GlaxoWellcome issued a warning letter to doctors across Europe last week that its drug for treating influenza, zanamivir (Relenza), could cause bronchospasm and serious respiratory deterioration.
The company now advises doctors to use special caution in prescribing the drug to patients with underlying asthma or chronic obstructive pulmonary disease. Such patients, it suggests, should be informed of the risk of bronchospasm and should ensure that a fast acting bronchodilator is available.
Over 500000 prescriptions of the drug have been issued in Europe and the United States during the current flu season.
In the United States, the Food and Drug Administration sent out a “public health advisory” notice on the safe and appropriate use of flu drugs, including zanamivir and a second new drug, oseltamivir (Tamiflu).
Laura Bradbard, spokeswoman for the administration, said: “As of January 12, there were five deaths of people with influenza who were treated with Relenza. Two died of bacterial infection, in two there was an underlying disease contributing to the death, such as diabetes or respiratory disease, and one had complicated influenza.”
The advisory notice warns doctors that “anti-viral products have no activity against bacterial infections” and advises them to be suspicious of primary or concomitant bacterial infection in patients with flu-like symptoms.
The National Institute for Clinical Excellence (NICE) ruled last year that doctors in England and Wales should not prescribe zanamivir (16 October, p 1024). It made its ruling partly because no clear evidence exists for its safety and efficacy in patients with serious respiratory or cardiac disease, as these patients have been excluded from clinical trials (11 September, p 659).