Abstract
Piperacillin metabolism and biliary excretion are different between humans and preclinical species. In the present study, piperacillin metabolites were characterized in bile and urine of healthy humans and compared with metabolites formed in vitro. Volunteers were administered 2 g of piperacillin IV; blood, urine, and duodenal aspirates (obtained via a custom-made oroenteric catheter) were collected. The metabolism of piperacillin in humans also was investigated in vitro using pooled human liver microsomes and sandwich-cultured human hepatocytes. Piperacillin and metabolites were estimated by high-performance liquid chromatography with tandem mass spectrometry detection. Piperacillin, desethylpiperacillin, and desethylpiperacillin glucuronide were detected in bile, urine, and human liver microsomal incubates. Similar to the in vivo results, desethylpiperacillin was formed and excreted into bile canaliculi of sandwich-cultured human hepatocytes. This is the first report of glucuronidation of desethylpiperacillin in vitro or in vivo. The clinical method employed in this study to determine biliary clearance of drugs also facilitates bile collection as soon as bile is excreted from the gallbladder, thereby minimizing the exposure of labile metabolites to the intestinal environment. This study exemplifies how a combination of in vitro and in vivo tools can aid in the identification of metabolites unique to the human species.
Footnotes
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This work was supported by National Institutes of Health Grant R01-GM41935 and Grant RR00046 from the General Clinical Research Center program of the Division of Research Resources. G.G. was an American Foundation for Pharmaceutical Education Predoctoral Fellow.
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K.B. is a co-founder and Chair of the Scientific Advisory Board for Qualyst, Inc., which has exclusively licensed the sandwich-cultured hepatocyte technology for quantification of biliary excretion (B-CLEAR). None of the other authors has any conflict of interest.
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.106.012278.
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ABBREVIATIONS: SCHH, sandwich-cultured human hepatocytes; MS-MS tandem mass spectrometry; HPLC, high-performance liquid chromatography; DEX, dexamethasone; HBSS, Hanks' balanced salt solution; HLM, human liver microsome(s); UDPGA, uridine diphosphate glucuronic acid; DMEM, Dulbecco's modified Eagle's medium; BEI, biliary excretion index; IS, internal standard.
- Received August 1, 2006.
- Accepted December 27, 2006.
- The American Society for Pharmacology and Experimental Therapeutics
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