A radiocalibration method with pseudo internal standard to estimate circulating metabolite concentrations.

BACKGROUND It has become important for metabolism scientists to identify and quantify prominent circulating human metabolites in order to develop a metabolite safety-qualification package that meets regulatory standards. Often these metabolites cannot be analyzed using traditional bioanalytical methods because a standard is not available. RESULTS A radiocalibration method is described that can estimate circulating metabolite concentrations in nonradioactive human and animal plasma. The key to this method is application of a pseudo internal standard (PIS) that is present in both radioactive reference and nonradioactive (i.e., unknown) samples. Metabolite exposure in the unknown samples is estimated from measured PIS exposure using a relative molar ratio established between the metabolite and PIS (usually parent drug). CONCLUSION Two case studies demonstrate that the method can be used to establish human metabolite safety coverage in animal plasma and method validation is demonstrated by comparing estimated metabolite concentrations in human plasma with concentrations obtained directly using a metabolite calibration curve.

[1]  Dominic P. Williams,et al.  Clearing the MIST (metabolites in safety testing) of time: The impact of duration of administration on drug metabolite toxicity. , 2009, Chemico-biological interactions.

[2]  K. Pang,et al.  Safety testing of metabolites: Expectations and outcomes. , 2009, Chemico-biological interactions.

[3]  Shelby Anderson,et al.  Predicting circulating human metabolites: how good are we? , 2009, Chemical research in toxicology.

[4]  D. Luffer-Atlas,et al.  Overview of metabolite safety testing from an industry perspective. , 2010, Bioanalysis.

[5]  C. Maryanoff,et al.  Determination of relative response factors of impurities in paclitaxel with high performance liquid chromatography equipped with ultraviolet and charged aerosol detectors. , 2008, Journal of chromatography. A.

[6]  F. Guengerich,et al.  Safety Assessment of Stable Drug Metabolites , 2006 .

[7]  Adedayo Adedoyin,et al.  Obtaining exposures of metabolites in preclinical species through plasma pooling and quantitative NMR: addressing metabolites in safety testing (MIST) guidance without using radiolabeled compounds and chemically synthesized metabolite standards. , 2009, Chemical research in toxicology.

[8]  D. Luffer-Atlas.  Unique/Major Human Metabolites: Why, How, and When to Test for Safety in Animals , 2008 .

[9]  R. Obach,et al.  Metabolites in Safety Testing: “MIST” for the Clinical Pharmacologist , 2010, Clinical pharmacology and therapeutics.

[10]  A. Atrakchi.  Interpretation and considerations on the safety evaluation of human drug metabolites. , 2009, Chemical research in toxicology.

[11]  Karen L Davis-Bruno,et al.  A regulatory perspective on issues and approaches in characterizing human metabolites. , 2006, Chemical research in toxicology.

[12]  Philip Timmerman,et al.  Which human metabolites have we MIST? Retrospective analysis, practical aspects, and perspectives for metabolite identification and quantification in pharmaceutical development. , 2009, Chemical research in toxicology.

[13]  Abigail Jacobs,et al.  Metabolites in safety testing. , 2009, Bioanalysis.

[14]  R Scott Obach,et al.  Metabolites in safety testing (MIST): considerations of mechanisms of toxicity with dose, abundance, and duration of treatment. , 2009, Chemical research in toxicology.

[15]  Dominic P. Williams,et al.  Quantifying the Metabolic Activation of Nevirapine in Patients by Integrated Applications of NMR and Mass Spectrometries , 2010, Drug Metabolism and Disposition.

[16]  R Scott Obach,et al.  Metabolites and safety: What are the concerns, and how should we address them? , 2006, Chemical research in toxicology.

[17]  M. Ellis,et al.  Identification and quantification of fluorine-containing metabolites of 1-chloro-2,2,2-trifluoroethane (HCFC133A) in the rat by 19F-NMR spectroscopy. , 1995, Drug metabolism and disposition: the biological fate of chemicals.

[18]  Chungping Yu,et al.  A rapid method for quantitatively estimating metabolites in human plasma in the absence of synthetic standards using a combination of liquid chromatography/mass spectrometry and radiometric detection. , 2007, Rapid communications in mass spectrometry : RCM.

[19]  Jianyao Wang,et al.  Nuclear magnetic resonance spectroscopy as a quantitative tool to determine the concentrations of biologically produced metabolites: implications in metabolites in safety testing. , 2009, Chemical research in toxicology.

[20]  W Griffith Humphreys,et al.  Safety assessment of drug metabolites: Characterization of chemically stable metabolites. , 2006, Chemical research in toxicology.

[21]  D. Knapp,et al.  Handbook of Analytical Derivatization Reactions , 1980 .

[22]  T. Baillie,et al.  Drug metabolites in safety testing. , 2002, Toxicology and applied pharmacology.

[23]  Current opinion: safety evaluation of drug metabolites in development of pharmaceuticals. , 2007, The Journal of toxicological sciences.

[24]  Don Walker,et al.  A holistic strategy for characterizing the safety of metabolites through drug discovery and development. , 2009, Chemical research in toxicology.

[25]  T. Baillie.  Approaches to the assessment of stable and chemically reactive drug metabolites in early clinical trials. , 2009, Chemical research in toxicology.