Published:Journal of Chromatographic Science,
ISSN 0021-9665Volume
39, Number 1, January 2001, pp. 7-11
Stability-Indicating
High-Performance Liquid Chromatographic Assay Method and Photostability of CarprofenAn-Bang
Wu[1], Chau-Yang Chen[2], Shih-Der Chu[2], Yih-Chiao Tsai[2], and Fu-An Chen
[2] [1] Graduate Institute of Pharmaceutical Sciences, Taipei
Medical College, Taipei 11031, Taiwan, R.O.C. and [2] Department of Pharmacy,
Tajen Institute of Technology, Pingtung 90703, Taiwan, R.O.C.
A rapid, sensitive, and accurate stability-indicating high-performance
liquid chromatographic assay method for determining the degradation of carprofen
(CPF) is developed and validated under acidic, basic, or photo-irradiated conditions.
The analysis is monitored with a Cosmosil 5C18-AR column using a
mobile phase of CH3CN–H2O–AcOH (50:49:1, v/v/v)
at 260 nm. The developed method satisfies the system suitability criteria, peak
integrity, and resolution among the parent drug and its degradation products.
The results indicate that the established assay method shows good selectivity
and specificity suitable for stability measurements of CPF. CPF is found to
be more sensitive to exposure to light and in acidic conditions, but it is stable
in a basic medium. The kinetic study of the photodegradation of CPF follows
an apparent first-order reaction in a variety of solvents. The solvent effects
on the rates of degradation are in the decreasing order of chloroform > dichloromethane
> methanol > ethanol > 2-propanol, which is irrelevant to the dielectric
constant e. However, the hydrogen-donating ability of the solvents is essential
to the photochemical decomposition of CPF. A plot of log k versus the Kirkwood
function exhibits a linear relationship in aqueous ethanolic solutions, which
implies that degradation proceeds via an ionic mechanism.
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