An investigation into the subambient behavior of aqueous mannitol solutions using differential scanning calorimetry, cold stage microscopy, and X-ray diffractometry

Kett, V.L, Fitzpatrick, S, Cooper, B and Craig, D.Q.M (2003) An investigation into the subambient behavior of aqueous mannitol solutions using differential scanning calorimetry, cold stage microscopy, and X-ray diffractometry. Journal of Pharmaceutical Sciences, 92 (9). pp. 1919-1929. ISSN 0022-3549

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Abstract

The subambient behavior of aqueous mannitol solutions is of considerable relevance to the preparation of freeze dried formulations. In this investigation the properties of 3% w/v mannitol solutions were investigated using differential scanning calorimetry (DSC), cold stage microscopy (CSM), and X-ray diffraction (XRD) to identify the thermal transitions and structural transformations undergone by this system. It was found that on cooling from ambient the system formed ice at circa -20°C while a further exotherm was seen at approximately -30°C. Upon reheating an endotherm was seen at circa -30°C followed immediately by an exotherm at circa -25°C. Temperature cycling indicated that the thermal transitions observed upon reheating were not reversible. Modulated temperature DSC (MTDSC) indicated that the transitions observed upon reheating corresponded to a glass transition immediately followed by recrystallization, XRD data showed that recrystallization was into the ß form. Annealing at -35°C for 40 min prior to cooling and reheating resulted in a maximum enthalpy being observed for the reheating exotherm. It is concluded that on cooling 3% w/v aqueous mannitol solutions an amorphous phase is formed that subsequently recrystallises into the ß form. The study has also shown that DSC, CSM, and XRD are useful complementary techniques for the study of frozen systems.

Item Type: Article
Uncontrolled Keywords: thermal analysis,microscopy,calorimetry (dsc),lyophilization,x-ray diffractometry,cryoprotectant,mannitol,amorphous
Faculty \ School: Faculty of Science > School of Pharmacy
Related URLs:
Depositing User: Rachel Smith
Date Deposited: 09 Mar 2011 15:53
Last Modified: 05 Nov 2018 16:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/25855
DOI: 10.1002/jps.10449

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