HIV Post-Exposure Prophylaxis (PEP) Dosage Recommendations
The preferred HIV post-exposure prophylaxis (PEP) regimens for most adults and adolescents are bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) as a single-tablet regimen, or dolutegravir (DTG) plus (tenofovir alafenamide [TAF] or tenofovir disoproxil fumarate [TDF]) plus (emtricitabine [FTC] or lamivudine [3TC]), administered for a 28-day course. 1, 2
Timing and Duration
- PEP should be initiated as soon as possible after exposure, ideally within 24 hours, but no later than 72 hours 1, 2
- The first dose should not be delayed due to pending laboratory test results 1
- The complete course of PEP is 28 days 1, 2
Specific Regimen Details
Preferred Regimens for Adults and Adolescents:
- Option 1: Bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF) - single tablet regimen 1, 2
- Option 2: Dolutegravir (DTG) plus (tenofovir alafenamide [TAF] OR tenofovir disoproxil fumarate [TDF]) plus (emtricitabine [FTC] OR lamivudine [3TC]) 1, 2
Alternative Regimens (when preferred regimens are not available):
- Older guidelines suggested zidovudine (ZDV) + lamivudine (3TC) as the backbone with lopinavir/ritonavir (LPV/r) or atazanavir/ritonavir (ATV/r) as the third drug, but these are now considered outdated 1, 3
Follow-up and Monitoring
- Clinical follow-up should occur at 24 hours (remote or in-person) with a medical provider 1
- Laboratory testing should be performed at 4-6 weeks and 12 weeks after exposure 1, 2
- HIV testing should include laboratory-based HIV Ag/Ab combination immunoassay and diagnostic HIV NAT at 12 weeks post-exposure 2
- For persons with long-acting injectable PrEP exposure in the past 12 months, add a diagnostic HIV nucleic acid test (NAT) at initial assessment 2
Special Considerations
- For pregnant individuals, the regimen should be tailored to clinical circumstances, though older guidelines considered ZDV + 3TC a safe regimen for pregnant healthcare workers 3
- For individuals with renal impairment, TAF-containing regimens may be preferred over TDF-containing regimens 3, 2
- Assess for medical comorbidities, current medications, and potential drug interactions at the initial assessment 2
Transition to PrEP
- Consider immediate transition from PEP to PrEP for persons with anticipated repeat or ongoing potential HIV exposures 2
- Perform HIV testing at the completion of the PEP regimen before transitioning to PrEP 2
Common Pitfalls to Avoid
- Delaying PEP initiation beyond 72 hours significantly reduces effectiveness 2, 4
- Incomplete adherence to the full 28-day course reduces effectiveness 2, 4
- Failing to consider drug interactions with the patient's current medications 3, 2
- Not providing adequate follow-up for medication adherence and toxicity monitoring 2
It's important to note that the recommendations have evolved significantly over time, with a shift from older zidovudine-based regimens to newer tenofovir-based regimens with integrase inhibitors, which offer better tolerability and completion rates 4.