HPLC/ICP-MS in Combination with 鈥淩everse鈥?Online Isotope Dilution in Drug Metabolism Studies

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• 作者：Bj枚rn Meermann ; Anne Hulstaert ; Aline Laenen ; Cis Van Looveren ; Maarten Vliegen ; Filip Cuyckens ; Frank Vanhaecke
• 刊名：Analytical Chemistry
• 出版年：2012
• 出版时间：March 6, 2012
• 年：2012
• 卷：84
• 期：5
• 页码：2395-2401
• 全文大小：261K
• 年卷期：v.84,no.5(March 6, 2012)
• ISSN：1520-6882

文摘

During the development of a new drug compound, its metabolism needs to be unraveled. For quantification of the metabolites formed, the drug under investigation is traditionally synthesized with a radiolabel (¹⁴C or ³H) and the metabolites present in different matrixes (blood, urine, feces) upon drug administration are determined by means of high-performance liquid chromatography (HPLC) coupled to radiodetection. This approach allows for quantification of the metabolites formed and enables a straightforward distinction between exogenous (i.e., drug-related) and endogenous species (as only the radiolabeled species are detected). However, in some cases, the use of a radiolabeled compound in human in vivo studies is not advisible, e.g., for drug compounds or their metabolites showing a long plasma or tissue half-life. In cases where the candidate drug molecule contains an element detectable by means of inductively coupled plasma mass spectrometry (ICP-MS), HPLC/ICP-MS is a promising alternative approach. However, the method lacks specificity when a distinction between drug-related species and endogenous compounds containing the same target element needs to be accomplished. As a result, we have developed an HPLC/ICP-MS-based method combined with 鈥渞everse鈥?online isotope dilution (鈥渞everse鈥?online ID) for metabolite quantification. The methodology was evaluated by the analysis of feces samples from rats dosed with a ⁸¹Br-labeled drug compound. The method allows for both (i) valid quantification of the drug metabolites and (ii) distinction among endogenous, exogenous, and 鈥渕ixed鈥?species, based on their isotopic 鈥渇ingerprint鈥? A good repeatability (relative standard deviation of 4.2%) and limit of detection (0.35 mg of drug compound L^鈥? of feces extract), of the same order of magnitude as those observed for 鈥渘ormal鈥?online ID HPLC/ICP-MS and HPLC/radiodetection, were achieved.