A day after revealing safety concerns about its investigational insomnia treatment, Actelion says earnings for 2009 will be reduced by $80 million after losing a legal dispute with a Japanese drugmaker.

The problem centres around the decision of an arbitration proceeding in California which has ruled against Actelion’s US unit CoTherix in a dispute with Asahi Kasei Pharma Corp over a licence agreement to develop the latter’s rho kinase inhibitor fasudil signed in June 2006.

However in January 2007, Actelion acquired CoTherix which in turn told Asahi Kasei that it would not continue development of the heart drug and returned the rights. The Tokyo-headquartered group disputed the basis for terminating the deal and initiated arbitration proceedings and filed a lawsuit against Actelion.

The arbitration panel has now decided that CoTherix should pay Asahi Kasei some $91 million, plus interest, while the lawsuit remains ongoing. Actelion says it is “surprised and disappointed by both the panel's decision as well as by the amount awarded” and will “evaluate possible judicial review”.

All this means that the Allschwil-based firm expects 2009 operating profit to be reduced by approximately $80 million. Actelion’s shares ended the day down 1.2% to 55.40 Swiss francs a day after taking a hefty fall on fears about the safety profile of its investigational insomnia drug almorexant.