(2-(((4S,6S)-6-methyl-7,7-dioxido-2-sulfamoyl-5,6-dihydro-4H-thieno[2,3-b]thiopyran-4-yl)amino)ethyl)boronic acid hydrochloride,(2-(((4S,6S)-6-methyl-7,7-dioxido-2-sulfamoyl-5,6-dihydro-4H-thieno[2,3-b]thiopyran-4-yl)amino)ethyl)boronic acid hydrochloride,Dorzolamide Impurity