LONDON The failure by drugmakers and researchers to publish results from all clinical trials - whether good or bad - is risking patient safety, MPs said on Tuesday in a report that adds to pressure for more transparency.
The parliamentary Science and Technology Committee also asked the government to take steps to ensure greater sharing of the raw data generated during a trial.
"Many of the trials taking place today are unregistered and unpublished, meaning that the information that they generate remains invisible to both the scientific community and the public," said committee chairman Andrew Miller.
"This is unacceptable, undermining public trust, slowing the pace of medical advancement and potentially putting patients at risk."
The pharmaceutical industry is under increasing pressure to not only publish the main results of all clinical studies - including unfavourable ones - but also provide independent researchers with access to the raw data behind the tests.
Some companies, such as GlaxoSmithKline, have made a commitment to greater openness and the British group this year launched a new online system to provide researchers with access to clinical data about its medicines. But other firms are reluctant to share information that might help competitors.
Public distrust of drug companies has been fuelled by a series of scandals over the safety of medicines, such as Merck & Co's now-withdrawn painkiller Vioxx.