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Morar-Mitrica S, Pohl T, Theisen D, Boll B, Bechtold-Peters K, Schipflinger R, Beyer B, Zierow S, Kammüller M, Pribil A, Schmelzer B, Boehm S, Goetti M, Serno T. An Intra-Company Analysis of Inherent Particles in Biologicals Shapes the Protein Particle Mitigation Strategy Across Development Stages. J Pharm Sci 2023; 112:1476-1484. [PMID: 36731778 DOI: 10.1016/j.xphs.2023.01.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 01/24/2023] [Accepted: 01/24/2023] [Indexed: 02/01/2023]
Abstract
To better understand protein aggregation and inherent particle formation in the biologics pipeline at Novartis, a cross-functional team collected and analyzed historical protein particle issues. Inherent particle occurrences from the past 10 years were systematically captured in a protein particle database. Where the root cause was identified, a number of product attributes (such as development stage, process step, or protein format) were trended. Several key themes were revealed: 1) there was a higher propensity for inherent particle formation with non-mAbs than with mAbs; 2) the majority of particles were detected following manufacturing at scale, and were not predicted by the small-scale studies; 3) most issues were related to visible particles, followed by subvisible particles; 4) 50% of the issues were manufacturing related. These learnings became the foundation of a particle mitigation strategy across development and technical transfer, and resulted in a set of preventive actions. Overall, this study provides further insight into a recognized industry challenge and hopes to inspire the biopharmaceutical industry to transparently share their experiences with inherent particles formation.
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Affiliation(s)
| | - Thomas Pohl
- Biologics Analytical Development, Novartis Pharma, Basel, Switzerland
| | | | | | | | | | - Beate Beyer
- Biologics Drug Substance Development, Sandoz, Schaftenau, Austria
| | - Swen Zierow
- Biologics Drug Substance Development, Sandoz, Schaftenau, Austria
| | - Michael Kammüller
- Translational Medicine - Preclinical Safety, Novartis Institute for Biomedical Research, Basel, Switzerland
| | - Andreas Pribil
- Global PAT & Statistics MS&T, Novartis, Schaftenau, Austria
| | - Bernhard Schmelzer
- Biologics Analytical Development Statistics and Modeling, Sandoz, Schaftenau, Austria
| | - Stephan Boehm
- Biologics Drug Product Development, Sandoz, Schaftenau, Austria
| | - Micheline Goetti
- Advanced Accelerator Applicator, a Novartis company, Geneva, Switzerland
| | - Tim Serno
- Biologics Drug Product Development, Novartis Pharma, Basel, Switzerland
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2
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Thorlaksen C, Stanciu AM, Busch Neergaard M, Jiskoot W, Groenning M, Foderà V. Subtle pH variation around pH 4.0 affects aggregation kinetics and aggregate characteristics of recombinant human insulin. Eur J Pharm Biopharm 2022; 179:166-172. [PMID: 36087880 DOI: 10.1016/j.ejpb.2022.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/30/2022] [Accepted: 09/02/2022] [Indexed: 11/24/2022]
Abstract
Insulin is a biotherapeutic protein, which, depending on environmental conditions such as pH, has been shown to form a large variety of aggregates with different structures and morphologies. This work focuses on the formation and characteristics of insulin particulates, dense spherical aggregates having diameters spanning from nanometre to low-micron size. An in-depth investigation of the system is obtained by applying a broad range of techniques for particle sizing and characterisation. An interesting observation was achieved regarding the formation kinetics and aggregate characteristics of the particulates; a subtle change in the pH from pH 4.1 to pH 4.3 markedly affected the kinetics of the particulate formation and led to different particulate sizes, either nanosized or micronsized particles. Also, a clear difference between the secondary structure of the protein particulates formed at the two pH values was observed, where the nanosized particulates had an increased content of aggregated β-structure compared to the micronsized particles. The remaining characteristics of the particles were identical for the two particulate populations. These observations highlight the importance of carefully studying the formulation design space and of knowing the impact of parameters such as pH on the aggregation to secure a drug product in control. Furthermore, the identification of particles only varying in few parameters, such as size, are considered highly valuable for studying the effect of particle features on the immunogenicity potential.
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Affiliation(s)
- Camilla Thorlaksen
- Biophysical analysis, Novo Nordisk A/S, Novo Nordisk Park 1, 2760 Måløv, Denmark; Department of pharmacy, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
| | - Adriana-Maria Stanciu
- Biophysical analysis, Novo Nordisk A/S, Novo Nordisk Park 1, 2760 Måløv, Denmark; Department of pharmacy, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | | | - Wim Jiskoot
- Division of BioTherapeutics, Leiden University, Einsteinweg 55, 2300 RA Leiden, Netherlands
| | - Minna Groenning
- Biophysical analysis, Novo Nordisk A/S, Novo Nordisk Park 1, 2760 Måløv, Denmark.
| | - Vito Foderà
- Department of pharmacy, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
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3
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Thorlaksen C, Stanciu AM, Busch Neergaard M, Hatzakis N, Foderà V, Groenning M. Morphological integrity of insulin amyloid-like aggregates depends on preparation methods and post-production treatments. Eur J Pharm Biopharm 2022; 179:147-155. [PMID: 36058445 DOI: 10.1016/j.ejpb.2022.08.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 08/26/2022] [Accepted: 08/28/2022] [Indexed: 11/28/2022]
Abstract
Protein aggregates are often varying extensively in their morphological characteristics, which may lead to various biological outcomes, such as increased immunogenicity risk. However, isolation of aggregates with a specific morphology within an ensemble is often challenging. To gain vital knowledge on the effects of aggregate characteristics, samples containing a single morphology must be produced by direct control of the aggregation process. Moreover, the formed aggregates need to be in an aqueous solution suitable for biological assays, while keeping their morphology intact. Here we evaluated the dependence of morphology and integrity of amyloid-like fibrils and spherulites on preparation conditions and post-treatment methods. Samples containing either amyloid-like fibrils or spherulites produced from human insulin in acetic acid solutions are dependent on the presence of salt (NaCl). Moreover, mechanical shaking (600 rpm) inhibits spherulite formation, while only affecting the length of the formed fibrils compared to quiescent conditions. Besides shaking, the initial protein concentration in the formulation was found to control fibril length. Surprisingly, exchanging the solution used for aggregate formation to a physiologically relevant buffer, had a striking effect on the morphological integrity of the fibril and spherulite samples. Especially the secondary structure of one of our spherulite samples presented dramatic changes of the aggregated β-sheet content after exchanging the solution, emphasizing the importance of the aggregate stability. These results and considerations have profound implications on the data interpretation and should be implemented in the workflow for both fundamental characterization of aggregates as well as assays for evaluation of their corresponding biological effects.
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Affiliation(s)
- Camilla Thorlaksen
- Biophysical analysis, Novo Nordisk A/S, Novo Nordisk Park 1, 2760 Måløv, Denmark; Department of Pharmacy and Nanoscience Center University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark.
| | - Adriana-Maria Stanciu
- Biophysical analysis, Novo Nordisk A/S, Novo Nordisk Park 1, 2760 Måløv, Denmark; Department of Pharmacy and Nanoscience Center University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | | | - Nikos Hatzakis
- Department of Chemistry and Nanoscience Center, University of Copenhagen, Thorvaldsensvej 40, 1871 Frederiksberg, Denmark; NovoNordisk Center for Protein Research, University of Copenhagen, Blegdamsvej 3B, 2200 København N, Denmark
| | - Vito Foderà
- Department of Pharmacy and Nanoscience Center University of Copenhagen, Universitetsparken 2, 2100 Copenhagen, Denmark
| | - Minna Groenning
- Biophysical analysis, Novo Nordisk A/S, Novo Nordisk Park 1, 2760 Måløv, Denmark.
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4
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Zhou X, Fennema Galparsoro D, Østergaard Madsen A, Vetri V, van de Weert M, Mørck Nielsen H, Foderà V. Polysorbate 80 controls Morphology, structure and stability of human insulin Amyloid-Like spherulites. J Colloid Interface Sci 2022; 606:1928-1939. [PMID: 34695760 DOI: 10.1016/j.jcis.2021.09.132] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 09/09/2021] [Accepted: 09/21/2021] [Indexed: 01/09/2023]
Abstract
Amyloid protein aggregates are not only associated with neurodegenerative diseases and may also occur as unwanted by-products in protein-based therapeutics. Surfactants are often employed to stabilize protein formulations and reduce the risk of aggregation. However, surfactants alter protein-protein interactions and may thus modulate the physicochemical characteristics of any aggregates formed. Human insulin aggregation was induced at low pH in the presence of varying concentrations of the surfactant polysorbate 80. Various spectroscopic and imaging methods were used to study the aggregation kinetics, as well as structure and morphology of the formed aggregates. Molecular dynamics simulations were employed to investigate the initial interaction between the surfactant and insulin. Addition of polysorbate 80 slowed down, but did not prevent, aggregation of insulin. Amyloid spherulites formed under all conditions, with a higher content of intermolecular beta-sheets in the presence of the surfactant above its critical micelle concentration. In addition, a denser packing was observed, leading to a more stable aggregate. Molecular dynamics simulations suggested a tendency for insulin to form dimers in the presence of the surfactant, indicating a change in protein-protein interactions. It is thus shown that surfactants not only alter aggregation kinetics, but also affect physicochemical properties of any aggregates formed.
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Affiliation(s)
- Xin Zhou
- Drug Delivery and Biophysics of Biopharmaceuticals, Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen 2100, Denmark
| | - Dirk Fennema Galparsoro
- Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Ed. 18, Palermo 90128, Italy
| | - Anders Østergaard Madsen
- Manufacturing and Materials, Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen 2100, Denmark
| | - Valeria Vetri
- Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Ed. 18, Palermo 90128, Italy.
| | - Marco van de Weert
- Drug Delivery and Biophysics of Biopharmaceuticals, Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen 2100, Denmark
| | - Hanne Mørck Nielsen
- Drug Delivery and Biophysics of Biopharmaceuticals, Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen 2100, Denmark
| | - Vito Foderà
- Drug Delivery and Biophysics of Biopharmaceuticals, Department of Pharmacy, University of Copenhagen, Universitetsparken 2, Copenhagen 2100, Denmark.
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5
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Clénet D, Clavier L, Strobbe B, Le Bon C, Zoonens M, Saulnier A. Full-length G glycoprotein directly extracted from rabies virus with detergent and then stabilized by amphipols in liquid and freeze-dried forms. Biotechnol Bioeng 2021; 118:4317-4330. [PMID: 34297405 PMCID: PMC9291542 DOI: 10.1002/bit.27900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 06/22/2021] [Accepted: 07/09/2021] [Indexed: 11/11/2022]
Abstract
Pathogen surface antigens are at the forefront of the viral strategy when invading host organisms. These antigens, including membrane proteins (MPs), are broadly targeted by the host immune response. Obtaining these MPs in a soluble and stable form constitutes a real challenge, regardless of the application purposes (e.g. quantification/characterization assays, diagnosis, and preventive and curative strategies). A rapid process to obtain a native-like antigen by solubilization of a full-length MP directly from a pathogen is reported herein. Rabies virus (RABV) was used as a model for this demonstration and its full-length G glycoprotein (RABV-G) was stabilized with amphipathic polymers, named amphipols (APols). The stability of RABV-G trapped in APol A8-35 (RABV-G/A8-35) was evaluated under different stress conditions (temperature, agitation, and light exposure). RABV-G/A8-35 in liquid form exhibited higher unfolding temperature (+6°C) than in detergent and was demonstrated to be antigenically stable over 1 month at 5°C and 25°C. Kinetic modeling of antigenicity data predicted antigenic stability of RABV-G/A8-35 in a solution of up to 1 year at 5°C. The RABV-G/A8-35 complex formulated in an optimized buffer composition and subsequently freeze-dried displayed long-term stability for 2-years at 5, 25, and 37°C. This study reports for the first time that a natural full-length MP extracted from a virus, complexed to APols and subsequently freeze-dried, displayed long-term antigenic stability, without requiring storage under refrigerated conditions.
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Affiliation(s)
- Didier Clénet
- Bioprocess R&D Department, Sanofi Pasteur, Marcy l'Etoile, France
| | - Léna Clavier
- Bioprocess R&D Department, Sanofi Pasteur, Marcy l'Etoile, France
| | - Benoît Strobbe
- Bioprocess R&D Department, Sanofi Pasteur, Marcy l'Etoile, France
| | - Christel Le Bon
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, CNRS, Institut de Biologie Physico-Chimique, Université de Paris, Paris, France
| | - Manuela Zoonens
- Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, CNRS, Institut de Biologie Physico-Chimique, Université de Paris, Paris, France
| | - Aure Saulnier
- Bioprocess R&D Department, Sanofi Pasteur, Marcy l'Etoile, France.,Department of Analytical Sciences, Sanofi Pasteur, Marcy l'Etoile, France
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6
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Sekulovic A, Verrijk R, Rades T, Grabarek A, Jiskoot W, Hawe A, Rantanen J. Simultaneous automated image analysis and Raman spectroscopy of powders at an individual particle level. J Pharm Biomed Anal 2020; 193:113744. [PMID: 33217710 DOI: 10.1016/j.jpba.2020.113744] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/26/2020] [Accepted: 10/27/2020] [Indexed: 10/23/2022]
Abstract
Solid form diversity of raw materials can be critical for the performance of the final drug product. In this study, Raman spectroscopy, image analysis and combined Raman and image analysis were utilized to characterize the solid form composition of a particulate raw material. Raman spectroscopy provides chemical information and is complementary to the physical information provided by image analysis. To demonstrate this approach, binary mixtures of two solid forms of carbamazepine with a distinct shape, an anhydrate (prism shaped) and a dihydrate (needle shaped), were characterized at an individual particle level. Partial least squares discriminant analysis classification models were developed and tested with known, gravimetrically mixed test samples, followed by analysis of unknown, commercially supplied carbamazepine raw material samples. Classification of several thousands of particles was performed, and it was observed that with the known binary mixtures, the minimum number of particles needed for the combined Raman spectroscopy - image analysis classification model was approximately 100 particles per solid form. The carbamazepine anhydrate and dihydrate particles were detected and classified with a classification error of 1 % using the combined model. Further, this approach allowed the identification of raw material solid form impurity in unknown raw material samples. Simultaneous automated image analysis and Raman spectroscopy of powders at an individual particle level has its potential in accurate detection of low amounts of unwanted solid forms in particulate raw material samples.
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Affiliation(s)
- Andrea Sekulovic
- University of Copenhagen, Department of Pharmacy, Denmark; Dr Reddy's Research & Development B.V., Leiden, The Netherlands
| | - Ruud Verrijk
- Dr Reddy's Research & Development B.V., Leiden, The Netherlands
| | - Thomas Rades
- University of Copenhagen, Department of Pharmacy, Denmark
| | - Adam Grabarek
- Coriolis Pharma, Martinsried, Germany; Leiden University, Division of BioTherapeutics, The Netherlands
| | - Wim Jiskoot
- Coriolis Pharma, Martinsried, Germany; Leiden University, Division of BioTherapeutics, The Netherlands
| | | | - Jukka Rantanen
- University of Copenhagen, Department of Pharmacy, Denmark.
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Grabarek AD, Bozic U, Rousel J, Menzen T, Kranz W, Wuchner K, Jiskoot W, Hawe A. What Makes Polysorbate Functional? Impact of Polysorbate 80 Grade and Quality on IgG Stability During Mechanical Stress. J Pharm Sci 2019; 109:871-880. [PMID: 31614127 DOI: 10.1016/j.xphs.2019.10.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 10/04/2019] [Accepted: 10/08/2019] [Indexed: 11/18/2022]
Abstract
Polysorbate 80 (PS80) is a commonly used surfactant in therapeutic protein formulations to mitigate adsorption and interface-induced protein aggregation. Several PS80 grades and qualities are available on the market for parenteral application. The role of PS80 grade on protein stability remains debatable, and the impact of (partially) degraded PS on protein aggregation is not yet well understood. In our study, a monoclonal antibody (IgG) was subjected to 3 different mechanical stress conditions in the presence of multicompendial (MC) and Chinese pharmacopeia (ChP) grade PS80. Furthermore, IgG formulations were spiked with (partly) hydrolyzed PS80 to investigate the effect of PS80 degradants on protein stability. PS80 functionality was assessed by measuring the extent of protein aggregation and particle formation induced during mechanical stress by using size-exclusion chromatography, dynamic light scattering, backgrounded membrane imaging, and flow imaging microscopy. No distinguishable differences in PS80 functionality between MC and ChP grade were observed in the 3 stress tests. However, with increasing degree of PS80 hydrolysis, higher counts of subvisible particles were measured after stress. Furthermore, higher levels of PS80 degradants at a constant PS80 concentration may destabilize the IgG. In conclusion, MC and ChP grade PS80 are equally protective, but PS80 degradants compromise IgG stability.
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Affiliation(s)
- Adam Dariusz Grabarek
- Coriolis Pharma Research, Fraunhoferstr. 18b, 82152 Martinsried, Germany; Division of BioTherapeutics, Leiden Academic Centre for Drug Research (LACDR), Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
| | - Ula Bozic
- Coriolis Pharma Research, Fraunhoferstr. 18b, 82152 Martinsried, Germany
| | - Jannik Rousel
- Coriolis Pharma Research, Fraunhoferstr. 18b, 82152 Martinsried, Germany; Division of BioTherapeutics, Leiden Academic Centre for Drug Research (LACDR), Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
| | - Tim Menzen
- Coriolis Pharma Research, Fraunhoferstr. 18b, 82152 Martinsried, Germany
| | - Wendelin Kranz
- Coriolis Pharma Research, Fraunhoferstr. 18b, 82152 Martinsried, Germany
| | - Klaus Wuchner
- Janssen Research & Development, Pharmaceutical Development & Manufacturing Sciences, Large Molecule Analytical Development, Schaffhausen, Switzerland
| | - Wim Jiskoot
- Coriolis Pharma Research, Fraunhoferstr. 18b, 82152 Martinsried, Germany; Division of BioTherapeutics, Leiden Academic Centre for Drug Research (LACDR), Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
| | - Andrea Hawe
- Coriolis Pharma Research, Fraunhoferstr. 18b, 82152 Martinsried, Germany.
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Schack MM, Dahl K, Rades T, Groenning M, Carpenter JF. Spectroscopic Evidence of Tertiary Structural Differences Between Insulin Molecules in Fibrils. J Pharm Sci 2019; 108:2871-2879. [DOI: 10.1016/j.xphs.2019.04.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Revised: 04/01/2019] [Accepted: 04/10/2019] [Indexed: 11/29/2022]
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9
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Wang W, Ohtake S. Science and art of protein formulation development. Int J Pharm 2019; 568:118505. [PMID: 31306712 DOI: 10.1016/j.ijpharm.2019.118505] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Revised: 07/08/2019] [Accepted: 07/08/2019] [Indexed: 02/07/2023]
Abstract
Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.
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Affiliation(s)
- Wei Wang
- Biological Development, Bayer USA, LLC, 800 Dwight Way, Berkeley, CA 94710, United States.
| | - Satoshi Ohtake
- Pharmaceutical Research and Development, Pfizer Biotherapeutics Pharmaceutical Sciences, Chesterfield, MO 63017, United States
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10
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Schack MM, Møller EH, Friderichsen AV, Carpenter JF, Rades T, Groenning M. Optimization of Infrared Microscopy to Assess Secondary Structure of Insulin Molecules Within Individual Subvisible Particles in Aqueous Formulations. J Pharm Sci 2019; 108:1117-1129. [DOI: 10.1016/j.xphs.2018.10.028] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/16/2018] [Accepted: 10/16/2018] [Indexed: 11/30/2022]
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11
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Malmstrøm J. Quantification of Silicone Oil and Its Degradation Products in Aqueous Pharmaceutical Formulations by 1H-NMR Spectroscopy. J Pharm Sci 2018; 108:1512-1520. [PMID: 30471289 DOI: 10.1016/j.xphs.2018.11.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/09/2018] [Accepted: 11/14/2018] [Indexed: 11/18/2022]
Abstract
During the past years, there has been an increasing focus on the presence of silicone oil as a contaminant in pharmaceutical formulations kept in prefilled syringes (PFSs). As the PFSs are coated on the inner wall with silicone oil (polydimethylsiloxane), there is a potential risk that the oil can migrate from the inner surface of the primary packing material into the aqueous solution. Several studies have demonstrated that presence of silicone oil as droplets in a high-concentrated protein formulation can cause protein aggregation. Hence, because the use of silicone-coated primary packing material for protein formulations are increasing, the call for an easy and quantitative method for determination of silicone oil and its degradation products in pharmaceutical formulations is therefore needed. Several analytical techniques have in the past been developed with the aim of detecting the presence of silicone oil and degradation products hereof. Most of these methods require hydrolyzation, derivatization, and extraction steps followed by, for example, gas chromatography-mass spectrometry analysis. Applying these methods can cause a loss in detection or an overestimation of the hydrolytic degradation products of silicone oil, that is, trimethylsilanol and dimethylsilanediol. The 2 silanols are highly hydrophilic and prefers the aqueous environment. Analysis of an aqueous formulation obtained from a PFS by 1H-NMR spectroscopy provides data about the content and levels of silicone oil and the 2 silanols even in levels below 10 ppm. The 1H-NMR method offers an easy and direct, quantitative measurement of samples intended for clinical use and samples kept at elevated temperature for a prolonged time (i.e., stability studies). The result of the study presented here showed dimethylsilanediol to be the main silicone compound present in the aqueous formulation when kept in baked-on PFSs. The degradation product dimethylsilanediol, in full accordance with expected hydrolytic degradation of silicone oil, increased during storage and with elevated temperature. In addition, the method can be applied to aqueous samples where polydimethylsiloxane has been added as, for example, the major constituent of antifoam.
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