Hiv Antiretroviral Therapy

Also written as HAART, cART.

Antiretroviral therapy (ART) suppresses HIV replication, restores immune function, and prevents disease progression. Effective lifelong treatment requires selecting drug classes, monitoring response, and managing side effects.

Overview

HIV infects CD4+ T‑cells, leading to progressive immune loss. ART combines drugs that target different steps of the viral life cycle to keep viral load undetectable.

• Goal: viral load <50 copies/mL after 24 weeks
• Start ART in all diagnosed persons, regardless of CD4 count
• Regimens are usually 2‑drug (integrase inhibitor + NRTI) or 3‑drug

Key concepts

Understanding drug classes, resistance barriers, and drug‑drug interactions guides regimen choice and long‑term success.

• Baseline HIV RNA: Is the viral load high enough to need urgent ART? Detectable >1000 copies/mL confirms active replication; if unavailable, start standard regimen empirically.
• CD4 count: Guides prophylaxis for opportunistic infections; <200 cells/µL → start PCP prophylaxis.
• Hepatitis B serology: Identifies need for agents active against HBV (e.g., tenofovir); if unavailable, choose regimen with dual activity.
• Renal function (eGFR): Determines suitability of tenofovir; if eGFR < 30 mL/min, avoid tenofovir and use abacavir if HLA‑B*5701 negative.

• NRTIs block reverse transcription; backbone of most regimens
• Integrase strand transfer inhibitors (INSTIs) prevent viral DNA integration – high barrier to resistance
• Protease inhibitors (PIs) inhibit viral maturation – require boosting, many interactions
• NNRTIs bind reverse transcriptase – low barrier, avoid if resistance risk

Clinical relevance

Effective ART reduces morbidity, mortality, and transmission. In low‑resource settings, fixed‑dose combinations simplify adherence and supply chain.

• First‑line: INSTI + 2 NRTIs (e.g., dolutegravir + tenofovir + lamivudine)
• Second‑line: PI + 2 NRTIs (e.g., lopinavir/ritonavir + tenofovir + lamivudine)
• Switch only for toxicity, resistance, or drug interactions

Exam pearls

Focus on regimen selection, monitoring, and handling common complications.

• When to add PCP prophylaxis
• Interpretation of a rising viral load after initial suppression
• Management of integrase inhibitor‑related weight gain

Common mistakes

Errors often stem from ignoring baseline labs, drug interactions, or resistance patterns.

• Starting a PI without boosting in patients on rifampicin (TB treatment) → subtherapeutic levels
• Prescribing tenofovir to patients with severe renal impairment
• Switching drugs without confirming adherence first

Questions an examiner may ask

• Explain how each ART drug class interferes with the HIV life cycle.
• A patient on tenofovir develops rising creatinine; what is your next step?
• Interpret a viral load of 200 copies/mL after 12 weeks of therapy.

When to seek help

• Acute HIV syndrome with high fever, severe diarrhoea, or meningitis
• New opportunistic infection despite ART
• Severe drug toxicity (e.g., hepatic failure, lactic acidosis)

Quick questions

Why is an integrase inhibitor preferred for first‑line therapy?

INSTIs have the highest barrier to resistance, rapid viral suppression, and few drug interactions.

Can ART be started in pregnancy?

Yes, early ART is recommended; regimens avoid efavirenz in the first trimester and use agents with safety data.

What if viral load testing is not available?

Start standard first‑line regimen and monitor clinical response; repeat CD4 count and assess for opportunistic infections.