title: Quantitation of dolastatin-10 using HPLC/electrospray ionization mass spectrometry: application in a phase I clinical trial.
abstract: A highly sensitive and specific assay for the quantitation of the anticancer agent dolastatin-10 (DOL-10) in human plasma is described. The method was based on the use of electrospray ionization-high-performance liquid chromatography/mass spectrometry (ESP-LC/MS). The analytical procedure involved extraction of plasma samples containing DOL-10 and the internal standard (DOL-15) with n-butyl chloride, which was then evaporated under nitrogen. The residue was dissolved in 50 microl mobile phase and 10 microl was subjected to ESP-LC/MS analysis using a C18 microbore column. A linear gradient using water/acetonitrile was used to keep the retention times of the analytes of interest under 5 min. The method exhibited a linear range from 0.005 to 50 ng/ml with a lower limit of quantitation (LLQ) at 0.005 ng/ml. Absolute recoveries of extracted samples in the 85-90% range were obtained. The method's accuracy (< or =5% relative error) and precision (< or =10% CV) were well within industry standards. The analytical procedure was applied to extract DOL-10 metabolites from samples obtained following incubation of the drug with an activated S9 rat liver preparation. Two metabolic products were detected and were tentatively identified as a N-demethyl-DOL-10 and hydroxy-DOL-10. Structural assignments were made based on the fragmentation patterns obtained using the electrospray source to produce collision-induced dissociation (CID). The method was also applied to the measurement of DOL-10 in the plasma of patients treated with this drug. Preliminary investigation of the pharmacokinetics suggested that drug distribution and elimination may be best described by a three-compartment model with t1/2alpha = 0.087 h, t1/2beta = 0.69 h and t1/2gamma = 8.0 h. Plasma clearance was 3.7 l/h per m2.
authors.affiliation: TEXms Inc., Houston, Tx, 77060, USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Garteiz
authors.forename: T
authors.initials: T
authors.lastname: Madden
authors.forename: D E
authors.initials: DE
authors.lastname: Beck
authors.forename: W R
authors.initials: WR
authors.lastname: Huie
authors.forename: K T
authors.initials: KT
authors.lastname: McManus
authors.forename: J L
authors.initials: JL
authors.lastname: Abbruzzese
authors.forename: W
authors.initials: W
authors.lastname: Chen
authors.forename: R A
authors.initials: RA
authors.lastname: Newman
mesh_terms: D000970:Antineoplastic Agents / Q000097:blood / Q000493:pharmacokinetics*; D001274:Atmospheric Pressure; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D047630:Depsipeptides; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods; D009369:Neoplasms / Q000188:drug therapy; D009842:Oligopeptides / Q000097:blood / Q000493:pharmacokinetics*; D012015:Reference Standards; D014018:Tissue Distribution
chemical_list: D000970:Antineoplastic Agents; D047630:Depsipeptides; D009842:Oligopeptides; C075610:dolastatin 15; C064570:dolastatin 10