The world's leading drug companies have promised to publish more data about clinical trials into new medicines to reassure the public about their safety.
Pressure has mounted on firms to publish negative trial results
Results of all industry clinical trials will be published on the internet later this year under plans drawn up by pharmaceutical trade associations.
The database is voluntary but all the major pharmaceutical companies are said to have signed up to it.
The move follows years of pressure on drug firms to publish negative results.
In September, 11 medical journals published a joint editorial calling for more transparency so unflattering results could not be covered up.
The editorial was published a month after GlaxoSmithKline agreed to release information on all its clinical studies to settle a lawsuit filed by New York Attorney General Eliot Spitzer, who had accused the firm of suppressing data on the anti-depressant Paxil, known as Seroxat in the UK and Europe.
A study by the National Collaborating Centre for Mental Health published in the Lancet in April also accused drug firms of suppressing negative data about SSRIs, a type of anti-depressant drug.
Recently, several trade associations, including the Association of the British Pharmaceutical Industry (ABPI), have set up their own registers as have several of the biggest firms.
The database will only contain results of trials sponsored by the industry - about half of the total number carried out.
The others are sponsored by bodies such as the NHS and various research charities.
And the drug firms are only required to publish trials a year after they have been approved.
There is no requirement to publish data on trials on drugs that do not make it to the market and it will not be retrospective either.
However, Dr Richard Barker, director general of the ABPI, said: "The industry recognises that there are important public health benefits associated with making clinical trial information more widely available to healthcare practitioners, patients and others.
"By publishing not just the results of trials that have taken place - whether positive or negative - but also those that are just starting, the industry has made a major step towards achieving greater transparency."
Trade associations across Europe and in the US and Japan have signed up to the plan.
But Tim Kendall, co-director of the National Collaborating Centre for Mental Health in London, said he was not convinced an industry-backed voluntary register would work.
"I do not think self-regulation is going to change things. It is not in the interests of pharmaceutical companies to be honest and open.
"People do not trust industry-backed publications. I think it is better we are sceptical."