A 38-year-old patient presents with influenza symptoms for 36 hours. Oseltamivir is prescribed. Its mechanism of action against influenza virus is:

• A Inhibition of influenza RNA-dependent RNA polymerase (PA subunit)
• B Blocking M2 ion channel to prevent viral uncoating
• C Blocking hemagglutinin binding to sialic acid receptors on host cells
• D Inhibition of viral neuraminidase, preventing release of new virions from infected cells ✓

Explanation

Oseltamivir (Tamiflu) and zanamivir are neuraminidase inhibitors. Influenza neuraminidase cleaves sialic acid residues on the host cell surface, releasing newly formed virions from infected cells for systemic spread. Inhibition of neuraminidase causes virion aggregation on the cell surface, limiting further infection. They are active against both influenza A and B. Amantadine/rimantadine block the M2 ion channel (influenza A only); baloxavir inhibits the PA endonuclease subunit of the viral polymerase.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.