What is the recommended regimen for prescribing Pre-Exposure Prophylaxis (PrEP) for Human Immunodeficiency Virus (HIV) prevention?

Pre-Exposure Prophylaxis (PrEP) for HIV Prevention

The recommended first-line regimen for HIV pre-exposure prophylaxis (PrEP) is daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC 300/200 mg) for all populations at risk of HIV infection. 1

Patient Selection for PrEP

PrEP should be considered for the following high-risk populations:

• Men who have sex with men (MSM) with any of these risk factors:

  • Condomless anal intercourse in past 6 months
  • Score ≥10 on MSM risk index (includes age, number of partners, HIV+ partners, condomless receptive/insertive anal sex, methamphetamine use) 2

• Transgender women with similar risk factors as MSM

• Heterosexual men and women:

  • In serodiscordant relationships (where one partner has HIV)
  • Multiple partners with inconsistent condom use
  • History of STIs

• People who inject drugs:

  • Sharing injection equipment
  • High-risk sexual behavior

Recommended PrEP Regimens

Daily Oral Regimen (Standard for All Populations)

• TDF/FTC (300/200 mg) once daily 1
• Maximum protection achieved after:
  • 7 days of daily use for receptive anal intercourse
  • 20 days for receptive vaginal intercourse or injection drug exposure

Alternative Regimens

• For MSM only: Event-driven "2-1-1" dosing (on-demand) 1

  • 2 tablets 2-24 hours before sex
  • 1 tablet 24 hours after first dose
  • 1 tablet 24 hours after second dose
  • Continue daily dosing if ongoing sexual exposure

• For patients with renal dysfunction: TAF/FTC (25/200 mg) once daily (for MSM and transgender women only, not for those at risk through vaginal sex) 1, 3

Pre-PrEP Laboratory Testing

Before initiating PrEP, the following tests are required:

• HIV testing (4th generation antibody/antigen test)
• Serum creatinine (estimated creatinine clearance)
• Hepatitis B surface antigen
• Hepatitis C antibody
• STI screening (gonorrhea and chlamydia at all potential exposure sites)
• Pregnancy test for women of childbearing potential

Monitoring Schedule

• At 1 month:

  • HIV antibody/antigen test
  • Assess adherence and side effects

• Every 3 months:

  • HIV antibody/antigen test
  • STI screening
  • Adherence counseling

• Every 6 months:

  • Serum creatinine/estimated creatinine clearance
  • More frequent monitoring for patients >50 years or with comorbidities

Duration of PrEP Use

• For MSM: Continue TDF/FTC for at least 2 days after last potential exposure 1
• For all others: Continue TDF/FTC for at least 7 days after last potential exposure 1

Special Considerations

Hepatitis B Infection

• TDF/FTC has activity against HBV
• Monitor liver function closely if PrEP is discontinued in patients with chronic HBV infection due to risk of hepatitis flare 1, 4

Pregnancy and Breastfeeding

• Daily TDF/FTC is recommended for at-risk individuals who are pregnant or breastfeeding 1

Renal Function

• TDF/FTC should be avoided in patients with CrCl <60 mL/min
• Consider TAF/FTC for MSM and transgender women with renal concerns 3

Common Pitfalls to Avoid

1. Initiating PrEP without confirming HIV-negative status

   • False-negative results can occur during acute HIV infection
   • Defer PrEP if symptoms of acute HIV infection are present

2. Poor adherence monitoring

   • Adherence is critical for PrEP efficacy
   • Address barriers to adherence at each visit

3. Inappropriate regimen selection

   • TAF/FTC is not currently recommended for individuals at risk through vaginal sex 1, 5

4. Inadequate STI screening

   • PrEP does not prevent other STIs
   • Regular screening is essential

5. Extended prescription without follow-up

   • Limit prescriptions to 90 days to ensure regular HIV testing

Emerging PrEP Options

While daily oral TDF/FTC remains the standard, newer options are becoming available:

• Long-acting injectable cabotegravir (CAB-LA) shows superior efficacy to TDF/FTC with lower risk of HIV infection (HR = 0.22) and less impact on renal function, though with more injection site reactions 6, 5

• TAF/FTC demonstrates non-inferior efficacy to TDF/FTC with improved bone and renal safety profiles, but is currently only approved for MSM and transgender women 3

By implementing appropriate PrEP regimens based on risk factors and ensuring proper monitoring, healthcare providers can significantly reduce HIV transmission risk and improve public health outcomes.