TAMIFLU

What it is

Oseltamivir STR (also known by the brand name TAMIFLU) is oseltamivir phosphate supplied in capsule form. The capsules are available in three strengths: 75 mg, 45 mg and 30 mg. Oseltamivir phosphate is a pro-drug of the active metabolite oseltamivir carboxylate, which is a selective inhibitor of influenza virus neuraminidase enzymes found on the virion surface. Viral neuraminidase is essential for the release of recently formed virus particles from infected cells and the further spread of infectious virus in the body.

Approved indications

— Treatment of infections due to influenza A and B viruses in adults and children including full-term neonates. — Prevention of influenza in adults and children aged 1 year and older.

Dosing overview

For adults and adolescents aged 13 years and older, the recommended oral dose for treatment is 75 mg twice daily for 5 days. For prevention following close contact with an infected individual, the recommended dose is 75 mg once daily for 10 days, with therapy commencing within two days of exposure. For prevention during a community outbreak of influenza, the recommended dose is 75 mg once daily, with safety and efficacy demonstrated for up to six weeks. For children aged 1 year to under 13 years, treatment doses are weight-adjusted: 30 mg twice daily for those weighing ≤15 kg; 45 mg twice daily for those weighing >15–23 kg; 60 mg twice daily for those weighing >23–40 kg; and 75 mg twice daily for those weighing >40 kg. Prophylactic doses for the same age group are weight-adjusted for a 10-day course: 30 mg once daily for those weighing ≤15 kg; 45 mg once daily for those weighing >15–23 kg; 60 mg once daily for those weighing >23–40 kg; and 75 mg once daily for those weighing >40 kg. No dose adjustment is required for patients with mild or moderate hepatic dysfunction in the treatment or prevention of influenza. For renal impairment in adults during treatment, no adjustment is necessary if creatinine clearance is above 60 mL/min; for clearance of >30–60 mL/min, the dose should be reduced to 30 mg twice daily for 5 days; for clearance of 10–30 mL/min, the dose should be reduced to 30 mg once daily for 5 days.

Key safety warnings

There is no current evidence for the safety or efficacy of oseltamivir in persons with complications of an acute influenza episode such as viral or bacterial pneumonia, and such patients may require extensive supportive and adjunctive care that antiviral therapy has not been shown to reduce the need for. Convulsion and delirium (including symptoms such as altered level of consciousness, confusion, abnormal behaviour, delusions, hallucinations, agitation, anxiety and nightmares) have been reported during oseltamivir administration in patients with influenza, predominantly in children and adolescents, often with abrupt onset and rapid resolution; in rare cases these events resulted in accidental injury or fatal outcome, although the contribution of oseltamivir is unknown, and such events have also been reported in influenza patients not taking oseltamivir. Patients with influenza should be closely monitored for signs of abnormal behaviour throughout the treatment period. Hypersensitivity reactions such as allergic skin reactions including dermatitis, rash, eczema and urticaria, erythema multiforme, allergy, anaphylactic/anaphylactoid reactions, face oedema, Stevens-Johnson-Syndrome and toxic epidermal necrolysis have been reported during post-marketing use.

Contraindications

Oseltamivir STR is contraindicated in patients with known hypersensitivity to oseltamivir phosphate or to any components of the product.

PBS listing

PBS listing information is not provided in the source documents.

Regulatory history

The 75 mg capsule formulation of TAMIFLU oseltamivir was first registered on the ARTG on 13 September 2000. The 45 mg and 30 mg capsule formulations were first registered on 8 August 2008. A 6 mg/mL powder for oral suspension formulation was first registered on 11 May 2012.