The conclusions come from a review of neuraminidase inhibitors by the Cochrane Collaboration published in the British Medical Journal (BMJ) today and are based on analysis of 20 trials of the Roche drug.
The authors found that while Tamiflu “led to a quicker alleviation of influenza-like symptoms” the difference from placebo was only 0.7 days in adults and uncertain in children.
They also said that there is no evidence the Roche drug reduces the number of hospitalisations or serious influenza complications; confirmed pneumonia, bronchitis, sinusitis or ear infection in either adults or children.
In fact the Cochrane authors said Tamiflu “increased the risk of nausea and vomiting in adults by around 4% and in children by 5%” and pointed to a 1% increase in the risk of psychiatric events when the drug was used to prevent influenza.
They added that: “Evidence also suggests that Tamiflu prevented some people from producing sufficient numbers of their own antibodies to fight infection.”
Tamiflu and GSK’s neuraminidase inhibitor Relenza have been stockpiled by Governments worldwide in preparation for an influenza pandemic.
In the UK , for example, £424m has been spent on building up supplies of Tamiflu and £136m on Relenza since 2006. Similarly, the US has spent $1.3bn on antivirals over the same period.
The Cochrane authors - who also reviewed 26 trials of GSK’s drug – questioned this stockpiling and suggested that, in light of their findings, the “guidance on the use of both neuraminidase inhibitors in the prevention or treatment of influenza should be revised to take account of the evidence of small benefit and increased risk of harms.”
A GSK spokesperson told in-Pharmatechnologist.com that: “We were committed to giving the Cochrane team access to the data they required from the outset and we are pleased to have been able to support their research. We are also glad our commitments to transparency have been recognised by the team.
“We continue to believe the data from Relenza’s clinical trial programme support its effectiveness against flu and that when used appropriately, in the right patient, it can reduce duration of flu symptoms. Relenza remains an important option for health professionals who are responsible for deciding when these medicines should be used.”
Roche, whose product bore the brunt of the criticism in the Cochrane review, also maintained its belief in the efficacy of its drug.
“Roche fundamentally disagrees with the overall conclusions of the Cochrane Acute Respiratory Infections Group’s (ARI) report on Tamiflu. We firmly stand by the quality and integrity of our data, reflected in decisions reached by 100 medicines regulators across the world and subsequent real-world evidence demonstrating that Tamiflu is an effective medicine in the treatment and prevention of influenza."
This Swiss drugmaker added that it “is disappointing that the patient-level data requested by and provided to Cochrane has not been used to inform this current analysis” and added that it “believes it is important that public health bodies and influenza experts provide their opinion on this review, alongside the totality of Tamiflu data, before any conclusions are drawn."