The invention provides a crystalline form of 2-(2,6-dichlorophenyl)-1-[(1S,3R)-3-(hydroxymethyl)-5-(3-hydroxy-3-methylbutyl)-1-methyl-3,4-dihydroisoquinolin-2(1H)-yl]ethanone, and pharmaceutical compositions thereof. The invention further provides methods of using a crystalline form of 2-(2,6-dichlorophenyl)-1-[(1S,3R)-3-(hydroxymethyl)-5-(3-hydroxy-3-methylbutyl)-1-methyl-3,4-dihydroisoquinolin-2(1H)-yl]ethanone to treat cognitive impairment associated with Parkinson’s disease or schizophrenia.本發明提供結晶形式之2-(2,6-二氯苯基)-1-[(1S,3R)-3-(羥甲基)-5-(3-羥基-3-甲基丁基)-1-甲基-3,4-二氫異喹啉-2(1H)-基]乙酮及其醫藥組合物。本發明進一步提供使用結晶形式之2-(2,6-二氯苯基)-1-[(1S,3R)-3-(羥甲基)-5-(3-羥基-3-甲基丁基)-1-甲基-3,4-二氫異喹啉-2(1H)-基]乙酮以治療與帕金森氏症(Parkinson’s disease)或精神分裂症相關認知損傷之方法。
