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MD Pharmacology NMC syllabus ~5 min read Recent advances last updated on 2026-08-22

Pharmacotherapy of Opportunistic Infections

Drug-by-Drug Treatment and Prophylaxis of PCP, Cryptococcosis, CMV, Toxoplasmosis, MAC and Mucosal Candidiasis in HIV

Past RGUHS · 3 RGUHSDec '23 RGUHSJul '23 RGUHSMay '10

Introduction

  • An opportunistic infection (OI) is caused by an organism that is normally innocuous but becomes invasive once cell-mediated immunity fails. In HIV, OI risk tracks the falling CD4+ count — the single most useful pharmacotherapeutic trigger in this topic.
  • Six OIs carry the examinable drug therapy — PCP, cryptococcal meningitis, CMV end-organ disease, toxoplasma encephalitis, disseminated MAC and mucosal candidiasis — each appearing at a predictable CD4 level.
  • ART is itself the definitive anti-OI drug. Prophylaxis is only a time-limited bridge until immune restoration, chosen on the OI's local prevalence, the patient's immune status and access to ART.
  • Polypharmacy is the norm and the hazard — overlapping organ toxicity and cytochrome-P450 interactions dominate practice. OI therapy is not interrupted for anything but intolerance, interaction or toxicity.
The CD4 ladder — which opportunistic infection appears at which CD4 count
CD4 count (cells/mm3)Opportunistic infection that becomes likely
350–500Herpes zoster
≤350Tuberculosis
≈250Oral candidiasis
<200PCP · oesophageal candidiasis · mucocutaneous herpes
<100Toxoplasmosis · cryptococcosis · cryptosporidiosis · PML
<50CMV end-organ disease · disseminated MAC
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Opportunistic Infections Pharmacotherapy

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