Use of purified donepezil maleate for preparing pharmaceutically pure amorphous donepezil hydrochloride

摘要

The present invention provides a crystalline donepezil maleate, which is used as an intermediate in the preparation of donepezil hydrochloride. Also provided are novel processes for producing same in substantially pure form and a process for producing pharmaceutically pure amorphous donepezil hydrochloride therefrom.