From the Guidelines
Tamiflu (oseltamivir) is recommended as postexposure chemoprophylaxis for patients with influenza A and/or B, with a preferred dosage of 75 mg once daily for 7 days, initiated within 48 hours of exposure. The use of oseltamivir for chemoprophylaxis is supported by the American Academy of Pediatrics (AAP) and is based on the latest guidelines for the prevention and control of influenza in children 1.
Key Considerations for Oseltamivir Prophylaxis
- The dosage for children is weight-based, with recommendations as follows:
- 30 mg once daily for those weighing less than 15 kg
- 45 mg once daily for 15-23 kg
- 60 mg once daily for 23-40 kg
- 75 mg once daily for those over 40 kg
- For infants, the dosing is as follows:
- Term infants 0-8 months: 3 mg/kg per dose, once daily
- Term infants 9-11 months: 3.5 mg/kg per dose, once daily
- Patients with renal insufficiency require dose adjustment based on creatinine clearance.
Importance of Timely Initiation
Prophylaxis should ideally begin within 48 hours of exposure for maximum effectiveness, as recommended by the AAP 1. It's crucial to note that chemoprophylaxis is not a substitute for vaccination, and both vaccination with IIV or RIV and antiviral chemoprophylaxis may be considered for some high-risk individuals.
Side Effects and Administration
Common side effects of oseltamivir include nausea, vomiting, and headache, which can be minimized by taking the medication with food. Oseltamivir is administered orally or by feeding tube without regard to meals, although administration with meals may improve gastrointestinal tolerability.
Comparison with Other Evidence
While earlier studies and guidelines, such as those from 2012 1 and 2007 1, provide valuable insights into the use of oseltamivir for chemoprophylaxis, the most recent and highest quality evidence from 2024 1 takes precedence in guiding clinical practice. This ensures that recommendations are based on the latest research and expert consensus, optimizing outcomes in terms of morbidity, mortality, and quality of life.
From the FDA Drug Label
1.2 Prophylaxis of Influenza Oseltamivir phosphate for oral suspension is indicated for the prophylaxis of influenza A and B in patients 1 year and older. 2.3 Recommended Dosage for Prophylaxis of Influenza Initiate post-exposure prophylaxis with oseltamivir phosphate for oral suspension within 48 hours following close contact with an infected individual. Initiate seasonal prophylaxis with oseltamivir phosphate for oral suspension during a community outbreak Adults and Adolescents (13 years of age and older) The recommended dosage of oseltamivir phosphate for oral suspension for prophylaxis of influenza in adults and adolescents 13 years and older is 75 mg orally once daily
The role of Tamiflu (Oseltamivir) in prophylaxis is to prevent influenza A and B in patients 1 year and older, with a recommended dosage of 75 mg orally once daily for adults and adolescents 13 years and older. Prophylaxis can be initiated either post-exposure, within 48 hours of close contact with an infected individual, or seasonally during a community outbreak 2. Key points:
- Indicated for prophylaxis of influenza A and B
- Recommended for patients 1 year and older
- Dosage: 75 mg orally once daily for adults and adolescents 13 years and older
From the Research
Role of Tamiflu (Oseltamivir) in Prophylaxis
The role of Tamiflu (Oseltamivir) in prophylaxis can be understood through the following points:
- Oseltamivir has demonstrated efficacy when used for seasonal or household prophylaxis, with a significant prevention of the development of naturally acquired influenza by >70% compared with placebo in unvaccinated otherwise healthy adults 3.
- The drug also demonstrated efficacy when used adjunctively in previously vaccinated high-risk elderly patients, with a 92% protective efficacy 3.
- A 3-day regimen of oseltamivir as post-exposure prophylaxis (PEP) for preventing transmission of influenza in wards was shown to be comparable to 7- to 10-day regimens provided index cases were immediately separated from close contacts 4.
- Five-day postexposure prophylaxis with oseltamivir was noninferior to 10-day regimen in preventing hospital transmission of influenza 5.
- Oseltamivir probably achieves important reductions in symptomatic influenza in individuals at high risk of severe disease when given promptly after exposure to seasonal influenza, with a risk ratio of 0·40,95% CI 0·26-0·62 6.
Key Findings
- Oseltamivir is effective in preventing influenza in healthy adults and high-risk patients, including the elderly and those with chronic cardiac or respiratory disease 3, 7.
- The optimal duration of postexposure prophylaxis with oseltamivir is still being studied, with some evidence suggesting that a 3-day or 5-day regimen may be sufficient 4, 5.
- Oseltamivir is well-tolerated, with nausea and vomiting being the most commonly reported adverse events, which can be reduced by taking the medication with food 3, 7.
Prophylaxis Regimens
- Oral oseltamivir 75 mg once or twice daily for 6 weeks has been shown to be effective in preventing influenza in unvaccinated otherwise healthy adults 3.
- A 3-day regimen of oseltamivir 75 mg once daily for adults or 2 mg/kg (maximum of 75 mg) once daily for children has been studied as post-exposure prophylaxis 4.
- Five-day postexposure prophylaxis with oseltamivir 75 mg once daily has been shown to be noninferior to 10-day regimen in preventing hospital transmission of influenza 5.