UK’s antitrust regulator has charged Pfizer and Flynn Pharma a fine totaling more than $100 million for hiking the prices of their phenytoin sodium capsules for epilepsy.

Pfizer and Flynn Pharma plan to appeal the decision from the UK’s Competition and Market Authority, contending they complied with established competition law and sold the drug for a cheaper price than alternative epilepsy therapies marketed in the UK.

CMA has ordered the companies to lower the prices of the treatment in addition to Pfizer paying a record fine of about $106 million and Flynn Pharma paying roughly $6.5 million.