Comprehensive degradation profiling and influence of different oxidizing reagents on tinoridine hydrochloride: Structural characterization of its degradation products using HPLC and HRMS

RATIONALE

Stress testing on tinoridine hydrochloride was carried out using a multidimensional approach. This included different conditions: hydrolytic (acidic, alkaline, and neutral conditions), different oxidative reagents, thermal, photolytic conditions, HPLC method development, and structural elucidation using high-resolution mass spectrometry (HRMS). It provides the basis for quality control of tinoridine hydrochloride and its derivatives during storage conditions.

METHODS

The tinoridine hydrochloride was subjected to a variety of stress conditions. A gradient reversed-phase HPLC method was developed on a X-Bridge C18 column (250 × 4.6 mm, 5 μm) to separate all the degradation products (DPs). HRMS studies have been performed to elucidate the structure of DPs.

RESULTS

HPLC-PDA study revealed that significant degradation products were formed in hydrolytic, AIBN (radical initiator at 40°C), thermal, and solid-state photolight stress conditions, but the drug was stable under oxidative conditions (H₂ O_2, Fenton's reagent at room temperature and ferric chloride at 40°C). The structure of degradation products was elucidated, and mechanism of their formation was explained.

CONCLUSION

Stress study was successfully carried out as per ICH Q1A (R2) guideline on tinoridine hydrochloride. A total of six new degradation products were characterized, DP 2 and DP 6 formed by the effect of co-solvent. This study provides the scientifically sound basis for quality monitoring and storage conditions of tinoridine hydrochloride.

A Tribute to Professor Saranjit Singh - A Critical Thinker, Innovator, Mentor, and Educator

This commentary presents contributions and accomplishments of Professor Saranjit Singh, National Institute of Pharmaceutical Education and Research (NIPER), SAS Nagar, India, to pharmaceutical research and education. Prof. Singh completed his successful tenure in October 2021. Over his 40+ years of illustrious academic career, he trained 147 Masters and 15 PhD students in the fields of drug stability testing, degradation chemistry, impurity and metabolite characterization, and advanced analytical technologies. He has published ∼250 research articles, reviews, editorials, patent, book, and book chapters, and received numerous awards, including the Professor M.L. Khorana Memorial Lecture Award from the Indian Pharmaceutical Association (IPA) and the Outstanding Analyst and Eminent Analyst awards from the Indian Drug Manufacturers' Association (IDMA). This commentary highlights Prof. Singh's inspiring personal and renowned professional journey, including early life, education, career, accomplishments, as well as his services to academia, industry, and regulatory. By sharing the contributions and accomplishments of Prof. Singh, we strongly believe that his story will inspire the next generation of scientists to continue his legacy to advance the field.

Characterization of stress degradation products of nintedanib by UPLC, UHPLC-Q-TOF/MS/MS and NMR: Evidence of a degradation product with a structure alert for mutagenicity

Nintedanib is an anti-cancer drug used for the treatment of idiopathic pulmonary fibrosis and non-small cell lung cancer. The purpose of this study was to explore its degradation chemistry under various stress conditions recommended in ICH guidelines Q1A R(2). The drug was subjected to hydrolytic, photolytic, thermal and oxidative (H₂O₂, AIBN, FeCl₃ and FeSO₄) stress conditions. The degradation products formed in stressed solutions were successfully separated on an ACQUITY UPLC CSH C18 (2.1 × 100 mm, 1.7 μm) column, using a gradient UPLC-PDA method, developed with acetonitrile:methanol (90:10) and 0.1 % formic acid (pH 3.0) as the mobile phase. The drug proved to be labile to acidic, neutral and alkaline hydrolytic, and H₂O₂/AIBN oxidative conditions. It was stable to photolytic and thermal stress conditions, and even in oxidative reaction solutions containing FeCl₃ or FeSO₄. Additionally, the drug exhibited instability when its powder with added sodium bicarbonate was stored at 40 °C/75 % RH for 3 months. In total, nine degradation products (DPs 1-9) were formed. To characterize them, a comprehensive mass fragmentation pathway of the drug was first established using UHPLC-Q-TOF/MS/MS data. Similarly, the mass studies were then carried out on the stressed samples using the developed UPLC method. All the degradation products were primarily characterized through comparison of their mass fragmentation profiles with that of the drug. To confirm the structure in one case (DP 3), additional nuclear magnetic resonance (NMR) studies were carried out on the isolated product. Subsequently, mechanisms for their formation were laid down. A significant finding was the formation of a degradation product upon acid hydrolysis having a free aromatic amine moiety, which is considered as a structural alert for mutagenicity. Furthermore, the physicochemical and ADMET properties of the drug and its degradation products were predicted using ADMET predictor™ software.

Insights into the degradation chemistry of tazarotene, a third generation acetylenic retinoid: LC-HRMS (Orbitrap), LC-MSn and NMR characterization of its degradation products, and prediction of their physicochemical and ADMET properties

Tazarotene is a prodrug that belongs to the acetylenic class of retinoids. The drug was subjected to hydrolytic, oxidative and photolytic stress testing to establish its comprehensive degradation chemistry. The drug proved to be unstable under acidic and basic hydrolytic conditions, yielding tazarotenic acid, which is a known major degradation product (DP) and an active metabolite. Additionally, two DPs each were generated upon interaction of drug and tazarotenic acid with HCl, used as an acid stressor. These were experimentally proven as pseudo DPs, as they did not originate when H₂SO₄ was employed as the stressor. The drug was also unstable under oxidative and photolytic conditions, yielding six DPs. All the products were separated on reversed phase (C18) column, using mobile phase composed of 10 mM ammonium formate (pH 3.5) and acetonitrile, which was run in a gradient mode. The separated DPs were subjected to LC-HRMS and LC-MSⁿ studies for their initial characterization. Seven hydrolytic and oxidative DPs that could be isolated using semi-preparative column were subjected to extensive 1D (¹H, ¹³C and DEPT-135) and 2D (COSY, HSQC and HMBC) NMR studies to confirm their structures. In total, five novel DPs were characterized, apart from two previously reported DPs, viz., tazarotenic acid and tazarotene sulfoxide, and four additional pseudo DPs. The complete degradation pathway of the drug was established. In silico ADMET properties of the drug and its DPs were evaluated using ADMET Predictor™.

In silico approach in reveal traditional medicine plants pharmacological material basis

In recent years, studies of traditional medicinal plants have gradually increased worldwide because the natural sources and variety of such plants allow them to complement modern pharmacological approaches. As computer technology has developed, in silico approaches such as virtual screening and network analysis have been widely utilized in efforts to elucidate the pharmacological basis of the functions of traditional medicinal plants. In the process of new drug discovery, the application of virtual screening and network pharmacology can enrich active compounds among the candidates and adequately indicate the mechanism of action of medicinal plants, reducing the cost and increasing the efficiency of the whole procedure. In this review, we first provide a detailed research routine for examining traditional medicinal plants by in silico techniques and elaborate on their theoretical principles. We also survey common databases, software programs and website tools that can be used for virtual screening and pharmacological network construction. Furthermore, we conclude with a simple example that illustrates the whole methodology, and we present perspectives on the development and application of this in silico methodology to reveal the pharmacological basis of the effects of traditional medicinal plants.

Application of the UHPLC method for separation and characterization of major photolytic degradation products of trazodone by LC-MS and NMR

This article is about the characterization of degradation products of trazodone which is used in the treatment of depression.