⚠️ Key Point: Nevirapine is a first-generation Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI) with good CNS penetration but significant risk of hepatotoxicity and rash.
🔬 Avoid initiation in patients with high baseline CD4 counts due to increased risk of severe hepatic reactions.
🧠 About
- Nevirapine is a Non-Nucleoside Reverse Transcriptase Inhibitor (NNRTI) used in the treatment of HIV-1 infection as part of combination antiretroviral therapy (cART).
- It was one of the earliest NNRTIs, now largely superseded by newer agents (e.g. efavirenz, doravirine) due to its toxicity profile.
- Always check the BNF entry for up-to-date dosing and monitoring guidance.
⚙️ Mode of Action
- Binds directly and non-competitively to the HIV-1 reverse transcriptase enzyme at an allosteric site, causing a conformational change that blocks DNA synthesis.
- Inhibits viral replication without requiring phosphorylation (unlike NRTIs).
- Demonstrates good CNS penetration, making it effective in reducing viral load within cerebrospinal fluid.
💊 Indications & Dosing
- HIV-1 infection:
- Start with 200 mg once daily for 14 days (“lead-in” period) to reduce rash risk, then increase to 200 mg twice daily.
- No food restrictions.
- Always used in combination with other antiretrovirals (usually NRTI backbone).
⚠️ Interactions
- Potent inducer of cytochrome P450 (especially CYP3A4) - may reduce plasma levels of many co-administered drugs.
- Reduces concentrations of oral contraceptives, azole antifungals, and some protease inhibitors.
- Avoid co-administration with other hepatotoxic agents where possible.
- See BNF for full list of drug–drug interactions.
⚕️ Cautions
- Monitor LFTs closely for the first 18 weeks - most hepatic events occur early.
- Use with caution in pre-existing hepatic impairment or Hepatitis B/C co-infection.
- Rash is common but may rarely progress to Stevens–Johnson syndrome or TEN - stop immediately if severe rash develops.
🚫 Contraindications
- High baseline CD4 counts - risk of severe hepatotoxicity:
- Men: CD4 > 400 cells/mm³
- Women: CD4 > 250 cells/mm³
- Moderate to severe hepatic impairment.
- Hypersensitivity to nevirapine or excipients.
💥 Side Effects
- Common: Rash (often mild and self-limiting), nausea, fatigue, headache.
- Serious: Hepatotoxicity (can be fatal), Stevens–Johnson syndrome, toxic epidermal necrolysis.
- Metabolic: Lipodystrophy, hyperlipidaemia, insulin resistance (with long-term use).
- Note: Hepatotoxicity risk is greatest in the first 6–12 weeks and in patients with high CD4 counts or female sex.
📖 Educational Summary
Nevirapine is a landmark drug in the history of HIV therapy - one of the first NNRTIs to demonstrate sustained viral suppression.
Its role today is mainly historical or limited to specific resource-limited settings, as safer alternatives exist.
The hallmark teaching point is the immunologically driven hepatotoxicity, which is paradoxically more common in patients with higher CD4 counts - a pattern unique to this class.
It also illustrates the classic mechanism of NNRTIs: non-competitive binding to reverse transcriptase rather than chain termination.
In UK and European guidelines, it’s now rarely initiated but remains important for understanding the evolution of ART toxicity management.
📚 References
- Nevirapine – British National Formulary
- BHIVA Guidelines for the Treatment of HIV-1 Positive Adults (2023)
- Harrison’s Principles of Internal Medicine, 21st Edition – Antiretroviral Pharmacology
- European AIDS Clinical Society (EACS) Guidelines, 2023
