What is the recommended HIV pre-exposure prophylaxis (PrEP) regimen for a 24-year-old cisgender female with a history of injection drug use who is in a substance use treatment program?

HIV Pre-Exposure Prophylaxis for a 24-Year-Old Cisgender Female with Injection Drug Use History

This patient should be prescribed daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) as HIV pre-exposure prophylaxis, as she meets clear criteria for PrEP based on her injection drug use history and represents a population with elevated HIV acquisition risk. 1, 2

PrEP Indication and Rationale

• Women who inject drugs are prime candidates for PrEP due to elevated HIV risk through both injection practices and associated sexual behaviors 3, 4
• The fact that she is in a substance use treatment program does not preclude PrEP prescription—rather, it provides an ideal setting for integrated HIV prevention services 1
• PrEP reduces HIV acquisition risk by at least 74% in people who inject drugs when taken as prescribed 1

Recommended Regimen

Daily oral tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) once daily is the evidence-based regimen for cisgender women with injection drug use risk 1, 2

• Tenofovir alafenamide/emtricitabine (TAF/FTC) is not currently recommended for PrEP in this population, as available data are insufficient 1
• Daily dosing is critical for cisgender women, as tenofovir concentrates at 10-fold lower levels in vaginal tissue compared to rectal tissue, with faster clearance 1
• Cisgender women require at least 6 of 7 doses per week for adequate protection, unlike MSM who may achieve protection with 4 of 7 doses 1

Pre-Initiation Testing Requirements

Before prescribing PrEP, obtain the following baseline tests 1:

• Combined HIV antibody and antigen testing (laboratory-based preferred; use rapid test only if lab-based unavailable) 1
• HIV RNA testing if any clinical suspicion of acute infection exists, as antiretroviral exposure can delay seroconversion 5
• Serum creatinine with calculated creatinine clearance 1
• Hepatitis B surface antigen 1
• Hepatitis C antibody (with RNA confirmation if positive and not recently documented) 1
• Hepatitis A antibody for people who inject drugs (if immunity unknown) 1
• Pregnancy test 1
• Genital and nongenital gonorrhea and chlamydia testing by NAAT 1
• Syphilis testing 1

Ongoing Monitoring Schedule

At 1 Month 1:

• Combined HIV antibody and antigen test
• Assess adherence and tolerability

Every 3 Months 1:

• Combined HIV antibody and antigen test
• Estimated creatinine clearance (at first quarterly visit, then annually if stable; every 3-6 months if kidney injury risk exists)
• Gonorrhea and chlamydia testing by NAAT at all exposure sites
• Syphilis testing
• Pregnancy testing
• Adherence assessment and counseling

Annually 1:

• Hepatitis C antibody testing (consider every 3-6 months given active injection drug use history)

Critical Adherence Considerations for This Population

Cisgender women require higher adherence levels than MSM for equivalent protection 1, 6:

• Studies demonstrate that consistently daily adherence (7 doses/week) resulted in zero HIV infections among 498 women 6
• Consistently high adherence (4-6 doses/week) resulted in only 1 infection among 658 women (incidence 0.13/100 person-years) 6
• Declining or low adherence significantly increases HIV acquisition risk 6

Provide individualized adherence support strategies 1:

• Electronic reminders, text messaging services, or pill boxes for those willing to use technology
• Address barriers specific to women who use drugs, including HIV stigma, fear of side effects, and concerns about long-term medication access 3
• Integrate PrEP care within her substance use treatment program to reduce structural barriers 3

Special Considerations for Women Who Inject Drugs

• History of injection drug use should never deter PrEP prescription when indicated 1
• Women who use prescription opioids and engage in polydrug use often have higher HIV risk perception and PrEP initiation intention, but lower PrEP awareness 4
• Address co-occurring risks: 75% of women who use drugs report getting high or drunk before sex, increasing HIV exposure risk 4
• Provide comprehensive harm reduction counseling, including access to sterile injection equipment and safer injection practices 1

Common Pitfalls to Avoid

• Do not withhold PrEP based on active substance use or treatment program enrollment—these patients have substantial HIV risk and benefit from PrEP 1, 3
• Do not assume 4 doses per week is adequate for cisgender women—they require near-daily dosing for protection 1
• Do not delay PrEP initiation for extensive counseling—start medication promptly while providing ongoing support 1
• Do not use PrEP as a substitute for comprehensive harm reduction services—integrate with substance use treatment, mental health support, and STI prevention 3

Transition Planning

• If she experiences a high-risk HIV exposure while on PrEP with suboptimal adherence (fewer than 6 of past 7 doses), discontinue PrEP and initiate 28-day post-exposure prophylaxis (PEP), then resume PrEP 1
• Reassess PrEP continuation at each visit based on ongoing risk and patient preference 1
• If she discontinues PrEP for ≥7 consecutive days, repeat HIV testing before restarting 1