Gas chromatography mass spectrometry study of isosorbide 5-mononitrate stability

The stability of isosorbide 5-mononitrate (5-ISMN) was investigated at 40 degrees C under dry and wet air (75% relative humidity). The degradation products were identified and quantified by means of capillary GC-MS preceded by drying and silylation of the samples. The only degradation products identified were the two diastereoisomers of isosorbide. From the initial slope of degradation curves the maximal degradation rates were estimated to be 0.17 and 2.44% year(-1) under dry and wet conditions, respectively