Oseltamivir is used for influenza treatment and prophylaxis. Its mechanism of action is:

• A Inhibition of influenza RNA-dependent RNA polymerase, preventing viral RNA synthesis
• B Blockade of the M2 ion channel, preventing viral uncoating and entry into host cell nucleus
• C Inhibition of hemagglutinin-mediated fusion with the endosomal membrane, blocking viral entry
• D Competitive inhibition of viral neuraminidase (sialidase), preventing release of new virions from infected cells and reducing spread ✓

Explanation

Oseltamivir (and zanamivir) are neuraminidase inhibitors. Influenza neuraminidase (sialidase) cleaves sialic acid residues on the host cell surface and on budding viral particles, allowing new virions to be released and preventing self-aggregation. By competitively inhibiting neuraminidase, oseltamivir traps newly assembled virions at the infected cell surface, limiting spread. M2 channel blockade is the mechanism of older adamantane antivirals (amantadine, rimantadine) only active against influenza A.

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

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Written and medically reviewed by the StethoPrep medical team.