ROCKVILLE, Md. - The Food and Drug Administration (FDA) has approved a new indication for oseltamivir (Tamiflu, Roche, Gilead Sciences) for the prevention of influenza in adults and children 13 years and older. Previously, oseltamivir was only indicated for the treatment of uncomplicated influenza in adults.
The approval comes at a critical time. Production of the influenza vaccine has been delayed for several months and officials were prompting the public to delay getting vaccinated to allow those at greater risk of developing more serious complications to be vaccinated.
Results of several clinical studies prompted the FDA decision. Analysis of two seasonal prophylaxis studies in healthy, unvaccinated adults and adolescents showed that oseltamivir (75 mg) reduced the incidence of laboratory-confirmed clinical influenza from 4.8% in the placebo group to 1.2% for those taking the drug. In the study, oseltamivir was administered once a day for 42 days during a community outbreak.
Oseltamivir has also shown efficacy for influenza prevention in the elderly. Another study evaluated oseltamivir for seasonal influenza prevention in elderly nursing home residents, a group in which an influenza outbreak could have devastating effects. According to the FDA, the study showed that the same dosage of oseltamivir taken for the same duration reduced the incidence of clinically confirmed influenza from 4.4% in the placebo group to 0.4% in the oseltamivir group. However, the FDA reports that approximately 80% of the population included in this study had already been vaccinated against influenza.
Oseltamivir has shown other benefits against influenza as well. According to the FDA, oseltamivir may help prevent the onset of flu symptoms even after exposure to the virus has occurred. The FDA reports that a study of post-exposure prevention in households showed that oseltamivir reduced the incidence of influenza from 12% in the placebo group to 1% in the oseltamivir group. In the study, oseltamivir was administered within two days of the onset of flu-like symptoms in the first household case and dosage was continued once a day for seven days.
Although delays in manufacturing have prevented adequate supplies of the flu vaccine from being available to all the public, the FDA does not recommend oseltamivir as a substitute for influenza vaccine. According to the FDA, patients should continue to receive an annual influenza vaccination according to immunization practice guidelines. Officials expected that adequate amounts of the vaccine should be available by December, although by press time, some physicians were still reporting that they did not have adequate vaccine.
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