title: Further characterization of a ¹³C-dextromethorphan breath test for CYP2D6 phenotyping in breast cancer patients on tamoxifen therapy.
abstract: In a previous study, we found that the CYP2D6 phenotype determined by (13)C-dextromethorphan breath test (DM-BT) might be used to predict tamoxifen treatment outcome in breast cancer patients in the adjuvant setting. However, large variation in the delta-over-baseline (DOB) values was observed in the extensive metabolizer predicted phenotype group based on single point measures. In the present work we aimed to analyze the variability of phenotype results and determine reproducibility to further characterize the clinical utility of DM-BT by introducing multiple breath sampling instead of single breath sampling and by administration of a fixed dose of (13)C-DM.
authors.affiliation: Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands. Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: F L
authors.initials: FL
authors.lastname: Opdam
authors.forename: A S
authors.initials: AS
authors.lastname: Modak
authors.forename: H
authors.initials: H
authors.lastname: Gelderblom
authors.forename: H J
authors.initials: HJ
authors.lastname: Guchelaar
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000378:metabolism / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy*; D001944:Breath Tests / Q000379:methods; D002247:Carbon Isotopes; D019389:Cytochrome P-450 CYP2D6 / Q000235:genetics* / Q000378:metabolism; D003915:Dextromethorphan / Q000493:pharmacokinetics; D018691:Excitatory Amino Acid Antagonists / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D010641:Phenotype; D011446:Prospective Studies; D015203:Reproducibility of Results; D013629:Tamoxifen / Q000031:analogs & derivatives / Q000378:metabolism / Q000627:therapeutic use
chemical_list: D018931:Antineoplastic Agents, Hormonal; D002247:Carbon Isotopes; D018691:Excitatory Amino Acid Antagonists; D013629:Tamoxifen; C055492:4-hydroxy-N-desmethyltamoxifen; D003915:Dextromethorphan; D019389:Cytochrome P-450 CYP2D6