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Schrode B, Bodak B, Riegler H, Zimmer A, Christian P, Werzer O. Solvent Vapor Annealing of Amorphous Carbamazepine Films for Fast Polymorph Screening and Dissolution Alteration. ACS OMEGA 2017; 2:5582-5590. [PMID: 28983522 PMCID: PMC5623942 DOI: 10.1021/acsomega.7b00783] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 08/24/2017] [Indexed: 06/07/2023]
Abstract
Solubility enhancement and thus higher bioavailability are of great importance and a constant challenge in pharmaceutical research whereby polymorph screening and selection is one of the most important tasks. A very promising approach for polymorph screening is solvent vapor annealing where a sample is exposed to an atmosphere saturated with molecules of a specific chemical/solvent. In this work, amorphous carbamazepine thin films were prepared by spin coating, and the transformation into crystalline forms under exposure to solvent vapors was investigated. Employing grazing incidence X-ray diffraction, four distinct carbamazepine polymorphs, a solvate, and hydrates could be identified, while optical microscopy showed mainly spherulitic morphologies. In vitro dissolution experiments revealed different carbamazepine release from the various thin-film samples containing distinct polymorphic compositions: heat treatment of amorphous samples at 80 °C results in an immediate release; samples exposed to EtOH vapors show a drug release about 5 times slower than this immediate one; and all the others had intermediate release profiles. Noteworthy, even the sample of slowest release has a manifold faster release compared to a standard powder sample demonstrating the capabilities of thin-film preparation for faster drug release in general. Despite the small number of samples in this screening experiment, the results clearly show how solvent vapor annealing can assist in identifying potential polymorphs and allows for estimating their impact on properties like bioavailability.
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Affiliation(s)
- Benedikt Schrode
- Institute
of Pharmaceutical Sciences, NAWI Graz, Department of Pharmaceutical
Technology, University Graz, Universtitätsplatz 1, 8010 Graz, Austria
- Institute
for Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Brigitta Bodak
- Institute
of Pharmaceutical Sciences, NAWI Graz, Department of Pharmaceutical
Technology, University Graz, Universtitätsplatz 1, 8010 Graz, Austria
| | - Hans Riegler
- Institute
of Pharmaceutical Sciences, NAWI Graz, Department of Pharmaceutical
Technology, University Graz, Universtitätsplatz 1, 8010 Graz, Austria
| | - Andreas Zimmer
- Institute
of Pharmaceutical Sciences, NAWI Graz, Department of Pharmaceutical
Technology, University Graz, Universtitätsplatz 1, 8010 Graz, Austria
| | - Paul Christian
- Institute
for Solid State Physics, NAWI Graz, Graz
University of Technology, Petersgasse 16, 8010 Graz, Austria
| | - Oliver Werzer
- Institute
of Pharmaceutical Sciences, NAWI Graz, Department of Pharmaceutical
Technology, University Graz, Universtitätsplatz 1, 8010 Graz, Austria
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Christian P, Ehmann H, Coclite AM, Werzer O. Polymer Encapsulation of an Amorphous Pharmaceutical by initiated Chemical Vapor Deposition for Enhanced Stability. ACS APPLIED MATERIALS & INTERFACES 2016; 8:21177-84. [PMID: 27467099 PMCID: PMC4999961 DOI: 10.1021/acsami.6b06015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 07/28/2016] [Indexed: 05/22/2023]
Abstract
The usage of amorphous solids in practical applications, such as in medication, is commonly limited by the poor long-term stability of this state, because unwanted crystalline transitions occur. In this study, three different polymeric coatings are investigated for their ability to stabilize amorphous films of the model drug clotrimazole and to protect against thermally induced transitions. For this, drop cast films of clotrimazole are encapsulated by initiated chemical vapor deposition (iCVD), using perfluorodecyl acrylate (PFDA), hydroxyethyl methacrylate (HEMA), and methacrylic acid (MAA). The iCVD technique operates under solvent-free conditions at low temperatures, thus leaving the solid state of the encapsulated layer unaffected. Optical microscopy and X-ray diffraction data reveal that at ambient conditions of about 22 °C, any of these iCVD layers extends the lifetime of the amorphous state significantly. At higher temperatures (50 or 70 °C), the p-PFDA coating is unable to provide protection, while the p-HEMA and p-MAA strongly reduce the crystallization rate. Furthermore, p-HEMA and p-MAA selectively facilitate a preferential alignment of clotrimazole and, interestingly, even suppress crystallization upon a temporary, rapid temperature increase (3 °C/min, up to 150 °C). The results of this study demonstrate how a polymeric coating, synthesized directly on top of an amorphous phase, can act as a stabilizing agent against crystalline transitions, which makes this approach interesting for a variety of applications.
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Affiliation(s)
- Paul Christian
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, 8010 Graz, Austria
| | - Heike
M.A. Ehmann
- Institute of Pharmaceutical Science, Department of Pharmaceutical
Technology, University of Graz, 8010 Graz, Austria
| | - Anna Maria Coclite
- Institute of Solid State Physics, NAWI Graz, Graz University of Technology, 8010 Graz, Austria
| | - Oliver Werzer
- Institute of Pharmaceutical Science, Department of Pharmaceutical
Technology, University of Graz, 8010 Graz, Austria
- E-mail:
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3
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Zhong J, Yan J. Seeing is believing: atomic force microscopy imaging for nanomaterial research. RSC Adv 2016. [DOI: 10.1039/c5ra22186b] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Atomic force microscopy can image nanomaterial properties such as the topography, elasticity, adhesion, friction, electrical properties, and magnetism.
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Affiliation(s)
- Jian Zhong
- College of Food Science & Technology
- Shanghai Ocean University
- Shanghai 201306
- People's Republic of China
| | - Juan Yan
- College of Food Science & Technology
- Shanghai Ocean University
- Shanghai 201306
- People's Republic of China
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Röthel C, Ehmann HMA, Baumgartner R, Reischl D, Werzer O. Alteration of texture and polymorph of phenytoin within thin films and its impact on dissolution. CrystEngComm 2016. [DOI: 10.1039/c5ce01889g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
By a change of texture and polymorph the dissolution characteristic of a drug molecule changes.
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Affiliation(s)
- Christian Röthel
- Institute of Pharmaceutical Science
- Department of Pharmaceutical Technology
- University of Graz
- 8010 Graz, Austria
- BioTechMed – Graz
| | - Heike M. A. Ehmann
- Graz University of Technology
- Institute for Chemistry and Technology of Materials
- Graz, Austria
| | - Ramona Baumgartner
- Institute of Pharmaceutical Science
- Department of Pharmaceutical Technology
- University of Graz
- 8010 Graz, Austria
- Research Center Pharmaceutical Engineering GmbH
| | - Daniela Reischl
- Institute of Pharmaceutical Science
- Department of Pharmaceutical Technology
- University of Graz
- 8010 Graz, Austria
| | - Oliver Werzer
- Institute of Pharmaceutical Science
- Department of Pharmaceutical Technology
- University of Graz
- 8010 Graz, Austria
- BioTechMed – Graz
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Reischl D, Röthel C, Christian P, Roblegg E, Ehmann HA, Salzmann I, Werzer O. Surface-Induced Polymorphism as a Tool for Enhanced Dissolution: The Example of Phenytoin. CRYSTAL GROWTH & DESIGN 2015; 15:4687-4693. [PMID: 26366128 PMCID: PMC4561386 DOI: 10.1021/acs.cgd.5b01002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/07/2015] [Indexed: 05/22/2023]
Abstract
Polymorphism and morphology can represent key factors tremendously limiting the bioavailability of active pharmaceutical ingredients (API), in particular, due to solubility issues. Within this work, the generation of a yet unknown surface-induced polymorph (SIP) of the model drug, 5,5-diphenylimidazolidin-2,4-dion (phenytoin), is demonstrated in thin films through altering the crystallization kinetics and the solvent type. Atomic force microscopy points toward the presence of large single-crystalline domains of the SIP, which is in contrast to samples comprising solely the bulk phase, where extended dendritic phenytoin networks are observed. Grazing incidence X-ray diffraction reveals unit cell dimensions of the SIP significantly different from those of the known bulk crystal structure of phenytoin. Moreover, the aqueous dissolution performance of the new polymorph is benchmarked against a pure bulk phase reference sample. Our results demonstrate that the SIP exhibits markedly advantageous drug release performance in terms of dissolution time. These findings suggest that thin-film growth of pharmaceutical systems in general should be explored, where poor aqueous dissolution represents a key limiting factor in pharmaceutical applications, and illustrate the experimental pathway for determining the physical properties of a pharmaceutically relevant SIP.
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Affiliation(s)
- Daniela Reischl
- Institute
for Pharmaceutical Sciences, Department of Pharmaceutical Technology, Karl-Franzens University of Graz, Universitätsplatz 1, 8010 Graz, Austria
| | - Christian Röthel
- Institute
for Pharmaceutical Sciences, Department of Pharmaceutical Technology, Karl-Franzens University of Graz, Universitätsplatz 1, 8010 Graz, Austria
- Institute for Solid State Physics, Institute for Chemistry and Technology of Materials, Graz University of Technology, 8010 Graz, Austria
| | - Paul Christian
- Institute
for Pharmaceutical Sciences, Department of Pharmaceutical Technology, Karl-Franzens University of Graz, Universitätsplatz 1, 8010 Graz, Austria
- Institute for Solid State Physics, Institute for Chemistry and Technology of Materials, Graz University of Technology, 8010 Graz, Austria
| | - Eva Roblegg
- Institute
for Pharmaceutical Sciences, Department of Pharmaceutical Technology, Karl-Franzens University of Graz, Universitätsplatz 1, 8010 Graz, Austria
| | - Heike
M. A. Ehmann
- Institute for Solid State Physics, Institute for Chemistry and Technology of Materials, Graz University of Technology, 8010 Graz, Austria
| | - Ingo Salzmann
- Department
of Physics, Humboldt-Universität
zu Berlin, Brook-Taylor
Straße 6, 12489 Berlin, Germany
| | - Oliver Werzer
- Institute
for Pharmaceutical Sciences, Department of Pharmaceutical Technology, Karl-Franzens University of Graz, Universitätsplatz 1, 8010 Graz, Austria
- E-mail:
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Ehmann HA, Baumgartner R, Reischl D, Roblegg E, Zimmer A, Resel R, Werzer O. One Polymorph and Various Morphologies of Phenytoin at a Silica Surface Due to Preparation Kinetics. CRYSTAL GROWTH & DESIGN 2015; 15:326-332. [PMID: 25593545 PMCID: PMC4288062 DOI: 10.1021/cg501391j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Revised: 11/03/2014] [Indexed: 05/22/2023]
Abstract
The preparation of solid crystalline films at surfaces is of great interest in a variety of fields. Within this work the preparation of pharmaceutically relevant thin films containing the active pharmaceutical ingredient phenytoin is demonstrated. The preparation techniques applied include drop casting, spin coating, and vacuum deposition. For the solution processed samples a decisive impact of the solution concentration and the applied film fabrication technique is observed; particular films form for all samples but with their extensions along different crystallographic directions strongly altered. Vacuum deposition of phenytoin reveals amorphous films, which over time crystallize into needle-like or particular-type structures whereby a nominal thickness of 50 nm is required to achieve a fully closed layer. Independent of all preparation techniques, the resulting polymorph is the same for each sample as confirmed by specular X-ray diffraction scans. Thus, morphologies observed via optical and atomic force microscope techniques are therefore a result of the preparation technique. This shows that the different time scales for which crystallization is obtained is the driving force for the various morphologies in phenytoin thin films rather than the presence of another polymorph forming.
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Affiliation(s)
- Heike
M. A. Ehmann
- Institute
of Pharmaceutical Sciences, Department of Pharmaceutical Technology, Graz University, 8010 Graz, Austria
| | - Ramona Baumgartner
- Institute
of Pharmaceutical Sciences, Department of Pharmaceutical Technology, Graz University, 8010 Graz, Austria
| | - Daniela Reischl
- Institute
of Pharmaceutical Sciences, Department of Pharmaceutical Technology, Graz University, 8010 Graz, Austria
| | - Eva Roblegg
- Institute
of Pharmaceutical Sciences, Department of Pharmaceutical Technology, Graz University, 8010 Graz, Austria
- Research Center
Pharmaceutical Engineering GmbH, 8010 Graz, Austria
| | - Andreas Zimmer
- Institute
of Pharmaceutical Sciences, Department of Pharmaceutical Technology, Graz University, 8010 Graz, Austria
| | - Roland Resel
- Institute
for Solid State Physics, Graz University
of Technology, 8010 Graz, Austria
| | - Oliver Werzer
- Institute
of Pharmaceutical Sciences, Department of Pharmaceutical Technology, Graz University, 8010 Graz, Austria
- E-mail:
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Ehmann HA, Baumgartner R, Kunert B, Zimmer A, Roblegg E, Werzer O. Morphologies of Phenytoin Crystals at Silica Model Surfaces: Vapor Annealing versus Drop Casting. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2014; 118:12855-12861. [PMID: 24966892 PMCID: PMC4065161 DOI: 10.1021/jp502330e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 05/27/2014] [Indexed: 05/11/2023]
Abstract
The controlled preparation of different crystal morphologies with varying preferential orientation with respect to the substrate is of crucial importance in many fields of applications. In this work, the controlled preparation of different phenytoin morphologies and the dependency of the preferential orientation of those crystallites is related with the preparation method (solvent annealing vs drop casting), as well as the physical-chemical interaction with the solvents in use. While solvent annealing induces the formation of particular structures that are partially dewetted, the drop casting technique from various solvent results in the formation of needle-like and elongated structures, with each having a distinct morphology. The morphologies are explained via the Hansen solubility parameters and correlated with the solvent vapor pressures. X-ray diffraction experiments reveal preferential orientations with respect to the solid substrate and indicate the surface-mediated stabilization of an unknown polymorph of phenytoin with an elongated unit cell in the b-axis.
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Affiliation(s)
- Heike
M. A. Ehmann
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
| | | | - Birgit Kunert
- Institute
for Solid State Physics, Graz University
of Technology, 8010 Graz, Austria
| | - Andreas Zimmer
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
| | - Eva Roblegg
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
- Research Center
Pharmaceutical Engineering GmbH, 8010 Graz, Austria
| | - Oliver Werzer
- Institute
of Pharmaceutical Science, Department of Pharmaceutical Technology, University of Graz, 8010 Graz, Austria
- E-mail:
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