No, Isentress (raltegravir) should NOT be used as monotherapy for PEP
Raltegravir must be combined with two nucleoside reverse transcriptase inhibitors (NRTIs) for post-exposure prophylaxis—monotherapy is never appropriate and will not provide adequate protection against HIV acquisition. 1
Current PEP Guidelines Require 3-Drug Regimens
The 2025 CDC PEP guidelines explicitly recommend 28-day courses of three-drug combinations, not monotherapy 1:
Preferred Regimens for Adults/Adolescents:
- Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) - single tablet regimen
- Dolutegravir PLUS (tenofovir alafenamide OR tenofovir disoproxil fumarate) PLUS (emtricitabine OR lamivudine)
Raltegravir's Role in PEP:
When raltegravir is used for PEP, it appears only as an alternative regimen for specific pediatric populations 1:
- Infants/children aged ≥4 weeks to 2 years: Raltegravir (≥2 kg) PLUS zidovudine PLUS (emtricitabine OR lamivudine)
- Always combined with two NRTIs, never alone
Why Three Drugs Are Required
The biological rationale demands combination therapy:
- While raltegravir can inhibit HIV integration even after reverse transcription has occurred (giving it a theoretical advantage in the PEP window) 2, this does NOT justify monotherapy
- Monotherapy provides inadequate coverage against viral replication and risks resistance development
- The 2025 IAS-USA guidelines emphasize that PEP requires the same multi-drug approach as treatment regimens 3
Clinical Pitfalls to Avoid
Common errors in PEP prescribing:
- Never prescribe single-agent prophylaxis for any HIV exposure scenario
- Do not confuse PEP (post-exposure) with maintenance therapy protocols—even maintenance requires combination therapy 4
- Raltegravir monotherapy has been studied for maintenance in already-suppressed patients 4, but this is fundamentally different from preventing new infection
Practical Prescribing
If you choose a raltegravir-containing PEP regimen:
- Use raltegravir 400 mg twice daily (the standard dose, not the 1200 mg once-daily formulation used for treatment) 5
- Must combine with two NRTIs appropriate for the patient's age and weight
- Complete the full 28-day course 1
- Preferred regimens (BIC/FTC/TAF or DTG-based) offer simpler dosing and better tolerability 6
The evidence is unequivocal: PEP requires triple-drug therapy, and raltegravir monotherapy would constitute substandard care that fails to meet current guidelines.