(4R,6S)-rel-4-(Ethylamino)-5,6-dihydro-6-methyl-4H-thieno[2,3-b]thiopyran-2-sulfonamide 7,7-Dioxide Monohydrochloride; cis-4-(Ethylamino)-5,6-dihydro-6- methyl-4H-thieno[2,3-b]thiopyran-2-sulfonamide 7,7-Dioxide Monohydrochloride; Dorzolamide Related Compound B USP