The flu season is upon us. If your patients have a family member who has already been diagnosed with the flu, they may ask you about a prescription for zanamivir. According to findings in last week's New England Journal of Medicine, zanamivir, an inhaled drug, could keep the virus at bay for the rest of the patient's household. Results of the study appeared to the general public in the November 2, 2000 issue of USA Today.
According to the NEJM study, zanamivir cuts the risk of giving the disease to relatives by almost 80 percent. Lucky for Glaxo Wellcome, the company that sells zanamivir (Relenza), the study is particularly timely, coming on the eve of a flu season marked by a projected shortage of vaccine against the virus.
Recommendations from the Centers for Disease Control and US Surgeon General, Dr. David Satcher, urge physicans to begin the influenza season by immunizing those at highest risk of the infection, such as the elderly, pregnant women and people with chronic diseases. Physicians and other health practitioners should encourage young, healthy people to wait their shots.
Zanamivir has been approved in United States for the treatment, not prevention, of flu. The drug, like another newcomer, Tamiflu, from Hoffmann-La Roche, blocks the ability of the virus to leave infected cells and migrate to healthy ones.
While neither drug has been approved for preventing flu, several recent studies have suggested that they work well in this application. The FDA is reviewing both medications for preventive purposes.
The University of Virginia study of zanamivir tested the medication against dummy treatment in 321 families with one member suffering from flu-like symptoms. Roughly half of these "index cases" were given 10 mg of the drug twice a day for five days, while their family members -- all over age 5 -- got 10 mg a day for 10 days.
In families that didn't get the drug, nearly one in five members fell ill with flu, the researchers say, compared with one in 25 in the treated families -- a difference of nearly 80 percent. The drug, which caused few, generally mild side effects, also cut the length of the average flu bout in the index cases from 7.5 days to 5 days.
The same advice that was issued last year by the CDC still holds true for this year. Vaccination is still the best bet for influenza prevention, saving both money and lives. University of Virginia researchers are stating firmly that their study should in no way be construed as an approach that should replace vaccination. However, zanamivir could play an important role in reducing the transmission of the virus.
Practitioners should look at the published data and decide for themselves whether to offer the drugs to their patients as a preventive.
The study results yield other good news for patients and practitioners. It appears that the "flu drugs" and possibly other anti-viral medications don't lead to resistant flu strains, and appear to work in family members who had already been exposed to flu and ultimately, courses of zanamivir could prevent one case of flu per 10 individuals taking the drug.
Like most medical wonders, there is a downside. The most obvious in this case is the cost of the medication. While a single flu shot runs about $10 five days worth of zanamivir costs about $50. Another problem is the nature of the medication. Zanamivir must be taken within two days of infection to work best which makes it hard for your patients to realize when they need the medication.