Understanding the Stress Testing Characteristics of Apixaban, Structural Elucidation of a Novel Degradation Impurity, and Stability-Indicating Method Development for Quantification of Related Substances

BACKGROUND

People who have non-valvular atrial fibrillation may benefit from taking a new oral anticoagulant called apixaban, which has recently been given the green light by the U.S. Food and Drug Administration. During stress testing, apixaban was found to have a high degree of degradability when subjected to both acidic and basic conditions, and one significant unknown impurity was observed in addition to the major known impurities.

OBJECTIVE

Our aim is the isolation and characterization of degradation product observed in stress/forced degradation studies, and also the development of a single HPLC method that is both reliable and accurate for quantifying all 10 related impurities of apixaban.

METHODS

Preparative HPLC was used to isolate the degradation product, and 1H NMR, 13C NMR, and MS were used to elucidate the structure of the product. Additionally, a single reverse-phase (RP) HPLC method was developed for quantification of all related impurities of apixaban.

RESULTS

Based on the spectral characterization data, the identified unknown degradation impurity was found to be a pH-independent hydrolysis degradation impurity of apixaban. The developed method is specific, linear, accurate, robust, and rugged.

CONCLUSION

The isolated and characterized impurities were the same as those found during stress testing. The developed method has been validated for its intended purpose in accordance with the regulatory requirements that were outlined.

HIGHLIGHTS

The unknown impurity is a new apixaban degradation impurity that helps us understand its toxicity. The scientific community will benefit from the developed analytical method information as it relates to understanding drug product impurity profiling.

Investigating Betrixaban Maleate drug degradation profiles, isolation and characterization of unknown degradation products by mass-triggered preparative HPLC, HRMS, and NMR

Betrixaban Maleate, a novel oral, once-daily factor Xa inhibitor drug substance, was subjected to stress testing under a wide range of degradation conditions, including acidic hydrolysis, alkaline hydrolysis, oxidative, thermal, and photolytic, to determine its inherent stability. The drug was biodegradable in acidic and alkaline environments, and three new degradation products were identified. Two degraded products are formed in an acidic environment, while the third is in alkaline conditions. The three degradants were identified using UPLC-ESI/MS and isolated using mass-triggered preparative HPLC, and their structures were unambiguously elucidated using HRMS and 2D NMR techniques. Based on spectral and chromatographic data, it was firmly proven that these distinct degradation products were the betrixaban chemical's hydrolysis components. The formation of the degradants has been hypothesized through several possible mechanisms.

Identification, isolation, and structural characterization of novel forced degradation products of apixaban using advanced analytical techniques

The current research explains the stress degradation behavior of Apixaban, which is an anticoagulant or blood thinner. The degradation was conducted using hydrolytic, oxidative, thermal, and photolytic conditions. Apixaban is relatively stable in oxidative, thermal, and photolytic conditions; however, considerable degradation was observed in acid and base hydrolysis. Degradation products were identified using ultra-high performance liquid chromatography-mass spectrometry, isolated using semi-preparative high-performance liquid chromatography, and structural characterization by high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. A total of five degradation products were identified and isolated in acid and base degradation. Degradation products 1, 2 & 3 were observed in acid conditions, whereas in base conditions, along with those three, two more degradation products 4, and 5 were identified. The representative thing was that among the 5 degradation products, two sets of positional isomers 1, 4, & 2, 5 were observed; out of which 2 & 5 are novel. The remaining degradation products 1, 3, and 4 are already reported tentatively using a single analytical technique of mass analysis without any evidence from nuclear magnetic resonance spectroscopy. Hence, the present study focused on using high-resolution mass, and nuclear magnetic resonance spectroscopy data for concrete confirmation of structures for degradation products. This article is protected by copyright. All rights reserved.

Unequal Behaviour between Hydrolysable Functions of Nirmatrelvir under Stress Conditions: Structural and Theoretical Approaches in Support of Preformulation Studies

Nirmatrelvir is an antiviral drug approved for the treatment of COVID-19. The available dosage form consists of tablets marketed under the brand name PAXLOVID^®. Although knowledge of nirmatrelvir’s intrinsic stability may be useful for any potential development of other pharmaceutical forms, no data regarding this matter is available to date. Preliminary forced degradation studies have shown that the molecule is stable under oxidative and photolytic conditions, while hydrolytic conditions, both acidic and basic, have proven deleterious. Indeed, the molecule presents a priori several functions that can undergo hydrolysis, i.e., three amide moieties and a nitrile function. However, considering the degradation products formed under forced conditions and which were detected and identified by LC-UV-HRMSⁿ, the hydrolysis process leading to their formation is selective since it involved only 2 of the 4 hydrolysable functions of the molecule. Ab initio studies based on density functional theory (DFT) have helped better understand these reactivity differences in aqueous media. Some hydrolyzable functions of nirmatrelvir differ from others in terms of electrostatic potential and Fukui functions, and this seems to correlate with the forced degradation outcomes.

The Development of a Liquid Chromatography High-Resolution Mass Spectrometric Method for Apixaban Quantification in Dried Plasma Spots in Parallel Reaction Monitoring Mode

This work aimed at developing and validating a rapid, sensitive, and robust method of liquid chromatography with high-resolution mass spectrometry (LC–HRMS) in parallel reaction monitoring (PRM) mode for apixaban quantification in dried plasma spots (DPSs) with a simple extraction procedure. A 25 µL sample of human plasma was placed onto Whatman 903 Protein Saver Cards and allowed to dry; 3.2 mm diameter disks were cut out from DPSs using a puncher, and 100 µL of a working internal standard solution was added to each sample. After this, they were vortexed on a shaker for 15 min at 800 rpm and 40 °C and quick centrifugation (10,000× g, 10 s), and then the extracts were transferred into a 300 µL vial for LC–HRMS. Data were acquired in PRM mode via detection of all target product ions with 10 ppm tolerance. Total analysis time was 5 min. The LC–HRMS method was validated for the 10–400 ng/mL range with R2 > 0.99. Within this range, intra- and interday variability of precision and accuracy was <10%, and recovery was 69.7–85.1%. Apixaban was stable after brief storage at room temperature, and at 4 °C for up to a month. The method development and validation results proved that this LC–HRMS assay of apixaban in DPSs is selective and robust.

Ruxolitinib photodegradation mechanisms by theoretical and experimental chemistry

Ruxolitinib is a Janus Kinase inhibitor currently approved for the treatment of myelofibrosis. It is also a promising drug for the treatment of skin and infectious diseases. In terms of pharmaceutical stability, although ruxolitinib has been established as being sensitive to light, no data on photodegradation processes are available to date, while these may be useful for quality risk management and any potential development of other pharmaceutical forms for other routes of administration. One way to partially fill this gap was to carry out a study that combines a consistent determination of the most sensitive sites of the molecule to photolysis through theoretical calculations based on functional density, with the identification of the main photodegradation products obtained after forced degradation. This integrated approach has shown converging results describing the mechanisms based on photo-oxidation that can lead to the opening of the pyrrole ring. Having access to the structure of the degradation products and intermediates then made it possible to carry out an in silico evaluation of their potential mutagenicity and it appears that some of them feature alert structures.

Photodegradation of aqueous argatroban investigated by LC/MSn: Photoproducts, transformation processes and potential implications

Argatroban (ARGA), used as intravenous anticoagulant drug, has been reported to photodegrade under light exposure, requiring specific precautions at handling, storage and administration. Thus, for the first time, aqueous ARGA photodegradation under aerobic conditions has been described in terms of photoproducts, phototransformation processes and potential implications. ARGA significant photoproducts were successfully separated and characterized by gradient reversed-phase liquid chromatography coupled with high-resolution multistage mass spectrometry (LC/HR-MSⁿ). Hitherto still not available in literature, ARGA in-depth fragmentation study was conducted so as to thoroughly sort out the main mechanisms specific to the molecule and therefore, to propose a fragmentation pattern relevant to the identification of ARGA related substances. Thereafter, in view of the structural characteristics of the photoproducts formed, ARGA photodegradation pathways could be worked out, showing that whether by direct photolysis or through photosensitization, the methyltetrahydroquinoline nitrogen and that of guanidine group would be mainly involved in photolysis initiation reactions, through one-electron oxidation along with proton loss. Desulfonation, cyclisation affording compounds of diazinane type, and/or rearrangements with transfer of the methyltetrahydroquinoline group toward the guanidine function were observed accordingly. Having a good insight into ARGA photodegradation pathways allows for consistent measures in view of mitigating or avoiding the drug decay and the related potential effects.

Stability-indicating spectrophotometric methods for determination of the anticoagulant drug apixaban in the presence of its hydrolytic degradation product

Apixaban (a novel anticoagulant agent) was subjected to a stress stability study including acid, alkali, oxidative, photolytic, and thermal degradation. The drug was found to be only liable to acidic and alkaline hydrolysis. The degradation product was then isolated and identified by IR and GC-mass spectrometry. Four spectrophotometric methods, namely; first derivative (D(1)), derivative ratio (DR), ratio difference (RD) and mean centering of ratio spectra (MCR), have been suggested for the determination of apixaban in presence of its hydrolytic degradation product. The proposed methods do not require any preliminary separation step. The accuracy, precision and linearity ranges of the proposed methods were determined, and the methods were validated as per ICH guidelines and the specificity was assessed by analyzing synthetic mixtures containing different percentages of the degradation product with the drug. The developed methods were successfully applied for the determination of apixaban in bulk powder and its tablet dosage form.

Fe3O4@PEG-SO3H rod-like morphology along with the spherical nanoparticles: novel green nanocomposite design, preparation, characterization and catalytic application

A new heterogeneous nanocatalyst was successfully synthesized, completely characterized and efficiently applied in the synthesis of dihydropyrimidines.

Phototransformation patterns of the antiplatelet drug tirofiban in aqueous solution, relevant to drug delivery and storage

Tirofiban in aqueous solution mostly photodegrades through photosensitized oxidation reactions and the photoproducts formed are not structurally alerting for genotoxicity.

Density functional theory and liquid chromatography-multistage mass spectrometry to characterize raltitrexed photo-degradation mechanisms

The structure of raltitrexed photoproducts was elucidated by LC-ESI-HR-MSⁿ. Photodegradation pathways are proposed, using DFT approach to support assumptions. Ralitrexed photodegrades as per photosensitization mechanisms.