The UK’s Competition and Markets Authority (CMA) fined four pharma companies more than $4 million for conspiring to share the market and fix prices for the antidepressant drug nortriptyline.

The CMA found King Pharmaceuticals and Auden Mckenzie entered an anti-competitive arrangement to share the market by supplying nortriptyline to a large pharmaceutical wholesaler. The authority fined Accord-UK $2.45 million because the company took control of Auden Mckenzie’s nortriptyline business after the market sharing ended.

Accord-UK and Auden Mckenzie also agreed to pay $1.3 million to the National Health Service in connection with the case.

The authority also fined Lexon UK $1.6 million for sharing information on pricing and volumes with King Pharmaceuticals and Alissa Healthcare Research. King and Alissa received smaller fines.