title: Application of dried blood spot sampling combined with LC-MS/MS for genotyping and phenotyping of CYP450 enzymes in healthy volunteers.
abstract: An early clinical development study (phase I) was conducted to determine the usefulness of dried blood spot (DBS) sampling as an alternative to venous sampling for phenotyping and genotyping of CYP450 enzymes in healthy volunteers. Midazolam (MDZ) was used as a substrate for phenotyping CYP3A4 activity; the concentrations of MDZ and its main metabolite 1'-hydroxymidazolam (1-OH MDZ) were compared between the DBS method from finger punctures, plasma and whole blood (WB), drawn by venipuncture, whereby several methodological parameters were studied (i.e. punch width, amount of dots analyzed and storage time stability). Genotyping between DBS and venous WB samples was compared for CYP2D6 (*3, *4, *6), CYP2C19 (*2, *3), CYP3A4 (*1B) and CYP3A5 (*3C). In addition, the subject's and phlebotomist's satisfaction with venous blood sampling compared with the DBS method was evaluated using a standardized questionnaire. An LC-MS/MS method for the quantification of the MDZ and 1-OH MDZ concentrations in DBS samples was developed and validated in the range of 0.100-100 ng/mL. No compromises were made for the limits of quantification of the DBS-LC-MS/MS method vs the authentic plasma and WB methods.
authors.affiliation: QPS Netherlands, Groningen, The Netherlands. theo.de.boer@qps.com
authors.forename: Theo
authors.initials: T
authors.lastname: de Boer
authors.forename: Jaap
authors.initials: J
authors.lastname: Wieling
authors.forename: Erik
authors.initials: E
authors.lastname: Meulman
authors.forename: Mariska
authors.initials: M
authors.lastname: Reuvers
authors.forename: Gonda
authors.initials: G
authors.lastname: Renkema
authors.forename: Izaak
authors.initials: I
authors.lastname: den Daas
authors.forename: Thijs
authors.initials: T
authors.lastname: van Iersel
authors.forename: Johan
authors.initials: J
authors.lastname: Wemer
authors.forename: LingSing
authors.initials: L
authors.lastname: Chen
mesh_terms: D000328:Adult; D002853:Chromatography, Liquid / Q000379:methods*; D051544:Cytochrome P-450 CYP3A / Q000097:blood / Q000235:genetics; D003577:Cytochrome P-450 Enzyme System / Q000097:blood* / Q000235:genetics; D004355:Drug Stability; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008874:Midazolam / Q000031:analogs & derivatives / Q000097:blood / Q000493:pharmacokinetics; D017060:Patient Satisfaction; D010641:Phenotype; D018962:Phlebotomy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D003577:Cytochrome P-450 Enzyme System; C040081:1-hydroxymethylmidazolam; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human; D008874:Midazolam