By Susan Vogel-Misicka and Jessica Dacey
Medical opinion is split over the efficacy of Tamiflu, the widely prescribed influenza drug produced by Swiss pharmaceutical giant Roche.
Around 90 million people have taken Tamiflu over the past decade and sales of the drug have generated billions of francs for Roche. But a leading medical journal and an international healthcare network now say its effectiveness in treating flu complications can’t be entirely proven.
In a scathing article published on Wednesday, the British Medical Journal said there was a lack of publicly available evidence to support its capabilities and Roche had “broken successive pledges to make full study reports available” for more cross-checking.
In parallel, the non-profit Cochrane Collaboration organisation concluded an independent review of studies into Tamiflu. It says there are discrepancies between published papers on Tamiflu and available clinical study data. The drug’s success couldn’t be fully tested and proven because Roche has not released full data from its clinical trials, it says.
Cochrane says while Tamiflu helps flu sufferers feel better an average of 21 hours quicker after experiencing initial symptoms, it didn’t reduce the number of people who went on to be hospitalised.
The drug has been stockpiled in various countries as a principal way of treating influenza in critical care. The World Health Organization maintains that it will keep Tamiflu on its list of essential drugs, as it takes into account evidence collected on the ground during outbreaks as well as clinical trials.
“Generally good safety”
Tom Jefferson of Cochrane argues that Roche – although not legally required to – should have given them more data to work with. They were given only part of the clinical study reports – the summary of the study methods and the results. But this was just a quarter of what they had asked for.
“What we want is a complete record,” Jefferson told swissinfo.ch.
Basel-based Roche insists that it provided ample information. In an emailed statement to swissinfo.ch, a spokesman wrote: “Roche provided the Cochrane group with access to 3,200 pages of very detailed information, enabling their questions to be answered.”
“Extensive clinical research and real-life experience show that Tamiflu has a generally good safety and tolerability profile.”
Tamiflu, known generically as oseltamivir, was used extensively to combat avian flu in 2005 and swine flu in 2009-2010.
According to Roche, data from the 2009 pandemic showed Tamiflu was “effective and well-tolerated, reduces the risk of complications, intensive care unit admission, length of stay in hospital and improves the chance of survival”.
“We stand behind the robustness and integrity of our data supporting the efficacy and safety of Tamiflu.”
Jefferson says however that the performance during the 2009 pandemic was based on “very sketchy … sporadic studies”.
“Formal clinical trials are the best source of evidence and effectiveness and safety of the drug.”
Tried and true
Despite this backlash, oseltamivir still has its supporters. Pascal Meylan of Vaud university hospital’s institute of microbiology told swissinfo.ch that while he was not familiar with the Cochrane report, he found it to be a good drug, and that it proved its usefulness during the 2009-2010 pandemic.
“On the one hand obviously I wonder what exactly is the problem with the Cochrane Collaboration study accessing data from Roche. But on the other hand I think this is an effective drug and this is the best we have for the time being to treat influenza and I think it would be a pity not to use these drugs.”
However, what he emphasises is how important it is to take it early enough – within the first 48 hours of catching the flu. “I would propose it to people, looking very carefully at the timing. There are very few adverse effects.”
He added that by nature independent verifiers were bound to be demanding and “cut evidence to the bone”.
“There may be a problem here but to dismiss the drug outright would be to throw the baby out with the bathwater.”
But that’s not good enough, according to Jefferson. He’s incensed that government money has gone into stockpiling a drug, the efficacy and safety of which is questionable.
“As a physician, if I prescribe a drug I want to know how it works, what it interacts with.”
Cochrane researchers found little evidence to support all the manufacturer’s published claims but they did pick up unpublished evidence of nausea as a side-effect.
“I would be very cautious about using drugs for which there is uncertain evidence,” Jefferson commented.
He says the ball is now in the court of the European Medicines Agency (EMA), as it has the legal right to reopen the “Tamiflu file” and look at all the evidence.
The EMA was unavailable for comment.