Lenacapavir for HIV Prevention
Yes, lenacapavir is FDA-approved for HIV pre-exposure prophylaxis (PrEP) and is administered as a subcutaneous injection every 6 months following an oral loading regimen. 1
FDA Approval and Efficacy
Lenacapavir received FDA approval in June 2025 as the first twice-yearly injectable PrEP option, based on two landmark randomized controlled trials (PURPOSE 1 and PURPOSE 2) that demonstrated exceptional efficacy 1. The CDC PrEP Guidelines Work Group strongly recommends lenacapavir injections as an HIV PrEP option in persons weighing ≥77 lbs (≥35 kg) who would benefit from PrEP 1.
The efficacy data is remarkable:
- 100% efficacy in preventing HIV infection among cisgender women (PURPOSE 1) 1
- 96% efficacy in a primarily male trial population including cisgender men, transgender women, transgender men, and gender-nonbinary persons (PURPOSE 2) 1, 2
- HIV incidence with lenacapavir was 0.10 per 100 person-years compared to 2.37 per 100 person-years background incidence 2
Recommended Dosing Regimen
Loading Phase (Days 1-2):
- Day 1: 927 mg (3 mL) subcutaneous injection (two 1.5-mL injections at least 4 inches apart) PLUS 600 mg orally (two 300-mg tablets) 1
- Day 2: 600 mg orally (two 300-mg tablets) 1
Maintenance Phase:
- 927 mg (3 mL) subcutaneous injection every 6 months (26 weeks) ±2 weeks from the date of the last injection 1
- Administer as two 1.5-mL injections at least 4 inches apart 1
- Injection sites: abdomen or anterior thigh 1
- Critical technique: Use 90° angle to minimize injection site reactions; angles ≤45° result in intradermal rather than subcutaneous injection and increase adverse reactions 1
Time to Protection
Protective levels are achieved 2 hours after the Day 2 oral dose if both days of oral loading are completed 1. This is a critical clinical detail—patients are protected almost immediately after completing the loading regimen.
If both days of oral loading are missed, time to protection extends to 21-28 days 1.
Eligibility Criteria
Before initiating lenacapavir, confirm:
- Weight ≥77 lbs (≥35 kg) and at risk for HIV acquisition 1
- Negative blood-based HIV antigen/antibody test within 7 days before first dose 1
- No signs or symptoms of acute HIV infection 1
- Negative confirmatory HIV RNA test if available (though results should not delay initial injection) 1
- No known significant drug interactions or contraindications 1
Important exception: When switching from oral tenofovir-based or cabotegravir PrEP without interruption, only a laboratory-based HIV antigen/antibody test is needed—no confirmatory RNA test required 1.
Critical Hepatitis B Considerations
When switching patients from tenofovir-based PrEP to lenacapavir, you must address hepatitis B:
- Determine HBV infection status or immunity before discontinuing tenofovir 1
- For HBV-infected patients: Initiate alternative HBV treatment if tenofovir is discontinued 1
- For non-immune patients: Provide HBV vaccination 1
This is non-negotiable because tenofovir treats chronic HBV infection, and abrupt discontinuation can cause hepatitis flares.
Managing Missed Injections
If a maintenance injection will be ≥14 days late, implement oral bridging 1:
- Prescribe 300 mg lenacapavir orally every 7 days for <6 months (<26 weeks) 1
- First oral dose should be taken 6 months after the last injection 1
- Resume maintenance injection within 7 days after the last oral dose 1
Drug-Drug Interactions
Lenacapavir is a substrate of CYP3A, P-gp, and UGT1A1, and is a moderate CYP3A inhibitor 3:
Requires supplemental dosing:
Increases concentrations of:
- Certain medications for up to 9 months after the last injection, requiring dose adjustments and monitoring 1
- Midazolam (3.59-4.08-fold increase in AUC) 3
- Rosuvastatin (1.31-fold increase) 3
Avoid oral HIV antibody tests—they have low sensitivity for detecting recent HIV infection 1. Use laboratory-based antigen/antibody tests.
Safety Profile
Lenacapavir is generally well tolerated with high-certainty evidence for safety 4:
Injection site reactions (most common):
- Nodules are the most frequent reaction—can be several centimeters in size and last months to >1 year 1
- Other reactions: pain, induration 1
- Only 1.2% discontinued due to injection site reactions 2
- Management: Ice packs and topical/oral analgesics before and after injection 1
Serious adverse events:
- Lenacapavir results in a slight reduction in SAEs compared to oral PrEP (RR 0.78,95% CI 0.61-0.99) 4
- No significant safety concerns identified in trials 1
Mortality:
- Little to no difference in all-cause mortality compared to oral PrEP 4
Follow-Up Schedule
Every 6 months (or more frequently as needed): 1
- HIV testing with laboratory-based antigen/antibody test
- STI screening (vaginal, oral, rectal, urine, or blood as indicated)—may need more frequent screening than lenacapavir visits based on risk 1
- Viral hepatitis screening
- Consider doxycycline post-exposure prophylaxis 1
- Provide support for behavioral risk reduction, reproductive health, substance use, mental health, and social needs 1
Clinical Advantages
The twice-yearly dosing addresses a critical gap in HIV prevention—adherence to daily oral PrEP is suboptimal 1. Lenacapavir's extended dosing interval has the potential to dramatically improve PrEP adherence and thus enhance HIV prevention effectiveness 1.
The number needed to treat is remarkably low: 70 people need to receive lenacapavir rather than oral PrEP to prevent one HIV infection over 52 weeks 4.
Common Pitfalls to Avoid
- Don't use oral HIV antibody tests—insufficient sensitivity for recent infection 1
- Don't inject at angles ≤45°—causes intradermal injection and increases reactions 1
- Don't forget HBV management when switching from tenofovir-based PrEP 1
- Don't delay initial injection waiting for HIV RNA results—obtain contact information to relay results 1
- Don't use anterior thigh for cabotegravir (different drug), but it's acceptable for lenacapavir 5