Alogliptin Impurity A Catalogue A164508 CAS 1638544-63-4 M.W 339.39 M.F C18H21N5O2 Specifications FAQs 4-[[6-[(3R)-3-Amino-1-piperidinyl]-3,4-dihydro-3-methyl-2,4-dioxo-1(2H)-pyrimidinyl]methyl] benzonitrile