Post-Exposure Prophylaxis Initiated 5 Days After HIV Exposure
While PEP initiated 5 days (120 hours) after exposure is significantly delayed beyond the recommended 72-hour window, it should still be continued to completion given the serious nature of the exposure and the potential—albeit reduced—benefit, particularly since the regimen of Tivicay (dolutegravir) and Truvada (tenofovir/emtricitabine) is appropriate and well-tolerated. 1
Critical Timing Considerations
The effectiveness of PEP is highly time-dependent:
- Optimal initiation is within 1-2 hours of exposure, with guidelines strongly recommending initiation within 72 hours 1
- Animal studies suggest PEP is probably not effective when started later than 24-36 hours post-exposure, though the exact interval beyond which there is no benefit in humans remains undefined 1
- For exposures beyond 72 hours, guidelines acknowledge that while efficacy is diminished, there is no absolute cutoff beyond which PEP provides zero benefit 1
- The risk-benefit calculation shifts when using safer, more tolerable modern regimens (like dolutegravir-based therapy) versus older toxic regimens, making late initiation more justifiable for high-risk exposures 1
Regimen Appropriateness
The prescribed combination is appropriate:
- Dolutegravir plus tenofovir disoproxil fumarate/emtricitabine is a CDC-recommended preferred regimen for PEP 1, 2
- This regimen should be continued for the full 28-day course 1, 3
- The single-pill integrase inhibitor-based regimen offers excellent tolerability with completion rates of 86-92% in clinical studies 4, 5, 6
Management Algorithm for This Patient
Immediate Actions:
- Continue the current regimen to complete 28 days total from initiation 1
- Perform baseline HIV testing using combination antigen/antibody assay plus HIV RNA testing 2, 3
- Assess baseline renal and hepatic function 1, 3
Follow-up Testing Schedule:
- Interim HIV testing at 4-6 weeks post-exposure with antigen/antibody test plus HIV RNA 2, 3
- Final HIV testing at 12 weeks post-exposure with laboratory-based combination immunoassay and HIV RNA 2, 3
- Monitor for drug toxicity at 2 weeks after PEP initiation 1
Risk Assessment Considerations:
- Evaluate the exposure risk level: type of exposure (receptive anal intercourse carries highest risk), known HIV status of source, viral load if known 1
- For highest-risk exposures (e.g., receptive anal intercourse with known HIV-positive source), even delayed PEP may offer benefit, as early treatment of acute infection can be beneficial even if transmission is not prevented 1
- If source person can be tested, obtain rapid HIV testing to inform ongoing decision-making; if source is HIV-negative, PEP can be discontinued 1, 3
Important Caveats
Common pitfalls to avoid:
- Do not discontinue PEP prematurely based solely on the delayed start—the medication is already initiated and well-tolerated 1
- Do not assume complete protection even with regimen completion, given the delayed initiation 1
- Most common side effects include nausea (15-28%), fatigue (9-28%), diarrhea (7-38%), and abdominal discomfort, but these are typically mild and self-limited 5, 7, 6
- Counsel the patient that while efficacy is reduced with delayed initiation, completing the course is still worthwhile and safer modern regimens justify continuation 1
Transition Planning
- After completing PEP, assess for ongoing HIV exposure risk and consider transition to pre-exposure prophylaxis (PrEP) if indicated 2, 3
- Ensure HIV testing is negative at PEP completion before initiating PrEP 2, 3
- Provide risk reduction counseling and support throughout the PEP course to maximize adherence 1