A rapid technique to evaluate the oxidative stability of a model drug

Effect of Oxygen and Water on the Stability of Imipenem and Cilastatin Sodium for Injection

The study aimed to investigate the factors affecting the stability of imipenem and cilastatin sodium for injection (IMI/CIL) to improve the quality and stability in IMI/CIL preparation. In this study, the effects of headspace oxygen (HO), water content, particle shape, and particle size on the stability of IMI/CIL were investigated. IMI/CIL was purged with air, premixed oxygen/nitrogen gas (5%/95%), or high-purity nitrogen (99.999%) at 20, 5, or 2% oxygen levels to prepare IMI/CIL with different HO levels. IMI/CIL was stored at 30, 45, and 75% relative humidity for 30 days to prepare IMI/CIL with different water contents. High-performance liquid chromatography method was used for analysis. The results showed that oxygen, water, particle shape, and particle size had significant effects on the stability of IMI/CIL, and free water content is a better predictor of the safety and stability of imipenem and cilastatin sodium than the total water content. The optimization scheme of the above parameters is proposed, which significantly improves the stability of IMI/CIL. This study led to a better understanding of the degradation mechanism of imipenem and cilastatin sodium, and could provide a reference for the selection and control of IMI/CIL process conditions. This study would contribute to the development of IMI/CIL with improved stability.

Oxidation of Drugs during Drug Product Development: Problems and Solutions

Oxidation is the second most common degradation pathway for pharmaceuticals, after hydrolysis. However, in contrast to hydrolysis, oxidation is mechanistically more complex and produces a wider range of degradation products; oxidation is thus harder to control. The propensity of a drug towards oxidation is established during forced degradation studies. However, a more realistic insight into degradation in the solid state can be achieved with accelerated studies of mixtures of drugs and excipients, as the excipients are the most common sources of impurities that have the potential to initiate oxidation of a solid drug product. Based on the results of these studies, critical parameters can be identified and appropriate measures can be taken to avoid the problems that oxidation poses to the quality of a drug product. This article reviews the most common types of oxidation mechanisms, possible sources of reactive oxygen species, and how to minimize the oxidation of a solid drug product based on a well-planned accelerated study.

Understanding the physicochemical properties and degradation kinetics of nicotinamide riboside, a promising vitamin B3nutritional supplement

Nicotinamide riboside (NR), a newly recognised form of vitamin B₃ and a precursor to nicotinamide adenine dinucleotide (NAD⁺), has been demonstrated to show therapeutic potential and the possibility of becoming a drug compound in addition to its proven role in rejuvenating ageing cells in mice. However, current literature is devoid of information relating to the physicochemical characterisation of NR and its respective impact upon formulation and final product processing. Here we report physicochemical properties of NR including pKa, log P, solubility, melting point, degradation mechanics, and kinetics, with a special focus on its stability under thermal and physiologically relevant conditions. A simple and rapid HPLC method confirms a base-catalysed hydrolysis degradation of NRCl to nicotinamide and sugar in simulated gastrointestinal (GI) fluids. Given the antagonising effect of nicotinamide against NR, the presented data have a profound impact on how NRCl should be handled both during formulation and storage to prevent formation and to limit accumulation of nicotinamide. The innovative combinatorial use of ¹H NMR and Differential Scanning Calorimetry (DSC) was employed to investigate thermal events during NR melting. NRCl degrades upon melting and in solution undergoes hydrolysis in a buffer and in simulated intestinal environments. The results suggest that a proper and evidence-based formulation of NRCl is vital to enable further investigation and clinical analysis of this promising and novel nutrient. Any formulation would need to promote the stability of NRCl and protect it from hostile environments to prevent the accumulation of a potentially antagonistic degradation product. With the current work, we have filled a niche but vital gap in NR literature and the data presented may prove useful in furthering the understanding, specifically the formulation and processing of NRCl.

A mathematical model for calculating the shelf life of ascorbic acid solution under given conditions

The objective of this paper is to calculate the shelf life of ascorbic acid solution under given conditions by using a mathematical model. An antioxidant, sodium metabisulfite, was added to the ascorbic acid solution. The kinetic parameters of the degradation reaction of ascorbic acid and sodium metabisulfite, were investigated, respectively, and then a mathematical model was developed. According to the mathematical model, the calculated shelf lives of ascorbic acid solution were 783, 835, 873, and 885 days for specifications 2, 5, 10, and 20 mL, respectively. The results showed that the obtained mathematical model can be used to calculate the shelf life of ascorbic acid solution under given conditions.