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In-situ Monitoring of Polymorph Crystallisation and Interconversion Solvent Dependence

In-situ Monitoring of Polymorph Crystallisation and Interconversion Solvent Dependence

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In-situ Monitoring of Polymorph Crystallisation and Interconversion Solvent Dependence

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  1. In-situ Monitoring of Polymorph Crystallisation and Interconversion Solvent Dependence N. Blagden1, A. C. Williams1, S. W. Booth2 and C. R. Petts2. 1School of Pharmacy, University of Bradford, UK. 2Merck Sharp & Dohme, Hoddesdon, UK. Luciana De Matos1

  2. INTRODUCTION • Polymorph behaviour. • Crystallisation. • Molecular aggregation. • Nucleation. • Crystal growth. • Phase-interconversion.

  3. AIMS • Polymorph screening of model drug. • Monitor phase-interconversions in different environments. • Molecular organisation relationship: - Molecular aggregates vs. crystalline forms.

  4. COMPOUND SELECTION • Three reported polymorphs. Piracetam (2-oxo-pyrrolidineacetamide) Form III Form II Form I Piracetam polymorphs diffraction patterns.

  5. Small molecule with high functionality. COMPOUND SELECTION Piracetam (2-oxo-pyrrolidineacetamide)

  6. Therapeutic application: - Pioneer nootropic drug. - Cognition enhancer. - Dementia, Alzheimer's disease, etc. COMPOUND SELECTION Piracetam (2-oxo-pyrrolidineacetamide)

  7. POLYMORPH SCREENING • Quench-cooling crystallisation: • Methanol, 2-Propanol and Nitromethane. • Characterisation: • Microscopy. • Thermal gravimetric analysis. • Differential scanning calorimetry. • Powder X-ray diffraction. • Single crystal X-ray diffraction.

  8. POLYMORPH SCREENING

  9. POLYMORPH SCREENING • Form I crystals: - White irregular shape, unstable at 25° C. • Forms II & III: - Prismatic morphology, stable at 25° C. 120 µm Form I Form II Form III

  10. EDS-XRD Energy Dispersive Synchrotron X-Ray Diffraction: • Station 16.4 at Daresbury Laboratory of CCLRC, UK. • Initially non-saturated solutions. • Sequence of fixed time scans. • Temperature reduced over time.

  11. Stirrer at 300 rpm Temperature probe Crystalliser * View of stirrer blade showing 5° torsion “Plume” of crystals Temperature control unit linked to digital monitor Copper sleeve Insulated crystalliser holder Electric heating unit. Cooling unit. (50/50 glycol/water) Heating-cooling loop X-Ray beam passage EDS-XRD • EDS-XRD experimental protocol: * Blagden, N., Davey, R.J., Song, M., Quayle, M.J., Clark, S., Taylor, D. & Nield, A. (2002). J. CrystalGrowth & Design 3 (2), 197-201.

  12. No crystals Form I Teflon Form III EDS-XRD • Piracetam crystallisation in methanol :

  13. No crystals Form I Teflon Form II Form III EDS-XRD • Piracetam crystallisation in 2-propanol:

  14. No crystals Form I Teflon Form II Form III EDS-XRD • Piracetam crystallisation in nitromethane: Rel. intensity / counts

  15. RAMAN SPECTROSCOPY • Spectra collected: - At room temperature. - Non-saturated solutions. - Crystalline material. - Measured at 488, 785 and 1064 nm.

  16. RAMAN SPECTROSCOPY • 2-Propanol and nitromethane solutions: - Low concentration at room temperature. - Piracetam not observed in solution. • Methanol solution: - Piracetam molecular clusters observed. • Form I spectrum not obtained.

  17. RAMAN SPECTROSCOPY • Example of Raman spectra measured at 785 nm.

  18. CONCLUSIONS • Form I acts as an initial intermediate. • Piracetam polymorphs observed: - Methanol: Form I Form III. - 2-Propanol: Form I Form III Form II. - Nitromethane: Form I Form III Form II.

  19. CONCLUSIONS • Suggested lattice organisation of piracetam molecules in methanol. • Solution organisation of clusters does not reflect the ones observed in forms II or III. • Polymorph-specific clusters?

  20. ACKNOWLEDGEMENTS • School of Life Sciences, University of Bradford. • Merck Sharp & Dohme. • Erice Organising Committee. • Station 16.4 at Daresbury Laboratory CCLRC. • Prof. Roger Davey and group, UMIST. • Dr. Ian Scowen and Dr. Colin Seaton, University of Bradford.

  21. THANK YOU