51
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López-Mejías V, Kampf JW, Matzger AJ. Polymer-induced heteronucleation of tolfenamic acid: structural investigation of a pentamorph. J Am Chem Soc 2009; 131:4554-5. [PMID: 19334766 PMCID: PMC2729806 DOI: 10.1021/ja806289a] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nonsteroidal anti-inflammatory drug (NSAID) tolfenamic acid (TA), previously thought to be dimorphic, is demonstrated to have at least five polymorphs. The new forms were uncovered through the emerging screening technique of polymer-induced heteronucleation (PIHn). The presence of conformational changes among forms, whole molecule disorder, space group diversity, and varying number of molecules in the asymmetric unit occurring within a very narrow free energy window (approximately 0.3 kcal/mol) make the solid-state chemistry of this molecule uniquely complex among pharmaceuticals. These aspects make it a particularly suitable benchmark compound for crystal structure prediction methods.
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Affiliation(s)
- Vilmalí López-Mejías
- Department of Chemistry and the Macromolecular Science and Engineering Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109-1055
| | - Jeff W. Kampf
- Department of Chemistry and the Macromolecular Science and Engineering Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109-1055
| | - Adam J. Matzger
- Department of Chemistry and the Macromolecular Science and Engineering Program, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109-1055
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52
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Aitipamula S, Chow PS, Tan RBH. Trimorphs of a pharmaceutical cocrystal involving two active pharmaceutical ingredients: potential relevance to combination drugs. CrystEngComm 2009. [DOI: 10.1039/b904616j] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first example of a trimorphic cocrystal involving two active pharmaceutical ingredients, ethenzamide and gentisic acid, is reported; metastable polymorphs convert to the stable form upon solid-state grinding; pharmaceutical cocrystals involving two or more APIs have potential relevance to combination drugs.
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Affiliation(s)
- Srinivasulu Aitipamula
- Institute of Chemical and Engineering Sciences
- A*STAR (Agency for Science, Technology and Research)
- Jurong Island
- Singapore
- Singapore
| | - Pui Shan Chow
- Institute of Chemical and Engineering Sciences
- A*STAR (Agency for Science, Technology and Research)
- Jurong Island
- Singapore
- Singapore
| | - Reginald B. H. Tan
- Institute of Chemical and Engineering Sciences
- A*STAR (Agency for Science, Technology and Research)
- Jurong Island
- Singapore
- Singapore
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53
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Roy S, Matzger AJ. Unmasking a third polymorph of a benchmark crystal-structure-prediction compound. Angew Chem Int Ed Engl 2009; 48:8505-8. [PMID: 19774578 PMCID: PMC3140642 DOI: 10.1002/anie.200903285] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Saikat Roy
- Department of Chemistry and the Macromolecular Science and Engineering Program, University of Michigan, Ann Arbor, MI 48109-1055, USA
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54
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55
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Hooton JC, Jones MD, Harris H, Shur J, Price R. The Influence of Crystal Habit on the Prediction of Dry Powder Inhalation Formulation Performance Using the Cohesive–Adhesive Force Balance Approach. Drug Dev Ind Pharm 2008; 34:974-83. [DOI: 10.1080/03639040802149087] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Jennifer C. Hooton
- Pharmaceutical Surface Science Research Group, Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Matthew D. Jones
- Pharmaceutical Surface Science Research Group, Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Haggis Harris
- Pharmaceutical Surface Science Research Group, Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Jagdeep Shur
- Pharmaceutical Surface Science Research Group, Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
| | - Robert Price
- Pharmaceutical Surface Science Research Group, Department of Pharmacy and Pharmacology, University of Bath, Bath, UK
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56
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Babu NJ, Reddy LS, Aitipamula S, Nangia A. Polymorphs and polymorphic cocrystals of temozolomide. Chem Asian J 2008; 3:1122-33. [PMID: 18512823 DOI: 10.1002/asia.200800070] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Crystal polymorphism in the antitumor drug temozolomide (TMZ), cocrystals of TMZ with 4,4'-bipyridine-N,N'-dioxide (BPNO), and solid-state stability were studied. Apart from a known X-ray crystal structure of TMZ (form 1), two new crystalline modifications, forms 2 and 3, were obtained during attempted cocrystallization with carbamazepine and 3-hydroxypyridine-N-oxide. Conformers A and B of the drug molecule are stabilized by intramolecular amide N--HN(imidazole) and N--HN(tetrazine) interactions. The stable conformer A is present in forms 1 and 2, whereas both conformers crystallized in form 3. Preparation of polymorphic cocrystals I and II (TMZBPNO 1:0.5 and 2:1) were optimized by using solution crystallization and grinding methods. The metastable nature of polymorph 2 and cocrystal II is ascribed to unused hydrogen-bond donors/acceptors in the crystal structure. The intramolecularly bonded amide N-H donor in the less stable structure makes additional intermolecular bonds with the tetrazine C==O group and the imidazole N atom in stable polymorph 1 and cocrystal I, respectively. All available hydrogen-bond donors and acceptors are used to make intermolecular hydrogen bonds in the stable crystalline form. Synthon polymorphism and crystal stability are discussed in terms of hydrogen-bond reorganization.
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Affiliation(s)
- N Jagadeesh Babu
- School of Chemistry, University of Hyderabad, Hyderabad 500046, India
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57
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Pasquali I, Bettini R, Giordano F. Supercritical fluid technologies: an innovative approach for manipulating the solid-state of pharmaceuticals. Adv Drug Deliv Rev 2008; 60:399-410. [PMID: 17964684 DOI: 10.1016/j.addr.2007.08.030] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2006] [Accepted: 08/16/2007] [Indexed: 11/25/2022]
Abstract
Solid-state, crystallographic purity and careful monitoring of the polymorphism of drugs and excipients are currently an integral part of the development of modern drug delivery systems. The reproducible preparation of organic crystals in a specific form and size is a major issue that must be addressed. A recent approach for obtaining pharmaceutical materials in pure physical form is represented by the technologies based on supercritical fluids. The present work aims to provide a critical review of the recent advances in the use of supercritical fluids for the preparation and control of the specific physical form of pharmaceutical substances with particular attention to those fluids used for drug delivery systems. These innovative technologies are highly promising for future application in particle design and engineering.
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58
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Dobrzańska L, Kleinhans DJ, Barbour LJ. Influence of the metal-to-ligand ratio on the formation of metal organic complexes. NEW J CHEM 2008. [DOI: 10.1039/b800720a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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59
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Baruah JB, Karmakar A, Barooah N. Solvent induced symmetry non-equivalence in the crystal lattice of 7-carboxymethyl-1,3,6,8-tetraoxo-3,6,7,8-tetrahydro-1H-benzo[lmn][3,8]phenathrolin-2-yl) acetic acid. CrystEngComm 2008. [DOI: 10.1039/b712967j] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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60
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Gelbrich T, Hughes DS, Hursthouse MB, Threlfall TL. Packing similarity in polymorphs of sulfathiazole. CrystEngComm 2008. [DOI: 10.1039/b807898j] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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61
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Crystal structures of sulfathiazole polymorphs in the temperature range 100–295 K: A comparative analysis. J STRUCT CHEM+ 2008. [DOI: 10.1007/s10947-008-0013-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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62
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Guiry KP, Kelleher JM, Lawrence SE, McAuliffe MT, Moynihan HA, Ryan AL. Crystal polymorphism of pharmaceuticals: probing crystal nucleation at the molecular level. J Enzyme Inhib Med Chem 2007; 22:550-5. [PMID: 18035822 DOI: 10.1080/14756360701425147] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Paracetamol, sulfathiazole and L-glutamic acid are presented as examples of pharmaceutical crystal polymorphic systems. The effect of N-acylated sulfathiazole derivatives (3-6) on sulfathiazole crystallisation is discussed, and possible modes of action presented. Methods for the control of the crystal polymorphism of L-glutamic acid which utilise the principles of conformation mimicry and co-operative binding are presented. The preparation of a series of bis-amides of EDTA derived from sulfathiazole, 5-aminoisophthalic acid and 4-hydroxyaniline (i.e. compounds 9a-c) is presented, as is data on the effect of these compounds on the crystallisation of, respectively, sulfathiazole, L-glutamic acid and paracetamol.
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Affiliation(s)
- Kevin P Guiry
- Analytical and Biological Chemistry Research Facility, School of Pharmacy, University College Cork, College Road, Cork, Ireland
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63
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Lee IS, Lee AY, Myerson AS. Concomitant Polymorphism in Confined Environment. Pharm Res 2007; 25:960-8. [PMID: 17896099 DOI: 10.1007/s11095-007-9424-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Accepted: 07/31/2007] [Indexed: 10/22/2022]
Abstract
PURPOSE The aim of this paper is to demonstrate that multiple crystal forms can be generated on patterned self-assembled monolayers (SAMs) substrates in single experiments in a given solvent system. METHODS Functionalized metallic islands are fabricated and utilized as individual templates for crystal formation. Taking advantage of the different wetting properties that patterned surfaces offered, arrays of small solution droplets on the nano- and pico- liter scale were produced on the substrates. Different droplet dimensions were deposited on the substrate. As the solvent evaporates from the droplets, crystals were formed within the constrained volume. Crystal habits were examined with optical microscopy while the solid form was identified with Raman microscopy. RESULTS With mefenamic acid (MA) and sulfathiazole as model pharmaceutical compounds, two and four different polymorphs, respectively, were observed under identical conditions. Moreover, it is established that the polymorphic distribution is highly dependent on the solvent evaporation rate and the solution concentration. These results imply that multiple crystal forms competitively nucleate in solution, and the probability of each form nucleating is strongly dependent on the supersaturation of the solution. Additionally, solvent was observed to play a role in controlling the solid state outcome. CONCLUSIONS Multiple crystal forms can concomitantly nucleate on patterned substrates. This technique can particularly be attractive to screen for polymorphs as elusive, metastable solid forms are favored with the creation of high supersaturation and can be stabilized due to the minimal volumes generated.
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Affiliation(s)
- In Sung Lee
- Department of Chemical & Biological Engineering, Illinois Institute of Technology, Chicago, Illinois 60616, USA
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64
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Näther C, Bhosekar G, Jess I. Preparation of Stable and Metastable Coordination Compounds: Insight into the Structural, Thermodynamic, and Kinetic Aspects of the Formation of Coordination Polymers. Inorg Chem 2007; 46:8079-87. [PMID: 17705372 DOI: 10.1021/ic701079x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reaction of ZnI2 and pyrimidine in acetonitrile results in the formation of the 1:2 compound ZnI2(pyrimidine)2 (1), which consists of discrete tetrahedral building blocks. Slow heating of 1 at 1 degrees C/min leads to its transformation into the ligand-deficient intermediate 1:1 compound ZnI2(pyrimidine) (3), which upon further heating decomposes into the most ligand-deficient 2:1 compound (ZnI2)2(pyrimidine) (4). In contrast, the 2:3 compound (ZnI2)2(pyrimidine)3 (2) is formed as an intermediate by decomposing 1 using a faster heating rate of 8 degrees C/min. Compound 2 consists of oligomeric units in which each ZnI2 unit is coordinated by two iodine atoms and one bridging and one terminal pyrimidine ligand. The crystal structure of compound 3 is built up of ZnI2 units, which are connected by the ligands into chains. For the thermal transformation of 1 into 3 via 2 as the intermediate, a smooth reaction pathway is found in the crystal structure, for which only small translational and rotational changes are needed. The metastable solvated compound (ZnI2)(pyrimidine)(acetonitrile)0.25 (5) consisting of (ZnI2)4(pyrimidine)4 rings is obtained by quenching the reaction of ZnI2 and pyrimidine in acetonitrile using an antisolvent. On heating, 5 decomposes into a new polymorphic 1:1 compound 6, which consists of (ZnI2)(pyrimidine) chains. On further heating, 6 transforms into a third polymorphic 1:1 compound 7, which consists of (ZnI2)3(pyrimidine)3 rings, and finally into the 1:1 compound 3. Solvent-mediated conversion experiments reveal that compounds 1-4 are thermodynamically stable, whereas compounds 5-7 are metastable. Time-dependent crystallization experiments unambiguously show that compound 7 is formed by kinetic control and transforms within minutes into compound 6, which finally transforms into 3. Compound 3 represents the thermodynamically most stable 1:1 modification, whereas compounds 6 and 7 are metastable. The different compounds obtained by thermal decomposition and by crystallization from solution represent a snapshot of the species in solution and thus provide insight into the formation of coordination compounds.
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Affiliation(s)
- Christian Näther
- Institut für Anorganische Chemie der Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany.
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65
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Picker-Freyer KM, Liao X, Zhang G, Wiedmann TS. Evaluation of the compaction of sulfathiazole polymorphs. J Pharm Sci 2007; 96:2111-24. [PMID: 17565752 DOI: 10.1002/jps.21042] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The aim of this study was to relate the tableting performance assessed by an instrumented tableting machine to the mechanical properties measured by nanoindentation. Three different polymorphic forms of sulfathiazole were prepared by recrystallization, and the density and X-ray powder diffraction patterns were measured and compared with theoretical density and simulated powder patterns, respectively. Tablets were prepared using a series of applied pressures, and the results were subjected to energy analysis, three dimensional (3D) modeling, and the traditional Heckel analysis. With these approaches, form I was found to be consistently the most brittle material, but the subtle differences between forms II and III were only revealed by 3D modeling. The rank order of the crushing force was found to be I is congruent to II < III. From nanoindentation, form III was found to be much harder than forms I and II, and III also had a much higher Young's modulus. The energy calculations of the nanoindentation curves showed that form III was distinct from forms I and II, which is consistent with the presence of slip planes that are only present in form III. However, in this system, there was little correspondence between the macroscopic and microscopic measurements, and thus particle-particle interactions may to be of paramount importance.
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Affiliation(s)
- Katharina Maria Picker-Freyer
- Institute of Pharmaceutics and Biopharmaceutics, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle/Saale, Germany.
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66
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Caputo G, Reverchon E. Use of Urea as Habit Modifier in the Supercritical Antisolvent Micronization of Sulfathiazole. Ind Eng Chem Res 2007. [DOI: 10.1021/ie061629z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Giuseppe Caputo
- Dipartimento di Ingegneria Chimica e Alimentare, Università di Salerno, Via Ponte don Melillo 1, Fisciano (SA), I-84084, Italy
| | - Ernesto Reverchon
- Dipartimento di Ingegneria Chimica e Alimentare, Università di Salerno, Via Ponte don Melillo 1, Fisciano (SA), I-84084, Italy
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67
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Drebushchak TN, Mikhailenko MA, Drebushchak VA, Boldyreva EV. Synthesis and crystal structures of two polymorphs of sulfathiazole:pyridine (1:1) adducts. Struct Chem 2007. [DOI: 10.1007/s11224-007-9173-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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68
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Zeitler JA, Newnham DA, Taday PF, Threlfall TL, Lancaster RW, Berg RW, Strachan CJ, Pepper M, Gordon KC, Rades T. Characterization of Temperature-Induced Phase Transitions in Five Polymorphic Forms of Sulfathiazole by Terahertz Pulsed Spectroscopy and Differential Scanning Calorimetry. J Pharm Sci 2006; 95:2486-98. [PMID: 16892211 DOI: 10.1002/jps.20719] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The far-infrared properties of all five known polymorphic forms of the drug sulfathiazole have been studied by terahertz pulsed spectroscopy and low-frequency Raman spectroscopy. The observed spectra of the different polymorphs are distinctly different. Terahertz pulsed spectroscopy proves to be a rapid and complementary alternative to other physical characterization techniques reported in the literature for distinguishing between the five forms. Variable-temperature measurements (293-473 K) of all polymorphic forms have been performed. The phase transitions observed have been related to thermal analysis data. Form I is the form stable at high temperature of sulfathiazole with a melting point of about 475 K. Form II melts at around 470 K and recrystallizes at higher temperatures to form I. Forms III, IV, and V all convert to form I via a solid-solid phase transition at temperatures below 450 K. The phase transitions can be monitored by terahertz pulsed spectroscopy. Polymorphic impurities of the samples can be detected in the room temperature spectra and their effect on the phase transition behavior can be studied.
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Affiliation(s)
- J Axel Zeitler
- School of Pharmacy, University of Otago, PO Box 56, Dunedin, New Zealand
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69
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Florence AJ, Johnston A, Price SL, Nowell H, Kennedy AR, Shankland N. An Automated Parallel Crystallisation Search for Predicted Crystal Structures and Packing Motifs of Carbamazepine. J Pharm Sci 2006; 95:1918-30. [PMID: 16850425 DOI: 10.1002/jps.20647] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
An automated parallel crystallisation search for physical forms of carbamazepine, covering 66 solvents and five crystallisation protocols, identified three anhydrous polymorphs (forms I-III), one hydrate and eight organic solvates, including the single-crystal structures of three previously unreported solvates (N,N-dimethylformamide (1:1); hemi-furfural; hemi-1,4-dioxane). Correlation of physical form outcome with the crystallisation conditions demonstrated that the solvent adopts a relatively nonspecific role in determining which polymorph is obtained, and that the previously reported effect of a polymer template facilitating the formation of form IV could not be reproduced by solvent crystallisation alone. In the accompanying computational search, approximately half of the energetically feasible predicted crystal structures exhibit the C=O...H--N R2(2)(8)dimer motif that is observed in the known polymorphs, with the most stable correctly corresponding to form III. Most of the other energetically feasible structures, including the global minimum, have a C=O...H--N C(4) chain hydrogen bond motif. No such chain structures were observed in this or any other previously published work, suggesting that kinetic, rather than thermodynamic, factors determine which of the energetically feasible crystal structures are observed experimentally, with the kinetics apparently favouring nucleation of crystal structures based on the CBZ-CBZ R2(2)(8) motif.
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Affiliation(s)
- Alastair J Florence
- Department of Pharmaceutical Sciences, University of Strathclyde, 27 Taylor Street, Glasgow G4 0NR, UK.
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70
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Hooton JC, German CS, Davies MC, Roberts CJ. A comparison of morphology and surface energy characteristics of sulfathiazole polymorphs based upon single particle studies. Eur J Pharm Sci 2006; 28:315-24. [PMID: 16713199 DOI: 10.1016/j.ejps.2006.03.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2005] [Revised: 01/26/2006] [Accepted: 03/20/2006] [Indexed: 10/24/2022]
Abstract
The morphological, adhesion and surface energetic properties of three sulfathiazole polymorphs (III, IV and polymorph I prepared from both acetone and methanol, designated I-ace and I-met, respectively) produced using Nektar supercritical fluid (SCF) technology have been characterized using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface roughness values for each polymorph were determined at different length scales. At sample sizes less than 1micromx1microm the polymorphs rank in terms of roughness as follows: I-met>I-ace approximately equal to IV>III. At the larger scales the polymorphs rank in terms of roughness as follows: I-met>III>I-ace approximately equal to IV. The surface energies for polymorphs determined against graphite (HOPG) and particles of the same polymorph were, respectively, I-met: 0.99mJm(-2) (S.D. 1.25mJm(-2)), 3.09mJm(-2) (S.D. 2.67mJm(-2)); I-ace: 309mJm(-2) (S.D. 329mJm(-2)), 16mJm(-2) (S.D. 11mJm(-2)); III: 1.17mJm(-2) (S.D. 1.5mJm(-2)), 5.4mJm(-2) (S.D. 3.6mJm(-2)); IV: 20.35mJm(-2) (S.D. 28.5mJm(-2)), 16.8mJm(-2) (S.D. 9.6mJm(-2)). In terms of surface energies the polymorphs hence rank I-ace>IV>III approximately equal to I-met (HOPG adhesion measurements) and IV approximately equal to I-ace>III>I-met (particle cohesion measurements). Consideration of contacting asperities and surface roughness was shown to have limited effect on the surface energies, and instead the differences were ascribed to variations in the surface chemistry as a result of changes in crystallization mechanisms.
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Affiliation(s)
- Jennifer C Hooton
- Laboratory of Biophysics and Surface Analysis, School of Pharmacy, University of Nottingham, NG7 2RD United Kingdom
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71
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Kelleher JM, Lawrence SE, Moynihan HA. Effect of the steric demand and hydrogen bonding capability of additives on the crystal polymorphism of sulfathiazole. CrystEngComm 2006. [DOI: 10.1039/b516716g] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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72
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Muster TH, Prestidge CA. Water Adsorption Kinetics and Contact Angles of Pharmaceutical Powders. J Pharm Sci 2005; 94:861-72. [PMID: 15736196 DOI: 10.1002/jps.20296] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Water sorption kinetics and water contact angles have been characterized for a range of pharmaceutical powders: ambroxol hydrochloride, griseofulvin, N,n-octyl-D-gluconamide, paracetamol, sulfathiazole, and theophylline. The uptake of water by powder samples at saturated vapor pressure was modeled using a pseudo first-order kinetic relationship. Parameters from this model have been correlated with the concentration and reactivity of the active surface sites of the pharmaceutical powders and their contact angles. The study has shown that analysis of water adsorption kinetics can be a powerful technique for characterizing the surface chemistry and wettability of pharmaceutical powders, and is particularly sensitive to their surface modification through excipient adsorption: ethyl(hydroxyethyl)cellulose treatment of griseofulvin and butyryl chloride treatment of sulfathiazole are reported as case studies.
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Affiliation(s)
- Tim H Muster
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
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73
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Gu CH, Li H, Gandhi RB, Raghavan K. Grouping solvents by statistical analysis of solvent property parameters: implication to polymorph screening. Int J Pharm 2004; 283:117-25. [PMID: 15363508 DOI: 10.1016/j.ijpharm.2004.06.021] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Revised: 06/24/2004] [Accepted: 06/24/2004] [Indexed: 11/19/2022]
Abstract
The success rate of discovering new polymorphs by crystallization from solution may be increased if solvents with diverse properties are used during initial polymorph screening. In this study, eight solvent parameters, including hydrogen bond acceptor propensity, hydrogen bond donor propensity, polarity/dipolarity, dipole moment, dielectric constant, viscosity, surface tension and cohesive energy density (equal to square of solubility parameter), of 96 solvents were collected. Using the cluster statistical analysis of the parameters, these 96 solvents were separated into 15 solvent groups. Such solvent groups may provide guidelines for the judicious choice of solvents with diverse properties for polymorph screening.
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Affiliation(s)
- Chong-Hui Gu
- Biopharmaceutics R&D, Bristol-Myers Squibb Co., 1 Squibb Drive, PO 191, New Brunswick, NJ, USA.
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74
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Aaltonen J, Rantanen J, Siiriä S, Karjalainen M, Jørgensen A, Laitinen N, Savolainen M, Seitavuopio P, Louhi-Kultanen M, Yliruusi J. Polymorph Screening Using Near-Infrared Spectroscopy. Anal Chem 2003. [DOI: 10.1021/ac034205c] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jaakko Aaltonen
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Jukka Rantanen
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Simo Siiriä
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Milja Karjalainen
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Anna Jørgensen
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Niklas Laitinen
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Marja Savolainen
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Paulus Seitavuopio
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Marjatta Louhi-Kultanen
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
| | - Jouko Yliruusi
- Pharmaceutical Technology Division and Viikki Drug Discovery Technology Center (DDTC) 00014 University of Helsinki, P.O. Box 56, Helsinki, Finland, and Department of Chemical Technology, Lappeenranta University of Technology, P.O. Box 20, 53851 Lappeenranta, Finland
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75
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Abstract
A variety of surface specific techniques have been used to determine the face-specific structure, chemistry, and wettability of model pharmaceutical crystals, i.e., N,n-octyl-d-gluconamide and sulfathiazole (polymorphic forms I and III). The surface energetics of individual crystal faces were investigated by studying their wetting characteristics and interaction with chemically modified silica spheres using colloid probe atomic force microscopy (AFM). Contact angles (dynamic and static), interaction forces, and adhesion properties have been shown to correlate strongly with the face specific surface chemistry. This, in turn, is controlled by the molecular arrangement at the specific crystal face, which has been characterized by time-of-flight secondary-ion mass spectrometry (ToF SIMS) and inferred from molecular models. Of specific note, the magnitude of the adhesion force between a crystal face and a hydrophobic colloid probe is related linearly to the face-specific equilibrium contact angle. These studies further our understanding of the face-specific properties of pharmaceutical crystals and have implications when considering processing, formulation and delivery.
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Affiliation(s)
- Tim H Muster
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
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76
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Muster TH, Prestidge CA. Application of time-dependent sessile drop contact angles on compacts to characterise the surface energetics of sulfathiazole crystals. Int J Pharm 2002; 234:43-54. [PMID: 11839436 DOI: 10.1016/s0378-5173(01)00949-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The time-dependent wetting of sulfathiazole compacts with sessile water drops was evaluated using video microscopy. The influence of sulfathiazole crystalline form, particle size, pre-saturation with water, humidity and compaction pressure on the droplet spreading kinetics and contact angles are reported. The rate and extent of droplet spreading decreased for compact surfaces of high microscopic roughness; this was determined by atomic force microscopy (AFM). Pre-saturation of powder compacts with water (pre-saturated with sulfathiazole) enhanced droplet spreading and enabled pseudo-equilibrium contact angles to be determined for up to 10 min. Sessile-drop contact angles on both sulfathiazole powder compacts and single crystals are compared with particle contact angles determined by liquid penetration. This study has led to an improved understanding of the influence of physical heterogeneities and the face-specific surface chemistry of individual crystals on the wetting characteristics of pharmaceutical compacts.
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Affiliation(s)
- Tim H Muster
- Ian Wark Research Institute, University of South Australia, The Levels Campus, Mawson Lakes, SA 5095, Australia
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77
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Davey RJ, Allen K, Blagden N, Cross WI, Lieberman HF, Quayle MJ, Righini S, Seton L, Tiddy GJT. Crystal engineering – nucleation, the key step. CrystEngComm 2002. [DOI: 10.1039/b203521a] [Citation(s) in RCA: 157] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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78
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Gu CH, Young V, Grant DJ. Polymorph screening: influence of solvents on the rate of solvent-mediated polymorphic transformation. J Pharm Sci 2001; 90:1878-90. [PMID: 11745745 DOI: 10.1002/jps.1137] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Solvent-mediated polymorphic transformation is an efficient technique to obtain the most stable polymorph. The rate of solvent-mediated polymorphic transformation of sulfamerazine at 24 degrees C in various solvents and solvent mixtures is controlled by the nucleation rate of the more stable Form II. The transformation rate is generally higher in the solvent giving a higher solubility and is low in the solvent giving a low solubility (8 mmol/L). In these solvents, because of a high interfacial energy, the metastable zone may be wider than the solubility difference between two polymorphs, such that the critical free energy barrier for nucleation cannot be overcome. In addition to the solubility, the strength of the solvent-solute interactions is also important in determining the transformation rate. For sulfamerazine, the transformation rate is lower in the solvent with a stronger hydrogen bond acceptor propensity. Because solubility is higher in the solvent with stronger hydrogen bond acceptor propensity, the balance of solubility and strength of hydrogen bonding interactions between the solute and solvent molecules determines the polymorphic transformation rate. Degree of agitation and temperature also change the polymorphic transformation rate by influencing the crystallization kinetics of the more stable polymorph.
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Affiliation(s)
- C H Gu
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Weaver-Densford Hall, 308 Harvard Street SE, Minneapolis, Minnesota 55455-0343, USA
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79
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80
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Anderson JE, Moore S, Tarczynski F, Walker D. Determination of the onset of crystallization of N1-2-(thiazolyl)sulfanilamide (sulfathiazole) by UV-Vis and calorimetry using an automated reaction platform; subsequent characterization of polymorphic forms using dispersive Raman spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2001; 57:1793-1808. [PMID: 11506030 DOI: 10.1016/s1386-1425(01)00407-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This work describes the use of UV/visible spectroscopy and calorimetry to follow the onset of crystallization of a commercially available compound, N(1)-2-(thiazolyl)sulfanilamide (sulfathiazole), during crystallization reactions performed using an automated reaction platform. Sulfathiazole has been the subject of numerous publications through which considerable confusion about the morphic form is apparent. This work does not attempt to investigate exhaustively the polymorph issue, but rather to exploit the use of the HEL auto-MATE for monitoring the onset of crystal formation. Real-time calorimetry and UV-Vis spectroscopy are compared as tools for determining the onset of crystallization. Subsequently, differential scanning calorimetry, dispersive Raman, and infrared spectroscopy analysis serve to identify the crystal forms generated by the HEL auto-MATE. A solvent-anti-solvent matrix and several bench-top crystallization experiments were performed to supplement the investigation in terms of generating the desired polymorphs.
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Affiliation(s)
- J E Anderson
- GlaxoWellcome, Research Triangle Park, NC 27709, USA
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81
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Abstract
Many drugs exist in the crystalline solid state due to reasons of stability and ease of handling during the various stages of drug development. Crystalline solids can exist in the form of polymorphs, solvates or hydrates. Phase transitions such as polymorph interconversion, desolvation of solvate, formation of hydrate and conversion of crystalline to amorphous form may occur during various pharmaceutical processes, which may alter the dissolution rate and transport characteristics of the drug. Hence it is desirable to choose the most suitable and stable form of the drug in the initial stages of drug development. The current focus of research in the solid-state area is to understand the origins of polymorphism at the molecular level, and to predict and prepare the most stable polymorph of a drug. The recent advances in computational tools allow the prediction of possible polymorphs of the drug from its molecular structure. Sensitive analytical methods are being developed to understand the nature of polymorphism and to characterize the various crystalline forms of a drug in its dosage form. The aim of this review is to emphasize the recent advances made in the area of prediction and characterization of polymorphs and solvates, to address the current challenges faced by pharmaceutical scientists and to anticipate future developments.
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Affiliation(s)
- S R Vippagunta
- Department of Pharmaceutics, College of Pharmacy, University of Minnesota, Weaver-Densford Hall, 308 Harvard Street S.E., Minneapolis, MN 55455, USA
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82
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Vrcelj RM, Gallagher HG, Sherwood JN. Polymorphism in 2,4,6-trinitrotoluene crystallized from solution. J Am Chem Soc 2001; 123:2291-5. [PMID: 11456877 DOI: 10.1021/ja0031422] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An examination has been made of the role of solvent type in the definition of the polymorphic nature of 2,4,6-trinitrotoluene precipitated from solution. A combination of calorimetric and structural techniques including in situ crystallization studies using synchrotron radiation has shown that the variations in polymorphic form following precipitation from solution do not arise specifically from any stereospecific guidance that the nature of the solvent might impose on the structural form. Rather the differences are linked to the variations in solubility and hence supersaturation which might build up prior to nucleation and growth and to the isolation of the metastable orthorhombic phase from the solvent. The final conclusion is that the changes fit well with Ostwald's Law of Stages with the orthorhombic form always precipitating initially followed by its conversion to the stable monoclinic form. The previously observed tendency for some solvents to yield one or the other form then becomes attributable to kinetics in solution rather than structural control. It can be associated with the solubility of the material in the solvent used and the role of this factor in a solvent-mediated phase transformation. On this basis rules can be formulated for the isolation of the metastable forms of this and similarly related polymorphic systems.
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Affiliation(s)
- R M Vrcelj
- Contribution from the Department of Pure and Applied Chemistry and Department of Physics and Applied Physics, University of Strathclyde, Glasgow G1 1XL, Scotland, UK
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83
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Threlfall T. Crystallisation of Polymorphs: Thermodynamic Insight into the Role of Solvent. Org Process Res Dev 2000. [DOI: 10.1021/op000058y] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Terry Threlfall
- Chemistry Department, University of York, Heslington, York, YO10 5DD, U.K
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84
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Kapsabelis S, Prestidge CA. Adsorption of Ethyl(hydroxyethyl)cellulose onto Silica Particles: The Role of Surface Chemistry and Temperature. J Colloid Interface Sci 2000; 228:297-305. [PMID: 10926470 DOI: 10.1006/jcis.2000.6976] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The adsorption characteristics of an ethyl(hydroxyethyl)cellulose (EHEC) polymer onto colloidal silica particles from aqueous solution have been investigated. The influence of solution temperature and the silica surface chemistry on EHEC adsorption isotherms and adsorbed layer thicknesses have been determined in an attempt to elucidate the mechanisms of adsorption. As the hydrophobicity of the silica particles are increased by physical and chemical treatment, the plateau EHEC adsorbed amount increased, while the corresponding adsorbed layer thickness decreased. The estimated free energy of adsorption (DeltaG(o)(ads)) was shown to be dependent on the silica surface chemistry, but did not correlate directly with silica's advancing water contact angle and suggests that EHEC adsorption is not directly controlled by hydrophobicity alone. As the solution temperature increased from 18 to 37 degrees C, the plateau coverage of EHEC increased while the layer thickness generally decreased, this concurred with a reduction in the solvency. For hydrophilic and dehydrated silica particles, DeltaG(o)(ads) decreased in magnitude with increasing temperature, whereas for chemically treated silica, DeltaG(o)(ads) increased with temperature. These findings are discussed with respect to the specific interactions between EHEC segments and surface sites, which control the adsorption mechanisms of cellulose polymers. Copyright 2000 Academic Press.
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Affiliation(s)
- S Kapsabelis
- Ian Wark Research Institute, University of South Australia, Mawson Lakes, Adelaide, SA 5095, Australia
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85
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Yu L, Reutzel-Edens SM, Mitchell CA. Crystallization and Polymorphism of Conformationally Flexible Molecules: Problems, Patterns, and Strategies. Org Process Res Dev 2000. [DOI: 10.1021/op000028v] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lian Yu
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana 46285, U.S.A
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86
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Williams-Seton L, Davey RJ, Lieberman HF, Pritchard RG. Disorder and twinning in molecular crystals: impurity-induced effects in adipic acid. J Pharm Sci 2000; 89:346-54. [PMID: 10707015 DOI: 10.1002/(sici)1520-6017(200003)89:3<346::aid-jps6>3.0.co;2-i] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The variation in physical properties of crystals grown in the presence of additives or impurities have previously been attributed to lattice disorder developed during crystallization. Adipic acid crystallized in the presence of a variety of stereochemically related impurities typifies such behavior with disorder manifest in variations of dissolution rates and enthalpies of solution and fusion. In this case the most extreme habit, produced by the presence of added monoalkanoic acids, is a rounded dumbbell that was suggested previously to be a twinned crystal. In this contribution such crystals are fully characterized both through their external morphology and by means of single crystal X-ray diffraction. These techniques show that these particles are not twinned but rather are disordered single crystals comprising a small number of slightly misaligned domains. The interaction between additive and substrate is modeled and new additives selected that induce the formation of true mechanical twins in adipic acid.
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Affiliation(s)
- L Williams-Seton
- Colloids, Crystals and Interfaces Group, Department of Chemical Engineering, UMIST, Manchester M60 1QD, UK
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87
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Roberts RJ, Payne RS, Rowe RC. Mechanical property predictions for polymorphs of sulphathiazole and carbamazepine. Eur J Pharm Sci 2000; 9:277-83. [PMID: 10594385 DOI: 10.1016/s0928-0987(99)00065-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The mechanical properties of polymorphs of sulphathiazole and carbamazepine have been determined experimentally by three-point beam bending. It is shown that the mechanical properties of sulphathiazole and carbamazepine polymorphs can be predicted using the atom-atom potential model applied to lattice dynamics, as long as account is taken of crystal morphology when considering the experimental results.
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Affiliation(s)
- R J Roberts
- ZENECA Pharmaceuticals, Silk Road Business Park, Charter Way, Macclesfield, Cheshire, UK.
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88
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Apperley DC, Fletton RA, Harris RK, Lancaster RW, Tavener S, Threlfall TL. Sulfathiazole polymorphism studied by magic-angle spinning NMR. J Pharm Sci 1999; 88:1275-80. [PMID: 10585222 DOI: 10.1021/js990175a] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The literature on sulfathiazole polymorphs has many confusions and inconsistencies. These are largely resolved by the distinctive appearance of (13)C magic-angle spinning NMR spectra, which immediately show the number of molecules in the crystallographic asymmetric unit. The spectra presented include those of a newly-recognized form. The assignments of the spectra are established and discussed in relation to such factors as electronic structure of the aromatic ring, second-order quadrupolar effects originating from the nitrogen nuclei, and hydrogen bonding. The results are compared to literature information on the crystal structures. When the amino group acts as a hydrogen bond acceptor, there is a shielding effect on C-4 to the extent of ca. 8 ppm (which should be compared to a further shielding by ca. 10 ppm for sulfathiazole sulfate). The fact that the spectrum of form III is similar to the sum of those of forms IV and V is rationalized in relation to the crystal structures. Some surprising variability of spectra with temperature and with specific sample is reported.
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Affiliation(s)
- D C Apperley
- Industrial Research Laboratories, University of Durham, South Road, Durham, DH1 3LE, U.K
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89
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Hammond RB, Roberts KJ, Smith EDL, Docherty R. Application of a Computational Systematic Search Strategy to Study Polymorphism in Phenazine and Perylene. J Phys Chem B 1999. [DOI: 10.1021/jp984419b] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Robert B. Hammond
- Centre for Molecular and Interface Engineering, Department of Mechanical and Chemical Engineering, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, U.K
| | - Kevin J. Roberts
- Centre for Molecular and Interface Engineering, Department of Mechanical and Chemical Engineering, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, U.K
| | - Elaine D. L. Smith
- Centre for Molecular and Interface Engineering, Department of Mechanical and Chemical Engineering, Heriot-Watt University, Riccarton, Edinburgh, EH14 4AS, U.K
| | - Robert Docherty
- Zeneca Specialties Research Centre, Hexagon House, Blackley, Manchester, M9 8ZS, U.K
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90
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Rodríguez-Hornedo N, Murphy D. Significance of controlling crystallization mechanisms and kinetics in pharmaceutical systems. J Pharm Sci 1999; 88:651-60. [PMID: 10393562 DOI: 10.1021/js980490h] [Citation(s) in RCA: 299] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N Rodríguez-Hornedo
- College of Pharmacy, University of Michigan, Ann Arbor, Michigan 48109-1065, USA.
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91
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Williams-Seton L, Davey RJ, Lieberman HF. Solution Chemistry and Twinning in Saccharin Crystals: A Combined Probe for the Structure and Functionality of the Crystal−Fluid Interface. J Am Chem Soc 1999. [DOI: 10.1021/ja984112q] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- L. Williams-Seton
- Contribution from the Crystals, Colloids and Interfaces Group, Department of Chemical Engineering, UMIST, P.O. Box 88, Manchester M60 1QD, U.K
| | - R. J. Davey
- Contribution from the Crystals, Colloids and Interfaces Group, Department of Chemical Engineering, UMIST, P.O. Box 88, Manchester M60 1QD, U.K
| | - H. F. Lieberman
- Contribution from the Crystals, Colloids and Interfaces Group, Department of Chemical Engineering, UMIST, P.O. Box 88, Manchester M60 1QD, U.K
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92
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Blagden N, Davey R, Rowe R, Roberts R. Disappearing polymorphs and the role of reaction by-products: the case of sulphathiazole. Int J Pharm 1998. [DOI: 10.1016/s0378-5173(98)00205-1] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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