Quick Answer
Antifungal and antiviral pharmacology has climbed in NEET PG relevance since COVID and post-COVID mucormycosis.
- Amphotericin B — polyene, binds ergosterol; nephrotoxic. Liposomal spares kidneys.
- Azoles — inhibit 14-α-demethylase (ergosterol synthesis). Voriconazole for aspergillosis; isavuconazole/posaconazole for mucor prophylaxis.
- Echinocandins — block β-1,3-glucan synthase; first-line invasive candidiasis.
- Acyclovir — HSV/VZV; needs viral thymidine kinase; nephrotoxic (crystalluria).
- Oseltamivir — influenza neuraminidase inhibitor within 48 hours.
- HIV first-line India (NACO TLD) — Tenofovir + Lamivudine + Dolutegravir.
- HCV DAAs — sofosbuvir + velpatasvir 12 weeks, over 95 percent cure across genotypes.
Antifungal and antiviral pharmacology used to be a quiet corner of the syllabus. That changed with India's 2021 CAM (COVID-associated mucormycosis) epidemic, NACO's 2020 shift to dolutegravir-based ART, and the pan-genotypic DAA revolution that made HCV curable at scale.
This NEETPGAI deep dive covers polyene, azole, echinocandin and allylamine antifungals; HSV, VZV, CMV, influenza and RSV antivirals; the full HIV ART class map with NACO's TLD regimen; the pan-genotypic HCV DAAs; and COVID-era updates. Pair this with the HIV/AIDS management guide and the hepatitis serology guide for the clinical framing.
Antifungal drugs — class by class
Fungi have ergosterol (not cholesterol) in cell membranes and a β-glucan cell wall — the two major drug targets.
Polyenes — bind ergosterol
| Drug | Use | Toxicity |
|---|
| Amphotericin B deoxycholate | Invasive candidiasis, cryptococcosis, mucormycosis, aspergillosis | Nephrotoxicity (tubular dysfunction, hypokalaemia, hypomagnesaemia), infusion reactions (fever, rigors — pre-medicate), anaemia |
| Liposomal amphotericin B (L-AmB) | Same spectrum with less renal toxicity; single-dose 10 mg/kg is India's kala-azar regimen | Costly; still some renal risk |
| Nystatin | Topical oral / cutaneous candidiasis (too toxic for systemic use) | Local irritation |
Azoles — inhibit 14-α-demethylase (CYP51) → ergosterol depletion
| Drug | Spectrum | Toxicity / interaction |
|---|
| Fluconazole | Candida (not krusei/glabrata), cryptococcosis maintenance | QT prolongation, hepatotoxicity, CYP2C9/3A4 inhibition |
| Itraconazole | Histoplasmosis, blastomycosis, sporotrichosis, dermatophytosis | Negative inotrope — avoid in CHF; hepatotoxicity |
| Voriconazole | Invasive aspergillosis first-line; some Candida | Visual disturbances (photopsia), hepatotoxicity, skin phototoxicity + SCC risk, QT prolongation, CYP interactions |
| Posaconazole | Prophylaxis in neutropenic AML/MDS; mucor step-down | GI intolerance, hepatotoxicity |
| Isavuconazole | Mucormycosis alternative to L-AmB; aspergillosis | Shortens QT (unique); hepatotoxicity |
Mnemonic — voriconazole gives "vortex vision" (visual halos); isavuconazole is the "isolated QT shortener".
Echinocandins — inhibit β-1,3-glucan synthase (cell wall)
| Drug | Notes |
|---|
| Caspofungin, Micafungin, Anidulafungin | First-line invasive candidiasis (including glabrata, krusei); salvage aspergillosis; excellent safety, minimal drug interactions, IV only |
Allylamines and other agents
| Drug | Use | Toxicity |
|---|
| Terbinafine | Onychomycosis, tinea capitis in adults | Hepatotoxicity, taste disturbance, agranulocytosis |
| Griseofulvin | Tinea capitis in children (deposited in keratin) | Photosensitivity, disulfiram-like reaction |
| 5-Flucytosine | Adjunct with amphotericin in cryptococcal meningitis; converted to 5-FU intracellularly | Myelosuppression, hepatotoxicity |
India COVID-associated mucormycosis (CAM) — 2021 lessons
- Over 45,000 cases nationally; driven by uncontrolled hyperglycaemia and steroid overuse.
- Liposomal amphotericin B 5-10 mg/kg/day first-line, plus aggressive surgical debridement.
- Isavuconazole and posaconazole for step-down oral therapy.
- Voriconazole has NO activity against mucor — a classic MCQ trap.
- Iron chelation with deferoxamine is contraindicated (iron drives mucor growth).
Antiviral drugs — herpes group, influenza, RSV
HSV / VZV
| Drug | Notes |
|---|
| Acyclovir | Activated by viral thymidine kinase (TK) → mono → di → tri phosphate → viral DNA polymerase inhibitor; crystalluria and nephrotoxicity — hydrate + slow infusion; neurotoxicity in renal failure |
| Valacyclovir | Prodrug — better oral bioavailability |
| Famciclovir | Oral, similar spectrum |
| Foscarnet | Pyrophosphate analogue — no TK needed; used for acyclovir-resistant HSV and CMV; nephrotoxicity, hypocalcaemia, seizures |
| Ganciclovir / Valganciclovir | CMV treatment / prophylaxis in transplant, HIV; myelosuppression (neutropenia, thrombocytopaenia); mutagenic |
| Letermovir | Newer CMV prophylaxis in HSCT — no myelosuppression |
| Maribavir | Refractory CMV — pUL97 kinase inhibitor |
Influenza
| Drug | Mechanism |
|---|
| Oseltamivir (oral) | Neuraminidase inhibitor; give within 48 hours of symptom onset |
| Zanamivir (inhaled) | Neuraminidase inhibitor; caution in reactive airway disease |
| Baloxavir marboxil | Cap-dependent endonuclease inhibitor; single-dose |
| Amantadine, rimantadine | M2 ion channel inhibitors; obsolete due to resistance |
RSV
- Palivizumab — humanised anti-F monoclonal for preterm infants (5 monthly doses through RSV season).
- Nirsevimab — long-acting monoclonal; single dose covers entire season (approved 2023 in many countries; India rollout awaited).
- Ribavirin — inhaled; reserved for severe RSV in immunocompromised.
HIV antiretroviral therapy — the full class map
India's NACO 2020 first-line ART is TLD — Tenofovir DF + Lamivudine + Dolutegravir as a single once-daily tablet.
NRTIs / NtRTIs — nucleoside/nucleotide analogues, chain terminators
| Drug | Signature toxicity |
|---|
| Tenofovir DF (TDF) | Renal tubular dysfunction (Fanconi-like), decreased BMD |
| Tenofovir alafenamide (TAF) | Safer renal/bone profile; used in TAFED-based STRs |
| Lamivudine (3TC) | Well tolerated; dual HBV activity |
| Emtricitabine (FTC) | Well tolerated; hyperpigmentation of palms/soles |
| Abacavir (ABC) | HLA-B*5701 hypersensitivity reaction — screen first |
| Zidovudine (AZT) | Anaemia, lipoatrophy, myopathy (largely replaced) |
NNRTIs — allosteric RT binders
| Drug | Notes |
|---|
| Efavirenz | CNS side effects (vivid dreams, dysphoria); teratogenic in early pregnancy (though evidence softened) |
| Nevirapine | Hepatotoxicity, especially in women with CD4 more than 250 |
| Doravirine | Newer, better tolerated |
| Rilpivirine | Requires acid for absorption — avoid PPIs |
PIs — block HIV protease (polyprotein cleavage)
| Drug | Notes |
|---|
| Atazanavir | Indirect hyperbilirubinaemia (Gilbert-like); nephrolithiasis |
| Darunavir | Needs ritonavir or cobicistat boost; high barrier to resistance |
| Lopinavir/ritonavir | Legacy; GI intolerance, hyperlipidaemia |
INSTIs — block integrase (proviral DNA integration)
| Drug | Notes |
|---|
| Dolutegravir (DTG) | India NACO first-line; very high barrier to resistance; weight gain |
| Bictegravir | Only in Biktarvy STR |
| Raltegravir | First INSTI; twice daily |
| Elvitegravir | Needs cobicistat boost |
Entry / fusion inhibitors
- Maraviroc — CCR5 antagonist; only active on CCR5-tropic virus (needs tropism assay).
- Enfuvirtide — gp41 fusion inhibitor; injectable, salvage only.
Post-exposure prophylaxis (India NACO)
- TLD × 28 days for occupational or non-occupational HIV exposure — start within 72 hours (ideally within 2 hours).
HBV, HCV, COVID, SARS antivirals
HBV
- Tenofovir DF or TAF and Entecavir — first-line for chronic HBV suppression (high genetic barrier).
- Peg-IFN-α — finite duration alternative for HBeAg-positive patients under 40 years with high ALT.
HCV — DAAs (pan-genotypic)
| Drug | Class |
|---|
| Sofosbuvir | NS5B polymerase inhibitor (backbone) |
| Velpatasvir | NS5A inhibitor — pan-genotypic partner |
| Voxilaprevir | NS3/4A protease inhibitor — retreatment triple |
| Glecaprevir/pibrentasvir | 8-week pan-genotypic alternative |
India's National Viral Hepatitis Control Programme (NVHCP) provides free DAAs at government hepatology centres.
COVID-19
- Remdesivir — RdRp inhibitor; IV, 5-day course; benefit in oxygen-requiring patients not on ventilation.
- Nirmatrelvir/ritonavir (Paxlovid) — oral 3CL protease inhibitor; start within 5 days of symptom onset; boxed CYP3A4 drug interactions.
- Molnupiravir — mutagenic RdRp inhibitor; NEUTROPENIA and teratogenicity concerns limit use.
NEET PG MCQ traps
- Amphotericin B nephrotoxicity — hypokalaemia, hypomagnesaemia; use liposomal to reduce risk.
- Voriconazole visual disturbances and phototoxicity — SCC risk with chronic use.
- Isavuconazole — the only azole that shortens QT.
- Voriconazole is NOT active against mucor — use L-AmB, isavuconazole or posaconazole.
- Echinocandins IV only — no oral form; excellent safety for invasive candidiasis.
- Terbinafine hepatotoxicity + taste change — first-line onychomycosis.
- Acyclovir requires viral TK for activation — TK-deficient HSV needs foscarnet.
- Ganciclovir myelosuppression — CMV in transplant.
- Oseltamivir within 48 hours of influenza symptom onset.
- Abacavir + HLA-B*5701 hypersensitivity — mandatory pre-screen.
- Efavirenz — CNS dysphoria and vivid dreams.
- Nevirapine hepatotoxicity in women with CD4 more than 250.
- Atazanavir — unconjugated hyperbilirubinaemia (Gilbert-like).
- Dolutegravir + rifampicin — double DTG dose.
- TLD — India NACO first-line ART since 2020.
- Maraviroc — CCR5 antagonist; needs tropism testing.
- Sofosbuvir + velpatasvir — pan-genotypic HCV cure over 95 percent.
- Tenofovir + entecavir — chronic HBV first-line.
- Remdesivir + Paxlovid — COVID antivirals; Paxlovid has major CYP3A4 interactions.
- Palivizumab / nirsevimab — anti-RSV monoclonal for infants.
- Foscarnet — pyrophosphate analogue; no TK needed; nephrotoxicity + hypocalcaemia.
- Iron chelation contraindicated in mucor — deferoxamine drives Rhizopus growth.
Recent updates and India context
- NACO TLD — India's default ART since 2020; supplied free at over 700 ART centres nationwide.
- Post-Tsepamo reassurance — dolutegravir is now considered safe throughout pregnancy, including periconception, after updated Botswana surveillance showed no elevated neural tube defect signal.
- National Viral Hepatitis Control Programme (NVHCP) — free DAAs at government hepatology centres; target HCV elimination by 2030 leveraging generic sofosbuvir + velpatasvir.
- Kala-azar single-dose L-AmB — the National Kala-Azar Elimination Programme in Bihar uses a single 10 mg/kg L-AmB infusion, contributing to the sub-elimination threshold India reached in 2023.
- CAM (2021) mucormycosis lessons — glycaemic control is more powerful than any antifungal; L-AmB + surgical debridement remains the backbone.
- Isavuconazole — WHO Essential Medicines listed 2023; expanding role for mucor and aspergillosis with fewer drug interactions than voriconazole.
- Long-acting HIV therapy — cabotegravir + rilpivirine long-acting IM (every 2 months) approved in the US/EU; India rollout awaited.
- Nirmatrelvir/ritonavir (Paxlovid) — WHO strongly recommends in high-risk non-hospitalised COVID; India's ICMR guidelines include molnupiravir with caveats but Paxlovid uptake is limited by CYP interactions and cost.
- Nirsevimab — single-dose RSV monoclonal approved 2023 in the US/EU; expected to replace palivizumab where funded; India regulatory pathway underway.
Frequently asked questions
Why is liposomal amphotericin B preferred over conventional amphotericin B deoxycholate?
Liposomal amphotericin B (L-AmB, AmBisome) has substantially lower nephrotoxicity and infusion-related reactions than conventional deoxycholate. The lipid formulation preferentially delivers the drug to reticuloendothelial-rich tissues (liver, spleen, lung) while sparing renal tubular cells. It is first-line for invasive candidiasis in unstable patients, cryptococcal meningitis induction, mucormycosis (with surgical debridement) and visceral leishmaniasis. India has abundant experience — the single-dose 10 mg/kg L-AmB regimen for kala-azar was pioneered in Bihar under the National Kala-Azar Elimination Programme. The main drawback is cost.
What is the NACO TLD first-line ART regimen and why did India adopt it?
TLD is Tenofovir disoproxil fumarate (300 mg) plus Lamivudine (300 mg) plus Dolutegravir (50 mg) as a once-daily single-tablet regimen, adopted by NACO as India's first-line ART in 2020. Rationale — dolutegravir has a very high genetic barrier to resistance, faster viral suppression than efavirenz, better tolerability (no CNS side effects), and pan-genotypic activity. Cost fell dramatically after generic manufacturing at Cipla, Mylan and Aurobindo. It is safe in pregnancy (post-Tsepamo reassurance) and works with rifampicin using doubled dolutegravir dosing during co-TB treatment.
Which antifungal is first-line for mucormycosis and what surgical role?
Liposomal amphotericin B 5-10 mg/kg/day is first-line for mucormycosis (Rhizopus, Mucor, Cunninghamella), which surged during India's COVID-19 second wave (2021 CAM epidemic — over 45,000 cases). Isavuconazole and posaconazole are alternatives or step-down oral therapy. Aggressive surgical debridement of necrotic tissue is essential — antifungals alone cannot reach avascular necrotic zones. Reversal of underlying drivers (glycaemic control, stopping steroids, iron chelation avoidance) is equally important. Voriconazole has NO activity against mucor and must not be used empirically for suspected mucor.
How do NRTIs, NNRTIs, PIs, INSTIs and entry inhibitors differ mechanistically?
NRTIs (tenofovir, lamivudine, emtricitabine, abacavir, zidovudine) are nucleoside/nucleotide analogues that inhibit reverse transcriptase by chain termination. NNRTIs (efavirenz, nevirapine, doravirine, rilpivirine) bind allosterically at a distinct RT site. PIs (atazanavir, darunavir, lopinavir) block HIV protease, preventing polyprotein cleavage — usually ritonavir-boosted. INSTIs (dolutegravir, bictegravir, raltegravir, elvitegravir) inhibit integrase, blocking proviral DNA integration into the host genome — now the preferred backbone. Entry inhibitors — maraviroc (CCR5 antagonist) and enfuvirtide (fusion inhibitor) — target gp120-CCR5 binding and gp41 fusion respectively.
What are the pan-genotypic DAAs for chronic HCV and why is India a leader?
Sofosbuvir (NS5B polymerase inhibitor) combined with velpatasvir (NS5A inhibitor) and voxilaprevir (NS3/4A protease inhibitor for retreatment) is the pan-genotypic DAA backbone recommended by WHO. A 12-week course cures over 95 percent of chronic HCV across all six genotypes with minimal side effects, replacing older interferon-based regimens. India is a pharmaceutical leader — the Medicines Patent Pool licensed sofosbuvir generics to Cipla, Natco, Hetero, Mylan and others, driving global affordability. The National Viral Hepatitis Control Programme (NVHCP) provides free DAAs at government hepatology centres, aiming for HCV elimination by 2030.
This content is for educational purposes for NEET PG exam preparation. It is not a substitute for professional medical advice, diagnosis, or treatment. Clinical information has been reviewed by qualified medical professionals.
Written by: NEETPGAI Editorial Team
Reviewed by: Pending SME Review
Last reviewed: July 2026
