Mylan holds 71.5 in Indias Matrix Laboratories Ltd.
The companies had earlier sued three Indian pharmaceutical companiesOrchid Chemicals and Pharmaceuticals, Lupin and Wockhardtalong with four other manufacturers for coming up with imitations of patented drugs in the US.
The companies, plus Indias Ranbaxy Laboratories Ltd and Sun Pharma, Canadas Genpharm Inc and USAs Interpharm Inc are seeking the US Food and Drug Administrations approval to market generic versions of Namenda.
New York-based Forest, which licensed the drug in the US from Germanys Merz, stated that the Namenda patent at issue is valid until April 2010. Further, the drugmaker noted that it has applied for a patent term extension, which could extend protection for the drug until September 2013. Defendants named in the lawsuits filed in federal court in Delaware include Teva, Barr, Cobalt, Lupin, Orchid, Upsher-Smith and Wockhardt. Namenda is Forests second-best selling drug behind the Lexapro antidepressant and has generated $384.6 million in sales in the six months ended September 30.
About 5 million Americans have Alzheimers disease, a 10% increase since 2002, and the number will continue to rise, the Alzheimer Association said in a report in March. The illness destroys memory and the ability to communicate and perform daily activities.
The lawsuit was filed on Friday in the federal court in Wilmington, Delaware, and seeks a court order preventing FDA approval from being granted until expiry of the patent.
Mylan, based in Canonsburg, Pennsylvania, is the worlds third-biggest generic-drug maker, behind Teva and Novartis AGs Sandoz.
Ranbaxy and Dr Reddys are Indias two biggest drugmakers while Mumbai-based Sun is seventh.