Dipyridamole is used as drug for the treatment to inhibits blood clot formation and causes blood vessel dilation when given at high doses over a short time by inhibiting the phosphodiesterase enzymes that normally break down cAMP by increasing cellular cAMP levels and blocking the platelet aggregation response to ADP and cGMP. Presence of higher level of related substances or impurities may have harmful effect on body, hence needed to be identified, synthesised &characterised for safer use of the medicine. During process optimization of Dipyridamole drug, impurities were observed. These related substances or impurities were synthesised, characterized and proposed structures we reconfirmed by chemical synthesis. Dipyridamole impurities containing pyrimido-pyrimidine have been synthesized by the reaction of 2,4,6,8-tetrachloropyrimido[5,4-d] pyrimidine with sequential nucleophilic substitutions of piperidine, diethanolamine and ethanolamine in the pattern of C-4, C-8, C-2 and C-6 respectively3 . Which have been characterized by using LCMS, 1H NMR and HPLC analysis.
