Patent ID: 6218566
Filing Date: 2001-04-17
Classification: A61P,C07C

Abstract:
A process for preparing a composition comprising pharmaceutically acceptable, crystalline, non-hygroscopic L-DOPA ethyl ester as free base, which process comprises:(a) reacting L-DOPA with ethanol in the presence of thionyl chloride or an acid catalyst to produce a solution of crude L-DOPA ethyl ester salt;(b) removing any residual volatiles from the solution of crude L-DOPA ethyl ester salt produced in step (a);(c) diluting the solution from step (b) with water and adding a cosolvent and a suitable antioxidant;(d) adding a suitable base to the solution from step (c) under controlled conditions to precipitate a crude L-DOPA ethyl ester free base;(e) collecting the precipitated L-DOPA ethyl ester free base from step (d);(f) drying the precipitated crude L-DOPA ethyl ester free base collected in step (e); and(g) recrystallizing the dried, precipitated crude L-DOPA ethyl ester free base from step (f) in the presence of a suitable solvent containing an antioxidant to produce the composition of pharmaceutically acceptable, crystalline, non-hygroscopic L-DOPA ethyl ester free base.