Amprenavir and Nevirapine: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Nevirapine
Amprenavir
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Reduced amprenavir (active metabolite of fosamprenavir) exposure and an increased nevirapine exposure
Interaction Deep Dive
Both amprenavir (the metabolite of fosamprenavir) and nevirapine are substrates of CYP3A4. Amprenavir is also an inhibitor of the CYP3A4 isoenzyme, while nevirapine has CYP3A4-inducing properties. Coadministration of nevirapine and fosamprenavir without ritonavir has resulted in reduced amprenavir exposure and increased nevirapine plasma concentrations5. Coadministration of nevirapine and fosamprenavir without ritonavir is not recommended. There is no required dosage adjustment for the concurrent administration of nevirapine with fosamprenavir plus ritonavir twice daily. A regimen of once daily fosamprenavir/ritonavir in combination with nevirapine has not been studied 412.
Why it happens (mechanism)
Induction of CYP3A4-mediated metabolism of amprenavir, the active metabolite of fosamprenavir; inhibition of CYP3A4-mediated metabolism of nevirapine
Literature reports
1 report — tap to read
a) Pharmacokinetic parameters (AUC, Cmax, and Cmin) of amprenavir (APV) decreased significantly when HIV-infected adult patients were treated with concomitant fosamprenavir (FPV) and nevirapine (NVP) without ritonavir (RTV) in an open-label, single-sequence, three-period, steady-state study (current study; n=17) compared to healthy and HIV-infected adult patients who were treated with FPV 1400 mg in previous protocol trials (historical control; n=40). Subjects in the current study were required to have been receiving NVP 400 mg/day for at least 12 weeks prior to the study with HIV RNA levels less than 400 copies/mL at screening. There were 3 periods including: 1) treatment with NVP 200 mg twice daily; 2) addition of FPV 1400 mg twice daily for 14 days; 3) change from FPV 1400 mg to FPV 700 mg plus RTV 100 mg for another 14 days. Compared to FPV alone, FPV plus NVP resulted in decreases in APV AUC of 33% (geometric least-squares (GLS) mean ratio, 0.668; 90% confidence interval (CI), 0.555 to 0.803); Cmax of 25% (GLS mean ratio, 0.752; 90% CI, 0.632 to 0.896); and Cmin of 35% (GLS mean ratio, 0.65; 90% CI, 0.498 to 0.85). Changes in APV AUC and Cmax were not significant with the addition of RTV to FPV and NVP compared to FPV alone. However, APV Cmin was 19% lower in those treated with FPV, NVP, and RTV (GLS mean ratio, 0.809; 90% CI, 0.684 to 0.956). NVP plus FPV resulted in increases in NVP AUC, Cmax, and Cmin with GLS mean ratios of 1.29 (90% CI, 1.19 to 1.4), 1.25 (90% CI, 1.14 to 1.37) and 1.34 (90% CI, 1.21 to 1.49), respectively, compared to NVP alone. NVP, FPV, and RTV resulted in NVP AUC, Cmax, and Cmin GLS mean ratios of 1.14 (90% CI, 1.05 to 1.24), 1.13 (90% CI, 1.03 to 1.24), and 1.22 (90% CI, 1.1 to 1.35), respectively, compared to NVP alone 5.
Common questions
Can I take Amprenavir and Nevirapine together?
Reduced amprenavir (active metabolite of fosamprenavir) exposure and an increased nevirapine exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Amprenavir and Nevirapine interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "delayed". Effects tend to build up gradually over days to weeks.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Amprenavir or Nevirapine need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (5)
- Product Information: VIRAMUNE(R) oral suspension, nevirapine oral suspension. Boehringer Ingelheim Pharmaceuticals Inc (per FDA), Ridgefield, CT, 2024. DailyMed
- Product Information: VIRAMUNE XR(R) oral extended-release tablets, nevirapine oral extended-release tablets. Boehringer Ingelheim Pharmaceuticals Inc (per FDA), Ridgefield, CT, 2024. DailyMed
- Product Information: Agenerase(R) capsules. GlaxoSmithKline, Research Triangle Park, NC, 2003.
- Product Information: LEXIVA(R) oral solution, oral tablets, fosamprenavir calcium oral solution, oral tablets. GlaxoSmithKline, Research Triangle Park, NC, 2009. DailyMed
- DeJesus E, Piliero PJ, Summers K, et al: Interaction between fosamprenavir, with and without ritonavir, and nevirapine in human immunodeficiency virus-infected subjects. Antimicrob Agents Chemother 2006; 50(9):3157-3159. PubMed
Keep reading about Nevirapine
Keep reading about Amprenavir
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