The Basel Cocktail for Simultaneous Phenotyping of Human Cytochrome P450 Isoforms in Plasma, Saliva and Dried Blood Spots
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Background and Objective
Phenotyping cocktails use a combination of cytochrome P450 (CYP)-specific probe drugs to simultaneously assess the activity of different CYP isoforms. To improve the clinical applicability of CYP phenotyping, the main objectives of this study were to develop a new cocktail based on probe drugs that are widely used in clinical practice and to test whether alternative sampling methods such as collection of dried blood spots (DBS) or saliva could be used to simplify the sampling process.
In a randomized crossover study, a new combination of commercially available probe drugs (the Basel cocktail) was tested for simultaneous phenotyping of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4. Sixteen subjects received low doses of caffeine, efavirenz, losartan, omeprazole, metoprolol and midazolam in different combinations. All subjects were genotyped, and full pharmacokinetic profiles of the probe drugs and their main metabolites were determined in plasma, dried blood spots and saliva samples.
The Basel cocktail was well tolerated, and bioequivalence tests showed no evidence of mutual interactions between the probe drugs. In plasma, single timepoint metabolic ratios at 2 h (for CYP2C19 and CYP3A4) or at 8 h (for the other isoforms) after dosing showed high correlations with corresponding area under the concentration–time curve (AUC) ratios (AUC0–24h parent/AUC0–24h metabolite) and are proposed as simple phenotyping metrics. Metabolic ratios in dried blood spots (for CYP1A2 and CYP2C19) or in saliva samples (for CYP1A2) were comparable to plasma ratios and offer the option of minimally invasive or non-invasive phenotyping of these isoforms.
This new combination of phenotyping probe drugs can be used without mutual interactions. The proposed sampling timepoints have the potential to facilitate clinical application of phenotyping but require further validation in conditions of altered CYP activity. The use of DBS or saliva samples seems feasible for phenotyping of the selected CYP isoforms.
KeywordsMetoprolol Losartan Efavirenz Metabolic Ratio Probe Drug
The authors thank Claudia Blasi and Luisa Baselgia for their assistance with the clinical study, and Beatrice Vetter for technical assistance.
Massimiliano Donzelli, contributed to the study design, data analysis and drafting of the manuscript. Adrian Derungs contributed to the study design, conduct of the study and data analysis. Lana Nezic contributed to the conduct of the study. Maria-Giovanna Serratore contributed to the analytical tools and data analysis. Christoph Noppen contributed to the analytical tools and data analysis. Stephan Krähenbühl contributed to the study design and data analysis. Manuel Haschke contributed to the study design, data analysis and drafting of the manuscript.
This study was financed by the Division of Clinical Pharmacology & Toxicology, University Hospital Basel (Basel, Switzerland).
Conflicts of Interest
The authors have no conflicts of interest that are directly relevant to the content of this article.
- 2.Setiabudy R, Kusaka M, Chiba K, Darmansjah I, Ishizaki T. Dapsone N-acetylation, metoprolol alpha-hydroxylation, and S-mephenytoin 4-hydroxylation polymorphisms in an Indonesian population: a cocktail and extended phenotyping assessment trial. Clin Pharmacol Ther. 1994;56(2):142–53 (Epub 1994/08/01).CrossRefGoogle Scholar
- 5.Chainuvati S, Nafziger AN, Leeder JS, Gaedigk A, Kearns GL, Sellers E, et al. Combined phenotypic assessment of cytochrome p450 1A2, 2C9, 2C19, 2D6, and 3A, N-acetyltransferase-2, and xanthine oxidase activities with the “Cooperstown 5 + 1 cocktail”. Clin Pharmacol Ther. 2003;74(5):437–47 (Epub 2003/10/31).CrossRefGoogle Scholar
- 13.Wohlfarth A, Naue J, Lutz-Bonengel S, Dresen S, Auwarter V. 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. J Clin Pharmacol. 2012;52(8):1200–14 (Epub 2011/09/03).CrossRefGoogle Scholar
- 16.Scott RJ, Palmer J, Lewis IA, Pleasance S. Determination of a ‘GW cocktail’ of cytochrome P450 probe substrates and their metabolites in plasma and urine using automated solid phase extraction and fast gradient liquid chromatography tandem mass spectrometry. Rapid Commun Mass Spectrom RCM. 1999;13(23):2305–19 (Epub 1999/11/24).CrossRefGoogle Scholar
- 17.Yin OQ, Lam SS, Lo CM, Chow MS. Rapid determination of five probe drugs and their metabolites in human plasma and urine by liquid chromatography/tandem mass spectrometry: application to cytochrome P450 phenotyping studies. Rapid Commun Mass Spectrom RCM. 2004;18(23):2921–33 (Epub 2004/11/06).CrossRefGoogle Scholar
- 24.US Department of Health and Human Services, Food and Drug Administration, Center for Drug Evaluation and Research (CDER). Guidance for Industry. Drug interaction studies—study design, data analysis, implications for dosing, and labeling recommendations. Silver Spring: CDER, 2012.Google Scholar
- 25.Ward BA, Gorski JC, Jones DR, Hall SD, Flockhart DA, Desta Z. The cytochrome P450 2B6 (CYP2B6) is the main catalyst of efavirenz primary and secondary metabolism: implication for HIV/AIDS therapy and utility of efavirenz as a substrate marker of CYP2B6 catalytic activity. J Pharmacol Exp Ther. 2003;306(1):287–300 (Epub 2003/04/05).CrossRefGoogle Scholar