Abstract：
Dihydropyridine drugs are well known as photodegradable pharmaceuticals. Herein, we evaluate the photostability of felodipine (FL) medicine (Splendil® (SPL) tablets) and its altered forms (powders and suspensions). FL is a type of dihydropyridine drug, but its photochemical behavior is unknown. FL contents after ultraviolet light (UV) irradiation for 24 h were monitored using high-performance liquid chromatography (HPLC). Values of the residual amounts of FL in UV-irradiated SPL powders and suspensions were 32.76 ± 4.88% and 0.79 ± 0.74%, respectively, with the generation of two photoproducts (FL photoproduct 1 and 2). To identify the chemical structures of these photoproducts, electrospray ionization liquid chromatography mass spectrometry (ESI-LC/MS/MS) analysis was performed. Based on their mass-to-charge ratio values and fragment patterns, it was proposed that FL photoproduct 1 was a pyridine derivative and FL photoproduct 2 was an FL dimer. Interestingly, generation rates of FL photoproduct 1 and 2 were dependent on the presence of the aqueous media. The photodimerization of FL was induced in UV-irradiated SPL suspensions. This is the first report evaluating the photostability of SPL tablets and its altered forms and estimating FL photoproducts induced by UV irradiation in the formulation of SPL.
摘要：
二氢吡啶类药物是众所周知的光降解药物。在这里，我们评估了非洛地平（FL）药物（Splendil®（SPL）片剂）及其改变形式（粉末和悬浮液）的光稳定性。FL是一种二氢吡啶类药物，但是它的光化学行为是未知的。使用高效液相色谱（HPLC）监测紫外线（UV）照射24小时后的FL含量。紫外线照射的SPL粉末和悬浮液中FL的残留量为32.76±4.88%和0.79±0.74%，分别,随着两种光产物(FL光产物1和2)的产生。为了确定这些光产品的化学结构，进行电喷雾电离液相色谱质谱(ESI-LC/MS/MS)分析。根据它们的质荷比值和碎片模式，提出FL光产物1是吡啶衍生物,并且FL光产物2是FL二聚体。有趣的是,FL光产物1和2的生成速率取决于水性介质的存在。在紫外线照射的SPL悬浮液中诱导FL的光二聚化。这是第一份报告，评估了SPL片剂及其改变形式的光稳定性，并评估了SPL制剂中紫外线照射诱导的FL光产物。
