PURIFIED CRYSTALLINE DETOMIDINE HYDROCHLORIDE MONOHYDRATE, ANHYDRATE AND FREE BASE WITH LOW AMOUNTS OF ISO-DETOMIDINE AND OTHER IMPURITIES BY RECRYSTALLISATION IN WATER

摘要

The present disclosure relates to crystalline detomidine hydrochloride monohydrate, anhydrous detomidine hydrochloride and detomidine free base (4-[(2,3-dimethylphenyl)methyl]-1H-lmidazole ), purified by recrystallisation in water, with a low amount (total amount of impurities is not more than 0.1% area relative to detomidine based on HPLC, UV detection at 220 nm) of the impurities iso-detomidine (4-[(3,4-dimethylphenyl)methyl]-1H-lmidazole ), iso-impurity A (((RS)-(3,4-dimethylphenyl)(1H-imidazol-4-yl)methanol)), impurity A ((RS)-(2,3-dimethylphenyl)(1H-imidazol-4-yl)methanol), "ketone impurity" (2,3-dimethylphenyl)(1H-imidazol-4-yl) methanone, impurity B ((RS)-(1-benzyl-1H-imidazol-5-yl)(2, 3-dimethyl phenyl) methanol) and impurity C (4-[(2,3-dimethylcyclohexyl)methyl]-1H-imidazole). Also disclosed are processes for recrystallising detomidine hydrochloride monohydrate from commercially available anhydrous detomidine hydrochloride in water, pharmaceutical compositions comprising detomidine hydrochloride in purified form for use as an analgesic in methods of treating human subjects, a process for validating a batch of detomidine hydrochloride drug substance by determining the content of impurities iso-detomidine and iso- impurity A by HPLC, as well as XRPD, DSC and TGA data of crystalline detomidine free base.