Abstract
A hydrated form of theophylline-7-acetic acid obtained by recrystallization from water is described and characterized in terms of thermal properties, physical stability with respect to relative humidity and dehydration kinetics. The hydrate resulted to be stable at ambient conditions. Fitting of experimental dehydration data to solid state reaction equations suggests a three dimensional phase boundary reaction proceeding from the surface of the crystal inward along three dimensions. The relevant activation energy calculated from the Arrhenius plot is 173 kJ/mol.
Similar content being viewed by others
References
Giron D, Mutz M, Garnier S. Solid-state of pharmaceutical compounds. J Thermal Anal. 2004;77:709–47.
Ferretti C, Coppi G, Blengio M, Genazzani E. Inhibitory effect of theophylline, theophylline-7-acetic acid, ambroxol and ambroxol-theophylline-7-acetate on rat lung cAMP phosphodiesterase isoenzymes. Int J Tissue React. 1992;14:31–6.
Zhang LJ, Liu MC, Ding JC, Wu HY. Crystal structure of theophylline-7-acetic acid, C9H10N4O4. Kristallogr. 2006;NCS221:59–60.
Giordano F, Foppoli A, Gazzaniga A, Caira MR, Vilakazi S. Thermal and structural properties of theophylline-7-acetic acid. Proceed. Phand T A8. 2004;PO15.
Nyqvist H. Saturated salt solutions for maintaining specified relative humidities. Int J Pharm Tech Prod Mfr. 1983;4:47–8.
Giron D, Goldbronn Ch, Mutz M, Pfeffer S, Piechon Ph, Schwab Ph. Solid state characterizations of pharmaceutical hydrates. J Thermal Anal. 2002;68:453–65.
Sekiguchi K, Shirotani K, Sakata O, Suzuki E. Kinetic study of the dehydration of sulfaguanidine under isothermal conditions. Chem Pharm Bull. 1984;32(4):1558–67.
Agbada CO, York P. Dehydration of theophylline monohydrate powder—effects of particle size and sample weight. Int J Pharm. 1994;106:33–40.
Han J, Suryanarayanan R. Influence of environmental conditions on the kinetics and mechanism of dehydration of carbamazepine dihydrate. Pharm Dev Tech. 1998;3(4):587–96.
Taylor LS, York P. Effect of particle size and temperature on the dehydration kinetics of trehalose dihydrate. Int J Pharm. 1998;167:215–21.
Petit S, Mallet F, Petit M-N, Coquerel G. Role of structural and macrocrystalline factors in the desolvation behaviour of cortisone acetate solvates. J Thermal Anal. 2007;90:39–47.
Sharp JH, Bridley GW, Narahari Achar BN. Numerical data for some commonly used solid state reaction equations. J Am Ceram Soc. 1966;49:379–82.
Suzuki E, Shimomura K, Sekiguchi K. Thermochemical study of theophylline and its hydrate. Chem Pharm Bull. 1989;37(2):493–97.
Ledwige MT, Corrigan OI. Effects of environmental factors on the dehydration of diclofenac HEP dihydrate and theophylline monohydrate. Int J Pharm. 1997;147:41–9.
Acknowledgments
The authors wish to thank Prof. F. Giordano for helpful discussion and Miss S. Gabana for technical assistance in TG experiments.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Foppoli, A., Zema, L., Maroni, A. et al. Dehydration kinetics of theophylline-7-acetic acid monohydrate. J Therm Anal Calorim 99, 649–654 (2010). https://doi.org/10.1007/s10973-009-0196-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10973-009-0196-z