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ANTIINFECTIVES FOR SYSTEMIC USE › ANTIVIRALS FOR SYSTEMIC USE › DIRECT ACTING ANTIVIRALS › Antivirals for treatment of HIV infections, combinations
atazanavir and ritonavir
J05AR23
Forms & Strengths
- Atazanavir/Ritonavir 300 mg/100 mg oral combination or co-packaged capsules
Adult Dosing
- Atazanavir 300 mg plus ritonavir 100 mg orally once daily with food
- Treatment-experienced patients with prior failure: use standard once-daily dosing with food
- Pregnancy (treatment-naive): Atazanavir 300 mg plus ritonavir 100 mg once daily with food from second trimester through delivery
Pediatric Dosing
- Pediatric patients weighing 35 kg and greater: Atazanavir 300 mg plus ritonavir 100 mg once daily with food
- Not recommended for children weighing less than 35 kg due to fixed-dose ratio limitations
Indications
- Treatment of HIV-1 infection in antiretroviral-naive and experienced adults and pediatric patients weighing 35 kg and greater in combination with other antiretroviral agents
Mechanism of Action
- Atazanavir is an azapeptide HIV-1 protease inhibitor that selectively inhibits the virus-specific processing of viral Gag-Pol proteins in HIV-1 infected cells, preventing formation of mature virions
- Ritonavir acts as a pharmacokinetic booster by inhibiting cytochrome P450 3A4 (CYP3A4), thereby increasing plasma concentrations and prolonging the half-life of atazanavir
Contraindications
- Hypersensitivity to atazanavir, ritonavir, or any components
- Co-administration with drugs highly dependent on CYP3A for clearance and associated with elevated plasma concentrations causing serious/life-threatening events (e.g., alfuzosin, meaniside, cisapride, pimozide, quinidine, sildenafil for PAH, triazolam, oral midazolam, lovastatin, simvastatin, ergot derivatives)
- Co-administration with rifampin, St. John's wort, nevirapine, and efavirenz (specific dosing considerations apply)
Adverse Reactions
- Jaundice and ocular icterus due to indirect hyperbilirubinemia
- Nausea, diarrhea, abdominal pain, vomiting, dyspepsia
- Rash
- Headache, fatigue, insomnia
- PR interval prolongation, first- or second-degree AV block
- Nephrolithiasis and cholelithiasis
- Hyperglycemia, dyslipidemia, fat redistribution (lipodystrophy)
Drug Interactions
- CYP3A inhibitors and inducers significantly alter atazanavir exposure
- Acid-reducing agents (PPIs, H2-receptor antagonists, antacids) decrease atazanavir absorption; separate dosing and use maximum recommended doses
- Tenofovir DF concentrations are increased; monitor for tenofovir-associated toxicities
- HCV direct-acting antivirals (e.g., simeprevir, glecaprevir/pibrentasvir) may have altered concentrations; co-administration may not be recommended
- Co-administration with PDE5 inhibitors for erectile dysfunction may increase adverse events such as hypotension and visual changes
- Statins: avoid lovastatin and simvastatin; use caution and lower doses with atorvastatin or rosuvastatin
Curated Content: Needs Vetting Before Put to Clinical Use