A thermal analysis method to predict the complete phase diagram of drug-polymer solid dispersions.
Summary of "A thermal analysis method to predict the complete phase diagram of drug-polymer solid dispersions."
The aim of this work was to develop a method which uses experimentally obtainable data to predict the complete phase diagram of drug-polymer solid dispersion systems, for the first time in literature. Felodipine-poly(acrylic acid) (PAA) solid dispersion was used as an example to illustrate the application of this method. Samples were prepared with different drug loading and analyzed using differential scanning calorimetry (DSC). Values of the drug-polymer interaction parameter χ(T(m)) were calculated from the drug crystal melting point depression data. Since χ is a function of temperature (χ∼1/T) according to the Flory-Huggins theory, the obtained χ-T relationship thus enabled calculation of the complete temperature-composition phase diagram of a drug-polymer solid dispersion system. In experiments, felodipine was shown to be immiscible with PAA in almost the whole range of drug content at room temperature. Two glass transition temperatures were observed, corresponding to almost pure felodipine and pure PAA, respectively, in consistent with the predicted phase behavior.
Department of Chemical Engineering, Tsinghua University, Beijing, China.
This article was published in the following journal.
Name: International journal of pharmaceutics
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20727391
- DOI: http://dx.doi.org/10.1016/j.ijpharm.2010.08.013
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Medical and Biotech [MESH] Definitions
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Technique by which phase transitions of chemical reactions can be followed by observation of the heat absorbed or liberated.
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Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.