Oseltamivir (Tamiflu) is effective against influenza if started within 48 hours of symptom onset. Its mechanism is:

• A Inhibition of the viral RNA polymerase, preventing viral replication
• B Inhibition of neuraminidase, preventing cleavage of sialic acid bonds and trapping newly synthesized virions on the cell surface ✓
• C Competitive inhibition of hemagglutinin, blocking viral attachment to sialic acid receptors on host cells
• D Blocking the M2 ion channel, preventing viral uncoating and release of viral RNA into the cytoplasm

Explanation

Neuraminidase (sialidase) is an influenza surface glycoprotein that cleaves sialic acid residues from host cell receptors, allowing newly formed virions to be released from infected cells and spread to new cells. Oseltamivir is a prodrug converted to oseltamivir carboxylate, a competitive inhibitor of influenza A and B neuraminidase. Inhibition traps newly synthesized virions attached to the host cell via hemagglutinin-sialic acid bonds, prevents their release, and limits viral spread. Starting treatment within 48 hours is key because viral replication peaks in this period. M2 channel blockers (amantadine, rimantadine) inhibit uncoating but only work against influenza A and have high resistance rates.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.