 20° to 25°C (68° to 77°F) .