Dec. 9, 2009 -- Widely used antiviral drugs such as Tamiflu and Relenza may not prevent complications such as pneumonia in healthy people, according to a new investigation and analysis.
"We're not so sure the drugs are so magic a bullet as we previously thought," researcher Chris Del Mar, MD, dean of medicine at Bond University in Australia, tells WebMD. He is the coordinating editor of the Cochrane Acute Respiratory Infections Group and headed the research team that analyzed 20 published trials that focused on prevention, treatment, and adverse reactions of the antiviral drugs against the flu, known as neuraminidase inhibitors. The Cochrane Collection regularly updates evidence for and against the effectiveness of specific treatments.
The study is published in BMJ Online First, and the investigation developed into a joint project of BMJ and the U.K.'s Channel 4 news.
"Cochrane decided to update all the reviews that might inform influenza management," Del Mar tells WebMD. The use of the drugs has increased dramatically since the swine flu pandemic began in April 2009. Worldwide, governments have stockpiled Tamiflu to prepare for a pandemic.
The investigation, Del Mar says, was hampered by a scarcity of good data from the authors of the study and from Roche, the company that makes Tamiflu.
But Roche, in a statement, says it stands behind the integrity of the data, which supports the use and effectiveness of Tamiflu.
Tamiflu Effective? Review Details
Del Mar's team set out to update a 2005 Cochrane Library review that evaluated the effect of the drugs in preventing or improving influenza symptoms, transmission of the flu, and complications from the flu in healthy people and to estimate the effect of adverse effects.
"We found that the information we had wasn't as good as we initially thought when we first did the review," Del Mar says. "We were surprised at how poor the data [was ] on adverse effects."
They concluded that the neuraminidase inhibitors have "modest effectiveness against the symptoms of influenza in otherwise healthy adults." The drugs reduce the duration of illness by about a day.
"This benefit has been generalized to assume benefit for very ill people in hospital," the authors write. Although this seems reasonable, they say they have no data to support this.
The data on the effectiveness of Tamiflu against complications of the flu are "confusing," the researchers write. The researchers had to drop eight trials that were never fully published, although they were included in the previous review. But the researchers dropped them for this review because they could not verify the results independently.
Del Mar's bottom-line advice for healthy people? "Don't take [the antivirals] to prevent complications because we don’t have enough good data for that. It reduces the [duration of the] illness by one day. So you have to make a decision about whether it’s worth it or not."
A viable alternative, he tells WebMD, may be to take acetaminophen or "lemon sips" -- a hot lemon drink.
Roche responded by saying the company believes in the "robustness and integrity" of the data, claiming that if the Cochrane researchers had simply signed a confidentiality agreement to protect the anonymity of clinical trial patients, they could have had the data.
In a letter to BMJ, Roche officials say they responded fully to all questions asked by BMJ and the news channel. The pharmaceutical giant has now posted study summaries online and will provide full reports on a password-protected site.
Most of the information presented in the new review is known by physicians, says William Schaffner, MD, an infectious disease specialist and chairman of the department of preventive medicine at Vanderbilt University Medical Center in Nashville. "What’s new is bringing it all together."
Costs seem to be a major concern of the researchers, he says. "The editorialists are concerned that governments have purchased large stockpiles," he says. Their concerns focus on the fact that the money could have been better used elsewhere.
"We are not treating every patient who comes into our ER with Tamiflu," Schaffner says. Those with underlying conditions such as heart disease do get the drug, he says, as well as healthy people if something like trouble breathing develops.
Another doctor in practice, Peter Galier, MD, former chief of staff at Santa Monica-UCLA & Orthopaedic Hospital, says he is not seeing overuse of the drugs. Lessening the duration of flu for healthy people may be optional, he says, but if you use the drugs to lessen the severity of the disease in those who are immune compromised, asthmatic, or have lung disease or other problems, "you are doing a service."