Azelnidipine

A simple, accurate, and reliable high-performance thin-layer chromatographic technique has been developed and validated for the simultaneous quantitation of azelnidipine and chlorthalidone in bulk and synthetic mixtures.

The procedure was carried out using a precoated silica gel 60 F254 TLC plate with a mobile phase of chloroform, ethyl acetate, and methanol in the ratio of 6.5:3.5:0.6 (by volume). Thin-layer chromatographic densitometry at 240nm was used to quantify medicines chromatographically.

Over concentration ranges of 250.0 to 1000.0ng/band for chlorthalidone and 160.0 to 640.0ng/band for azelnidipine, the high-performance thin-layer chromatography technique was quantitated. This technique produced a tight and well-resolved band at retention factors of 0.67±0.02 and 0.24±0.02 for azelnidipine and chlorthalidone, respectively. Data from a linear regression study calibrating this method revealed a strong linear correlation between the two approaches, with regression coefficients of r2>0.99 for both. According to The International Conference for Harmonization of Technical Requirements for Pharmaceuticals for Human Use requirements, the procedures were validated for precision, robustness, accuracy, and specificity.

The developed method was also used to simultaneously estimate azelnidipine and chlorthalidone in a synthetic mixture. The results were found to be in exemplary % assay with label claims.

Photo-exposure has a crucial effect on the natures of photosensitive pharmaceuticals in addition to their contents in medicines through the photodegradation. Generated photoproducts might be more bioactive and contribute to the expression of adverse side effects. This study aimed to clarify the photochemical behavior of medicines of azelnidipine, which is a member of dihydropyridine antihypertensive drugs, by the evaluation of its photostability and the determination of chemical structures of generated photoproducts. Calblock® tablets and its altered forms (powders and suspensions) were UV-irradiated by a black light. Residual amounts of active pharmaceutical ingredients (APIs) were monitored by high-performance liquid chromatography. The chemical structures of two photoproducts were determined by electrospray ionization tandem mass spectrometry. API of Calblock® tablets was photodegraded with the generation of several photoproducts. Its photodegradability was more significant when Calblock® tablets were crushed or suspended. Structural determination revealed that two photoproducts were benzophenone and a pyridine derivative. It was speculated that these photoproducts were generated by the elimination of diphenyl methylene radical and additional chemical reaction including oxidation and hydrolysis. Azelnidipine was photosensitive and its photodegradation in Calblock® tablets was promoted by the change of the dosage form. This difference might be derived from the light emission efficiency. This study suggests that API contents of Calblock® tablets might decrease when tablets or its altered forms are exposed to sunlight irradiation with the generation of benzophenone, which is a toxicological potent.