What is the dosing for Oseltamivir (Tamiflu)?

From the Guidelines

Tamiflu (oseltamivir) dosing for influenza treatment in adults is 75 mg twice daily for 5 days, starting within 48 hours of symptom onset for maximum effectiveness, as recommended by the most recent guidelines 1.

Key Considerations

• For children, the dose is weight-based:
  • 30 mg twice daily for those weighing less than 15 kg
  • 45 mg twice daily for 15-23 kg
  • 60 mg twice daily for 23-40 kg
  • the adult dose for those over 40 kg
• For prevention after exposure, adults and children over 40 kg should take 75 mg once daily for 10 days, while children receive the same weight-based dosing as treatment but given only once daily 1.

Special Populations

• Dose adjustments are necessary for patients with kidney problems; those with creatinine clearance between 10-30 mL/min should receive 75 mg once daily for treatment or 30 mg once daily for prevention, as indicated in the guidelines 1.
• For preterm infants, the dosing recommendation is lower than for term infants, and the dose should be based on postmenstrual age 1.

Administration and Side Effects

• Tamiflu works by inhibiting viral neuraminidase, preventing new virus particles from being released from infected cells.
• Common side effects include nausea and vomiting, which can be reduced by taking the medication with food.
• The medication comes as capsules or as a suspension for those who cannot swallow pills 1.

From the FDA Drug Label

2 DOSAGE AND ADMINISTRATION

2.1 Dosage and Administration Overview Administer oseltamivir phosphate for oral suspension for the treatment of influenza in patients 2 weeks of age or older [see Dosage and Administration (2.2)] or for prophylaxis of influenza in patients 1 year and older [see Dosage and Administration (2. 3)] 2. 2 Recommended Dosage for Treatment of Influenza Initiate treatment with oseltamivir phosphate for oral suspension within 48 hours of influenza symptom onset. Adults and Adolescents (13 years of age and older) The recommended oral dosage of oseltamivir phosphate for oral suspension for treatment of influenza in adults and adolescents 13 years and older is 75 mg twice daily (12. 5 mL of oral suspension twice daily) for 5 days. Pediatric Patients (2 weeks of age through 12 years of age) Table 1 displays the recommended oral dosage of oseltamivir phosphate for oral suspension for treatment of influenza in pediatric patients 2 weeks of age through 12 years of age

The recommended dosage of Tamiflu (oseltamivir) for treatment of influenza is:

• Adults and Adolescents (13 years and older): 75 mg twice daily for 5 days
• Pediatric Patients (2 weeks to 12 years): dosage varies based on weight, as shown in Table 1 2

From the Research

Tamiflu Dosing

• The dosing of Tamiflu, also known as oseltamivir, is not explicitly stated in the provided studies, but its effectiveness in treating influenza is compared to other neuraminidase inhibitors (NAIs) such as zanamivir, laninamivir, and peramivir 3, 4, 5, 6, 7.
• A study from 2018 found that the duration of fever after administration of the first dose of an NAI was shorter in older patients and in patients with influenza A infection than in patients with influenza B infection 3.
• Another study from 2020 compared different regimens of NAIs in hospitalized patients and found that higher doses of NAIs or systemic peramivir therapy did not demonstrate significant benefits compared to standard doses of oral oseltamivir 4.
• A 2013 study compared the clinical effects of oseltamivir, zanamivir, laninamivir, and peramivir on seasonal influenza infection in outpatients in Japan and found that peramivir alleviated fever and other symptoms sooner than the other NAIs 5.
• A systematic review from 2011 found that the incidence of resistance to oseltamivir was 2.6%, while the incidence of resistance to zanamivir was 0% 6.
• A 2022 study compared the effectiveness of inhaled zanamivir and oral oseltamivir in preventing influenza-related hospitalization or death and found that inhaled zanamivir was not inferior to oral oseltamivir in outpatient treatment 7.

Neuraminidase Inhibitors Comparison

• The studies suggest that different NAIs have varying effectiveness in treating influenza, with peramivir showing faster alleviation of fever and symptoms in some studies 5.
• However, the studies also found that higher doses of NAIs or systemic peramivir therapy did not demonstrate significant benefits compared to standard doses of oral oseltamivir 4.
• The incidence of resistance to oseltamivir is a concern, with a pooled incidence rate of 2.6% found in a systematic review 6.

Patient Factors

• The studies found that older patients and patients with influenza A infection had shorter durations of fever after administration of an NAI 3.
• Patients with chronic lung diseases or aged ≥65 years may have different responses to inhaled zanamivir and oral oseltamivir, with inhaled zanamivir not being inferior to oral oseltamivir in these subgroups 7.