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Cocktail Approach for In Vivo Phenotyping of 5 Major CYP450 Isoenzymes: Development of an Effective Sampling, Extraction, and Analytical Procedure and Pilot Study With Comparative Genotyping
Author(s) -
Wohlfarth Ariane,
Naue Jana,
LutzBonengel Sabine,
Dresen Sebastian,
Auwärter Volker
Publication year - 2012
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1177/0091270011410570
Subject(s) - chromatography , chemistry , paraxanthine , triple quadrupole mass spectrometer , selected reaction monitoring , mass spectrometry , extraction (chemistry) , repeatability , tandem mass spectrometry , analyte , electrospray ionization , cyp1a2 , biochemistry , cytochrome p450 , metabolism
In this study, the authors developed a phenotyping method for CYP1A2, 2C9, 2C19, 2D6, and 3A4 using a cocktail of 100 mg caffeine, 125 mg tolbutamide, 20 mg omeprazole, 30 mg dextromethorphan, and 2 mg midazolam. A simple sampling scheme was established collecting 3 blood samples at 0, 4, and 24 hours followed by solid‐phase extraction and liquid chromatography/tandem mass spectrometry analysis. After addition of 8 deuterated internal standards and extraction, the analytes were separated using gradient elution with ammonium acetate and methanol. Data acquisition was performed on a triple quadrupole linear ion trap mass spectrometer in multiple‐reaction monitoring mode with positive electrospray ionization. The assay was validated according to international guidelines: limits of quantification (LOQs) were between 0.25 and 1.0 ng/mL for all analytes, except for paraxanthine and caffeine (20 ng/mL). Extraction efficiencies ranged between 77% and 103% and matrix effects between 23% and 95%; precision and accuracy data fulfilled accepted criteria. Calibration curves from LOQ to 1000 ng/mL were established for undiluted and 1:10 diluted plasma (r>0.998). The method was tested in a pilot study with 14 volunteers. Additional genotyping of the probands generally demonstrated good accordance with the measured phenotyping indices but also disclosed certain contradictory results.