Antimicrobials/Antiviral (non-HIV)low yield

Antivirals

also: aciclovir · valaciclovir · oseltamivir · ganciclovir

Overview

Antivirals for herpes/varicella, influenza and CMV (HIV antiretrovirals are in the Sexual Health section).

Mechanism

Aciclovir is activated by viral thymidine kinase → inhibits viral DNA polymerase (selective for infected cells). Oseltamivir inhibits neuraminidase → blocks influenza release. Ganciclovir inhibits CMV DNA polymerase.

The agents

Aciclovir / valaciclovirherpes/VZV

PO/IV

Genital herpes, shingles (within 72 h), HSV encephalitis (IV), severe chickenpox; AKI if dehydrated (IV).

Oseltamivirneuraminidase inhibitor

oral

Influenza — within 48 h of onset (treatment/prophylaxis in at-risk).

Gancicloviranti-CMV

CMV (immunocompromised); myelosuppression.

Adverse effects

Aciclovir: crystal nephropathy (IV — hydrate), neurotoxicitycommon

Ganciclovir: myelosuppressionserious

Oseltamivir: nausea, neuropsychiatric (children, rare)common

Cautions & contraindications

Renal impairment (dose-adjust aciclovir/ganciclovir)renal

Interactions

Nephrotoxins; probenecid

Monitoring & kinetics

Renal function (IV aciclovir/ganciclovir); FBC (ganciclovir)

Oral / IV. Time-critical (shingles <72 h, influenza <48 h).

Choosing it

Spectrum: Aciclovir/valaciclovir: HSV, VZV. Oseltamivir: influenza A/B. Ganciclovir: CMV.

Source: BNF — Antivirals