Apotex goes to court to get Alzheimer's drug OK

* Apotex tries to remove roadblocks to its Alzheimer's drug

* Says it's injured by Ranbaxy's regulatory muddle

TORONTO, July 7 (Reuters) - Canada's Apotex Inc is asking a U.S. court to rule that it did not infringe Eisai Co's (4523.T) patents on Aricept, the world's No. 1 Alzheimer's disease treatment.

A favorable ruling would pave the way for the U.S. Food and Drug Administration to approve Apotex's application to market its generic version of donepezil hydrochloride -- the bio-equivalent of Eisai's drug Aricept.

The patent on the treatment by Japan's Eisai expires in November 2010.

Two companies -- Ranbaxy Laboratories Ltd (RANB.BO) and Teva Pharmaceutical Industries Ltd (TEVA.TA), the world's biggest generic-drug maker -- are ahead of Apotex in the regulatory race to be the first to market a copycat version of the drug.

Ranbaxy is entitled to a 180-day exclusivity window before other companies can bring their drug to market in the United States because Ranbaxy was the first to file for permission to market a generic version of Aricept.

However, various patent filing shortcomings from both Ranbaxy and Teva may make it impossible for them to be ready to market their products when Eisai's patent on Aricept expires in November 2010.

Apotex argues in a court document filed last week that doubts about Ranbaxy's ability to launch on time injure Apotex because they disrupt planning for its own generic launch.

"Ranbaxy's inability to obtain approval of its Abbreviated New Drug Application and the FDA's erroneous identification of Teva as the first-to-file generic has created substantial uncertainty in the generic market for donepezil hydrochloride products bio-equivalent to Aricept," Apotex argues in its court document.

"While there are a number of generic manufacturers willing and able to enter the market for generic donepezil hydrochloride, the uncertainty prevents each from planning a launch."

The case number in the U.S. District Court for the Middle District of North Carolina is 09-CV-00477.

($1=$1.16 Canadian) (Reporting by Scott Anderson; editing by Peter Galloway)