Rookie Season for Flu Drugs
Did Relenza and Tamiflu work?By Leah Shafer
Now that much of the coughing and sneezing has quieted down, it's a good time to take stock of two new drugs that were released to fight the influenza virus, better known as the flu. Nearly 1 million Americans rushed to the doctor this winter for zanamivir (Relenza) and oseltamivir (Tamiflu), new antiviral drugs approved by the Food and Drug Administration (FDA) last year. In clinical studies, if started within two days after symptoms appear, these medications were shown to be moderately effective in increasing the rate of recovery.
But the number of people who took advantage of these new medications falls far short of the 75 million Americans who tried to prevent infection by getting the flu shot instead. With a 70 to 90 percent effectiveness rating, the influenza vaccination remains the primary means to prevent and control the spread of the virus and, as such, is the true MVP of the flu season.
Many medical experts would like it to stay that way. Since both Relenza and Tamiflu must be started within two days of symptom onset, many people who felt the flu coming on rushed to the emergency room or to their physician to get the new medications. Unfortunately, with the pressing need to make an early diagnosis, several patients who didn't, in fact, have the flu were given these antiviral medications, only to see their symptoms remain unchanged or worsen.
In mid-January, the FDA issued a public advisory in a memo to health care professionals cautioning them against being too heavy-handed in prescribing the new flu drugs. In it, Murray Lumpkin, M.D., the deputy director of the Center for Drug Evaluation at the FDA, noted several cases in which patients with influenza-like symptoms actually had severe bacterial infections that worsened during antiviral therapy.
Dr. Lumpkin also advised physicians to be cautious in prescribing Relenza for patients with underlying asthma or chronic obstructive pulmonary disease. Relenza is known to cause respiratory problems in some of those patients.
Officials at the Centers for Disease Control and Prevention (CDC) agree that the flu vaccination is the preferred choice. In a December 1999 report, the agency's doctors commented that "Antiviral agents are an adjunct ... not a substitute for the vaccine."
"From a public health perspective, the ideal would be for at-risk folks to get vaccinated [for the flu] and not wait until they get it," says Heidi Jolson, M.D., director of the Division of Antiviral Products at the FDA.
At the time Relenza and Tamiflu were introduced last fall, there was tremendous media attention given to the coming flu season and to the prospect of drugs that could fight off its worst effects, Dr. Jolson said. This winter, Glaxo Wellcome, maker of Relenza, and Hoffman-LaRoche, maker of Tamiflu, targeted cities hardest hit with influenza with heavy advertising ranging from full-page newspaper ads to television commercials. The resulting public clamor for these flu drugs prompted the FDA advisory in January.
"We thought we'd remind doctors and patients that symptoms of bacterial infections can be similar to those of the flu, and that patients with the flu may also have a bacterial infection," Dr. Jolson said.
Relenza and Tamiflu will surely step up to the plate many times during the next flu season, but the flu vaccination remains the heavy hitter against the virus.
Flu Shots for Whom? By Elizabeth Smoots, M.D.
National Institutes of Health -- flu fact page
Centers for Disease Control and Prevention -- flu prevention information
KidsHealth.org -- children and the flu