New Flu Drug Warning -- Watch Out for Breathing Problems

July 10, 2000 (Washington) -- The controversial flu drug Relenza is now the subject of a warning letter to medical professionals around the country that urges caution when the medicine is used in patients with asthma. The inhaled powder "is generally not recommended for treatment of patients with underlying airway diseases," says the alert sent out by the manufacturer, Glaxo Wellcome Inc. Some 50 million Americans are thought to get the flu annually, leading to 40,000 deaths.

During the past year, the company says it has received reports of serious breathing problems in some patients taking Relenza who also have underlying lung disease such as asthma and chronic obstructive pulmonary disease. There have even been reports of problems in people without lung disease.

The letter notes that some patients with breathing problems died while taking Relenza, although pinpointing the causes was difficult.

The letter also indicates that the safety information in the drug's labeling has been revised to reflect these potential hazards. "Really, what it's saying is be careful in the flu season in people with asthma and influenza," Michael Elliott, MD, director for influenza research at Glaxo Wellcome, tells WebMD. Elliott declined to give a specific number of deaths related to Relenza because the cases are so complex, but he says severe reactions are "very uncommon."

Elliott says the letter was worked out in cooperation with the FDA. In fact, the warning letter comes out almost exactly one year after the agency approved Relenza in spite of the negative recommendation from its advisory committee in February 1999. The panel was concerned the drug didn't actually shorten flu episodes, but that they simply rebounded days later.

However, the FDA was ultimately convinced that there was a benefit for patients suffering from either type A or type B influenza if Relenza was taken within two days after symptoms began. Still, critics were not convinced.

"The drug should not have been approved ... There would be no loss here if the drug were not on the market," Sidney Wolfe, MD, who heads the advocacy group Public Citizen, tells WebMD.

Another question is whether the dry-powder drug irritates the lungs of some individuals. "Unless you're incredibly well coordinated, which lots of older people aren't, you can't do it," says Wolfe.

Glaxo Wellcome's Elliott says the powder may be a factor, but he also notes the airways tend to be more sensitive in patients with the flu. Overall, he says Relenza has been a big success in its first year. Hundreds of thousands of prescriptions have been written for the drug, and a survey of 15,000 doctors and patients was 90% positive.

The FDA declined to comment directly on the warning letter, although one agency spokeswoman, speaking on condition of anonymity, says the alert coincides with updated approval information for use of the drug in children that was released in April.