Adult: In combination with other antiretroviral agents: For antiretroviral-naive patients: 300 mg once daily boosted with ritonavir or cobicistat. Alternatively, in patients unable to tolerate ritonavir or cobicistat, unboosted regimen of 400 mg once daily may be used. For antiretroviral-experienced patients: 300 mg once daily boosted with ritonavir or cobicistat. Dosage and treatment recommendations may vary among countries (refer to local guidelines). Child: In combination with other antiretroviral agents: As oral powder: ≥3 months For antiretroviral-naive and antiretroviral-experienced patients: 5-<15 kg: 200 mg once daily boosted with ritonavir; in antiretroviral-naive patients weighing 5-<10 kg who cannot tolerate the 200 mg dose, 150 mg once daily may be given with close monitoring of HIV viral load; 15-<25 kg: 250 mg once daily boosted with ritonavir; ≥25 kg (who cannot swallow a cap): 300 mg once daily boosted with ritonavir. As cap: 6-<18 years For antiretroviral-naive and antiretroviral-experienced patients: 15-<35 kg: 200 mg once daily boosted with ritonavir; ≥35 kg: 300 mg once daily boosted with ritonavir. In antiretroviral-naive patients aged ≥13 years and weighing ≥40 kg who are unable to tolerate ritonavir, unboosted regimen of 400 mg once daily may be used. Dosage and treatment recommendations may vary among countries (refer to local guidelines).
What are the brands available for Atazanavir in Malaysia?
Reyataz
Special Patient Group
Patients concomitantly taking efavirenz or PPI: 400 mg once daily boosted with ritonavir. Dosage and treatment recommendations may vary among countries and between individual products (refer to specific product guidelines).
Pharmacogenomics:
Atazanavir competitively inhibits hepatic UGT1A1 enzyme, preventing glucuronidation and elimination of bilirubin, which results in indirect hyperbilirubinaemia with jaundice. Studies show that the risk for bilirubin-related discontinuation of atazanavir is associated with UGT1A1 polymorphism. Genetic testing may be helpful if available before initiating atazanavir to determine the individual's likelihood of bilirubin-related treatment discontinuation.
Clinical Pharmacogenetics Implementation Consortium (CPIC) Guideline as of September 2015:
Phenotype and Genotype
Implications
Recommendations
UGT1A1 extensive metabolisers
Patients carrying 2 reference functional alleles and/or increased function alleles. Alternatively identified by homozygosity for rs887829 C/C.
e.g. *1/*1, *36/*36; rs887829 C/C
Reference UGT1A1 activity. The likelihood of bilirubin-related discontinuation of atazanavir is very low.
There is no need to avoid prescribing atazanavir based on the result of UGT1A1 genetic test.
UGT1A1 intermediate metabolisers
Patients carrying 1 reference functional allele or an increased function allele plus 1 decreased function allele. Alternatively identified by homozygosity for rs887829 C/T.
e.g. *1/*28, *1/*37, *36/*28, *36/*37; rs887829 C/T, *1/*6
Somewhat decreased UGT1A1 activity. The likelihood of bilirubin-related discontinuation of atazanavir is low.
There is no need to avoid prescribing atazanavir based on the result of UGT1A1 genetic test.
UGT1A1 poor metabolisers
Patients carrying 2 decreased function alleles. Alternatively, identified by homozygosity for rs887829 T/T (*80/*80).
e.g. *28/*28, *28/*37, *37/*37; rs887829 T/T (*80/*80), *6/*6
Markedly decreased UGT1A1 activity. The likelihood of bilirubin-related discontinuation of atazanavir is high.
Consider an alternative agent, particularly if development of jaundice would be of concern to the patient.
Renal Impairment
For antiretroviral-naive patients with ESRD undergoing haemodialysis: 300 mg once daily boosted with ritonavir. For antiretroviral-experienced patients with ESRD undergoing haemodialysis: Not recommended. Treatment recommendations may vary among countries (refer to local guidelines).
Hepatic Impairment
Unboosted regimen: For antiretroviral-naive patients: Mild (Child-Pugh class A): 400 mg once daily. Moderate (Child-Pugh class B): 300 mg once daily. Severe (Child-Pugh class C): Contraindicated. Boosted regimen: Moderate to severe impairment: Contraindicated. Dosage and treatment recommendations may vary among countries (refer to local guidelines).
Administration
Atazanavir Should be taken with food. Oral powder: Mix with food (e.g. applesauce or yoghurt) or beverage (e.g. water, milk, infant formula). Administer within 1 hour of preparation. Consult product literature for specific instructions.
Contraindications
Hypersensitivity. Severe hepatic impairment; moderate hepatic impairment (when administered in a boosted regimen). Concomitant use with agents that are highly dependent on CYP3A4 for clearance (e.g. simvastatin, lovastatin, quetiapine, pimozide, terfenadine, astemizole, bepridil, quinidine, amiodarone, ergot derivatives, cisapride, triazolam, midazolam [oral], alfuzosin, ivosidenib, lurasidone, lomitapide); grazoprevir-containing products, including elbasvir/grazoprevir; glecaprevir/pibrentasvir, strong CYP3A4 inducers (e.g. rifampicin, carbamazepine, encorafenib, phenobarbital, phenytoin, St. John's wort, apalutamide); irinotecan; sildenafil (when used for treatment of pulmonary arterial hypertension).
Special Precautions
Patient with preexisting conduction abnormalities (e.g. 2nd degree or higher AV block, complex bundle branch block), risk factors for QT interval prolongation (e.g. bradycardia, congenital long QT syndrome, electrolyte imbalances); haemophilia A or B; elevated transaminase, hepatitis B or C, liver cirrhosis. Patient taking efavirenz or PPI. UGT1A1 poor metabolisers. Cap and oral powder preparations of atazanavir are not interchangeable due to differences in bioavailability; refer to specific product guidelines. Use of atazanavir without ritonavir or cobicistat (unboosted regimen) is not recommended in antiretroviral-experienced patients with prior virologic failure. Patient with ESRD undergoing haemodialysis. Mild hepatic impairment. Children. Pregnancy; breastfeeding is not recommended to avoid HIV transmission.
Adverse Reactions
Significant: Hyperbilirubinaemia, redistribution or accumulation of fats (e.g. central obesity, buffalo hump, cushingoid appearance), hypersensitivity reactions (e.g. mild to moderate maculopapular rash, angioedema, erythema multiforme, drug rash with eosinophilia and systemic symptoms [DRESS] syndrome); immune reconstitution syndrome resulting in activation of autoimmune disorders (e.g. Guillain-Barre syndrome, Graves' disease, autoimmune hepatitis) or occurrence of inflammatory response to residual opportunistic infection; chronic kidney disease, nephrolithiasis, cholelithiasis, prolonged PR interval, hyperglycaemia, new-onset or exacerbation of diabetes, diabetic ketoacidosis; increased bleeding (in haemophiliac patients); dyslipidaemia; osteonecrosis (particularly during long-term use). Rarely, Stevens-Johnson syndrome. Cardiac disorders: Torsades de pointes, chest pain. Rarely, QT prolongation. Eye disorders: Scleral icterus. Gastrointestinal disorders: Nausea, diarrhoea, dysgeusia, vomiting, abdominal pain, dyspepsia, pancreatitis, gastritis, abdominal distention, stomatitis aphthous, flatulence, dry mouth. General disorders and administration site conditions: Fatigue, malaise, pyrexia, asthenia. Hepatobiliary disorders: Jaundice, hepatitis, cholestasis. Investigations: Weight gain or decreased weight. Metabolism and nutrition disorders: Anorexia, increased appetite. Musculoskeletal and connective tissue disorders: Muscle atrophy, arthralgia, myalgia. Nervous system disorders: Headache, peripheral neuropathy, syncope, amnesia, dizziness, somnolence. Psychiatric disorders: Depression, disorientation, anxiety, insomnia, sleep disorder, abnormal dreams. Renal and urinary disorders: Haematuria, proteinuria, pollakiuria, interstitial nephritis. Reproductive system and breast disorders: Gynaecomastia. Respiratory, thoracic and mediastinal disorders: Dyspnoea. Skin and subcutaneous tissue disorders: Urticaria, alopecia, pruritus. Vascular disorders: Hypertension.
Obtain serum creatinine, estimated CrCl, urinalysis with microscopic examination, and liver function tests (particularly in patients with existing liver disease) prior to initiation of therapy and as clinically indicated. Monitor viral load, CD4 count, serum glucose, and bilirubin (as clinically indicated). Perform ECG monitoring in patients with preexisting prolonged PR interval or concurrent treatment with AV nodal blocking drugs. Assess for signs and symptoms of hypersensitivity reactions.
Overdosage
Symptoms: Jaundice due to indirect hyperbilirubinaemia without associated LFT changes, PR interval prolongation.
Management: Supportive treatment. Monitor vital signs and ECG. May perform gastric lavage, induce emesis, or administer activated charcoal to eliminate or remove unabsorbed drug.
Drug Interactions
May increase the plasma concentrations of anticoagulants (e.g. apixaban, dabigatran, warfarin), calcium channel blockers (e.g. verapamil, diltiazem, felodipine, nifedipine, nicardipine), fluticasone, salmeterol and voxilaprevir. Increased risk of indirect hyperbilirubinaemia with indinavir. May decrease plasma concentration with corticosteroids (e.g. dexamethasone), buffered didanosine, tenofovir disoproxil fumarate, efavirenz, nevirapine, antacids, H2-receptor antagonists (e.g. famotidine) and PPIs (e.g. omeprazole). May increase the antiplatelet activity of ticagrelor. May reduce the antiplatelet activity of clopidogrel. Potentially Fatal: May increase the plasma concentration of alfuzosin, which may increase the risk of hypotension. May increase irinotecan toxicity. May increase the plasma concentrations of midazolam (oral) and triazolam, which may increase the risk of serious adverse effects (e.g. respiratory depression, prolonged or increased sedation). Increased risk of ergot toxicity (e.g. peripheral vasospasm, ischaemia of extremities and other tissues) with ergot alkaloids (e.g. ergotamine, dihydroergotamine, methylergonovine). Increased risk of cardiac arrhythmias with cisapride, pimozide and amiodarone. Increased risk of statin-associated adverse effects (including myopathy and rhabdomyolysis) with simvastatin and lovastatin. Increased risk of hypotension, visual disturbances, syncope and priapism with sildenafil (when used for pulmonary arterial hypertension). Increased plasma concentrations of other CYP3A4 substrates (e.g. quetiapine, tefenadine, astemizole, bepridil, alfuzosin, ivosidenib, lurasidone, grazoprevir, glecaprevir, pibrentasvir, lomitapide). Concomitant use with strong CYP3A4 inducers (e.g. carbamazepine, phenobarbital, phenytoin, rifampicin, encorafenib, apalutamide) may decrease plasma concentrations of atazanavir, which may lead to loss of virologic response and development of drug resistance.
Food Interaction
Enhanced absorption with food. Decreased plasma concentration with St. John's wort, which may result in loss of therapeutic effect and development of resistance.
Action
Description: Mechanism of Action: Atazanavir is an azapeptide HIV-protease inhibitor that binds to the site of HIV-1 protease activity. It inhibits the virus-specific processing of viral Gag-Pol polyprotein precursors in HIV-1 infected cells, thus preventing the maturation of virions and causing the formation of immature, non-infectious viral particles. Pharmacokinetics: Absorption: Rapidly absorbed from the gastrointestinal tract. Food enhances the absorption. Time to peak plasma concentration: 2-3 hours. Distribution: Distributed in semen and cerebrospinal fluid. Enters breast milk. Plasma protein binding: Approx 86%; binds to α1-acid glycoprotein and albumin. Metabolism: Extensively metabolised in the liver mainly by CYP3A4 isoenzyme; major biotransformation via monooxygenation and deoxygenation into inactive metabolites; minor pathways include glucuronidation, N-dealkylation, hydrolysis and oxygenation with dehydrogenation. Excretion: Mainly via faeces (79%; 20% as unchanged drug); urine (13%; 7% as unchanged drug). Elimination half-life: 7-8 hours (unboosted regimen); 9-18 hours (ritonavir-boosted regimen).
Chemical Structure
Atazanavir Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 148192, Atazanavir. https://pubchem.ncbi.nlm.nih.gov/compound/Atazanavir. Accessed Sept. 30, 2025.
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