A friend of mine says he just got a drug called Flumadine to treat the flu, and that it cut down his symptoms and the duration of the illness. He says it's a new drug, and that not all medical professionals are familiar with it yet. What can you tell me about this miracle drug? My friend was told that it has to be taken within 48 hours of contracting the flu. Does that mean within 48 hours of infection, or within 48 hours of the first symptoms?

Dan

Influenza (the flu) is an acute respiratory illness that occurs quite commonly worldwide. Although many people refer to any respiratory illness as "the flu," only a few of these infections are truly caused by the influenza virus. Classic influenza is a relatively severe illness with fever, severe myalgia (muscle aches), sore throat, nasal symptoms and cough. Pneumonia is the most important complication of the flu, and it most commonly occurs in the elderly and those with chronic lung disease.

The most important agent for managing influenza is the flu vaccine. The vaccine is recommended for anyone over 65, people with a variety of medical conditions, health-care workers and anyone else who wants it. It is very safe and is effective in preventing the flu about 75 percent of the time. Because the influenza virus changes each year, the vaccine contains three different strains (types) of virus. That means people may still become infected despite having had the vaccine, if they are exposed to a different strain than the ones in the vaccine.

As your friend mentioned, there are also a few specific medicines to treat influenza. The oldest drug, amantadine (Symmetrel), affects the way the virus replicates. It can be given before a person becomes infected, as a method of prevention. For example, if a few residents of a nursing home develop influenza, physicians may prescribe amantadine for the others. Amantadine is somewhat toxic, resulting in quite a few neurologic side effects.

Rimantadine (Flumadine) is a similar drug with about the same effectiveness as amantadine but fewer side effects. If rimantadine is given within 48 hours of the onset of symptoms, the duration of illness can be shortened by up to 50 percent. Rimantadine is only active against one strain of influenza (called influenza A). It is somewhat difficult to use this drug, because unless there is a real outbreak of the flu, it is difficult to know that a patient truly has influenza A infection. Many people with illnesses due to other viruses may be unnecessarily treated. Another point is that no studies have shown that these drugs prevent or help treat the complications of the flu (and complications such as pneumonia are the main danger of the flu).

A newer drug, zanamavir (Relenza), which works by a different mechanism, has also been shown to shorten the duration of illness in patients with influenza. This is especially true if the drug is started within 30 hours of the onset of illness. In addition, it is effective against both influenza A and influenza B, the two most common strains of the virus. This drug is very well tolerated.

Because most cases of influenza are relatively minor and resolve without treatment, doctors should be using the above medications sparingly. If I see a patient who I am confident has influenza, and if he or she comes to me early after the onset of symptoms, I will consider treatment with rimantadine and possibly zanamavir. Otherwise, I will let nature take its course.