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Influence of Air Temperature and Humidity on Dehydration Equilibria and Kinetics of Theophylline.

Touil A, Peczalski R, Timoumi S, Zagrouba F - J Pharm (Cairo) (2012)

Bottom Line: The water content evolutions with time were recorded at several temperatures from 20°C to 80°C and several relative humidities from 4% to 50%.Different mathematical models were used to fit the experimental data.The spatially averaged solution of 2D Fickian transient diffusion equation best represented the water mass loss versus time experimental relationship.

View Article: PubMed Central - PubMed

Affiliation: Ecole Nationale d'Ingénieurs de Gabès (ENIG), Université de Gabès, rue Omar Ibn-Elkhattab, Gabès 6029, Tunisia.

ABSTRACT
The effect of hygrothermal conditions (air temperature and relative humidity) on the dehydration of theophylline monohydrate was investigated. Firstly, the equilibrium states of theophylline were investigated. The data from gravimetric analysis at constant temperature and humidity were reported as desorption isotherms. The PXRD analysis was used to identify the different polymorphic forms of theophylline: the monohydrate, the metastable anhydrate, and the stable anhydrate. Solid-solid phase diagrams for two processing times were proposed. Secondly, the dehydration kinetics were studied. The water content evolutions with time were recorded at several temperatures from 20°C to 80°C and several relative humidities from 4% to 50%. Different mathematical models were used to fit the experimental data. The spatially averaged solution of 2D Fickian transient diffusion equation best represented the water mass loss versus time experimental relationship. The dehydration rate constant was found to increase exponentially with air temperature and to decrease exponentially with air relative humidity.

No MeSH data available.


Related in: MedlinePlus

Solid-solid phase diagram of theophylline after one month of processing at different environmental conditions.
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fig8: Solid-solid phase diagram of theophylline after one month of processing at different environmental conditions.

Mentions: A second solid-solid phase diagram corresponding to equilibrium states (after one month) of theophylline monohydrate processing at different relative humidities and different temperatures is presented on Figure 8. It exhibits only the two forms of theophylline: the monohydrate (M) and the stable anhydrate form (II). The data from studies of Suzuki et al. [2] and Ticehurst et al. [5] are also shown.


Influence of Air Temperature and Humidity on Dehydration Equilibria and Kinetics of Theophylline.

Touil A, Peczalski R, Timoumi S, Zagrouba F - J Pharm (Cairo) (2012)

Solid-solid phase diagram of theophylline after one month of processing at different environmental conditions.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4595972&req=5

fig8: Solid-solid phase diagram of theophylline after one month of processing at different environmental conditions.
Mentions: A second solid-solid phase diagram corresponding to equilibrium states (after one month) of theophylline monohydrate processing at different relative humidities and different temperatures is presented on Figure 8. It exhibits only the two forms of theophylline: the monohydrate (M) and the stable anhydrate form (II). The data from studies of Suzuki et al. [2] and Ticehurst et al. [5] are also shown.

Bottom Line: The water content evolutions with time were recorded at several temperatures from 20°C to 80°C and several relative humidities from 4% to 50%.Different mathematical models were used to fit the experimental data.The spatially averaged solution of 2D Fickian transient diffusion equation best represented the water mass loss versus time experimental relationship.

View Article: PubMed Central - PubMed

Affiliation: Ecole Nationale d'Ingénieurs de Gabès (ENIG), Université de Gabès, rue Omar Ibn-Elkhattab, Gabès 6029, Tunisia.

ABSTRACT
The effect of hygrothermal conditions (air temperature and relative humidity) on the dehydration of theophylline monohydrate was investigated. Firstly, the equilibrium states of theophylline were investigated. The data from gravimetric analysis at constant temperature and humidity were reported as desorption isotherms. The PXRD analysis was used to identify the different polymorphic forms of theophylline: the monohydrate, the metastable anhydrate, and the stable anhydrate. Solid-solid phase diagrams for two processing times were proposed. Secondly, the dehydration kinetics were studied. The water content evolutions with time were recorded at several temperatures from 20°C to 80°C and several relative humidities from 4% to 50%. Different mathematical models were used to fit the experimental data. The spatially averaged solution of 2D Fickian transient diffusion equation best represented the water mass loss versus time experimental relationship. The dehydration rate constant was found to increase exponentially with air temperature and to decrease exponentially with air relative humidity.

No MeSH data available.


Related in: MedlinePlus