Pfizer resists calls for greater clinical trial transparency

US drug maker says disclosure of all historical trial data offers little value to patients, but critics say lack of information paints distorted picture of safety

Pfizer, one of the world's largest pharmaceutical groups, has said it will resist demands from investors and transparency campaigners that it disclose results from all historical drug trials.

A powerful group of 85 investors, representing more than 2.5tn of assets, recently joined forces with medical research campaigners to press for greater transparency from the 25 largest pharmaceuticals groups in the world.