Model Answer
0 min readIntroduction
Post-Exposure Prophylaxis (PEP) for HIV is an emergency medical intervention involving the administration of antiretroviral (ARV) drugs to prevent HIV infection after potential exposure to the virus. It is a critical component of HIV prevention strategies, particularly in occupational settings (e.g., needlestick injuries for healthcare workers) and non-occupational settings (e.g., unprotected sexual contact, sexual assault). The efficacy of PEP is highly time-dependent, with guidelines emphasizing initiation as soon as possible, ideally within 24 hours and no later than 72 hours post-exposure. The goal is to interrupt the early stages of viral replication before the virus can establish a permanent infection.
Drugs, Doses, and Duration of Treatment for HIV Post-Exposure Prophylaxis (PEP)
The choice of antiretroviral (ARV) drugs, their dosages, and the duration of treatment for HIV Post-Exposure Prophylaxis (PEP) are guided by international and national health organizations, primarily the World Health Organization (WHO) and national bodies like India's National AIDS Control Organisation (NACO). These guidelines are regularly updated to reflect advancements in ARV therapies, aiming for increased efficacy, reduced side effects, and improved accessibility.
Key Principles of PEP Administration:
- Timeliness: PEP must be initiated as soon as possible after exposure, ideally within 24 hours, and definitely within 72 hours. Delay significantly reduces its effectiveness.
- Duration: The standard duration of PEP treatment is 28 days (4 weeks).
- Regimen: A three-drug regimen is generally preferred over a two-drug regimen for optimal effectiveness.
- Assessment: A thorough risk assessment is crucial, considering the type of exposure and the HIV status of the source.
Recommended PEP Regimens (General Guidelines - WHO and recent updates):
Recent guidelines, including updates from the US CDC (May 2025) and WHO (July 2024), favor newer, well-tolerated antiretroviral drugs. While specific national guidelines might have slight variations, the core components remain consistent.
Preferred Regimens for Adults and Adolescents:
The current preferred regimens typically include a combination of two Nucleoside/Nucleotide Reverse Transcriptase Inhibitors (NRTIs) and one Integrase Strand Transfer Inhibitor (INSTI).
- Option 1 (WHO, US CDC 2025 preferred):
- Drugs: Bictegravir (BIC) + Emtricitabine (FTC) + Tenofovir Alafenamide (TAF)
(often available as a single fixed-dose combination pill) - Dose: BIC 50 mg / FTC 200 mg / TAF 25 mg, once daily
- Duration: 28 days
- Drugs: Bictegravir (BIC) + Emtricitabine (FTC) + Tenofovir Alafenamide (TAF)
- Option 2 (WHO, US CDC 2025 preferred; also widely recommended):
- Drugs: Dolutegravir (DTG) + Emtricitabine (FTC) or Lamivudine (3TC) + Tenofovir Disoproxil Fumarate (TDF) or Tenofovir Alafenamide (TAF)
- Dose: DTG 50 mg once daily, plus FTC 200 mg once daily or 3TC 300 mg once daily, plus TDF 300 mg once daily or TAF 25 mg once daily. (Often combined into 2 pills: DTG + FDC of TDF/FTC or TAF/FTC)
- Duration: 28 days
Older/Alternative Regimens (Still used in some contexts, or where preferred regimens are not available):
Previous guidelines often recommended regimens including Efavirenz (EFV) or ritonavir-boosted protease inhibitors (PI/r).
- NACO (India) 2014 Guidelines (Still widely referred to in India, though newer WHO/CDC guidelines may be incorporated):
- Drugs: Tenofovir (TDF) + Lamivudine (3TC) + Efavirenz (EFV)
- Dose: TDF 300 mg + 3TC 300 mg + EFV 600 mg, once daily (often as a single fixed-dose combination pill, TLD)
- Duration: 28 days
- Note: If intolerance to Efavirenz, a regimen containing Tenofovir + Lamivudine + Protease Inhibitor (e.g., Atazanavir/ritonavir (ATV/r) or Lopinavir/ritonavir (LPV/r)) can be used after expert consultation.
Considerations for Special Populations:
- Children: Regimens and dosages are adjusted based on age and weight bands, often involving combinations like Abacavir (ABC) + Lamivudine (3TC) + Lopinavir/ritonavir (LPV/r) or Zidovudine (ZDV) + 3TC + LPV/r, or ABC + 3TC + DTG.
- Pregnancy and Breastfeeding: Specific ARV drugs are preferred based on safety profiles during pregnancy and breastfeeding. Dolutegravir-based regimens are generally recommended, with careful consideration and expert consultation.
- Source on ART or with potential drug resistance: Expert consultation is crucial to select a regimen less likely to be affected by potential drug resistance in the source.
Table: Summary of Key PEP Regimens and Duration
| Regimen Type | Drugs (Examples) | Typical Doses | Duration | Key Considerations |
|---|---|---|---|---|
| Preferred (WHO/US CDC 2025) | Bictegravir/Emtricitabine/Tenofovir Alafenamide (BIC/FTC/TAF) | One fixed-dose combination pill daily | 28 days | High efficacy, good tolerability. Often a single pill simplifies adherence. |
| Preferred (WHO/US CDC 2025) | Dolutegravir (DTG) + FDC of Tenofovir (TDF/TAF) / Emtricitabine (FTC) or Lamivudine (3TC) | DTG 50mg OD + FDC (e.g., TDF 300mg/FTC 200mg) OD | 28 days | Highly effective, widely available. |
| Older/Alternative (e.g., NACO 2014) | Tenofovir (TDF) + Lamivudine (3TC) + Efavirenz (EFV) | TDF 300mg OD + 3TC 300mg OD + EFV 600mg OD (often FDC) | 28 days | Effective, but EFV can have CNS side effects. Not recommended for two-drug regimens. |
Monitoring and Follow-up: After initiating PEP, individuals undergo baseline HIV testing and other relevant blood tests. Follow-up HIV testing (e.g., at 4-6 weeks and 12 weeks post-exposure) is critical to determine the success of PEP. Counseling on adherence to the regimen, potential side effects, and ongoing risk reduction strategies (including transition to Pre-Exposure Prophylaxis, PrEP, if at ongoing risk) are integral parts of the PEP management protocol.
Conclusion
HIV Post-Exposure Prophylaxis (PEP) is a vital intervention for preventing HIV infection after potential exposure, contingent on rapid initiation and strict adherence to the regimen. The current standard involves a 28-day course of a three-drug antiretroviral combination, with preferred options generally including an integrase inhibitor (like bictegravir or dolutegravir) alongside two NRTIs. Adherence to these guidelines, coupled with comprehensive counseling and follow-up, significantly reduces the risk of HIV transmission. Continuous updates in guidelines aim to improve drug efficacy, reduce side effects, and enhance accessibility, reflecting the evolving landscape of HIV prevention and treatment.
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