In a win for Allergan, the U.S. Court of Appeals for the Federal Circuit upheld a federal court ruling blocking Sandoz’s proposed generic of Allergan’s eye drops Combigan (brimodine/timolol).

The companies have been battling over the eye drops for years. The FDA approved brimonidine in 1996 for treatment of intraocular pressure in patients with glaucoma and the agency approved Sandoz’s eye drop product Alphagan (brimonidine tartrate) in December 2001.

Allergan sued Sandoz in 2017 in the U.S. District Court of New Jersey claiming that Sandoz’s proposed generic infringed on several new patents.