Dipyridamole EP Impurity E Catalogue S330655 CAS 2365420-11-5 M.W 504.63 M.F C24H40N8O4 Specifications FAQs 2,4-Di[di(2-hydroxyethyl)amino]-6,8-di(piperidin-1-yl)-pyrimido[5,4-d]pyrimidine