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Liu Y, Pickard FC, Sluggett GW, Mustakis IG. Robust fragment-based method of calculating hydrogen atom transfer activation barrier in complex molecules. Phys Chem Chem Phys 2024; 26:1869-1880. [PMID: 38175161 DOI: 10.1039/d3cp05028a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Dynamic processes driven by non-covalent interactions (NCI), such as conformational exchange, molecular binding, and solvation, can strongly influence the rate constants of reactions with low activation barriers, especially at low temperatures. Examples of this may include hydrogen-atom-transfer (HAT) reactions involved in the oxidative stress of an active pharmaceutical ingredient (API). Here, we develop an automated workflow to generate HAT transition-state (TS) geometries for complex and flexible APIs and then systematically evaluate the influences of NCI on the free activation energies, based on the multi-conformational transition-state theory (MC-TST) within the framework of a multi-step reaction path. The two APIs studied: fesoterodine and imipramine, display considerable conformational complexity and have multiple ways of forming hydrogen bonds with the abstracting radical-a hydroxymethyl peroxyl radical. Our results underscore the significance of considering conformational exchange and multiple activation pathways in activation calculations. We also show that structural elements and NCIs outside the reaction site minimally influence TS core geometry and covalent activation barrier, although they more strongly affect reactant binding and consequently the overall activation barrier. We further propose a robust and economical fragment-based method to obtain overall activation barriers, by combining the covalent activation barrier calculated for a small molecular fragment with the binding free energy calculated for the whole molecule.
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Affiliation(s)
- Yizhou Liu
- Analytical Research and Development, Pfizer Research and Development, 445 Eastern Point Road, Groton, CT 06340, USA.
| | - Frank C Pickard
- Pharmaceutical Sciences, Pfizer Research & Development, Groton, CT 06340, USA
- Medicine Design, Pfizer Research & Development, Cambridge, MA 02139, USA
| | - Gregory W Sluggett
- Analytical Research and Development, Pfizer Research and Development, 445 Eastern Point Road, Groton, CT 06340, USA.
| | - Iasson G Mustakis
- Chemical Research & Development, Pfizer Research & Development, Groton, CT 06340, USA
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2
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Zelesky T, Baertschi SW, Foti C, Allain LR, Hostyn S, Franca JR, Li Y, Marden S, Mohan S, Ultramari M, Huang Z, Adams N, Campbell JM, Jansen PJ, Kotoni D, Laue C. Pharmaceutical Forced Degradation (Stress Testing) Endpoints: A Scientific Rationale and Industry Perspective. J Pharm Sci 2023; 112:2948-2964. [PMID: 37690775 DOI: 10.1016/j.xphs.2023.09.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/01/2023] [Accepted: 09/01/2023] [Indexed: 09/12/2023]
Abstract
Forced degradation (i.e., stress testing) of small molecule drug substances and products is a critical part of the drug development process, providing insight into the intrinsic stability of a drug that is foundational to the development and validation of stability-indicating analytical methods. There is a lack of clarity in the scientific literature and regulatory guidance as to what constitutes an "appropriate" endpoint to a set of stress experiments. That is, there is no clear agreement regarding how to determine if a sample has been sufficiently stressed. Notably, it is unclear what represents a suitable justification for declaring a drug substance (DS) or drug product (DP) "stable" to a specific forced degradation condition. To address these concerns and to ensure all pharmaceutically-relevant, potential degradation pathways have been suitably evaluated, we introduce a two-endpoint classification designation supported by experimental data. These two endpoints are 1) a % total degradation target outcome (e.g., for "reactive" drugs) or, 2) a specified amount of stress, even in the absence of any degradation (e.g., for "stable" drugs). These recommended endpoints are based on a review of the scientific literature, regulatory guidance, and a forced degradation data set from ten global pharmaceutical companies. The experimental data set, derived from the Campbell et al. (2022) benchmarking study,1 provides justification for the recommendations. Herein we provide a single source reference for small molecule DS and DP forced degradation stress conditions and endpoint best practices to support regulatory submissions (e.g., marketing applications). Application of these forced degradation conditions and endpoints, as part of a well-designed, comprehensive and a sufficiently rigorous study plan that includes both the DS and DP, provides comprehensive coverage of pharmaceutically-relevant degradation and avoids unreasonably extreme stress conditions and drastic endpoint recommendations sometimes found in the literature.
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Affiliation(s)
- Todd Zelesky
- Analytical Research & Development, Pfizer Inc., Eastern Point Road, Groton, CT 06340, USA.
| | | | - Chris Foti
- Analytical Development and Operations, Gilead Sciences Inc., Foster City, California, USA.
| | | | - Steven Hostyn
- Predictive Analytics & Stability Sciences CoE, Janssen Pharmaceutica, Johnson & Johnson, Beerse, Belgium
| | | | - Yi Li
- Analytical Development and Operations, Gilead Sciences Inc., Foster City, California, USA
| | - Stacey Marden
- Advanced Drug Delivery, Pharmaceutical Sciences, R&D, AstraZeneca, Boston, MA, USA
| | - Shikhar Mohan
- Analytical Development and Operations, Gilead Sciences Inc., Foster City, California, USA
| | - Mariah Ultramari
- Spektra Soluções Científico-Regulatórias Ltda, São Paulo, Brazil
| | - Zongyun Huang
- Bristol-Myers Squibb Company, 1 Squibb Drive, New Brunswick, NJ 08901, USA
| | - Neal Adams
- Pfizer, Scientific and Laboratory Services - Analytical Sciences, Pfizer Inc., 7000 Portage Road, Kalamazoo, MI 49001, USA
| | - John M Campbell
- Analytical Development, GSK, Upper Providence, PA 19426, USA
| | - Patrick J Jansen
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN 46285, USA
| | - Dorina Kotoni
- Chemical & Analytical Development, Novartis Pharma AG, Basel, Switzerland
| | - Christian Laue
- Chemical & Pharmaceutical Development, Merck Healthcare KGaA, Darmstadt, Germany
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3
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Ossola R, Gruseck R, Houska J, Manfrin A, Vallieres M, McNeill K. Photochemical Production of Carbon Monoxide from Dissolved Organic Matter: Role of Lignin Methoxyarene Functional Groups. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:13449-13460. [PMID: 36054115 PMCID: PMC9494748 DOI: 10.1021/acs.est.2c03762] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/18/2022] [Accepted: 08/18/2022] [Indexed: 05/25/2023]
Abstract
Carbon monoxide (CO) is the second most abundant identified product of dissolved organic matter (DOM) photodegradation after CO2, but its formation mechanism remains unknown. Previous work showed that aqueous photodegradation of methoxy-substituted aromatics (ArOCH3) produces CO considerably more efficiently than aromatic carbonyls. Following on this precedent, we propose that the methoxy aromatic groups of lignin act as the C source for the photochemical formation of CO from terrestrial DOM via a two-step pathway: formal hydrolytic demethylation to methanol and methanol oxidation to CO. To test the reasonableness of this mechanism, we investigated the photochemistry of eight lignin model compounds. We first observed that initial CO production rates are positively correlated with initial substrate degradation rates only for models containing at least one ArOCH3 group, regardless of other structural features. We then confirmed that all ArOCH3-containing substrates undergo formal hydrolytic demethylation by detecting methanol and the corresponding phenolic transformation products. Finally, we showed that hydroxyl radicals, likely oxidants to initiate methanol oxidation to CO, form during irradiation of all models. This work proposes an explicit mechanism linking ubiquitous, abundant, and easily quantifiable DOM functionalities to CO photoproduction. Our results further hint that methanol may be an abundant (yet overlooked) DOM photoproduct and a likely precursor of formaldehyde, formic acid, and CO2 and that lignin photodegradation may represent a source of hydroxyl radicals.
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Affiliation(s)
- Rachele Ossola
- Department
of Environmental Systems Science, ETH Zurich, Zurich 8092, Switzerland
| | - Richard Gruseck
- Department
of Environmental Systems Science, ETH Zurich, Zurich 8092, Switzerland
| | - Joanna Houska
- Eawag
Swiss Federal Institute of Aquatic Science and Technology, Dübendorf 8600, Switzerland
- School
of Architecture, Civil, and Environmental Engineering, École Polytechnique Fédérale
de Lausanne, Lausanne 1015, Switzerland
| | - Alessandro Manfrin
- Department
of Environmental Systems Science, ETH Zurich, Zurich 8092, Switzerland
| | - Morgan Vallieres
- Department
of Environmental Systems Science, ETH Zurich, Zurich 8092, Switzerland
| | - Kristopher McNeill
- Department
of Environmental Systems Science, ETH Zurich, Zurich 8092, Switzerland
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4
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Grinberg Dana A, Wu H, Ranasinghe DS, Pickard FC, Wood GPF, Zelesky T, Sluggett GW, Mustakis J, Green WH. Kinetic Modeling of API Oxidation: (1) The AIBN/H 2O/CH 3OH Radical "Soup". Mol Pharm 2021; 18:3037-3049. [PMID: 34236207 DOI: 10.1021/acs.molpharmaceut.1c00261] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Stress testing of active pharmaceutical ingredients (API) is an important tool used to gauge chemical stability and identify potential degradation products. While different flavors of API stress testing systems have been used in experimental investigations for decades, the detailed kinetics of such systems as well as the chemical composition of prominent reactive species, specifically reactive oxygen species, are unknown. As a first step toward understanding and modeling API oxidation in stress testing, we investigated a typical radical "soup" solution an API is subject to during stress testing. Here we applied ab initio electronic structure calculations to automatically generate and refine a detailed chemical kinetics model, taking a fresh look at API oxidation. We generated a detailed kinetic model for a representative azobis(isobutyronitrile) (AIBN)/H2O/CH3OH stress-testing system with a varied cosolvent ratio (50%/50%-99.5%/0.5% vol water/methanol) for 5.0 mM AIBN and representative pH values of 4-10 at 40 °C that was stirred and open to the atmosphere. At acidic conditions, hydroxymethyl alkoxyl is the dominant alkoxyl radical, and at basic conditions, for most studied initial methanol concentrations, cyanoisopropyl alkoxyl becomes the dominant alkoxyl radical, albeit at an overall lower concentration. At acidic conditions, the levels of cyanoisopropyl peroxyl, hydroxymethyl peroxyl, and hydroperoxyl radicals are relatively high and comparable, while, at both neutral and basic pH conditions, superoxide becomes the prominent radical in the system. The present work reveals the prominent species in a common model API stress testing system at various cosolvent and pH conditions, sets the stage for an in-depth quantitative API kinetic study, and demonstrates the usage of novel software tools for automated chemical kinetic model generation and ab initio refinement.
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Affiliation(s)
- Alon Grinberg Dana
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.,Wolfson Department of Chemical Engineering, Technion, Israel Institute of Technology, Haifa 3200003, Israel
| | - Haoyang Wu
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Duminda S Ranasinghe
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Frank C Pickard
- Pfizer Global Research & Development, Groton Laboratories, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Geoffrey P F Wood
- Pfizer Global Research & Development, Groton Laboratories, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Todd Zelesky
- Pfizer Global Research & Development, Groton Laboratories, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Gregory W Sluggett
- Pfizer Global Research & Development, Groton Laboratories, Eastern Point Road, Groton, Connecticut 06340, United States
| | - Jason Mustakis
- Pfizer Global Research & Development, Groton Laboratories, Eastern Point Road, Groton, Connecticut 06340, United States
| | - William H Green
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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5
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Dhiman V, Balhara A, Singh S, Tiwari S, Gananadhamu S, Talluri MVNK. 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. J Pharm Biomed Anal 2021; 199:114037. [PMID: 33836462 DOI: 10.1016/j.jpba.2021.114037] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 03/20/2021] [Accepted: 03/22/2021] [Indexed: 12/17/2022]
Abstract
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.
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Affiliation(s)
- Vivek Dhiman
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), IDPL R&D Campus, Balanagar, Hyderabad, 500037, Telangana, India
| | - Ankit Balhara
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, 160062, Punjab, India
| | - Saranjit Singh
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, 160062, Punjab, India
| | - Shristy Tiwari
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), IDPL R&D Campus, Balanagar, Hyderabad, 500037, Telangana, India
| | - Samanthula Gananadhamu
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), IDPL R&D Campus, Balanagar, Hyderabad, 500037, Telangana, India
| | - M V N Kumar Talluri
- Department of Pharmaceutical Analysis, National Institute of Pharmaceutical Education and Research (NIPER), IDPL R&D Campus, Balanagar, Hyderabad, 500037, Telangana, India.
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6
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Nanda KK, Mozziconacci O, Small J, Allain LR, Helmy R, Wuelfing WP. Enrichment of Relevant Oxidative Degradation Products in Pharmaceuticals With Targeted Chemoselective Oxidation. J Pharm Sci 2019; 108:1466-1475. [DOI: 10.1016/j.xphs.2018.10.059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 10/07/2018] [Accepted: 10/30/2018] [Indexed: 11/30/2022]
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7
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Iron(III)-Mediated Oxidative Degradation on the Benzylic Carbon of Drug Molecules in the Absence of Initiating Peroxides. J Pharm Sci 2017; 106:1347-1354. [PMID: 28159642 DOI: 10.1016/j.xphs.2017.01.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 01/19/2017] [Accepted: 01/24/2017] [Indexed: 11/20/2022]
Abstract
Metal ions play an important role in oxidative drug degradation. One of the most ubiquitous metal ion impurities in excipients and buffers is Fe(III). In the field of oxidative drug degradation chemistry, the role of Fe(III) has been primarily discussed in terms of its effect in reaction with trace hydroperoxide impurities. However, the role of Fe(III) acting as a direct oxidant of drug molecules, which could operate in the absence of any hydroperoxide impurities, is less common. This work focuses on Fe(III)-induced oxidation of some aromatic drug molecules/drug fragments containing benzylic C-H bonds in the absence of initiating peroxides. Alcohol and ketone degradates are formed at the benzylic carbon atom. The formation of a π-stabilized cation radical is postulated as the key intermediate for the downstream oxidation. Implications are briefly discussed.
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8
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Nefliu M, Zelesky T, Jansen P, Sluggett GW, Foti C, Baertschi SW, Harmon PA. Artifacts Generated During Azoalkane Peroxy Radical Oxidative Stress Testing of Pharmaceuticals Containing Primary and Secondary Amines. J Pharm Sci 2015; 104:4287-4298. [DOI: 10.1002/jps.24667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 09/01/2015] [Accepted: 09/04/2015] [Indexed: 11/08/2022]
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9
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Alsante KM, Huynh-Ba KC, Baertschi SW, Reed RA, Landis MS, Furness S, Olsen B, Mowery M, Russo K, Iser R, Stephenson GA, Jansen P. Recent trends in product development and regulatory issues on impurities in active pharmaceutical ingredient (API) and drug products. Part 2: Safety considerations of impurities in pharmaceutical products and surveying the impurity landscape. AAPS PharmSciTech 2014; 15:237-51. [PMID: 24363207 DOI: 10.1208/s12249-013-0061-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 11/15/2013] [Indexed: 11/30/2022] Open
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