## Neuraminidase Inhibitors in Influenza Management **Key Point:** Oseltamivir is a selective neuraminidase inhibitor that blocks the release of newly synthesized influenza virions from infected cells, preventing viral spread. ### Mechanism of Action Neuraminidase inhibitors cleave sialic acid receptors on the host cell surface, which are essential for viral release. By inhibiting this enzyme, oseltamivir traps viral particles on the cell surface and prevents further infection. ### Spectrum and Efficacy | Feature | Oseltamivir | Amantadine | Ribavirin | |---------|-------------|-----------|----------| | **Target enzyme** | Neuraminidase | M2 ion channel | Viral RNA polymerase | | **Influenza A coverage** | Yes | Yes | Limited | | **Influenza B coverage** | Yes | No | Limited | | **Route** | Oral | Oral | IV/inhaled | | **Timing** | Within 48 hrs of symptom onset | Within 48 hrs | Early in illness | **High-Yield:** Oseltamivir is the **standard of care** for influenza prophylaxis and treatment in India and globally. It reduces symptom duration by ~1 day and prevents complications in high-risk groups. **Clinical Pearl:** Amantadine (M2 inhibitor) has poor activity against influenza B and widespread resistance; oseltamivir is preferred. Ribavirin is reserved for severe cases or immunocompromised patients. ### Dosing (Standard) - **Treatment:** 75 mg orally twice daily for 5 days - **Prophylaxis:** 75 mg orally once daily for 10 days (post-exposure) or throughout influenza season **Tip:** Remember: **Oseltamivir = Neuraminidase inhibitor = Both A & B**. Amantadine = M2 inhibitor = A only (and now resistant).
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