PH8.10 | PH8.10 | Antiviral Drugs Including HIV Therapy — SDL Guide — Summary & Reflection

KEY TAKEAWAYS

Aciclovir selective toxicity: activated ONLY by viral TK (3000× selectivity vs host TK) → active in infected cells only → viral DNA polymerase inhibition + chain termination. HSV-1, HSV-2, VZV — NOT CMV (CMV has UL97, not TK). Ganciclovir/valganciclovir — CMV (UL97-activated); myelosuppressive.

Oseltamivir: neuraminidase inhibitor → prevents virion release from infected cells. Influenza A+B. Start within 48 hours. Prophylaxis: 75mg once daily × 10 days.

HIV ART classes: NRTIs (chain termination; TDF+3TC backbone); NNRTIs (allosteric RT inhibitor — efavirenz; CYP inducer); PIs (protease cleavage block; metabolic syndrome; potent CYP3A4 inhibitors; avoid with rifampicin); INSTIs (integrase strand transfer block; dolutegravir — preferred first-line; high genetic barrier; few interactions; double-dose DTG with rifampicin).

Indian first-line ART: TDF + 3TC + DTG (TLD) or TDF + 3TC + EFV. For HIV-TB: TDF + 3TC + EFV standard doses; OR DTG 50mg BD (double dose) if EFV cannot be used.

HCV DAAs: sofosbuvir-based pan-genotypic regimens, >95% SVR (cure) × 8–12 weeks. PEP: TDF+FTC+DTG × 28 days within 72 hours. PrEP: TDF+FTC daily in HIV-negative high-risk individuals. U=U: Undetectable = Untransmittable.

REFLECT

HIV remains highly stigmatised in India — testing rates are suboptimal, many people learn their status only at late-stage AIDS, and ART adherence is undermined by social shame. The U=U message has the potential to change this. As a future clinician and community leader, how would you use the pharmacological truth of viral suppression — that a person with an undetectable viral load cannot transmit HIV — as a tool to reduce stigma, encourage testing, and improve adherence? And how does knowing that treatment = prevention change the ethics of how we discuss HIV with patients, families, and communities?