"Adverse event" reports filed with the FDA, the basis for stepped-up warnings throughout the past year, have prompted some critics to question whether Relenza's risks outweigh the benefits, reports CBS News Correspondent Sharyl Attkisson.
When Relenza hit the market last flu season, it was aggressively marketed by its maker Glaxo Wellcome Plc - Europe's second-largest drugmaker - as an exciting new treatment. The company claimed the inhalant attacked a type of flu immune to older drugs.
The ads were flashy, but the medical claim was more modest - to get rid of the flu one day faster.
Now with a new November-April flu season rapidly approaching, health officials have been warning of serious, sporadic flu vaccine shortages. That means more doctors and patients may be turning to prescription drugs to treat the flu.
Each year, some 20 million Americans become ill with the flu; some 20,000 die from the flu or its complications.
More than a million people have tried Relenza, which was released onto the market late last year. But as the drug's use has expanded, so have complaints about dangerous side effects - especially breathing problems.
Respiratory problems were also noted in 70 other serious or life-threatening cases reported to the FDA involving patients who took Relenza. CBS News obtained copies of the "adverse event" reports by filing Freedom of Information requests beginning last February.
Wittes said Glaxo Wellcome produced results from small foreign studies, claiming that patients reported their flu symptoms were relieved a day or two faster when they used Relenza. But Wittes said their relief was a subjective and not a scientific measure and that flu symptoms usually returned after the patient took the entire prescription.
Wittes also said that even a one-day benefit from the medication, as claimed by Glaxo Wellcome, was a stretch. She said her committee voted overwhelmingly not to allow it on the market, arguing that it did not feel the manufacturer had proved it effective.
Some FDA scientists agreed, writing in internal documents obtained by CBS News that Glaxo Wellcome "exaggerated" Relenza's benefits and that it "has not been shown to be effective in this country ... and should not be approved."
The FDA overruled the objections of other FDA scientists and the FDA advisory committee's recommendation, instead rushing Relenza's approval because there were no red flags about any significant health risks. The FDA claimed even a small potential benefit could be of "substantial public health importance."
But "adverse event" reports on Relenza quickly began piling up.
In January, the FDA issued a public health advisory urging "special caution" for people with conditions like asthma. Three months later the FDA ordered a stronger warning label emphasizing continuing reports of breathing problems, noting "some...have had fatal outcomes." And in July, the drug's maker sent a letter warning doctors about serious side effects "in patients without a history of airways disease."
Wittes said that's the very reason Relenza should not have been put on the market in the first place.
"To me, this confirms the importance of not approving a drug unless there's really good evidence that it works," she said.
Glaxo Wellcome says "adverse event" reports are often complex and incomplete, so it's impossible to know if there's a direct link between the drug and the deaths. Glaxo Wellcome declined to be interviewed.
Dr. Fred Hayden, a University of Virginia researcher who conducts paid studies on Relenza and other drugs, said his research has proven Relenza's effectiveness and that the drug may help patients recover even faster than first thought.
"A one day reduction in (flu) misery, I think, is important to many people," said Hayden, who said he could not address the drug's safety. "Certainly, when one is talking about a two to three day reduction, as has been seen in some of the studies with Relenza and other influenza drugs, these are clinically meaningful benefits."
Hayden said Relenza also shows promise as a drug to prevent the flu, not just treat it. Glaxo Wellcome hopes to soon win approval for preventivuse of Relenza. Ideally, the company would like the drug to be prescribed to groups - such as students and nursing home patients - where one person has developed the flu with Relenza used to help prevent a wider outbreak.
But critics still warn of the potential side effects.
"One of the doctors on FDA's advisory committee ... who voted against (Relenza's) approval said that he would never give this drug to people in his own family," Consumer advocate Dr. Sidney Wolfe of Public Citizen told CBS News. "That's something that people in this country should think about."
Nevertheless, FDA officials stand by their position that the drug is safe and effective when the new label and warnings are followed, and has now approved it for pediatric use.
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