HIV Protease Inhibitor (Antiretroviral) Pregnancy: A moderate amount of data in pregnant women (300-1000 pregnancy outcomes) indicates no malformative toxicity, and animal studies do not indicate reproductive toxicity. Use of atazanavir with ritonavir may be considered during pregnancy only if the potential benefit justifies the potential risk. Grade 3 to 4 hyperbilirubinaemia occurred in 30% (300/100 mg) and 62% (400/100 mg) of women in trial AI424-182; additional monitoring should be considered in the prepartum period. Atazanavir has been detected in human milk and women living with HIV are recommended not to breast-feed.

Atazanavir

Brand names: Reyataz

Atazanavir is an HIV protease inhibitor used, usually with pharmacokinetic boosting, as part of combination antiretroviral therapy.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: 300 mg atazanavir taken with ritonavir 100 mg

Route: Oral - capsules swallowed whole, taken with food

Frequency: Once daily (both atazanavir and ritonavir)

Therapy should be initiated by a physician experienced in the management of HIV infection. Ritonavir is used as a booster of atazanavir pharmacokinetics. Co-administration of atazanavir with ritonavir at doses greater than 100 mg once daily has not been clinically evaluated and is not recommended; only when co-administered with efavirenz could a ritonavir increase to 200 mg once daily be considered, with close clinical monitoring. HEPATIC IMPAIRMENT: atazanavir with ritonavir has not been studied in hepatic impairment - use with caution in mild impairment and it must not be used in moderate to severe impairment. If ritonavir is withdrawn from the initial recommended boosted regimen (only under restrictive conditions), unboosted atazanavir could be maintained at 400 mg in mild hepatic impairment and at a reduced dose of 300 mg once daily with food in moderate hepatic impairment; unboosted atazanavir must not be used in severe hepatic impairment. PREGNANCY (second and third trimesters): atazanavir 300 mg with ritonavir 100 mg may not provide sufficient exposure, and therapeutic drug monitoring may be considered; if tenofovir disoproxil or an H2-receptor antagonist is needed, a dose increase to atazanavir 400 mg with ritonavir 100 mg with therapeutic drug monitoring may be considered; it is not recommended to use atazanavir with ritonavir in pregnant patients receiving both tenofovir disoproxil and an H2-receptor antagonist. Postpartum patients should follow the same dose recommendations as non-pregnant patients and be closely monitored for adverse reactions. PAEDIATRIC (6 years to less than 18 years and weighing at least 15 kg, capsules with ritonavir, taken with food), by weight band: 15 to less than 35 kg - atazanavir 200 mg once daily with ritonavir 100 mg once daily; at least 35 kg - atazanavir 300 mg once daily with ritonavir 100 mg once daily; the recommended adult dose must not be exceeded. Other formulations may be available for children at least 3 months of age and weighing at least 5 kg - consult the relevant SPC, and note a change in dose may be needed when transitioning between formulations. Atazanavir should not be used in children less than 3 months because of safety concerns, especially the potential risk of kernicterus. Verify paediatric dosing against a children's formulary.

Dose adjustments

Renal

No dosage adjustment is needed in renal impairment. Atazanavir with ritonavir is not recommended in patients undergoing haemodialysis.

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to atazanavir or to any of the excipients
Severe hepatic insufficiency (atazanavir); moderate hepatic insufficiency (atazanavir with ritonavir)
Co-administration with simvastatin or lovastatin
Combination with rifampicin
Combination with sildenafil when used for the treatment of pulmonary arterial hypertension
Co-administration with CYP3A4 substrates with narrow therapeutic windows (e.g. quetiapine, lurasidone, alfuzosin, astemizole, terfenadine, cisapride, pimozide, quinidine, bepridil, triazolam, orally administered midazolam, and ergot alkaloids such as ergotamine, dihydroergotamine, ergonovine, methylergonovine)
Co-administration with grazoprevir-containing products, including elbasvir/grazoprevir, or with glecaprevir/pibrentasvir
Co-administration with products containing St John's wort (Hypericum perforatum)
Co-administration with apalutamide, encorafenib and ivosidenib
Co-administration with carbamazepine, phenobarbital and phenytoin

Side effects

Nausea (20%, very common)
Jaundice (13%; 19% in patients receiving atazanavir 300 mg with ritonavir 100 mg) and ocular icterus (common), with elevated total bilirubin
Diarrhoea (10%, very common)
Headache (common)
Chronic kidney disease reported during post-marketing surveillance, associated with cumulative exposure to atazanavir/ritonavir regimens - monitor renal function throughout treatment
QTc prolongation (rare) and torsades de pointes (uncommon)

Interactions

Atazanavir is an inhibitor of CYP3A and UGT1A1 - co-administration with drugs primarily metabolised by CYP3A or UGT1A1 may increase their plasma concentrations and prolong therapeutic and adverse effects [US label]
Atazanavir is a CYP3A4 substrate - CYP3A4 inducers may decrease atazanavir plasma concentrations and reduce its therapeutic effect [US label]
Atazanavir is a weak inhibitor of CYP2C8 - unboosted atazanavir is not recommended with drugs highly dependent on CYP2C8 with narrow therapeutic indices (e.g. paclitaxel, repaglinide) [US label]
Tenofovir disoproxil and H2-receptor antagonists reduce atazanavir exposure - see the pregnancy dosing note
Caution with medicinal products known to induce PR prolongation or to increase the QT interval; use with caution in pre-existing conduction problems
See the contraindications list for absolutely contraindicated co-administrations; SPC section 4.5 itself was not retrieved in this fetch and must be consulted in full

Clinical monograph

How it works

It inhibits HIV protease, preventing cleavage of viral polyproteins and producing immature, non-infectious virions.

Prescribing in practice

It commonly causes unconjugated hyperbilirubinaemia and jaundice, which is benign but should be distinguished from hepatotoxicity.
Its absorption depends on gastric acidity, so co-administration with acid-reducing agents such as proton pump inhibitors requires caution and specific spacing.
It interacts with many drugs via CYP3A4, so co-medication should be checked, and it is usually boosted to maintain adequate exposure.

Monitoring

Monitor virological response (HIV viral load and CD4 count), liver function, bilirubin and for signs of nephrolithiasis or cholelithiasis.

Counselling the patient

Yellowing of the eyes or skin can occur and is usually harmless, but report it so it can be assessed.
Tell your team before starting any indigestion or acid-reducing medicines.
Take exactly as prescribed, generally with food, and do not miss doses.

Evidence & guidelines

Atazanavir is an established protease inhibitor option within UK and international HIV treatment guidelines.

Reference: BHIVA HIV Treatment Guidelines (2022); Liverpool HIV Drug Interactions checker (hiv-druginteractions.org); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

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