3-Hydroxy-8-azaxanthine , its CAS NO. is 42028-33-1, the synonyms are 4-Hydroxy-3H-v-triazolo(4,5-d)pyrimidine-5,7(4H,6H)-dione ; 3H-v-Triazolo(4,5-d)pyrimidine-5,7(4H,6H)-dione, 4-hydroxy- .