Photodegradation of inclusion complexes of isradipine with methyl-beta-cyclodextrin.

The paper presents results of the studies on photochemical decomposition of isradipine (IS) and its liquid inclusion complexes with methyl-beta-cyclodextrin (M-betaCD). The process of photodegradation was assessed by the methods of UV spectrophotometry, HPLC (reverse-phase) and HPTLC (normal phase) chromatographic methods. The process of photodegradation of IS was analysed in the conditions of version I of the document of International Chemical Harmonization (ICH)-HBO-200 lamp. Quantitative evaluation of the photochemical decomposition was performed on the basis of the calculated photodegradation rate constant (k), half-life period (t0.5) and time of degradation of 10% of the compound (t0.1). Formation of inclusion complexes of IS with M-betaCD was proved to increase twice the photostability of the drug. The analytical methods used were subjected to a validation procedure in which the limits of detectability and determinability as well as specificity, precision and sensitivity of the method were determined.