ABSTRACT
A kinetic study of atosiban was conducted following repeated intravenous administration in Wistar rats. Sample analysis was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) following full validation of an in-house method. Eptifibatide, a cyclic peptide, was used as an internal standard (IS). The analyte and internal standard were extracted using solid phase extraction (SPE) method. Chromatographic separation was carried out using an ACE C18 5 microm 50 mm x 4.6 mm column with gradient elution. Mass spectrometric detection was performed using TSQ Quantum ultra AM. The lower limit of quantification was 0.01 microg/ml when 100 microl rat plasma was used. Plasma concentrations of atosiban were measured at 0 (pre-dose), 2, 15, 30, 45, 60, 120 min at the dosage levels of 0.125 mg/kg (low dose), 0.250 mg/kg (mid dose), and 0.500 mg/kg (high dose), respectively. Atosiban plasma concentration measured at Day 1 showed mean peak atosiban concentration (C(max)) 0.40, 0.57, 1.95 microg/ml for low, mid and high dose treated animals and mean peak concentration on Day 28 was 0.41, 0.88, 1.31microg/ml on Day 28 for low, mid and high dose treated animals.
Subject(s)
Chromatography, Liquid/methods , Hormone Antagonists/blood , Tandem Mass Spectrometry/methods , Vasotocin/analogs & derivatives , Animals , Drug Stability , Eptifibatide , Female , Hormone Antagonists/administration & dosage , Hormone Antagonists/chemistry , Hormone Antagonists/pharmacokinetics , Injections, Intravenous , Linear Models , Peptides/analysis , Peptides/chemistry , Rats , Rats, Wistar , Receptors, Oxytocin/antagonists & inhibitors , Reproducibility of Results , Sensitivity and Specificity , Solid Phase Extraction , Vasotocin/administration & dosage , Vasotocin/blood , Vasotocin/chemistry , Vasotocin/pharmacokineticsABSTRACT
Glycoforms of glargine expressed in Pichia pastoris were isolated by high-performance liquid chromatography and analyzed by a series of chemical and mass spectrometric methods for the identification of various glycoforms, glycosylation position, nature and structure of glycans. Reduction and alkylation, peptide mapping techniques were used to decipher the amino acid site at which glycosylation had taken place. Chemical methods were coupled with mass spectrometry techniques such as electrospray ionization and matrix-assisted laser desorption/ionization for identification of the glycosylation site.
