title: Simultaneous pharmacokinetic and pharmacodynamic analysis of 5α-reductase inhibitors and androgens by liquid chromatography tandem mass spectrometry.
abstract: Benign prostatic hyperplasia and prostate cancer can be treated with the 5α-reductase inhibitors, finasteride and dutasteride, when pharmacodynamic biomarkers are useful in assessing response. A novel method was developed to measure the substrates and products of 5α-reductases (testosterone, 5α-dihydrotestosterone (DHT), androstenedione) and finasteride and dutasteride simultaneously by liquid chromatography tandem mass spectrometry, using an ABSciex QTRAP(®) 5500, with a Waters Acquity™ UPLC. Analytes were extracted from serum (500 µL) via solid-phase extraction (Oasis(®) HLB), with (13)C3-labelled androgens and d9-finasteride included as internal standards. Analytes were separated on a Kinetex C18 column (150 × 3 mm, 2.6 µm), using a gradient run of 19 min. Temporal resolution of analytes from naturally occurring isomers and mass +2 isotopomers was ensured. Protonated molecular ions were detected in atmospheric pressure chemical ionisation mode and source conditions optimised for DHT, the least abundant analyte. Multiple reaction monitoring was performed as follows: testosterone (m/z 289 → 97), DHT (m/z 291 → 255), androstenedione (m/z 287 → 97), dutasteride (m/z 529 → 461), finasteride (m/z 373 → 317). Validation parameters (intra- and inter-assay precision and accuracy, linearity, limits of quantitation) were within acceptable ranges and biological extracts were stable for 28 days. Finally the method was employed in men treated with finasteride or dutasteride; levels of DHT were lowered by both drugs and furthermore the substrate concentrations increased.
authors.affiliation: Endocrinology, University/British Heart Foundation Centre for Cardiovascular Science, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom. Electronic address: ritaupreti@yahoo.com.
authors.forename: Rita
authors.initials: R
authors.lastname: Upreti
authors.affiliation: Mass Spectrometry Core, Wellcome Trust Clinical Research Facility, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom. Electronic address: g.naredo@ed.ac.uk.
authors.forename: Gregorio
authors.initials: G
authors.lastname: Naredo
authors.affiliation: Endocrinology, University/British Heart Foundation Centre for Cardiovascular Science, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom. Electronic address: A.M.M.Faqehi@sms.ed.ac.uk.
authors.forename: Abdullah M M
authors.initials: AM
authors.lastname: Faqehi
authors.affiliation: Endocrinology, University/British Heart Foundation Centre for Cardiovascular Science, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom. Electronic address: Katherine.Hughes@ed.ac.uk.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Hughes
authors.affiliation: Department of Urology, NHS Lothian, Western General Hospital, Crewe Road South, Edinburgh EH4 2XU, United Kingdom. Electronic address: laurence.stewart@nhslothian.scot.nhs.uk.
authors.forename: Laurence H
authors.initials: LH
authors.lastname: Stewart
authors.affiliation: Endocrinology, University/British Heart Foundation Centre for Cardiovascular Science, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom; Mass Spectrometry Core, Wellcome Trust Clinical Research Facility, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom. Electronic address: b.walker@ed.ac.uk.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Walker
authors.affiliation: Mass Spectrometry Core, Wellcome Trust Clinical Research Facility, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom. Electronic address: n.z.m.homer@ed.ac.uk.
authors.forename: Natalie Z M
authors.initials: NZ
authors.lastname: Homer
authors.affiliation: Endocrinology, University/British Heart Foundation Centre for Cardiovascular Science, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom; Mass Spectrometry Core, Wellcome Trust Clinical Research Facility, Queen׳s Medical Research Institute, University of Edinburgh, 47, Little France Crescent, Edinburgh EH16 4TJ, United Kingdom. Electronic address: ruth.andrew@ed.ac.uk.
authors.forename: Ruth
authors.initials: R
authors.lastname: Andrew
mesh_terms: D058891:5-alpha Reductase Inhibitors / Q000097:blood* / Q000493:pharmacokinetics / Q000494:pharmacology; D000728:Androgens / Q000097:blood* / Q000493:pharmacokinetics / Q000494:pharmacology; D000735:Androstenedione / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D001378:Azasteroids / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D002853:Chromatography, Liquid / Q000379:methods*; D013196:Dihydrotestosterone / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D000068538:Dutasteride; D018120:Finasteride / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000097:blood* / Q000188:drug therapy; D052616:Solid Phase Extraction / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013739:Testosterone / Q000097:blood / Q000493:pharmacokinetics / Q000494:pharmacology; D014018:Tissue Distribution
chemical_list: D058891:5-alpha Reductase Inhibitors; D000728:Androgens; D001378:Azasteroids; D013196:Dihydrotestosterone; D013739:Testosterone; D000735:Androstenedione; D018120:Finasteride; D000068538:Dutasteride
keywords: 5α-reductase; Dihydrotestosterone; Dutasteride; Finasteride; Liquid chromatography tandem mass spectrometry; Testosterone