Oseltamivir, Roche's neuraminidase inhibitor, is a safe and effective drug for the prevention of influenza, say Dr Frederick Hayden (University of Virginia, US) and colleagues.
Oseltamivir acts by the same mechanism as zanamivir (Relenza). It is a potent and selective inhibitor of influenza neuraminidase which prevents the replication of influenza A and B viruses, according to Dr Hayden. The drug is taken orally.
Roche told The Journal on November 2 that it is submitting a UK licence application for use of oseltamivir (Tamiflu) in treating influenza which it hopes to receive for next winter's season. It also plans to apply for a prophylaxis licence next year, for the 2001/02 influenza season.
Dr Hayden reports the results of a clinical trial of oseltamivir in the prevention of influenza in the New England Journal of Medicine (1999;341:1336). Treatment with oseltamivir (75mg), given once or twice a day, or placebo, was randomly assigned to 1,559 healthy, non-immunised adults and given for six weeks during a period of local influenza activity.
The proportion of laboratory confirmed cases of influenza-like illness was significantly lower in the oseltamivir groups - 1.2 and 1.3 per cent compared with 4.8 per cent in the placebo group. There was no significant difference between the once and twice daily doses of oseltamivir. The efficacy of oseltamivir as prophylaxis against influenza was 76 per cent when given once daily and 72 per cent when given twice daily.
Oseltamivir was generally well tolerated, the authors report. Upper gastrointestinal disturbances, specifically nausea, were most frequent (12.1 per cent in the once daily group, 14.6 per cent in the twice daily group and 7.1 per cent in the placebo group). Most of the gastrointestinal side effects occurred during the first two days of treatment following which levels decreased to those similar to the placebo group.
Dr Hayden and colleagues conclude that: chemoprophylaxis against influenza may be useful if a vaccine is unavailable, ineffective or cannot be tolerated; as an adjunct to vaccination in people at high risk; in the event of a pandemic; or for short term use, eg, in an institution, where an outbreak of influenza has occurred.
They also comment that zanamivir has been found to have prophylactic activity.
Glaxo-Wellcome told The Journal on November 2 that it will be submitting an application for a prophylaxis licence for zanamivir before the end of this year. It hoped that zanamivir would receive a prophylaxis licence in time for next winter's influenza season.