Nurses Compass
Drug Guide
Atazanavir Sulfate and Ritonavir
Classification
Therapeutic: Antiretroviral for HIV infection
Pharmacological: Protease inhibitor (Atazanavir), Pharmacokinetic enhancer (Ritonavir)
FDA Approved Indications
- Treatment of HIV-1 infection in combination with other antiretroviral agents
Mechanism of Action
Atazanavir inhibits the HIV-1 protease enzyme, preventing viral maturation. Ritonavir inhibits cytochrome P450 3A-mediated metabolism, boosting atazanavir levels by increased bioavailability and plasma concentrations.
Dosage and Administration
Adult: Typically, one tablet once daily, with or without food. Dose adjustments may be needed based on concomitant medications.
Pediatric: Not generally approved for children under 6 years or below 15 kg.
Geriatric: No specific dosage adjustment based solely on age; evaluate for concomitant conditions and medications.
Renal Impairment: No dose adjustment needed.
Hepatic Impairment: Use with caution; specific adjustments not well established.
Pharmacokinetics
Absorption: Well absorbed with food, which enhances absorption.
Distribution: Widely distributed, crosses blood-brain barrier.
Metabolism: Metabolized primarily by CYP3A4 enzyme.
Excretion: Mostly fecal excretion, minor renal excretion.
Half Life: Approximately 7 hours for atazanavir; ritonavir has a half-life of about 3-5 hours.
Contraindications
- Hypersensitivity to atazanavir, ritonavir, or any component.
- Concurrent use with drugs highly dependent on CYP3A for clearance and associated with significant risk of Torsades de Pointes (e.g., astemizole, cisapride).
Precautions
- Use with caution in patients with hepatic impairment, history of cardiovascular disease, or a history of bilirubin disorders. Liver function monitoring is advised.
Adverse Reactions - Common
- Nausea (Frequent)
- Headache (Common)
- Rash (Common)
- Elevated bilirubin (jaundice) (Common)
Adverse Reactions - Serious
- Cardiac arrhythmias (QT prolongation, Torsades de Pointes) (Uncommon)
- Hepatotoxicity (Uncommon)
- Severe skin reactions (Stevens-Johnson syndrome) (Rare)
Drug-Drug Interactions
- Drugs highly dependent on CYP3A4 for clearance (e.g., certain statins, sildenafil)
Drug-Food Interactions
- High-fat meals may alter absorption.
- Avoid excessive alcohol due to hepatotoxicity risk.
Drug-Herb Interactions
N/ANursing Implications
Assessment: Monitor liver function tests, lipid profile, and serum bilirubin.
Diagnoses:
- Risk for hepatotoxicity
- Impaired medication adherence
Implementation: Administer with food, educate about adherence, monitor for adverse reactions.
Evaluation: Assess viral load and CD4 counts periodically.
Patient/Family Teaching
- Take medication exactly as prescribed.
- Report signs of liver damage (jaundice, dark urine), allergic reactions, or severe skin reactions.
- Avoid alcohol and certain medications without consulting healthcare provider.
Special Considerations
Black Box Warnings:
- QT prolongation and Torsades de Pointes risk
Genetic Factors: Patients with HLA-B*57:01 allele may have increased risk of hypersensitivity reactions.
Lab Test Interference: May cause benign hyperbilirubinemia, leading to scleral icterus and jaundice.
Overdose Management
Signs/Symptoms: Nausea, vomiting, dizziness, symptoms of potential cardiac arrhythmias.
Treatment: Supportive care, activated charcoal if ingestion was recent, cardiac monitoring if arrhythmias are suspected.
Storage and Handling
Storage: Store at room temperature, away from moisture and heat.
Stability: Stable for at least 2 years when stored properly.