Words of caution when administering Tamiflu® and Relenza
Note to Pharmacists: When dispensing commercially-manufactured Tamiflu® Oral Suspension, pharmacists should ensure the units of measure on the prescription instructions match the dosing device.
If prescription instructions specify administration using millilters (mL) or teaspoons (tsp), then the device included in the Tamiflu® product package should be removed and replaced with an appropriate measuring device, such as an oral syringe if the prescribed dose is in milliliters (mL). When dispensing commercially-manufactured Tamiflu® Oral Suspension for children younger than 1 year of age, the oral dosing dispenser that is included in the Tamiflu® package should always be removed. An oral syringe that is capable of accurately measuring the prescribed dose in milliliters (mL) should be provided, and the caregiver counseled on how to administer the prescribed dose accurately with the oral syringe provided.
(The Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) for the use of Tamiflu® in pediatric patients younger than 1 year of age.)
Commercial and compounded formulationsOn September 22, 2009, CDC issued information about compounding an oral suspension from Tamiflu® 75mg capsules when commercially-manufactured Tamiflu® Oral Suspension is not available. Health care providers can suggest this compounding alternative when writing prescriptions for Tamiflu® Oral Suspension.
Note to Prescribers: The Tamiflu® Oral Suspension concentration is 12 mg/mL; the compounded suspension concentration is 15 mg/mL. We advise prescribers to specify the concentration (e.g. Tamiflu® oral suspension 12mg/mL) if prescribing in mL or teaspoons, or to prescribe the dose in milligrams (mg).
Warning on NebulizingOn October 10, 2009, GlaxoSmithKline (GSK) and the Food and Drug Administration notified health care professionals of a report of the death of a pregnant patient with influenza (outside the United States) who received Relenza® Inhalation Powder which was solubilized and administered by mechanical ventilation.
The patient's death was attributed to obstruction of the ventilator, possibly caused by the lactose present in the Relenza® Inhalation Powder formulation.
GSK has since issued a warning that Relenza® Inhalation Powder is not intended for reconstitution in any liquid formulation and is not recommended for use in any nebulizer or mechanical ventilator. Although the use of zanamivir for nebulizer delivery was investigated in clinical trials, GSK warns that the commercial formulation is not designed or intended to be administered by nebulization and of the risk of the lactose sugar obstructing proper functioning of mechanical ventilator equipment.
(The Food and Drug Administration has issued an Emergency Use Authorization (EUA) for the use of Relenza® in patients with severe illness.)