Determination of nifedipine and its three principal metabolites in plasma and urine by automated electron-capture capillary gas chromatography |
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Authors: | B J Schmid H E Perry J R Idle |
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Institution: | Department of Pharmacology and Toxicology, St. Mary's Hospital Medical School, London, U.K. |
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Abstract: | A sensitive, efficient, linear and reproducible capillary gas chromatographic method with electron-capture detection was developed for the quantitation of nifedipine and its primary metabolite M-I in plasma together with the urinary and principal metabolites M-II and M-III. On-column, rather than split-splitless, injection was employed to obviate oxidative degradation of nifedipine to M-I. The photosensitivity of nifedipine was re-examined under laboratory conditions and nifedipine was found to have a half-life in excess of two days when amber glassware and darkroom manipulations under red light were used. The method can determine nifedipine and its metabolites in plasma and urine after a single oral dose of 5 mg and can be applied to measure M-I production by human liver microsomes. |
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