Atazanavir
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Summary
Atazanavir is an azapeptide protease inhibitor developed for the treatment of human immunodeficiency virus type‑1 (HIV‑1) infection. It is administered orally once daily and works by inhibiting the viral protease required for maturation of infectious virions. Clinical studies have shown it reduces viral load in treatment‑naïve patients and is approved by the U.S. Food and Drug Administration for use in combination antiretroviral regimens.
Mechanism of Action
Atazanavir binds with high specificity to the active site of HIV‑1 protease, blocking the enzyme’s ability to cleave viral polyproteins into functional components. This inhibition prevents the formation of mature, infectious HIV particles. The drug’s azapeptide structure confers a distinct resistance profile, with the I50L protease substitution identified as a signature mutation associated with reduced susceptibility.
What the Research Shows
Randomised trials reported that once‑daily atazanavir (200–500 mg) combined with stavudine and didanosine produced rapid, sustained reductions in HIV‑1 RNA comparable to nelfinavir in treatment‑naïve patients over 48 weeks. A review of data up to 2004 noted similar efficacy to efavirenz or nelfinavir in antiretroviral‑naïve individuals, but inferiority to lopinavir/ritonavir in experienced patients unless low‑dose ritonavir was added. Resistance patterns include a unique 150L mutation after failure in naïve patients and an I50L substitution. Pharmacokinetic studies describe oral once‑daily dosing, moderate inhibition of CYP3A, and multiple drug‑interaction potential. A separate report highlighted atazanavir‑related crystalluria as a possible renal adverse effect.
Reported Benefits
Clinical evidence indicates that atazanavir effectively lowers HIV‑1 viral load in treatment‑naïve patients, achieving reductions comparable to other protease inhibitors. Unlike many protease inhibitors, it does not increase total cholesterol, LDL‑cholesterol, or triglycerides, and may be advantageous for patients with hyperlipidaemia or cardiovascular risk. Its once‑daily oral dosing simplifies regimen adherence.
Limitations of the Evidence
In antiretroviral‑experienced patients, atazanavir alone is less effective than lopinavir/ritonavir, requiring low‑dose ritonavir boosting to match efficacy. Resistance emerges when three or more protease inhibitors have failed, and a specific 150L mutation is observed after regimen failure. Evidence on long‑term outcomes beyond 108 weeks is limited in the cited literature.
Safety Considerations
The most frequently reported adverse event in trials was nausea. Atazanavir can raise unconjugated bilirubin levels, occasionally causing visible jaundice or scleral icterus, though these events are generally mild. Its moderate inhibition of CYP3A leads to numerous drug‑interaction risks, necessitating careful review of concomitant medications. Crystalluria associated with atazanavir has been described, suggesting a potential for renal crystal formation.
How It Is Administered
Atazanavir is formulated for oral administration, typically taken once daily. The drug is absorbed systemically and undergoes hepatic metabolism, primarily via CYP3A enzymes. No specific formulation details are provided in the cited abstracts.
Routes of Administration
No administration routes recorded yet.
Goals & Uses
No goal associations recorded yet.
Contraindications
No contraindications recorded yet.
Adverse Effects
No adverse effects recorded yet.
Drug Interactions
No drug interactions recorded yet.
Population Constraints
No population constraints recorded yet.
Regulatory Status
No regulatory status recorded yet.
Evidence & Sources
- Journal ArticleModerateDaudon M, Frochot V2015-01-01T00:00:00.000000Z
- Journal ArticleModerateGoldsmith DR, Perry CM2003-01-01T00:00:00.000000Z
- Journal ArticleModerateOrrick JJ, Steinhart CR2004-01-01T00:00:00.000000Z
Frequently Asked Questions
What type of virus does atazanavir target?
Atazanavir specifically inhibits the protease enzyme of HIV‑1, preventing the virus from maturing into infectious particles.
Is atazanavir taken once a day or multiple times?
Clinical studies describe atazanavir as a once‑daily oral medication, which can improve adherence compared with more frequent dosing regimens.
Does atazanavir affect cholesterol levels?
Trials reported no significant increases in total cholesterol, LDL‑cholesterol, or triglycerides after prolonged treatment, distinguishing it from many other protease inhibitors.
What are common side effects?
Nausea was the most commonly reported adverse event. Elevated unconjugated bilirubin, leading to mild jaundice, and the potential for crystalluria have also been observed.
Can atazanavir be used with other drugs?
Atazanavir moderately inhibits CYP3A, creating a high potential for drug‑drug interactions; co‑administration with other agents should be evaluated for possible metabolic effects.
What is Atazanavir?
Atazanavir is an azapeptide protease inhibitor developed for the treatment of human immunodeficiency virus type‑1 (HIV‑1) infection. It is administered orally once daily and works by inhibiting the viral protease required for maturation of infectious virions. Clinical studies have shown it reduces viral load in treatment‑naïve patients and is approved by the U.S. Food and Drug Administration for use in combination antiretroviral regimens.