Probing the Distribution of Water in a Multi-Component System by Solid-State NMR Spectroscopy
Purpose To characterize the distribution of water among various components in a powder blend using solid-state NMR spectroscopy. Methods Water sorption behavior of theophylline anhydrate and excipients was determined by dynamic vapor sorption (DVS) and Karl Fischer Titration (KFT) after storing them...
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Published in | Pharmaceutical research Vol. 33; no. 10; pp. 2470 - 2480 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
New York
Springer US
01.10.2016
Springer Springer Nature B.V |
Subjects | |
Online Access | Get full text |
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Summary: | Purpose
To characterize the distribution of water among various components in a powder blend using solid-state NMR spectroscopy.
Methods
Water sorption behavior of theophylline anhydrate and excipients was determined by dynamic vapor sorption (DVS) and Karl Fischer Titration (KFT) after storing them in humidity chambers for 1 week at room temperature (RT) and calibration curves were generated for water content
vs.
1
H
T
1
relaxation times. Powder blends (either with microcrystalline cellulose or lactose as diluent) were stored at different relative humidity (RH) conditions and analyzed periodically using solid-state NMR, powder X-ray diffraction, and KFT.
Results
Anhydrous theophylline converted to the hydrate at ≥ 84% RH. Based on the calibration curves of water content
vs.
relaxation times, the distribution of water in the powder blends was estimated. The total water content calculated using ssNMR was in good agreement with values measured using KFT. In blends stored at 90% RH, theophylline anhydrate-to-hydrate conversion did not occur in 1 week.
Conclusions
The distribution of water in multi-component powder blends was successfully determined using correlation between
1
H
T
1
relaxation times and total water content. Excipient water sorption inhibited hydrate formation in theophylline at 90% RH. Water distribution was affected by excipient type. The extent of water sorbed by excipients in blends was found to be different than their standalone equilibrium water content. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0724-8741 1573-904X |
DOI: | 10.1007/s11095-016-1972-7 |