What is the proper administration of Tamiflu (Oseltamivir)?

From the Guidelines

To use Tamiflu (oseltamivir) correctly, take it exactly as prescribed by your healthcare provider, typically twice daily (morning and evening) for 5 days, with the standard adult dose being 75 mg twice daily, as recommended by the most recent guidelines 1.

The dosing for children depends on their weight, with the following recommendations:

• For children 12 months or older, the dose is based on body weight:
  • 15 kg (33 lb) or less: 30 mg twice daily
  • More than 15 kg to 23 kg (33-51 lb): 45 mg twice daily
  • More than 23 kg to 40 kg (51-88 lb): 60 mg twice daily
  • More than 40 kg (88 lb): 75 mg twice daily
• For infants 9-11 months old: 3.5 mg/kg per dose, twice daily
• For term infants 0-8 months old: 3 mg/kg per dose, twice daily

It is essential to start Tamiflu as soon as possible after flu symptoms begin, ideally within 48 hours, as it works best when started early. Taking the medication with food can help reduce stomach upset. The entire course should be completed, even if symptoms improve. For prevention after exposure to the flu, the typical adult dose is 75 mg once daily for 10 days.

Tamiflu works by preventing the influenza virus from replicating in the body, which helps reduce symptom severity and duration. Common side effects include nausea and vomiting, which can be minimized by taking the medication with food. If a dose is missed, it should be taken as soon as remembered, unless it's nearly time for the next dose. Tamiflu is not a substitute for the flu vaccine and does not treat bacterial infections or the common cold.

In patients with renal insufficiency, the dose should be adjusted based on creatinine clearance. For treatment of patients with creatinine clearance 10-30 mL/min, the dose is 75 mg once daily for 5 days. For chemoprophylaxis of patients with creatinine clearance 10-30 mL/min, the dose is 30 mg once daily for 10 days after exposure or 75 mg once every other day for 10 days after exposure (5 doses) 1.

The balance between benefits and harms should be considered when making decisions about the use of oseltamivir for either treatment or chemoprophylaxis of influenza, especially in children with underlying conditions or those at high risk of complications. Clinical judgment is an important factor in treatment decisions for pediatric patients who present with influenzalike illness 1.

From the FDA Drug Label

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)] using: Oseltamivir phosphate for oral suspension (supplied as a powder). This is the preferred formulation (6 mg per mL) for patients who cannot swallow capsules. Prior to use, the supplied oseltamivir phosphate for oral suspension powder must be constituted with water by the pharmacist to produce the oral suspension [see Dosage and Administration (2.5)]. The oral suspension may be taken with or without food; however, tolerability may be enhanced if oseltamivir phosphate for oral suspension is taken with food.

The proper administration of Tamiflu (Oseltamivir) is as follows:

• Oral Suspension: The preferred formulation for patients who cannot swallow capsules, supplied as a powder that must be constituted with water by the pharmacist to produce the oral suspension.
• Administration: The oral suspension may be taken with or without food, but tolerability may be enhanced if taken with food.
• Dosage:
  • Treatment of Influenza:
    • Adults and Adolescents (13 years and older): 75 mg twice daily for 5 days.
    • Pediatric Patients (2 weeks of age through 12 years of age): dosage based on age and weight, as displayed in Table 1.
  • Prophylaxis of Influenza:
    • Adults and Adolescents (13 years and older): 75 mg orally once daily for at least 10 days following close contact with an infected individual and up to 6 weeks during a community outbreak.
    • Pediatric Patients (1 year to 12 years of age): dosage based on body weight, as displayed in Table 1. 2

From the Research

Administration of Tamiflu (Oseltamivir)

The proper administration of Tamiflu (Oseltamivir) is crucial for effective treatment of influenza. Here are some key points to consider:

• Oseltamivir should be initiated as soon as possible in patients at high-risk of influenza-related complications, with suspected or proven influenza, hospitalised patients and patients with severe or progressive disease 3.
• In previously healthy patients, the therapeutic efficacy of oseltamivir is time-dependent, with maximal benefit observed when therapy is initiated within 48 hours of symptom onset 3, 4.
• Oseltamivir can be considered in previously healthy patients when therapy can be initiated within 48 hours of symptom onset 3.
• The recommended dosage of oseltamivir is 75 mg twice daily for 5 days 4, 5.
• Oseltamivir may be effective in treating influenza in children, with a liquid formulation available for children who cannot swallow capsules 4, 6.
• In pregnant women, oseltamivir is recommended for treatment of suspected or confirmed influenza, regardless of vaccination status, and should be initiated promptly 7.
• Oseltamivir can be administered via nasogastric tube in intubated patients with severe influenza 3.

Special Considerations

• In hospitalised patients, oseltamivir may be effective even when initiated more than 48 hours after symptom onset 3, 5.
• There is limited evidence to support the use of high-dose or extended-duration oseltamivir in patients with severe influenza 3, 5.
• Oseltamivir should not be used in combination with other neuraminidase inhibitors, such as zanamivir 3.
• The use of oseltamivir in patients with renal impairment or other underlying health conditions should be carefully considered, and dosage adjustments may be necessary 4.