From the Guidelines
In Alberta, Canada, Tamiflu (oseltamivir) is prescribed for influenza treatment and prevention based on specific criteria, with priority given to high-risk individuals, including those with underlying health conditions, pregnant women, elderly patients (65+), young children (especially under 5), immunocompromised individuals, and those with severe or worsening symptoms, as recommended by the most recent guidelines 1.
Criteria for Prescribing Oseltamivir
The criteria for prescribing oseltamivir in Alberta, Canada, include:
- Presentation within 48 hours of symptom onset with laboratory-confirmed or clinically suspected influenza
- Priority given to high-risk individuals, including:
- Those with underlying health conditions, such as chronic pulmonary, cardiovascular, renal, hepatic, hematologic, or metabolic disorders
- Pregnant women
- Elderly patients (65+)
- Young children (especially under 5)
- Immunocompromised individuals
- Those with severe or worsening symptoms
Dosage and Administration
The standard adult treatment dose is 75mg twice daily for 5 days, while prophylaxis requires 75mg once daily for 10 days (duration may vary based on exposure) 1. Children's dosing is weight-based, with the following recommendations:
- Infants 9-11 months: 3.5 mg/kg per dose twice daily
- Term infants 0-8 months: 3 mg/kg per dose twice daily
- Preterm infants: dosing based on postmenstrual age (gestational age + chronological age)
Side Effects and Precautions
Side effects may include nausea, vomiting, and headache. Patients should contact their healthcare provider promptly if experiencing flu symptoms to determine if Tamiflu is appropriate for their situation. Oseltamivir is administered orally or by feeding tube without regard to meals, although administration with meals may improve gastrointestinal tolerability 1.
Recent Guidelines
The most recent guidelines from 2024 recommend oseltamivir as the preferred postexposure chemoprophylaxis for patients with influenza A and/or B, with a dosage of 75mg once daily for 7 days after last known exposure 1.
From the FDA Drug Label
The FDA drug label does not answer the question.
From the Research
Criteria for Prescribing Oseltamivir (Tamiflu) in Alberta, Canada
The criteria for prescribing Oseltamivir (Tamiflu) in Alberta, Canada, are based on the patient's risk of influenza-related complications and the timing of symptom onset.
- Patients at high-risk of influenza-related complications, such as young children, the elderly, pregnant and post-partum women, patients with co-morbidities, and the immunocompromised, should be initiated on Oseltamivir as soon as possible, with suspected or proven influenza, hospitalised patients, and patients with severe or progressive disease 2.
- In previously healthy patients, Oseltamivir can be considered when therapy can be initiated within 48 hours of symptom onset, as the therapeutic efficacy of Oseltamivir is time-dependent, with maximal benefit observed when therapy is initiated within this timeframe 2.
- However, several observational studies suggest therapeutic benefit beyond 48 hours, in hospitalised patients, severe disease, and patients at high risk of complications, including pregnant women 2.
- Pregnant women with suspected or confirmed influenza infection should receive antiviral treatment with Oseltamivir or zanamivir based on the current resistance patterns, and treatment within 48 hours of the onset of symptoms is ideal but treatment should not be withheld if the ideal window is missed 3, 4.
- The criteria for prescribing Oseltamivir in Alberta, Canada, may also consider the patient's vaccination status, as antiviral treatment is necessary for all pregnant women with suspected or confirmed influenza, regardless of vaccination status 3, 4.
Special Considerations
- In intubated patients with severe influenza, Oseltamivir (suspension) can be administered via nasogastric tube, and IV zanamivir can be obtained under Emergency Investigational New Drug access schemes when there are concerns about gastric absorption 2.
- Corticosteroids should not be used in the treatment of severe influenza, as this has been associated with increased risk of mortality and bacterial superinfection 2.
- Postexposure antiviral chemoprophylaxis can be considered for pregnant women and women who are up to 2 weeks postpartum who have had close contact with infectious individuals 3, 4.