Generics manufacturer, Ranbaxy, has won tentative US Food and Drug Administration for a copycat version of Eisai’s top-selling Alzheimer’s disease medicine, Aricept (donepezil).

The approval, which the agency revealed on its website last Friday, is for the 5mg and 10mg versions of the tablet.

Ranbaxy said in a statement that it would not be launching its version of the product until the expiration of Eisai’s patent in November 2010.