Journal of Chromatography B: Biomedical Sciences and Applications
Quantitation of cerivastatin and its seven acid and lactone biotransformation products in human serum by liquid chromatography–electrospray tandem mass spectrometry
Introduction
Inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase have been shown to reduce plasma cholesterol levels [1]. Cerivastatin (Fig. 1) is a synthetic HMG-CoA reductase inhibitor [2], [3]. A liquid chromatography (LC) method, based on post-column induced fluorometric detection, has been reported for the quantitation of cerivastatin in human plasma, with the lower limit of quantitation (LLQ) of 0.025 ng/ml [4]. Methods based on radioimmunoassay, HMG-CoA reductase inhibition assay and capillary gas chromatography for the quantitation of cerivastatin in human plasma have also been reported [5]. Since it has been reported that cerivastatin has a number of biotransformation products [3], a method was required for the quantitation of cerivastatin and the following biotransformation products in human serum: cerivastatin lactone, M-1 (acid), M-1 lactone, M-23 (acid), M-23 lactone, M-24 (acid) and M-24 lactone (Fig. 1). Because of the low oral dose used for cerivastatin due to its relatively high HMG-CoA reductase inhibitory activity [4], it was essential that the method possess a low-picogram LLQ for cerivastatin. We now report an LC–MS–MS method developed and validated for the simultaneous quantitative determination of cerivastatin and its seven biotransformation products in human serum.
Section snippets
Chemicals and reagents
Cerivastatin (acid) and its biotransformation products, cerivastatin lactone, M-1 (acid), M-1 lactone, M-23 (acid), M-23 lactone, M-24 (acid) and M-24 lactone, were characterized products obtained from the Bristol-Myers Squibb Pharmaceutical Research Institute. D3-cerivastatin, used as the internal standard for the four acid analytes, and D3-cerivastatin lactone, used as the internal standard for the four lactone analytes, were also synthesized at the Bristol-Myers Squibb Pharmaceutical
Results and discussion
Full-scan single MS (Q1) and MS–MS (Q3) mass spectra of the eight analytes and the two deuterium labeled internal standards are shown in Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11. For each compound, [M+H]+ was the predominant ion in the Q1 spectrum, which was used as the precursor ion for obtaining product ion spectra in MS–MS scans. Fragmentation pathways proposed for the generation of the product ions used in the SRM transition of the acid and lactone
Conclusions
A sensitive, specific, accurate and reproducible LC–MS–MS method for the simultaneous quantitation of the acid and lactone forms of cerivastatin and its biotransformation products (a total of eight analytes) in human serum was developed and validated. The desired sensitivity for cerivastatin and cerivastatin lactone was achieved with the LLQ of 0.0100 ng/ml. The LLQ for the other analytes was higher: 0.0500 ng/ml for M-1 (acid) and M-1 lactone; 0.100 ng/ml for M-23 (acid) and M-23 lactone; and
Acknowledgements
The authors are indebted to Peggy McCann, Gang Wu, Ravi Girotra, William Washburn, Peng Guo and Mark Bednarz for their involvement in the synthesis of the reference standards for the analytes and deuterium labeled analogs. The authors are grateful to Mark L. Powell for his critical review of the manuscript.
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