Anti-Influenza Agents
GENERAL PRINCIPLES
Zanamivir, oseltamivir, and peramivir are neuraminidase inhibitors that block influenza A and B neuraminidases. Neuraminidase activity is necessary for successful viral egress and release from infected cells.
Baloxavir is an endonuclease inhibitor that inhibits influenza gene transcription.TREATMENT
• Zanamivir (10 mg [two inhalations] q12h for 5 d, started within 48 h 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 lt;48 hours. It is also indicated for influenza prophylaxis in patients aged 5 years and older.
Adverse events such as headache, GI disturbances, dizziness, and upper respiratory symptoms are sometimes reported. Bronchospasm, a decline 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 ? 5 d) 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. Dose adjustment for renal function is indicated.
Adverse events include nausea, vomiting, and diarrhea. Dizziness, headache, and other neuropsychiatric events (e.g., confusion, delirium, hallucination, and/or self-injury) may also occur.
• Peramivir (600 mg IV ? 1 dose) 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 but is often given daily for up to 10 days in hospitalized patients unable to tolerate or absorb oral oseltamivir.Adverse events include diarrhea and rarely skin reactions, behavioral disturbances, neutrophils lt;1000#8725;#956;L, hyperglycemia, CK elevation, and LFT elevation.
• Baloxavir marboxil (lt;80 kg: 40 mg ? 1 dose; #8805;80 kg: 80 mg ? 1 dose started within 48 h of the onset of symptoms) is a first-in-class oral prodrug that inhibits influenza virus gene transcription, thereby preventing viral replication. It is FDA-approved for both treatment and postexposure prophylaxis of seasonal influenza caused by influenza A or B and should be given as a single dose within 48 hours of symptoms or exposure.
Adverse events are rare but include diarrhea and rash.
SPECIAL CONSIDERATIONS
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, zanamivir, and baloxavir 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 Postexposure Therapies).