LONDON (Reuters) - Pfizer’s antidepressant reboxetine is an “ineffective and potentially harmful” drug and published data on it overestimates the benefits and underplays the risks, a study by German researchers said on Wednesday.

In a review published in the British Medical Journal, researchers from the German Institute for Quality and Efficiency in Health Care (IQWiG) found that nearly three quarters of the data on patients who took part in trials of reboxetine was not published until now -- a factor they said underlined the urgent need for mandatory publication of all clinical trial results.

Reboxetine, sold under the brand name Edronax, has been approved for the treatment of major depressive disorder in many European countries since 1997 but doubts have been raised about its effectiveness on the basis of recent studies and rejection of the application for approval in the United States in 2001.

“It is not a major drug in depression but every patient that is treated with an ineffective drug is one too many,” said Beate Wieseler of IQWiG’s department of drug assessment, who led the study. “Depression is a severe disease and there are effective drugs available, so if a patient is given an ineffective drug, that is unacceptable.”

Reboxetine is one of the first in a class of anti-depressant drugs called selective serotonin re-uptake inhibitors, or SSRIs.

A Pfizer spokesperson said the drug was “an effective treatment option” for acute depression and said the U.S. drugmaker would review the BMJ studies and “provide further comment after completing the review.”

The German team analyzed the results of 13 trials of reboxetine, including eight previously unpublished trials from Pfizer, and concluded that overall the drug was ineffective as a treatment for depression and may have harmful side effects.

They found no significant difference in benefit for patients taking reboxetine when compared with patients taking a placebo, or dummy pill.

The team also said trial data showed that patients taking the Pfizer drug also did worse than those taking the SSRI Prozac, known generically as fluoxetine, in terms of side effects that were bad enough to prompt them to stop taking the drug.

“Published data overestimated the benefit of reboxetine versus placebo by up to 115 percent and reboxetine versus SSRIs by up to 23 percent, and also underestimated harm,” they wrote in the study.

The researchers also noted that data on 74 percent of patients in trials had not been published until now.

Wieseler said the study’s findings were a “striking example of publication bias” and experts commenting on the findings agreed they highlighted an unacceptable situation.

“Clinicians treating patients with depression absolutely need the full picture in order to help their patients make the right choices about the various treatments that are available,” said Anthony Cleare, a consultant psychiatrist at the Maudsley Hospital and Institute of Psychiatry at King’s College London.

Pfizer said it “discloses the results of its clinical trials to regulatory authorities all around the world.”

“These regulatory authorities carefully balance the risks and benefits of each medication and reflect all important safety and efficacy information in the approved product labeling,” it said in an emailed statement.

In an editorial about the study, BMJ editors Fiona Godlee and Elizabeth Loder said the medical evidence base was being “distorted by missing clinical trial data” and called for urgent action to restore trust.

“Full information about previously conducted clinical trials involving drugs, devices and other treatments is vital to clinical decision-making,” they said. “It is time to demonstrate a shared commitment to set the record straight.”