Makindo Medical Notes

🧠 HIV and Pre-Exposure Prophylaxis (PrEP)

💊 Key Point: Pre-exposure prophylaxis (PrEP) involves daily use of antiretroviral medication by HIV-negative individuals at high risk of infection. To remain effective, it must be taken consistently every day with 3-monthly medical review for HIV testing, renal function, and STI screening.

📖 What Is PrEP?

• PrEP = Pre-Exposure Prophylaxis. It prevents HIV infection before exposure.
• Standard regimen: Truvada® (Tenofovir disoproxil fumarate 300 mg + Emtricitabine 200 mg) once daily.
• An alternative formulation (Descovy®) is used in some regions but not yet widely licensed for vaginal exposure.
• Works best as part of a wider prevention strategy including condoms, STI screening, and harm-reduction advice.

🎯 Who Should Consider PrEP?

• Individuals with ongoing HIV exposure risk:
  • Men who have sex with men (MSM).
  • Heterosexual men or women with an HIV-positive partner not fully suppressed on ART.
  • People with multiple partners or inconsistent condom use.
  • People who inject drugs and share injecting equipment.
  • Those diagnosed with a bacterial STI in the past 6 months.

⚙️ How Does It Work?

• HIV replicates via reverse transcription. Tenofovir + Emtricitabine are nucleoside reverse-transcriptase inhibitors (NRTIs).
• They are taken up by host cells and act as false nucleotides, blocking viral DNA synthesis after exposure.
• When taken daily, intracellular drug levels remain high enough to prevent establishment of infection.
• With good adherence, PrEP reduces HIV acquisition by:
  • ≈ 99 % for sexual exposure,
  • ≈ 74 % for people who inject drugs.

🚀 Starting PrEP (Baseline Assessment)

• Full discussion with a trained clinician regarding risks, adherence, and alternatives.
• Baseline tests:
  • HIV Ag/Ab test (must be negative before starting).
  • Urea & electrolytes ± eGFR (TDF is renally cleared).
  • Hepatitis B surface antigen and Hepatitis C antibody.
  • STI screen (chlamydia, gonorrhoea, syphilis, trichomonas as relevant).
  • Pregnancy test where applicable.
• First prescription: usually 3 months supply with counselling on adherence.

📅 Follow-Up (Every 3 Months)

• Repeat HIV testing to confirm ongoing negative status.
• Renal function monitoring (tenofovir nephrotoxicity risk).
• STI screen and vaccination review (Hep A/B, HPV where indicated).
• Reinforce adherence and discuss side-effects or behavioural changes.

💊 Dosing Strategies

• Daily dosing: One tablet daily with or without food — most evidence-based approach.
• Event-based (2-1-1) dosing: For MSM only — two tablets 2–24 h before sex, then one 24 h and one 48 h later. Not recommended for women or PWID due to lower drug penetration in vaginal tissue.

⚠️ Side Effects and Safety

• Usually mild and transient: nausea, headache, GI upset within first weeks.
• Occasional: small fall in eGFR (usually reversible), mild bone-mineral loss.
• Serious toxicity is rare; discontinue if eGFR < 60 mL/min/1.73 m².
• Does not protect against other STIs — condoms remain important.

💡 Benefits

• Reduces HIV acquisition by up to 99 % when taken correctly.
• Improves engagement with sexual-health services through quarterly review.
• Empowers high-risk individuals and reduces anxiety around exposure.
• Population-level benefit: fewer new HIV transmissions and reduced stigma.

🇬🇧 UK Context

• Available free through NHS sexual-health clinics since 2020 (England, Scotland, Wales).
• Prescription and monitoring follow BHIVA/BASHH 2022 PrEP Guidelines.
• Rapid-start pathways exist for emergency initiation after high-risk exposure until confirmatory HIV testing completed.

🧾 Counselling & Adherence Tips

• Take PrEP at the same time daily to maintain plasma and intracellular levels.
• Use alarms, pillboxes, or smartphone reminders.
• Report symptoms of acute HIV infection (fever, rash, lymphadenopathy) immediately — stop PrEP until HIV ruled out.
• Maintain hydration and avoid nephrotoxic agents (e.g., NSAIDs) if possible.

📚 References

• BNF: Tenofovir Disoproxil & Emtricitabine
• BHIVA/BASHH. UK Guideline on the use of HIV Pre-Exposure Prophylaxis (2022).
• Grant RM et al. NEJM 2010;363:2587–99 — iPrEx study.
• Baeten JM et al. NEJM 2012;367:399–410 — Partners PrEP trial.