Alogliptin N-Desmethyl Impurity Catalogue A164501 M.W 325.37 M.F C17H19N5O2 Specifications FAQs 2-[[6-[(3R)-3-Amino-1-piperidinyl]-3,4-dihydro-2,4-dioxo-1(2H)-pyrimidinyl] methyl]benzonitrile