Oseltamivir (Tamiflu) is used for influenza A and B. Its mechanism of action is:

• A Inhibition of the M2 ion channel of influenza A, preventing uncoating
• B Competitive inhibition of influenza neuraminidase (sialidase), preventing release of newly formed virions from infected cells ✓
• C Inhibition of viral RNA-dependent RNA polymerase (PB1 subunit)
• D Blockade of haemagglutinin, preventing virus-cell attachment

Explanation

Oseltamivir phosphate (active form after intestinal/hepatic conversion of prodrug oseltamivir) competitively inhibits influenza neuraminidase (NA), which normally cleaves sialic acid residues from host cell receptors and newly synthesised virion surfaces to allow release and spread of progeny virions. NA inhibition traps newly formed virions at the surface of infected cells, limiting viral dissemination. Amantadine/rimantadine block M2 channels (influenza A only); baloxavir targets cap-dependent endonuclease (PA); there is no approved haemagglutinin inhibitor.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.