Feasibility of 19F-NMR for assessing the molecular mobility of flufenamic acid in solid dispersions

Chemical & Pharmaceutical Bulletin
Yukio AsoToru Kawanishi

Abstract

The purpose of the present study was to clarify the feasibility of 19F-NMR for assessing the molecular mobility of flufenamic acid (FLF) in solid dispersions. Amorphous solid dispersions of FLF containing poly(vinylpyrrolidone) (PVP) or hydroxypropylmethylcellulose (HPMC) were prepared by melting and rapid cooling. Spin-lattice relaxation times (T1 and T(1rho)) of FLF fluorine atoms in the solid dispersions were determined at various temperatures (-20 to 150 degrees C). Correlation time (tauc), which is a measure of rotational molecular mobility, was calculated from the observed T1 or T1rho value and that of the T1 or T1rho minimum, assuming that the relaxation mechanism of spin-lattice relaxation of FLF fluorine atoms does not change with temperature. The tauc value for solid dispersions containing 20% PVP was 2-3 times longer than that for solid dispersions containing 20% HPMC at 50 degrees C, indicating that the molecular mobility of FLF in solid dispersions containing 20% PVP was lower than that in solid dispersions containing 20% HPMC. The amount of amorphous FLF remaining in the solid dispersions stored at 60 degrees C was successfully estimated by analyzing the solid echo signals of FLF fluorine atoms, and it was possibl...Continue Reading

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Citations

Feb 8, 2011·Chemical & Pharmaceutical Bulletin·Keiji YamamotoKunikazu Moribe
Jan 6, 2016·AAPS PharmSciTech·Justin S LaFountaineRobert O Williams
Aug 17, 2011·Advanced Drug Delivery Reviews·Jared A Baird, Lynne S Taylor
Mar 2, 2017·Advanced Materials·Alessandro MarchettiXueqian Kong
Dec 6, 2018·Chemical Communications : Chem Comm·Rafael BarbasAntonio Frontera

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