A new study says several drugs used to treat certain types of flu viruses, including swine flu, are not as effective as they might claim, and could even lead to harmful side effects.

A new study that evaluated trial data of two drugs used to treat influenza called into question efficacy claims and other symptoms. The study suggests governments should reconsider stockpiling these drugs in light of this data. (Photo credit: Stuart Monk/Shutterstock)

A new study that evaluated trial data of two drugs used to treat influenza called into question efficacy claims and other symptoms. The study suggests governments should reconsider stockpiling these drugs in light of this data. (Photo credit: Stuart Monk/Shutterstock)

The review comes from the Cochrane Collaboration, a health care research network, and the British Medical Journal, which evaluated trials that involved more than 24,000 people who had taken either Tamiflu or Relenza to treat or prevent swine flu or influenza type A and type B. The trials’ data was obtained after a five-year campaign to “achieve appropriate and necessary independent scrutiny of data from clinical trials.”

While the study found that the drugs do shorten flu symptoms — by about a half a day — it didn’t find evidence that they reduced hospital admissions or other complications. Using these drugs as treatment was found to increase a person’s risk for nausea and vomiting.

Those who took Tamiflu in trials as preventative medicine were found to have an increased risk of headaches and “psychiatric disturbances,” among other issues. What’s more, the study found insufficient support to claims that the drug could help stop the spread of flu from person to person.

“We now have the most robust, comprehensive review on neuraminidase inhibitors that exists,” Dr. David Tovey, Cochrane’s editor-in-chief, said in a statement. “Initially thought to reduce hospitalizations and serious complications from influenza, the review highlights that Tamiflu is not proven to do this, and it also seems to lead to harmful effects that were not fully reported in the original publications. This shows the importance of ensuring that trial data are transparent and accessible.”

“Remember, the idea of a drug is that the benefits should exceed the harms,” Carl Heneghan, lead investigator on the study with Oxford University, told Reuters. ”So if you can’t find any benefits, that accentuates the harms.”

Cochrane says these findings call into question regulation and policies related to public health as it pertains to these drugs. For example, Cochrane pointed out that the U.S. has spent $1.3 billion on antiviral drug reserves.

Cochrane and the journal are asking governments if they would reconsider some of their policy decisions, stockpiling such drugs, in light of these recent findings.

“This review is the result of many years of struggles to access and use trial data, which was previously unpublished and even hidden from view,” Dr. Fiona Godlee, editor-in-chief of BMJ, said. “It highlights with certainty that future decisions to purchase and use drugs, particularly when on a mass scale, must be based on a complete picture of the evidence, both published and unpublished.

“We need the full data from clinical trials made available for all drugs in current use. With the new European Clinical Trials Directive bringing in rules for future drugs, it highlights the enormous challenge we face,” Godlee continued. “We need the commitment of organizations and drug companies to make all data available, even if it means going back 20 years. Otherwise we risk another knee-jerk reaction to a potential pandemic. And can we really afford it?”

But in a pandemic situation, flu expert Wendy Barclay told Reuters, the drugs’ benefits likely still make them worth it.

“If another pandemic came tomorrow, and the government had no drug with which to treat thousands of influenza infected patients, I imagine there would be a public outcry,” said Barclay, a researcher at Imperial College London, who was not involved in the trial data review

GlaxoSmithKlien, which manufactures Relenza, told TheBlaze in a statement that it is supportive of providing data for independent research reviews, but it stands by the effectiveness of its product.

“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,” the pharmaceutical company said in an email. “We’re also glad our commitments to transparency have been recognized by the team. We continue to believe the data from Relenza’s clinical trial program 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.”

Genentech, part of the Roche group, which manufactures Tamiflu, said in an emailed statement that it disagrees with the overall conclusions of the report.

“We firmly stand by the quality and integrity of our data, reflected in decisions reached by 100 regulators across the world, including the U.S. Food and Drug Administration who have approved Tamiflu to reduce the severity and duration of flu symptoms,” the statement read.

“We stand behind the abundance of data for Tamiflu as a treatment option recommended by public health agencies worldwide, including the Centers for Disease Control and Prevention and the World Health Organization,” it continued.

The CDC released its own statement Thursday, asserting that it “continues to recommend the use of the neuraminidase inhibitor antiviral drugs (oral oseltamivir and inhaled zanamivir) as an important adjunct to influenza vaccination in the treatment of influenza.”

Featured image via Shutterstock. This story has been updated to include a statement from Genentech. 

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