HIV Protease Inhibitor (Antiretroviral) Pregnancy: Use of atazanavir with ritonavir may be considered during pregnancy only if the potential benefit justifies the potential risk; must be administered with ritonavir in pregnancy. A moderate amount of data indicate no malformative toxicity. Grade 3-4 hyperbilirubinaemia observed in treated pregnant women; additional prepartum monitoring should be considered. Breastfeeding: 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 once daily taken with ritonavir 100 mg once daily

Route: Oral (capsules swallowed whole)

Frequency: Once daily, with food

Therapy should be initiated by a physician experienced in the management of HIV infection. Ritonavir is used as a booster of atazanavir pharmacokinetics. In case of withdrawal of ritonavir (only under restrictive conditions), unboosted atazanavir could be maintained in patients with mild hepatic impairment at 400 mg once daily, and in patients with moderate hepatic impairment at a reduced dose of 300 mg once daily with food. During the second and third trimesters of pregnancy, a dose increase to atazanavir 400 mg with ritonavir 100 mg with therapeutic drug monitoring may be considered if tenofovir disoproxil or an H2-receptor antagonist is needed.

Paediatric dose

Route: Oral (capsules with ritonavir, with food)

Frequency: Once daily

Max: Should not exceed the recommended adult dose

Weight-banded (capsules), not per-kg: paediatric patients 6 years to less than 18 years and weighing at least 15 kg — 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. Atazanavir must not be used in children less than 3 months of age (risk of kernicterus). Other formulations may be available for patients at least 3 months of age and weighing at least 5 kg — consult the relevant SPC.

Dose adjustments

Renal

No dosage adjustment 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 the active substance or to any of the excipients
Severe hepatic insufficiency; atazanavir with ritonavir contraindicated in moderate hepatic insufficiency
Co-administration with simvastatin or lovastatin
Combination with rifampicin
PDE5 inhibitor sildenafil when used for pulmonary arterial hypertension
CYP3A4 substrates with narrow therapeutic windows (e.g. quetiapine, lurasidone, alfuzosin, astemizole, terfenadine, cisapride, pimozide, quinidine, bepridil, triazolam, oral midazolam, ergot alkaloids)
Co-administration with grazoprevir-containing products, glecaprevir/pibrentasvir, St. John's wort, apalutamide, encorafenib, ivosidenib, carbamazepine, phenobarbital and phenytoin

Side effects

Jaundice / ocular icterus and elevated total bilirubin (reported very commonly; frequency of jaundice ~13%, or ~19% with ritonavir)
Nausea (~20%)
Diarrhoea (~10%)
Headache
Hyperbilirubinaemia; chronic kidney disease reported during post-marketing surveillance

Interactions

Ritonavir doses greater than 100 mg once daily not recommended (may alter safety profile); with efavirenz a ritonavir increase to 200 mg once daily could be considered
Atazanavir is a CYP3A4 substrate — drugs that induce CYP3A4 may decrease atazanavir plasma concentrations and reduce therapeutic effect
Caution with medicinal products known to induce PR prolongation and those that increase the QT interval
Exposure reduced by co-administration with tenofovir disoproxil or H2-receptor antagonists
Acid-reducing agents (H2-receptor antagonists, proton-pump inhibitors) may require dose separation

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.

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