Brimonidine tartrate70359-46-5100 % similar Brimonidine59803-98-475 % similar Varenicline tartrate375815-87-538 % similar Tizanidine51322-75-932 % similar 6-Amino-5-bromoquinoxaline50358-63-931 % similar Tizanidine hydrochloride64461-82-131 % similar