The drug is supplied to 48,000 patients through the UK’s National Health Service (NHS).

The price rise happened in 2013 after Pfizer sold the UK rights to the drug to a new distributor, Flynn Pharma, which changed the name of the drug. The CMA also fined Flynn £5.2m for its part in the price hike.

The CMA claimed that the two companies took advantage of the “debranding” exercise to inflate the drug’s price. “The companies deliberately exploited the opportunity offered by debranding to hike up the price for a drug which is relied upon by many thousands of patients. These extraordinary price rises have cost the NHS and the taxpayer tens of millions of pounds,” said Philip Marsden of the CMA.

Both companies are contesting the fines, and are appealing the judgement.