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Anti-Influenza Agents
Background: |
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Influenza A is the predominant virus type, accounting for 99.5% of
influenza cases. The incidence of influenza peaks in the last week of
December. The optimal time to vaccinate is during October and November.
Oseltamivir (Tamiflu) and zanamivir (Relenza) block the neuraminidase surface protein on both influenza A and influenza B. Amantadine and rimantadine prevent early viral replication of influenza A only. |
amantadine (Symmetrel ®): |
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Dosing (Adults): Influenza A treatment: Oral: 100 mg twice daily; initiate within 24-48 hours after onset of symptoms; discontinue as soon as possible based on clinical response (generally within 3-5 days or within 24-48 hours after symptoms disappear). Influenza A prophylaxis: Oral: 100 mg twice daily; continue treatment throughout the peak influenza activity in the community or throughout the entire influenza season in patients who cannot be vaccinated. Development of immunity following vaccination takes ~2 weeks; amantadine therapy should be considered for high-risk patients from the time of vaccination until immunity has developed. Drug-induced extrapyramidal symptoms: Oral: 100 mg twice daily; may increase to 300-400 mg/day, if needed. Parkinson's disease: Oral: 100 mg twice daily as sole therapy; may increase to 400 mg/day if needed with close monitoring; initial dose: 100 mg/day if with other serious illness or with high doses of other anti-Parkinson drugs. Elderly: Influenza A prophylaxis or treatment: 100 mg/day in patients over 65 years. Renal Dosing: CrCl 30-50 mL/minute: Administer 200 mg on day 1, then 100 mg/day. CrCl 15-29 mL/minute: Administer 200 mg on day 1, then 100 mg on alternate days. CrCl <15 mL/minute: Administer 200 mg every 7 days. Hemodialysis: Administer 200 mg every 7 days. Supplied: 100 mg capsule / tablet. Syrup: 50 mg/5 ml. |
oseltamivir phosphate (Tamiflu ®): |
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INDICATIONS Treatment of Influenza: TAMIFLU is indicated for the treatment of uncomplicated acute illness due to influenza infection in patients 1 year and older who have been symptomatic for no more than 2 days. Prophylaxis of Influenza: TAMIFLU is indicated for the prophylaxis of influenza in patients 1 year and older. TAMIFLU is not a substitute for early vaccination on an annual basis as recommended by the Centers for Disease Control and Prevention Advisory Committee on Immunization Practices. Dosage - Treatment of Influenza (Adults and Adolescents): The recommended oral dose of TAMIFLU for treatment of influenza in adults and adolescents 13 years and older is 75 mg twice daily for 5 days. Treatment should begin within 2 days of onset of symptoms of influenza. Renal Dosing: If crcl< 30 ml/min: give 75mg orally once daily x 5 days. Supplied: [75mg cap] |
rimantadine (Flumadine ®): |
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INDICATIONS: Rimantadine HCl is indicated for the
prophylaxis and treatment of illness caused by various strains of
influenza A virus in adults. Dosing (Adults): The recommended adult dose of rimantadine HCl is 100 mg twice a day. In patients with severe hepatic dysfunction, renal failure (CrCl </= 10 ml/min) and elderly nursing home patients, a dose reduction to 100 mg daily is recommended. There are currently no data available regarding the safety of rimantadine during multiple dosing in subjects with renal or hepatic impairment. Because of the potential for accumulation of rimantadine metabolites during multiple dosing, patients with any degree of renal insufficiency should be monitored for adverse effect, with dosage adjustments being made as necessary. Rimantadine HCl therapy should be initiated as soon as possible, preferably within 48 hours after onset of signs and symptoms of influenza A infection. Therapy should be continued for approximately seven days from the initial onset of symptoms. |
zanamivir (Relenza ®): |
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INDICATIONS Treatment of Influenza: RELENZA is indicated for treatment of uncomplicated acute illness due to influenza A and B virus in adults and pediatric patients 7 years of age and older who have been symptomatic for no more than 2 days. Prophylaxis of Influenza: RELENZA is indicated in adults and pediatric patients 5 years of age and older for prophylaxis of influenza. Dosing (Adults): Treatment The recommended dose of RELENZA for treatment of influenza in adults and pediatric patients ages 7 years of age and older is 2 inhalations (one 5-mg blister per inhalation for a total dose of 10 mg) twice daily (approximately 12 hours apart) for 5 days. Two doses should be taken on the first day of treatment whenever possible provided there is at least 2 hours between doses. On subsequent days, doses should be about 12 hours apart (e.g., morning and evening) at approximately the same time each day. There are no data on the effectiveness of treatment with RELENZA when initiated more than 2 days after the onset of signs or symptoms. Prophylaxis Household Setting: The recommended dose of RELENZA for prophylaxis of influenza in adults and pediatric patients 5 years of age and older in a household setting is 10 mg once daily for 10 days. The 10-mg dose is provided by 2 inhalations (one 5-mg blister per inhalation). The dose should be administered at approximately the same time each day. There are no data on the effectiveness of prophylaxis with RELENZA in a household setting when initiated more than 1.5 days after the onset of signs or symptoms in the index case. Community Outbreaks: The recommended dose of RELENZA for prophylaxis of influenza in adults and adolescents in a community setting is 10 mg once daily for 28 days. The 10-mg dose is provided by 2 inhalations (one 5-mg blister per inhalation). The dose should be administered at approximately the same time each day. There are no data on the effectiveness of prophylaxis with RELENZA in a community outbreak when initiated more than 5 days after the outbreak was identified in the community. The safety and effectiveness of prophylaxis with RELENZA have not been evaluated for longer than 28 days duration. |
Disclaimer |
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Listed dosages are for - Adult patients ONLY. PLEASE READ THE
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GlobalRPH does not directly or indirectly practice medicine or provide
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kind for the information and data accessed through the Service or for
any diagnosis or treatment made in reliance thereon. David F. McAuley, Pharm.D., R.Ph. GlobalRPh Inc. |
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