title: A HPLC-MS method to detect and quantify guanfacine in urine.
abstract: BACKGROUND
  Guanfacine, an α2-adrenergic α2A)agonist long indicated to treat hypertension, is now being used to treat attention deficit-hyperactivity disorder (ADHD) in adolescents. This new therapeutic use may require urine testing to document compliance or abuse. A simple rapid high pressure liquid chromatography-mass spectrometry (HPLC-MS) method to detect and quantify guanfacine in urine following therapeutic administration is presented.
  
  
  METHODS
  Guanfacine and protriptyline internal standard were extracted from alkalinized urine with ethyl acetate. The organic layer was evaporated, reconstituted with mobile phase and analyzed on a YMC Basic S-5 micron, 2.0 × 150 mm HPLC column connected to an MS detector operated in positive electrospray ionization mode with selected ion resonance. Elution times were <5 min.
  
  
  RESULTS
  The analytical measurement range for guanfacine was 20-2000 ng/mL. The limit of detection and quantitation were 5 ng/mL and 20 ng/mL, respectively. Precision as %CV was <15% at 40, 100 and 500 ng/mL (n=6). Percentage recovery using the same concentrations was >89%. Interference with drugs and biological constituents was assessed; no interferences were noted. Analysis of 100 random post-diagnostic urine specimens yielded 11 guanfacine positive results with concentrations ranging from 11 to 6390 ng/mL.
  
  
  CONCLUSIONS
  This HPLC-MS method provides a simple and rapid method for the routine detection and quantitation of guanfacine in urine specimens.
authors: Department of Forensic Science, Virginia Commonwealth University, Richmond, VA, USA.
authors: Carl E
authors: CE
authors: Wolf
authors: Sara J
authors: SJ
authors: Kester-Florin
authors: Alphonse
authors: A
authors: Poklis
mesh_terms: D058647:Adrenergic alpha-2 Receptor Agonists / Q000627:therapeutic use / Q000652:urine*; D001289:Attention Deficit Disorder with Hyperactivity / Q000188:drug therapy / Q000652:urine; D002138:Calibration; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D016316:Guanfacine / Q000627:therapeutic use / Q000652:urine*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D016482:Urinalysis / Q000379:methods*
chemical_list: D058647:Adrenergic alpha-2 Receptor Agonists; D016316:Guanfacine