1984 Volume 104 Issue 11 Pages 1191-1197
Photodecomposition of dipyridamol (I) on thin layer chromatography (TLC) and in org. solvents was studied. It was found that photodecomposition product (II) was yielded by oxidation of piperidine ring moiety of I, and the photolysis of I in org. solvents were pseudo first order kinetics. These reactions were shown to be inhibited by the addition of pyrazolone derivatives that gave the charge transfer complex of I, which had a stabilizing effect in org. solvents. It was comfirmed that the charge transfer complex between I and pyrazolone derivatives were composed of 1 : 1 molar ratio. Further, the stability of tablets of I was studied by aging in a room (at room temp., in room light). No significant decrease of I contents after aging for five years in a room was observed, and neither high performance liquid chromatography nor TLC chromatograms showed decomposition products.
