Drug Guide
Nevirapine
Classification
Therapeutic: Antiretroviral for HIV infection
Pharmacological: Non-nucleoside Reverse Transcriptase Inhibitor (NNRTI)
FDA Approved Indications
- Treatment of HIV-1 infection in combination with other antiretroviral agents
Mechanism of Action
Nevirapine inhibits HIV-1 reverse transcriptase, preventing conversion of viral RNA into DNA, thereby inhibiting viral replication.
Dosage and Administration
Adult: Viramune tablets: 200 mg once daily for 14 days, then increase to 200 mg twice daily. For oral suspension, 2 mg/kg/day in two divided doses. Viramune XR: starting dose 200 mg once daily, may increase to 400 mg once daily.
Pediatric: Dosing based on weight, typically 2 mg/kg twice daily for oral suspension; higher doses for XR formulation after initial phase.
Geriatric: No specific dose adjustment necessary, but caution in renal or hepatic impairment.
Renal Impairment: No specific adjustment needed, but caution advised.
Hepatic Impairment: Use with caution, especially in patients with pre-existing liver disease.
Pharmacokinetics
Absorption: Well absorbed orally, with peak plasma concentrations in 4 hours.
Distribution: Widely distributed, crosses the blood-brain barrier.
Metabolism: Primarily metabolized in the liver via CYP3A and CYP2B6 enzymes.
Excretion: Primarily via hepatic metabolism; small amounts excreted unchanged in urine.
Half Life: Approximately 25-30 hours, allows for once or twice daily dosing.
Contraindications
- Hypersensitivity to nevirapine or other NNRTIs.
Precautions
- Hepatotoxicity risk, especially in patients with pre-existing liver disease
- Rash should be monitored as it can be severe (Stevens-Johnson syndrome, toxic epidermal necrolysis)
- Use caution in patients with high CD4 counts (especially women with CD4 >250 cells/mm³ and men >400 cells/mm³) due to increased hepatotoxicity risk
Adverse Reactions - Common
- Rash (Common)
- Elevated liver function tests (Common)
- Nausea (Less common)
Adverse Reactions - Serious
- Hepatotoxicity leading to hepatic failure (Rare)
- Stevens-Johnson syndrome / Toxic epidermal necrolysis (Rare)
- Myelosuppression (rare) (Rare)
Drug-Drug Interactions
- Rifampin (reduces nevirapine levels)
- Other CYP3A4 inducers or inhibitors such as rifabutin, voriconazole, ketoconazole
Drug-Food Interactions
- None specifically
Drug-Herb Interactions
- St. John’s Wort (increases metabolism, reduces efficacy)
Nursing Implications
Assessment: Monitor liver function tests at baseline and periodically, watch for rash, signs of hepatotoxicity.
Diagnoses:
- Risk for hepatotoxicity
- Risk for skin reactions
- Adherence issues
Implementation: Educate patient on rash and hepatotoxicity symptoms, advise on adherence, schedule periodic labs.
Evaluation: Liver function stability, absence of rash or severe adverse reactions.
Patient/Family Teaching
- Take medication exactly as prescribed, on an empty stomach or with food as tolerated.
- Report symptoms of rash, dizziness, nausea, jaundice immediately.
- Avoid alcohol and hepatotoxic medications.
- Discuss importance of regular lab testing.
Special Considerations
Black Box Warnings:
- Severe, life-threatening hepatotoxicity and rash, including Stevens-Johnson syndrome and toxic epidermal necrolysis.
- Increased risk in women with high CD4 counts (>250 cells/mm³) and men >400 cells/mm³.
Genetic Factors: CYP2B6 polymorphisms may influence drug metabolism and toxicity.
Lab Test Interference: Possible elevations in liver enzymes; monitor regularly.
Overdose Management
Signs/Symptoms: Nausea, vomiting, dizziness, somnolence, rash, hepatotoxicity.
Treatment: Supportive care, symptomatic treatment, activated charcoal if ingestion recent, no specific antidote.
Storage and Handling
Storage: Store below 25°C (77°F), protect from moisture.
Stability: Stable for at least 24 months if properly stored.