The FDA has approved Relenza for prevention of flu in children ages 5 and older and adults, providing a second drug in addition to Tamiflu to prevent influenza A and B.
GlaxoSmithKline's Relenza (zanamivir) had previously been approved only for treating existing cases of the flu, and only Roche's Tamiflu (oseltamivir phosphate) was approved as a preventive treatment.
Relenza is not a substitute for the flu vaccine, which is the primary means for preventing influenza, the agency noted.
"This approval is a welcome addition to the available defenses against the flu," said Steven Galson, director of the FDA's Center for Drug Evaluation and Research. "This new use offers the medical community another option to prevent and control influenza A and B."
The agency made its March 29 decision because Relenza proved effective in preventing seasonal influenza through four large-scale studies comparing the drug with a placebo. In two of these trials, use of the drug substantially reduced the spread of influenza in households where participants were age 5 or older. In the other two trials, which were conducted in communities experiencing an influenza outbreak, Relenza reduced the incidence of the disease in both young and older populations.