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Zanamivir (Relenza) Must Not Be Given by Nebulization

Ventilator obstruction was blamed for the death of a woman who received zanamivir inhalation powder that was solubilized and administered by mechanical ventilation.

Zanamivir is a neuraminidase inhibitor with activity against influenza viruses, including the 2009 pandemic H1N1 strain. It is FDA approved for influenza treatment (patients aged 7 years) and prophylaxis (patients aged 5 years) in patients without underlying airway disease and is to be administered using a Diskhaler device. However, the drug is sometimes being removed from its approved packaging, dissolved, and administered by nebulization to individuals who are severely ill and unable to inhale it from the Diskhaler or to take oral oseltamivir.

Now, GlaxoSmithKline and the FDA have issued a Medwatch report describing a fatality — a pregnant woman on mechanical ventilation — thought to have been related to nebulization of zanamivir. The lactose-containing carrier is hypothesized to have obstructed proper functioning of the ventilator. Prescribers are reminded that zanamivir inhalation powder is neither designed nor intended to be administered by nebulization.

The Medwatch note indicates that early reports of nebulizer delivery involved an investigational aqueous formulation, not the currently FDA-approved lactose-containing preparation that may cause ventilator obstruction. Zanamivir should be administered only as directed in the prescribing information — i.e., by using the Diskhaler device provided with the product.

Comment: Fortunately, we now have an option for treating critically ill influenza patients. The FDA has just authorized emergency use of peramivir, an investigational neuraminidase inhibitor that is administered intravenously.

— Lynn L. Estes, PharmD

Published in Journal Watch Infectious Diseases October 28, 2009

Citation(s):

Food and Drug Administration (FDA). Relenza (zanamivir) Inhalation Powder. Oct 9 , 2009. (http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm186081.htm)