Shares of pharmaceutical company Allergan fell about 6% after a judge invalidated patents on its top-selling dry eye medicine Restasis on the grounds that the patents cover obvious ideas.
Restasis generated around $1.5 billion in sales for Allergan last year.
Judge William Bryson issued the ruling in federal court in Marshall, Texas, the latest twist in a long-running dispute between Allergan and generic drugmakers led by Mylan and Teva Pharmaceutical Industries Ltd.
In a statement, Allergan said: “Allergan … today acknowledged that the U.S. District Court for the Eastern District of Texas has issued an adverse trial decision finding that the four asserted patents covering Restasis (Cyclosporine Ophthalmic Emulsion) 0.05% are invalid.
“The company will appeal the court’s ruling.”
Allergan chief legal officer Robert Bailey said: “We are disappointed by the Federal District Court’s decision on the Restasis patents.
“We are carefully reviewing the decision and are considering all options.
“Allergan remains committed to vigorously defending the intellectual property of our products, which allows us to continue to invest in developing and bringing forward new medicines for millions of patients.”
Allergan said that to date, none of the proposed generic versions of Restasis have received approval and “none of these products would be able to launch in the market.”