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Antiviral Agents for Seasonal Influenza: Dosage
On this page:
- Children
- People Aged 65 Years and Older
- People with Impaired Renal Function
- People with Liver Disease
- People with Seizure Disorders
- People with Weakened Immune Systems
- Route
- Table
Dosage recommendations vary by age group and medical conditions:
Children
Zanamivir
Zanamivir is licensed for treatment of influenza among children aged 7 years and older. The recommended dosage of zanamivir for treatment of influenza is 2 inhalations (one 5-mg blister per inhalation for a total dose of 10 mg) twice daily (approximately 12 hours apart). Zanamivir is licensed for chemoprophylaxis of influenza among children aged 5 years and older; the chemoprophylaxis dosage of zanamivir for children aged 5 years and older is 10 mg (2 inhalations) once a day.
Oseltamivir
Oseltamivir is licensed for treatment and chemoprophylaxis among children aged 1 year and older. Recommended treatment dosages vary by the weight of the child: 30 mg twice a day for children who weigh less than or equal to 15 kg, 45 mg twice a day for children who weigh more than 15—23 kg, 60 mg twice a day for those who weigh more than 23—40 kg, and 75 mg twice a day for those who weigh more than 40 kg. Dosages for chemoprophylaxis are the same for each weight group, but doses are administered only once per day rather than twice.
People Aged 65 Years and Older
Zanamivir and Oseltamivir
No reduction in dosage for oseltamivir or zanamivir is recommended on the basis of age alone.
People with Impaired Renal Function
Zanamivir
Limited data are available regarding the safety and efficacy of zanamivir for patients with impaired renal function. Among patients with renal failure who were administered a single intravenous dose of zanamivir, decreases in renal clearance, increases in half-life, and increased systemic exposure to zanamivir were reported. However, a limited number of healthy volunteers who were administered high doses of intravenous zanamivir tolerated systemic levels of zanamivir that were substantially higher than those resulting from administration of zanamivir by oral inhalation at the recommended dose. On the basis of these considerations, the manufacturer recommends no dose adjustment for inhaled zanamivir for a 5-day course of treatment for patients with either mild-to-moderate or severe impairment in renal function.
Oseltamivir
Serum concentrations of oseltamivir carboxylate, the active metabolite of oseltamivir, increase with declining renal function. For patients with creatinine clearance of 10—30 mL per minute, a reduction of the treatment dosage of oseltamivir to 75 mg once daily and in the chemoprophylaxis dosage to 75 mg every other day is recommended. No treatment or chemoprophylaxis dosing recommendations are available for patients undergoing routine renal dialysis treatment.
People with Liver Disease
Zanamivir and Oseltamivir
Use of zanamivir or oseltamivir has not been studied among persons with hepatic dysfunction.
People with Seizure Disorders
Zanamivir and Oseltamivir
Seizure events have been reported during postmarketing use of zanamivir and oseltamivir, although no epidemiologic studies have reported any increased risk for seizures with either zanamivir or oseltamivir use.
People with Weakened Immune Systems
Oseltamivir
A recent retrospective case-control study demonstrated that oseltamivir was safe and well tolerated when used during the control of an influenza outbreak among hematopoietic stem cell transplant recipients living in a residential facility.
Route
Oseltamivir is administered orally in capsule or oral suspension form. Zanamivir is available as a dry powder that is self-administered via oral inhalation by using a plastic device included in the package with the medication. Patients should be instructed about the correct use of this device.
| Antiviral agent | Age group (yrs) | |||||
|---|---|---|---|---|---|---|
| 1-6 | 7-9 | 10-12 | 13-64 | ≥65 | ||
| Zanamivir* | Treatment, influenza A and B | N/A† | 10 mg (2 inhalations) twice daily | 10 mg (2 inhalations) twice daily | 10 mg (2 inhalations) twice daily | 10 mg (2 inhalations) twice daily |
| Chemoprophylaxis, influenza A and B | Ages 1-4 N/A |
Ages 5-9 10 mg (2 inhalations) once daily |
10 mg (2 inhalations) once daily | 10 mg (2 inhalations) once daily | 10 mg (2 inhalations) once daily | |
| Oseltamivir | Treatment§, influenza A and B | Dose varies by child's weight¶ | Dose varies by child's weight¶ | Dose varies by child's weight¶ | 75 mg twice daily | 75 mg twice daily |
| Chemoprophylaxis, influenza A and B | Dose varies by child's weight** | Dose varies by child's weight** | Dose varies by child's weight** | 75 mg/day | 75 mg/day | |
NOTE: Zanamivir is manufactured by GlaxoSmithKline (Relenza®—inhaled powder). Zanamivir is approved for treatment of persons aged 7 years and older and approved for chemoprophylaxis of persons aged 5 years and older. Oseltamivir is manufactured by Roche Pharmaceuticals (Tamflu®—tablet). Oseltamivir is approved for treatment or chemoprophylaxis of persons aged 1 year and older. No antiviral medications are approved for treatment or chemoprophylaxis of influenza among children aged <1 year of age. This information is based on data published by the Food and Drug Administration (FDA). * Zanamivir is administrated through oral inhalation by using a plastic device included in the medication package. Patients will benefit from instruction and demonstration of the correct use of the device. Zanamivir is not recommended for those persons with underlying airway disease. † Not applicable. § A reduction in the dose of oseltamivir is recommended for persons with creatinine clearance less than 30 mL/min. ¶ The treatment dosing recommendation for children weighing 15 kg or less is 30 mg twice a day; for children weighing more than 15 kg and up to 23 kg, the dose is 45 mg twice a day; for children weighing >15-23 kg, the dose is 45 mg twice a day; for children weighing >23-40 kg, the dose is 60 mg twice a day; and for children >40 kg, the dose is 75 mg twice a day. ** The chemoprophylaxis dosing recommendation for children weighing 15 kg or less is 30 mg once a day; for children weighing >15-23 kg, the dose is 45 mg once a day; for children weighing >23-40 kg, the dose is 60 mg once a day; and for children >40 kg, the dose is 75 mg once a day. |
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NOTE: The text above is taken from Prevention & Control of Influenza - Recommendations of the Advisory Committee on Immunization Practices (ACIP) 2008. MMWR 2008 Jul 17; Early Release:1-60. (Also available as PDF, 586K).
- Page last updated August 29, 2008
- Content Source: Coordinating Center for Infectious Diseases (CCID)
- National Center for Immunization and Respiratory Diseases (NCIRD)
