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Published on: September 20, 2017
Surface-Induced Polymorphism as a Tool for Enhanced Dissolution: The Example of Phenytoin
Daniela Reischl1, Christian Röthel2, Paul Christian2
1Institute for Pharmaceutical Sciences, Department of Pharmaceutical Technology, Karl-Franzens University of Graz , Universitätsplatz 1, 8010 Graz, Austria.
A new surface-induced polymorph (SIP) of phenytoin was created in thin films. This novel phenytoin form shows improved dissolution performance, offering a promising approach for enhancing drug bioavailability.
Area of Science:
- Pharmaceutical Science
- Materials Science
- Crystallography
Background:
- Polymorphism and morphology significantly impact active pharmaceutical ingredient (API) bioavailability, often due to solubility limitations.
- Controlling crystallization kinetics and solvent type are crucial for generating desired API solid-state forms.
- Phenytoin, a model drug, faces bioavailability challenges that can be addressed through solid-state modifications.
Purpose of the Study:
- To generate and characterize a novel surface-induced polymorph (SIP) of phenytoin.
- To investigate the impact of thin-film crystallization on phenytoin's solid-state properties.
- To evaluate the aqueous dissolution performance of the newly discovered phenytoin SIP.
Main Methods:
- Thin-film crystallization was employed, manipulating crystallization kinetics and solvent choice.
- Atomic force microscopy (AFM) was used to analyze surface morphology and domain structure.
- Grazing incidence X-ray diffraction (GIXRD) determined the unit cell dimensions and crystal structure.
- Aqueous dissolution studies compared the performance of the SIP against the bulk phase.
Main Results:
- A previously unknown surface-induced polymorph (SIP) of phenytoin was successfully generated in thin films.
- AFM revealed large single-crystalline domains of the SIP, contrasting with dendritic networks of the bulk phase.
- GIXRD confirmed distinct unit cell dimensions for the SIP compared to the known phenytoin crystal structure.
- The phenytoin SIP demonstrated significantly improved aqueous dissolution performance and faster drug release.
Conclusions:
- Thin-film growth offers a viable strategy for producing novel polymorphs with enhanced pharmaceutical properties.
- The identified phenytoin SIP exhibits superior dissolution characteristics, potentially improving drug bioavailability.
- This study highlights the importance of exploring thin-film crystallization for optimizing APIs with poor aqueous solubility.
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