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Liquid chromatographic-tandem mass spectrometric method for the quantitation of sildenafil in human plasma.

Wang Y, Wang J, Cui Y, Fawcett JP, Gu J

Research Center for Drug Metabolism, College of Life Science, Jilin University, Changchun 130023, China.

A method to determine sildenafil in human plasma involving liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Sildenafil and the internal standard (I.S.), diazepam, are extracted from human plasma with ether-dichloromethane (3:2, v/v) at basic pH and analyzed by reversed-phase high-performance liquid chromatography (HPLC) using methanol-10mM ammonium acetate pH 7.0 (85:15, v/v) as the mobile phase. Detection by electrospray positive ionization mass spectrometry in the multiple-reaction monitoring mode was linear over the concentration range 0.125-40.0 ng/ml. Intra- and inter-day precision of the assay at four concentrations within this range were 2.5-8.0%. The method was used to evaluate plasma concentration-time profiles in healthy volunteers given an oral dose of 20mg sildenafil as a combination tablet also containing apomorphine.

Published 5 December 2005 in J Chromatogr B Analyt Technol Biomed Life Sci, 828(1): 118-21.
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