The UK’s Competition Appeal Tribunal has overturned a fine imposed by the Competition and Markets Authority (CMA) on Pfizer and Flynn Pharma for hiking the price of an epilepsy drug.

The CMA had issued fines totaling £90 million in December 2016, ruling that both companies had abused their dominant market position by charging excessive and unfair prices for the phenytoin sodium capsules. The authority said spending by the UK’s National Health Service on the drug, used by 48,000 patients in the country, spiraled from £2 million in 2012 to around £50 million in 2013.

However, the tribunal ruled against the CMA’s finding of abuse, stating that the authority erred in its reliance on the approach by which it found that Pfizer’s and Flynn’s prices were excessive because they materially exceeded their respective costs plus a reasonable rate of return.

It also said the authority had not properly assessed the possible impact of meaningful comparators (in particular, phenytoin sodium tablets) for the purpose of assessing whether the prices were unfair. The tribunal has referred the case back to the CMA for further consideration.

“The tribunal’s judgment makes it clear that a finding of abuse remains possible given the size of the price increase that occurred. It is regrettable that the tribunal chose not to make its own finding as to whether Pfizer and/or Flynn Pharma had committed an abuse, which was within its powers,” the CMA said, adding it would now carefully review the judgment and consider whether to appeal.