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Song S, Yao X, Wang C, Sun CC, Siegel RA. Delaying the First Nucleation Event of Amorphous Solid Dispersions Above the Polymer Overlap Concentration (c*): PVP and PVPVA in Posaconazole. J Pharm Sci 2024:S0022-3549(24)00154-0. [PMID: 38685452 DOI: 10.1016/j.xphs.2024.04.026] [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: 03/12/2024] [Revised: 04/23/2024] [Accepted: 04/23/2024] [Indexed: 05/02/2024]
Abstract
A thorough understanding of effects of polymers on crystallization of amorphous drugs is essential for rational design of robust amorphous solid dispersion (ASD), since crystallization of the amorphous drug negates their solubility advantage. In this work, we measured the first nucleation time (t0, time to form the first critical nucleus in fresh liquid/glass) in posaconazole (POS)/polyvinylpyrrolidone vinyl acetate (PVPVA) and POS/polyvinylpyrrolidone (PVP K25) ASDs and showed that the polymer overlap concentration (c*, concentration above which adjacent polymer chains begin to contact) is critical in controlling crystallization of ASDs. When polymer concentration c < c*, t0 of POS ASDs is approximately equal to that of the neat amorphous POS, but it increases significantly when c > c*. This observation supports the view that the effective inhibitory effect of crystallization in ASDs above c* is primarily correlated with delay in the first nucleation event. Our finding is useful in efficient polymer selection and performance prediction of high drug loaded ASD formulations.
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Affiliation(s)
- Sichen Song
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, 55455, United States; School of Mathematics, University of Minnesota, Minneapolis, MN, 55455, United States
| | - Xin Yao
- School of Pharmacy, University of Wisconsin-Madison, Madison, WI, 53705, United States; Research and Development, AbbVie Inc., North Chicago, IL, 60064, United States
| | - Chenguang Wang
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, 55455, United States
| | - Changquan Calvin Sun
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, 55455, United States
| | - Ronald A Siegel
- Department of Pharmaceutics, University of Minnesota, Minneapolis, MN, 55455, United States; Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, 55455, United States.
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Lalge R, Kumar NSK, Suryanarayanan R. Understanding the Effect of Nucleation in Amorphous Solid Dispersions through Time-Temperature Transformation. Mol Pharm 2023; 20:4196-4209. [PMID: 37358932 DOI: 10.1021/acs.molpharmaceut.3c00313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2023]
Abstract
In an earlier investigation, the critical cooling rate to prevent drug crystallization (CRcrit) during the preparation of nifedipine (NIF) amorphous solid dispersions (ASDs) was determined through a time-temperature transformation (TTT) diagram (Lalge et al. Mol. Pharmaceutics 2023, 20 (3), 1806-1817). The current study aims to use the TTT diagram to determine the critical cooling rate to prevent drug nucleation (CRcrit N) during the preparation of ASDs. ASDs were prepared with each polyvinylpyrrolidone (PVP) and hydroxypropyl methylcellulose acetate succinate (HPMCAS). The dispersions were first stored under conditions promoting nucleation and then heated to the temperature that favors crystallization. The crystallization onset time (tC) was determined by differential scanning calorimetry and synchrotron X-ray diffractometry. TTT diagrams for nucleation were generated, which provided the critical nucleation temperature (50 °C) and the critical cooling rate to avoid nucleation (CRcrit N). The strength of the drug-polymer interactions as well as the polymer concentration affected the CRcrit N, with PVP having a stronger interaction than HPMCAS. The CRcrit of amorphous NIF was ∼17.5 °C/min. The addition of a 20% w/w polymer resulted in CRcrit of ∼0.05 and 0.2 °C/min and CRcrit N of ∼4.1 and 8.1 °C/min for the dispersions prepared with PVP and HPMCAS, respectively.
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Affiliation(s)
- Rahul Lalge
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, 9-177 WDH, 308 Harvard Street S.E., Minneapolis, Minnesota 55455, United States
| | - N S Krishna Kumar
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, 9-177 WDH, 308 Harvard Street S.E., Minneapolis, Minnesota 55455, United States
| | - Raj Suryanarayanan
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, 9-177 WDH, 308 Harvard Street S.E., Minneapolis, Minnesota 55455, United States
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Kawakami K. Rigid Nuclei and Flexible Nuclei: Appearance and Disappearance of Nuclei in Indomethacin Glass Revealed by a Long-Term Annealing Study. J Phys Chem B 2023; 127:5967-5977. [PMID: 37408472 DOI: 10.1021/acs.jpcb.3c02127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023]
Abstract
In this study, nucleation/crystallization behaviors of indomethacin glass are discussed with emphasis on the fate of nuclei, which is explained using a notion of "rigid" and "flexible" nuclei. The observation was made mainly by thermal analysis of indomethacin glass after long-term annealing at various temperatures. Formation of nuclei was evaluated by observing cold crystallization behaviors of the annealed glasses, as they should be dominated by the "nuclei form" produced in the glass. Nuclei of forms α and γ, which have opposite stability trends, were found to appear over a wide temperature range. The nuclei of form α were stable even in the presence of other crystal forms, whereas those of form γ were likely to be easily integrated into other crystals during their growth, which was explained by a notion of rigid and flexible nuclei. Moreover, unconventionally fast crystallization in the glass-transition region and the finding of a new crystal form are also reported.
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Affiliation(s)
- Kohsaku Kawakami
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
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Yao X, Yu L, Zhang GGZ. Impact of Crystal Nuclei on Dissolution of Amorphous Drugs. Mol Pharm 2023; 20:1796-1805. [PMID: 36749110 DOI: 10.1021/acs.molpharmaceut.2c00989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Amorphous drugs are used to improve bioavailability of poorly water-soluble drugs. Crystallization must be managed to take full advantage of this formulation strategy. Crystallization of amorphous drugs proceeds in a sequence of crystal nucleation and growth, with different kinetics. At low temperatures, crystal nucleation is fast, but crystal growth is slow. Therefore, amorphous drugs may generate dense but nanoscale crystal nuclei. Such tiny nuclei cannot be detected using routine powder X-ray diffraction (PXRD) and polarized light microscopy (PLM). However, they may negate the dissolution advantage of amorphous drugs. In this work, for the first time, the impact of crystal nuclei on dissolution of amorphous drugs was studied by monitoring the real-time dissolution from amorphous drug films, with and without crystal nuclei, and the evolving crystallinity in the films. Three model drugs (ritonavir/RTV, posaconazole/POS, and nifedipine/NIF) were chosen to represent different crystallization tendencies in the supercooled liquid state, namely, slow-nucleation-and-slow-growth (SN-SG), fast-nucleation-and-slow-growth (FN-SG), and fast-nucleation-and-fast-growth (FN-FG), respectively. We find that although the amorphous films containing nuclei do not show obvious differences from the nuclei-free films under PLM and PXRD before dissolution, they have inferior dissolution performance relative to the nuclei-free amorphous films. For SN-SG drug RTV, crystal nuclei have negligible impact on the crystallization of amorphous films, dissolution rate, and supersaturation achieved. However, they cause earlier de-supersaturation by inducing crystallization in solution as heterogeneous seeds. For FN-SG drug POS and FN-FG drug NIF, crystal nuclei accelerate crystallization in the amorphous films leading to lower supersaturation achieved with POS, and elimination of any supersaturation with NIF. Dissolution profiles of amorphous films can be further analyzed using a derivative function of the apparent dissolution rate, which yields amorphous solubility, initial intrinsic dissolution rate, and onset of crystallization in the amorphous films. This study highlights that although crystal nuclei are undetectable with routine analytical methods, they can significantly negate, or even eliminate, the dissolution advantage of amorphous drugs. Hence, understanding crystal nucleation process and developing approaches to prevent it are necessary to fully realize the benefits of amorphous solids.
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Affiliation(s)
| | | | - Geoff G Z Zhang
- Development Sciences, Research and Development, AbbVie, Inc., North Chicago, Illinois 60064, United States
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Zhang J, Liu M, Xu M, Chen Z, Peng X, Yang Q, Cai T, Zeng Z. Discovery of a new polymorph of clotrimazole through melt crystallization: Understanding nucleation and growth kinetics. J Chem Phys 2023; 158:034503. [PMID: 36681648 DOI: 10.1063/5.0130600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Clotrimazole (CMZ) is a classical antifungal drug for studying crystallization. In this study, a new CMZ polymorph (Form 2) was discovered during the process of nucleation and growth rate determination in the melt. High-quality single crystals were grown from melt microdroplets to determine the crystal structure by x-ray diffraction. Form 2 is metastable and exhibits a disordered structure. The crystal nucleation and growth kinetics of the two CMZ polymorphs were systematically measured. Form 2 nucleates and grows faster than the existing form (Form 1). The maximum nucleation rate of Forms 1 and 2 was observed at 50 °C (1.07 Tg). The summary of the maximum nucleation rate temperature of CMZ and the other six organic compounds indicates that nucleation near Tg in the supercooled liquid is a useful approach to discovering new polymorphs. This study is relevant for the discovering new drug polymorphs through an understanding of nucleation and growth kinetics during melt crystallization.
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Affiliation(s)
- Jie Zhang
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
| | - Minzhuo Liu
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
| | - Meixia Xu
- Yantai Key Laboratory of Nanomedicine and Advanced Preparations, Yantai Institute of Materia Medica, Shandong 264000, China
| | - Zhiguo Chen
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
| | - Xucong Peng
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
| | - Qiusheng Yang
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
| | - Ting Cai
- Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, Nanjing 210009, China
| | - Zhihong Zeng
- College of Biological and Chemical Engineering, Changsha University, Changsha 410022, China
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Ritonavir Form III: A New Polymorph After 24 Years. J Pharm Sci 2023; 112:237-242. [PMID: 36195132 DOI: 10.1016/j.xphs.2022.09.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/25/2022] [Accepted: 09/25/2022] [Indexed: 11/20/2022]
Abstract
Polymorphism occurs widely in pharmaceutical solids, and must be thoroughly studied during product development. Twenty-four years after ritonavir (RTV) Form II materialized, we report a new polymorph, Form III, discovered via melt crystallization. Form III has a unique PXRD pattern, Raman spectrum, lower melting point and heat of fusion, compared to the known polymorphs, Form I and Form II. It is the least stable form, monotropically, among the three polymorphs. Form III differs from Form I and Form II in molecular conformation and hydrogen bonding motifs in crystal lattice. Nucleation from RTV supercooled liquid is slow, and selected Form III exclusively. The discovery of RTV Form III demonstrates the importance of crystal nucleation studies. Crystallization from supercooled liquids should be incorporated as part of polymorph screening workflow.
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Shi Q, Chen H, Wang Y, Wang R, Xu J, Zhang C. Amorphous Solid Dispersions: Role of the Polymer and Its Importance in Physical Stability and In Vitro Performance. Pharmaceutics 2022; 14:pharmaceutics14081747. [PMID: 36015373 PMCID: PMC9413000 DOI: 10.3390/pharmaceutics14081747] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 08/15/2022] [Accepted: 08/18/2022] [Indexed: 01/25/2023] Open
Abstract
Amorphous solid dispersions stabilized by one or more polymer(s) have been widely used for delivering amorphous drugs with poor water solubilities, and they have gained great market success. Polymer selection is important for preparing robust amorphous solid dispersions, and considerations should be given as to how the critical attributes of a polymer can enhance the physical stability, and the in vitro and in vivo performances of a drug. This article provides a comprehensive overview for recent developments in the understanding the role of polymers in amorphous solid dispersions from the aspects of nucleation, crystal growth, overall crystallization, miscibility, phase separation, dissolution, and supersaturation. The critical properties of polymers affecting the physical stability and the in vitro performance of amorphous solid dispersions are also highlighted. Moreover, a perspective regarding the current research gaps and novel research directions for better understanding the role of the polymer is provided. This review will provide guidance for the rational design of polymer-based amorphous pharmaceutical solids with desired physicochemical properties from the perspective of physical stability and in vitro performance.
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Affiliation(s)
- Qin Shi
- School of Pharmacy, Jiangsu Vocational College of Medicine, Yancheng 224005, China
- Correspondence: (Q.S.); (C.Z.)
| | - Haibiao Chen
- Institute of Marine Biomedicine, Shenzhen Polytechnic, Shenzhen 518055, China
| | - Yanan Wang
- School of Pharmacy, Jiangsu Vocational College of Medicine, Yancheng 224005, China
| | - Ruoxun Wang
- School of Pharmacy, Jiangsu Vocational College of Medicine, Yancheng 224005, China
| | - Jia Xu
- School of Pharmacy, Jiangsu Vocational College of Medicine, Yancheng 224005, China
| | - Chen Zhang
- Institute of Marine Biomedicine, Shenzhen Polytechnic, Shenzhen 518055, China
- Correspondence: (Q.S.); (C.Z.)
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Yao X, Benson EG, Gui Y, Stelzer T, Zhang GGZ, Yu L. Surfactants Accelerate Crystallization of Amorphous Nifedipine by Similar Enhancement of Nucleation and Growth Independent of Hydrophilic-Lipophilic Balance. Mol Pharm 2022; 19:2343-2350. [PMID: 35477294 DOI: 10.1021/acs.molpharmaceut.2c00156] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Amorphous formulations, increasingly employed to deliver poorly soluble drugs, generally contain surfactants to improve wetting and dissolution. These surfactants are often liquids and can potentially increase the mobility of the drug and reduce its stability, but little is known about this effect. Here we investigate the effect of four common nonionic surfactants (Tween 80, Span 80, Triton X-100, and Poloxamer 407) on the crystallization of amorphous nifedipine (NIF). We find that the surfactants significantly enhance the rates of crystal nucleation and growth even at low concentrations, by up to 2 orders of magnitude at 10 wt %. The surfactants tested show similar enhancement effects independent of their structural details and hydrophilic-lipophilic balance (HLB), suggesting that surfactant adsorption at solid/liquid interfaces does not play a major role in crystal nucleation and growth. Importantly, the surfactants accelerate crystal nucleation and growth by a similar factor. This result mirrors the previous finding that a polymer dopant in a molecular glass-former causes similar slowdown of nucleation and growth. These results indicate that nucleation and growth in a deeply supercooled liquid are both mobility-limited, and a dopant mainly functions as a mobility modifier (enhancer or suppressor depending on the dopant). The common surfactants tested are all mobility enhancers and destabilize the amorphous drug, and this negative effect must be managed using stabilizers such as polymers. The effect of surfactants on nucleation can be predicted from the effect on crystal growth and the crystallization kinetics of the pure system, using the same principle previously established for drug-polymer systems. We show how the independently measured nucleation and growth rates enable predictions of the overall crystallization rates.
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Affiliation(s)
| | | | | | - Torsten Stelzer
- Department of Pharmaceutical Sciences, University of Puerto Rico, Medical Sciences Campus, San Juan, Puerto Rico 00936, United States.,Crystallization Design Institute, Molecular Sciences Research Center, University of Puerto Rico, San Juan, Puerto Rico 00926, United States
| | - Geoff G Z Zhang
- Drug Product Development, Research and Development, AbbVie Inc., North Chicago, Illinois 60064, United States
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