What is the best pre-exposure prophylaxis (PrEP) regimen for a 31-year-old cisgender woman with multiple sexual partners and high-risk behaviors?

PrEP Recommendation for a High-Risk Cisgender Woman

Emtricitabine/tenofovir disoproxil fumarate 200/300 mg orally daily is the best PrEP regimen to recommend for this patient. 1, 2

Rationale for Daily Oral TDF/FTC

This 31-year-old cisgender woman with multiple sexual partners and inconsistent condom use is at high risk for HIV acquisition and is an excellent candidate for PrEP. The evidence strongly supports daily oral TDF/FTC as the optimal choice for her specific situation:

• The International Antiviral Society-USA Panel guidelines explicitly recommend daily tenofovir disoproxil fumarate/emtricitabine as the first-line oral PrEP regimen for all populations at risk (evidence rating: AIa) 1
• For cisgender women specifically, daily dosing is required for optimal protection, as pharmacokinetic studies show that tenofovir concentrations in vaginal tissues take longer to reach protective levels compared to rectal tissues 2

Why Other Options Are Not Appropriate

1. Emtricitabine/tenofovir disoproxil fumarate 2-1-1 dosing (event-driven):

   • The 2-1-1 (on-demand) dosing schedule is recommended ONLY for MSM (evidence rating: AIa) 1
   • This dosing strategy is not recommended for cisgender women due to inadequate drug concentrations in vaginal tissues with intermittent dosing 2

2. Emtricitabine/tenofovir alafenamide 200/25 mg daily:

   • While TAF/FTC is effective for PrEP, it is specifically recommended as an alternative for MSM with or at risk for kidney dysfunction, osteopenia, or osteoporosis 1, 2
   • There are no data supporting the use of TAF/FTC in cisgender women for PrEP 1
   • The patient has no mentioned renal or bone issues that would necessitate TAF over TDF

3. Cabotegravir long-acting injectable:

   • While injectable cabotegravir has shown efficacy in clinical trials, at the time of the most recent guidelines, it was recommended pending approval by regulatory agencies 1
   • The guidelines specifically mention its use for cisgender men and transgender women who have sex with men, but data for cisgender women was still being collected 1
   • The every 2-week dosing schedule mentioned in the question does not align with the recommended 8-week interval for cabotegravir injections 1, 3

Monitoring and Follow-up

For this patient on daily TDF/FTC, the following monitoring schedule should be implemented:

• Baseline testing before initiation:

  • HIV antibody/antigen test (to confirm HIV-negative status)
  • Serum creatinine (to assess renal function)
  • Hepatitis B surface antigen
  • STI screening (already indicated for chlamydia treatment)
  • Pregnancy test 1, 2

• Follow-up monitoring:

  • 1-month visit: HIV antibody/antigen test
  • Quarterly visits: HIV testing, STI screening, pregnancy testing
  • Every 6 months: Creatinine clearance assessment 1, 2

Additional Considerations

• Adherence counseling: Recent data shows that cisgender women with consistently daily or high adherence (4-6 doses/week) experienced very low HIV incidence (0.13/100 person-years) 4
• Comprehensive approach: Provide condoms, STI treatment, and risk-reduction counseling alongside PrEP
• Medication supply: Initially prescribe a 30-day supply, then 90-day supplies with appropriate follow-up testing 1

Common Pitfalls to Avoid

• Assuming all PrEP regimens work equally for all populations: The pharmacokinetics of TDF differ between rectal and vaginal tissues, making daily dosing essential for cisgender women
• Overlooking concurrent STI treatment: The patient needs treatment for chlamydia in addition to PrEP initiation
• Inadequate follow-up: Regular HIV testing is crucial to avoid developing resistance if breakthrough infection occurs
• Not addressing other risk factors: The patient's sex work and inconsistent condom use should be discussed in a non-judgmental manner, with emphasis on comprehensive prevention strategies

By prescribing daily oral TDF/FTC and implementing appropriate monitoring, this patient will receive the most evidence-based protection against HIV acquisition while maintaining her sexual health.