Tamiflu and Relenza are drugs commonly used for the prevention and treatment of influenza in adults and children. Past research has hailed the drugs for reducing hospital admissions and complications as a result of the virus. But in the latest Cochrane Review, recently published in the BMJ, researchers say there is no solid evidence to support such claims.

Tamiflu (oseltamivir) and Relenza (zanamivir) are classes of drugs known as neuraminidase inhibitors. Both drugs are thought to prevent and reduce symptoms of flu by stopping the influenza virus from spreading inside the body.

At present, Tamiflu is used to combat flu in patients 2 weeks of age and older whose symptoms have not lasted longer than 2 days. It can be used to prevent flu in patients aged 1 year and older. Relenza is used to tackle flu in patients aged 7 years and older and can be used for flu prevention in those aged 5 years and older.

According to the researchers involved in this latest review, including Dr. Carl Heneghan of the University of Oxford in the UK and Dr. Peter Doshi of the University of Maryland School of Pharmacy in the US, both drugs are stockpiled for use against seasonal and pandemic influenza. For example, the US has spent over $1.3 billion on reserves of influenza antivirals.

This stockpiling has been based on international and national recommendations from bodies such as the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC). But what are their recommendations based on?

Share on Pinterest The latest Cochrane Review has questioned the benefits of influenza antivirals Tamiflu and Ralenza.

The team says that for the European CDC, neuraminidase inhibitor recommendations were based on a summary of benefits and harms carried out by the European Medicines Agency (EMA), while other recommendations have been based on findings of trials from drug manufacturers, such as GlaxoSmithKline (GSK).

In 2009, Cochrane researchers looked to verify the safety and effectiveness of neuraminidase inhibitors. However, drug manufacturers refused to provide full access to clinical trial data of the drugs, which hindered their efforts.

This raised questions as to whether the risks and benefits of influenza antivirals have been accurately reported, and whether they should be stockpiled for the treatment of seasonal and pandemic flu in children and adults.

In 2012, Medical News Today reported on a story detailing how the BMJ were putting pressure on Roche – the manufacturers of Tamiflu – to release trial data for the drug.

Having now gained access to original clinical trial data, the researchers were able to analyze 20 full internal reports on the effects of Tamiflu and 26 reports on the effects of Relenza. In total, the reports included more than 24,000 people.