Studies of the stability of cardiocyclide in substance and a solid dosage form by HPLC

The aim of the present work was to assess the specificity of an HPLC method developed for analysis of the purity of cardiocyclide within the framework of a study of the stability of cardiocyclide as substance and as a solid dosage formulation. Studies were performed using a liquid chromatograph with a spectrophotometric detector at a wavelength of 210 nm with a linear gradient using two mobile phases (MP): 0.02 M phosphate buffer pH 3.3 (MP A) and a mixture of acetonitrile, methanol, and 0.02 Mphosphate buffer pH 3.3 (50:50:20) (MP B). The gradient regime was: MP A/MP B from 35:65 to 0:100 over 15 min. The chromatography column was of size 150 × 4.6 mm, the sorbent was Luna C18(2), particle size 5 μm. This HPLC method allowed separation of cardiocyclide and its most likely contaminants - the intermediate products of the last two synthesis stages, some of which are also products of hydrolysis, as well as a series of unidentified contaminants in substance and the solid dosage formulation as released. The method also allows other contaminants to be detected, i.e., cardiocyclide degradation products forming on exposure to aggressive environmental factors. The method thus yields data on the stability of the substance and medicinal formulation both at the preparation stages and after incorrect storage.