Antiinfluenza Agents (Neuraminidase Inhibitors)
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Zanamivir, oseltamivir, and peramivir block influenza A and B neuraminidases. Neuraminidase activity is necessary for successful viral egress and release from infected cells. These drugs have shown modest activity in clinical trials, with a 1- to 2-day improvement in symptoms in patients who are treated within 48 hours of the onset of influenza symptoms. At the onset of each influenza season, a consultation with local health department officials is recommended to determine the most effective antiviral agent. Although oseltamivir and zanamivir are effective for prophylaxis of influenza, annual influenza vaccination remains the most effective method for prophylaxis in all high-risk patients and health care workers (see Appendix A, Immunizations and Post-exposure Therapies).
- Zanamivir (10 mg [two inhalations] q12h for 5 days, started within 48 hours of the onset of symptoms) is an inhaled neuraminidase inhibitor that is active against influenza A and B. It is indicated for treatment of uncomplicated acute influenza infection in adults and children 7 years of age or older who have been symptomatic for <48 hours. The drug is also indicated for influenza prophylaxis in patient’s age 5 years and older.
Adverse events such as headache, GI disturbances, dizziness, and upper respiratory symptoms are sometimes reported. Bronchospasms or declines in lung function, or both, may occur in patients with underlying respiratory disorders and may require a rapid-acting bronchodilator for control.
- Oseltamivir (75 mg PO q12h for 5 days) is an orally administered neuraminidase inhibitor that is active against influenza A and B. It is indicated for treatment of uncomplicated acute influenza in adults and children 1 year of age or older who have been symptomatic for up to 2 days. This agent is also indicated for prophylaxis of influenza A and B in adults and children 1 year of age or older.
Adverse events include nausea, vomiting, and diarrhea. Dizziness and headache may also occur.
- Peramivir (600 mg IV single-dose therapy) is an IV neuraminidase inhibitor that is active against influenza A and B. It is FDA approved for single-dose treatment of acute, uncomplicated influenza in adults who have been symptomatic for up to 2 days. The agent has not been proven to be effective for serious influenza requiring hospitalization.
Adverse events include diarrhea and rare cases of skin reactions, behavioral disturbances, neutrophils <1000/μL, hyperglycemia, creatine phosphokinase elevation, and elevation of hepatic transaminases.