Patent ID: 7393974
Filing Date: 2008-07-01
Classification: C07C

Abstract:
1. A conversion process of gabapentin hydrochloride into gabapentin form (II) comprising: a) dissolution of gabapentin hydrochloride in water in which the gabapentin hydrochloride and the gabapentin are completely soluble; b) subsequent addition of an amine selected from the group consisting of: monocyclohexylamine, dicyclohexylamine, dibenzylamine and tricyclohexylamine, that allows the removal of the chloride ion from the solution containing gabapentin hydrochloride, by precipitation of the hydrochloride of the same amine, leaving gabapentin in solution in free amino acid form; (c) removing the precipitated amine hydrochloride salt from the solution containing gabapentin of step b) by filtration; and d) concentrating by distillation the aqueous solution containing gabapentin in free amino acid form coming from step (c) and taking the residue with an alcohol selected from the group consisting of linear or branched alkyl alcohols with one to four carbon atoms or mixtures thereof, thereby obtaining the precipitation of raw gabapentin in polymorphic Form II and isolating gabapentin form (II) by filtration; e) further purifying the raw gabapentin isolated in step (d) by treatment with an alcohol selected from the group consisting of linear or branched alkyl alcohols with one to four carbon atoms and mixture thereof.