(RxWiki News) It's important to have as much information as possible to properly weigh the risks and benefits of medication. Sometimes it's difficult to get all that data, as has been the case with Tamiflu.
A recent review of the evidence for the medication oseltamivir (Tamiflu) included updated information provided by the medication's manufacturer.
Oseltamivir is a medication used to treat symptoms of influenza or to prevent people from developing flu symptoms if they've been exposed to the virus.
However, until this year, not all the data from the clinical trials had been available to determine how effective the medication was.
The research review showed that oseltamivir did reduce the time individuals experienced flu symptoms, and can cause nausea and vomiting as well.
"Weigh the risks and benefits of Tamiflu with your doctor."
This study, led by Tom Jefferson, of the Cochrane Acute Respiratory Infections Group in Rome, analyzed the possible benefits and harms of oseltamivir based on available clinical trials and research.
This review took into account all the clinical trial data from the Tamiflu manufacturer, the pharmaceutical company Roche, that had not been made available previously.
It took several years and a great deal of communication back and forth with Roche to convince the company to release the data. Past reviews could not take into account all of the clinical data.
In total, the review included data from 83 clinical trials and appears to include all the results available related to trials involving oseltamivir.
An analysis of all the results together revealed that oseltamivir appeared to reduce the symptoms of flu by 16.8 hours in adults.
Children with asthma did not appear to benefit from oseltamivir, but healthy children who came down with the flu appeared to have their symptoms reduced by an average 29 hours.
The use of oseltamivir did not appear to make a difference in the number of adults' admissions to hospitals for the flu, and there was not enough information to determine if the medication changed the number of hospital admissions for kids.
There also was not enough data to determine whether taking oseltamivir prevented a person from developing flu symptoms.
In adults, oseltamivir did appear to reduce the risk of developing pneumonia, but this data was based on self-reported pneumonia by the patients which was not verified by a chest x-ray.
Based on the patients who reported having pneumonia or not, 100 people with the flu would need to take oseltamivir to prevent one case of pneumonia.
In the trials that more carefully documented which patients had pneumonia, the effects of oseltamivir were too small to rule out the possibility of chance.
Similarly, using oseltamivir did not lead to a reduction in pneumonia or to preventing flu in children at rates that were statistically strong enough to rule out chance.
Use of oseltamivir also did not reduce the cases of bronchitis, ear infection, sinusitis or other serious complication, based on this data.
The side effects of oseltamivir were also reported and included nausea and vomiting.
For every 28 people who took oseltamivir, one adult would experience nausea, and for every 22 who took it, an adult would experience vomiting from the medication.
Further, for every 19 children who took oseltamivir, one child would experience vomiting.
The researchers found some evidence that taking oseltamivir might reduce the likelihood that a person would have flu symptoms, especially in a household with other family members who had it.
However, this finding was based only on one study, and the medication did not appear to reduce the likelihood of transmitting the flu in this case.
Among adults who took oseltamivir to prevent flu symptoms while around someone with the flu, psychiatric side effects occurred to one of every 94 adults who took it.
Headaches were another possible side effect identified with oseltamivir, occurring in one of every 32 people who took it.
Overall, therefore, the medication appeared to offer both benefits and harms, but weighing these will depend on individual situations.
This study was published April 10 in the journal BMJ. The research was funded by the National Institutes of Health.
One author occasionally provides interviews to industry companies for pharmaceutical products and was an expert witness in a court case related to oseltamivir. He has also previously consulted for Roche, GlaxoSmithKline and Sanofi-Synthelabo.
One author has given a talk on oseltamivir, and another is an associate editor for BMJ. Beyond book royalties unrelated to this research, no other disclosures were reported.
