title: A rapid & sensitive liquid chromatography- tandem mass spectrometry method for the quantitation of busulfan levels in plasma & application for routine therapeutic monitoring in haematopoietic stem cell transplantation.
abstract: OBJECTIVE
  Busulfan (Bu) in combination with cyclophosphamide is widely used in myeloablative conditioning regimen prior to haematopoietic stem cell transplantation (HSCT). Its narrow therapeutic range and toxic side effects at high systemic exposure and graft rejection at low exposure emphasize the need for busulfan dose optimization using targeted dose adjustment prior to HSCT. We report here a rapid and sensitive method to quantitate busulfan plasma levels in patients receiving busulfan as part of pre-transplant conditioning.
  
  
  METHODS
  The method involves simple protein precipitation of the plasma followed by analysis using a high performance liquid chromatography (HPLC) with tandem mass spectrometry - electrospray ionization technique (LC-ESI MS/MS) in positive ionization mode and quantified using multiple reaction monitoring (MRM). Deuterated busulfan (d₈-busulf`an) was used as the internal standard.
  
  
  RESULTS
  The method was linear for the concentration ranging from 0 to 4000 ng/ml of busulfan with a limit of detection of 2 ng/ml and limit of quantitation of 5 ng/ml. The assay was accurate for serial concentrations of Bu in plasma for five consecutive days and the CV was less than 10 per cent.
  
  
  CONCLUSIONS
  Using this rapid and sensitive method, busulfan levels were targeted and subsequent doses adjusted at our center in 26 patients receiving high dose busulfan in combination with cyclophosphamide or fludarabine.
authors.affiliation: Department of Haematology, Christian Medical College, Vellore, India.
authors.forename: Salamun
authors.initials: S
authors.lastname: Desire
authors.forename: Ezhil Pavai
authors.initials: EP
authors.lastname: Mohanan
authors.forename: Biju
authors.initials: B
authors.lastname: George
authors.forename: Vikram
authors.initials: V
authors.lastname: Mathews
authors.forename: Mammen
authors.initials: M
authors.lastname: Chandy
authors.forename: Alok
authors.initials: A
authors.lastname: Srivastava
authors.forename: Poonkuzhali
authors.initials: P
authors.lastname: Balasubramanian
mesh_terms: D000293:Adolescent; D000328:Adult; D002066:Busulfan / Q000008:administration & dosage / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D016903:Drug Monitoring; D005260:Female; D006084:Graft Rejection / Q000188:drug therapy*; D018380:Hematopoietic Stem Cell Transplantation; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D021241:Spectrometry, Mass, Electrospray Ionization; D053719:Tandem Mass Spectrometry; D019172:Transplantation Conditioning
chemical_list: D002066:Busulfan