Antonella Risoli

Application of a classical least-squares regression method to the assay of 1,4-dihydropyridine antihypertensives and their photoproducts.

A multicomponent UV spectrophotometric method using a classical least-squares (CLS) algorithm has been developed for the quantitative determination of 1,4-dihydropyridine (DHP) calcium antagonists and respective photoproducts. The procedure was optimized by defining a fractionation scheme for selecting the more useful wavelength ranges to be used in the calibration model. The method is potentially able to be extended to the other drugs of the same family. The recovery values from synthetic mixtures and commercial formulations were verified to be 99.09 and 97.85% for drug parents and degradation products, respectively. The sensitivity for the photoproducts determination was found to be below 0.8%. The results obtained from laboratory mixtures and commercial formulations were compared with those provided by UV derivative spectrophotometry.

COMPARATIVE EVALUATION OF ANALYTICAL METHODS FOR SIMULTANEOUS DETERMINATION OF NISOLDIPINE AND ITS PHOTODEGRADATION PRODUCTS

ABSTRACT Simultaneous determination of Nisoldipine and two photolytic products in pharmaceutical preparations and raw material was performed by two spectrophotometric methods, utilizing a derivative procedure and a multivariate analysis based on classical least square algorithm. In order to improve the prediction ability of CLS analysis, a selection procedure of the useful wavelengths has been performed. Both methods were compared with a conventional gas chromatographic method. The recovery values were estimated to be within 96 and 106% and RSD values below 5%. The LOD for both photoproducts was 1%.