Varenicline Tartrate: C~13~H~13~N~3~ C~4~H~6~O~6~. Mw: 361.35. (1) 6,10-Methano-6H-pyrazino[2,3-h][3]benzazepine, 7,8,9,10-tetrahydro-, (2R,3R)-2,3-dihydroxybutanedioate (1:1); (2) 7,8,9,10-Tetrahydro-6,10-methano-6H-pyrazino[2,3-h][3]benzazepine (2R,3R)-2,3-dihydroxybutanedioate. CAS-375815-87-5; CAS-249296-44-4 (varenicline)(2003).