Researchers said trials of Pfizer’s Neurontin epilepsy treatment for uses that are yet to be approved may have been emphasised to indicate that the drug worked better than internal documents showed.

A report in the New England Journal of Medicine shows comparisons of internal company documents with published data from 12 clinical trials.

The researchers found inconsistencies between data from the original trials and information published in medical journals, Bloomberg reports.

The research by the University of California at San Francisco and the Johns Hopkins Bloomberg School of Public Health has been released two months after Pfizer was fined $2.3bn for illegally marketing another drug.