What is the efficacy of Biktarvy (bictegravir, emtricitabine, and tenofovir alafenamide) as post-exposure prophylaxis (PEP)?

Efficacy of Biktarvy as Post-Exposure Prophylaxis (PEP) for HIV

Biktarvy (bictegravir, emtricitabine, and tenofovir alafenamide) is a safe, well-tolerated, and highly effective option for HIV post-exposure prophylaxis with completion rates of over 90% in clinical studies.

Current PEP Recommendations and Biktarvy's Position

The Centers for Disease Control and Prevention (CDC) and other major guidelines currently recommend specific regimens for PEP:

• Traditional recommended PEP regimens include TDF/FTC (tenofovir disoproxil fumarate/emtricitabine) plus raltegravir or dolutegravir 1
• Alternative regimens include TDF/FTC with boosted darunavir or TDF/FTC/cobicistat/elvitegravir 1
• PEP should be initiated as soon as possible after exposure (ideally within 1-2 hours) and continued for 28 days 1

Evidence Supporting Biktarvy for PEP

Recent research specifically evaluating Biktarvy for PEP shows promising results:

• A 2022 study demonstrated that BIC/FTC/TAF had a 96.4% completion rate when used as PEP, with excellent safety profile and adherence of 98.9% 2
• Another 2022 study showed 90.4% completion rate with BIC/FTC/TAF as PEP, which was higher than historical PEP regimens, with minimal side effects (primarily nausea/vomiting 15.4%, fatigue 9.6%, and diarrhea 7.7%) 3
• Animal studies using two-dose FTC/TAF plus bictegravir showed complete protection as PrEP and >80% risk reduction when initiated up to 24 hours post-exposure 4

Advantages of Biktarvy for PEP

Biktarvy offers several advantages as a PEP regimen:

1. Single-tablet regimen: Once-daily dosing improves adherence compared to multi-pill regimens
2. High completion rates: Studies show >90% completion rates, higher than many traditional PEP regimens 3, 2
3. Favorable side effect profile: Lower rates of adverse events compared to other integrase inhibitor-based regimens 3
4. No food requirements: Can be taken with or without food
5. Few drug interactions: Compared to boosted protease inhibitor regimens

Comparison with Other PEP Regimens

When comparing Biktarvy to other recommended PEP regimens:

• Dolutegravir with TDF-FTC showed a 90% completion rate in a 2017 study 5, similar to Biktarvy's completion rates
• Traditional PEP regimens with protease inhibitors have historically had lower completion rates due to gastrointestinal side effects
• The WHO recommends TDF + 3TC (or FTC) as the preferred backbone with LPV/r or ATV/r as the preferred third drug 1, but these may have more side effects than integrase inhibitor-based regimens

Implementation Considerations

When using Biktarvy as PEP:

• Initiate as soon as possible after exposure, ideally within 1-2 hours but no later than 72 hours 1
• Prescribe the full 28-day course immediately rather than using "starter packs" 1
• Perform baseline HIV testing, renal function assessment, hepatitis B screening, and STI screening 1
• Follow-up testing should include HIV testing at 4-6 weeks, 3 months, and 6 months post-exposure 1
• Monitor for adverse events, particularly mild gastrointestinal symptoms and headache

Potential Limitations and Caveats

• Cost: Biktarvy may be more expensive than some alternative PEP regimens
• Renal function: Monitor renal function as studies show a mean eGFR decrease of 14 ml/min/1.73m² with integrase inhibitor/TAF regimens 5
• Hepatitis B: Caution in those with chronic hepatitis B due to potential for hepatitis flare if PEP is discontinued
• Limited guideline inclusion: Current guidelines have not yet specifically included Biktarvy in their PEP recommendations, though newer integrase inhibitor-based regimens are increasingly preferred

Conclusion

Based on recent evidence, Biktarvy appears to be an excellent option for HIV PEP with high completion rates, good tolerability, and a favorable safety profile. While not yet specifically included in major guidelines, the available data supports its use as an effective single-tablet regimen for PEP.