What is the recommended regimen for Pre-Exposure Prophylaxis (PrEP) to prevent HIV infection?

Pre-Exposure Prophylaxis (PrEP) for HIV Prevention

Daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) is the recommended primary regimen for all populations at high risk of HIV infection, with alternative options including emtricitabine/tenofovir alafenamide (TAF/FTC) for men who have sex with men and transgender women, and long-acting injectable cabotegravir administered at 8-week intervals. 1

Recommended PrEP Regimens

Primary Recommended Regimen

• Daily oral TDF/FTC (Truvada) is the standard regimen with proven efficacy across all populations 2, 1
• High adherence is essential for efficacy:
  • MSM and transgender women: At least 4 of 7 doses per week
  • Cisgender women, people who inject drugs, and heterosexual men: At least 6 of 7 doses per week 1

Alternative Regimens

• TAF/FTC (Descovy) for MSM and transgender women only 1, 3
  • May be preferred for those with or at risk for bone or renal conditions
  • Not yet approved for cisgender women or people who acquire HIV through vaginal sex
• Event-driven PrEP (2-1-1 dosing) may be considered for MSM and likely transgender women 2
  • Not recommended for vaginal exposures or people who inject drugs

Candidates for PrEP

PrEP should be considered for:

• Populations with HIV incidence of at least 2% per year 2
• HIV-seronegative partners of HIV-infected persons who do not have viral suppression 2
• MSM and transgender women (strong recommendation, high quality evidence) 2, 1
• Heterosexual serodiscordant couples (strong recommendation, high quality evidence) 2
• People who inject drugs (weak recommendation, high quality evidence) 2
• At-risk heterosexual men and women (weak recommendation, moderate quality evidence) 2

Pre-Initiation Assessment

Before starting PrEP, the following tests must be performed within 7 days:

• HIV testing with combination antigen-antibody assay (essential to rule out existing infection) 2, 1
• Serum creatinine with estimated creatinine clearance 2, 1
• Hepatitis B surface antigen testing 2, 1
• Comprehensive STI screening (oral, rectal, urine, and vaginal as appropriate) 2, 1
• HIV RNA testing if acute HIV infection is suspected 1

Monitoring and Follow-up

• Initial prescription: Limited to 30-day supply 1
• Subsequent prescriptions: 90-day supplies with appropriate monitoring 1
• Follow-up testing:
  • HIV testing: Every 2-3 months 2, 1
  • Creatinine assessment: At least every 6 months 2, 1
  • STI screening: Every 3 months 2, 1
  • More frequent renal monitoring (every 3-6 months) for patients:
    • Over age 50
    • With baseline creatinine clearance <90 mL/min
    • With comorbidities like diabetes or hypertension 1

Contraindications and Cautions

• Absolute contraindications:

  • Active HIV infection 1
  • Creatinine clearance <60 mL/min for TDF-based PrEP 2, 1

• Relative contraindications:

  • Osteopenia or osteoporosis (TDF may cause bone mineral density loss) 2, 1
  • Chronic hepatitis B virus infection (use with caution due to risk of hepatitis flares if PrEP is discontinued) 2

Adherence Support

Adherence is crucial for PrEP efficacy. Studies show a direct correlation between adherence levels and protection rates 4, 5. Strategies to support adherence include:

• Regular adherence counseling at each visit 2
• Personal telephone and interactive text reminders 2
• Integration with other services for people with substance use disorders 2

Special Considerations

HIV Seroconversion While on PrEP

• Stop PrEP immediately if HIV infection is suspected 1
• Perform confirmatory testing with HIV RNA and genotype testing 1
• Initiate full antiretroviral therapy if HIV infection is confirmed 1
• Drug resistance (typically M184V/I mutation) can develop if PrEP is started during undiagnosed acute HIV infection 1, 6

PrEP and Post-Exposure Prophylaxis (PEP)

• For recent exposure (<72 hours): Provide 3-drug PEP for 1 month, then transition to 2-drug PrEP 1
• For exposure >72 hours ago: Initiate standard PrEP protocol 1

Clinical Pitfalls to Avoid

1. Failing to rule out acute HIV infection before starting PrEP - This can lead to drug resistance 1, 6
2. Inadequate monitoring - Regular HIV testing is essential to detect breakthrough infections early 1
3. Overlooking adherence issues - PrEP efficacy is directly tied to adherence levels 2, 4
4. Not considering alternative regimens for patients with risk factors - TAF/FTC may be more appropriate for MSM and transgender women with renal or bone concerns 1, 3

PrEP is a highly effective HIV prevention strategy when used correctly and consistently, with efficacy rates exceeding 90% in adherent individuals 4, 5.