Synonyms: 6H-Purine-6-thione, 1,2,3,9-tetrahydro-, hydrate (1:1), 6H-Purine-6-thione, 1,7-dihydro-, monohydrate (9CI), Purine-6-thiol, monohydrate (8CI), 6-Mercaptopurine monohydrate, 9H-Purine-6-thiol hydrate, Mercaptopurine hydrate, 7H-Purine-6-thiol hydrate, Azathioprine Impurity B as Monohydrate