title: Development and validation of an UPLC-MS/MS method for the quantification of ethoxzolamide in blood, brain tissue, and bioequivalent buffers: applications to absorption, brain distribution, and pharmacokinetic studies.
abstract: The purpose of this study is to develop and validate an UPLC-MS/MS method to quantify ethoxzolamide in plasma (EZ) and apply the method to absorption, brain distribution, as well as pharmacokinetic studies. A C₁₈ column was used with 0.1% of formic acid in acetonitrile and 0.1% of formic acid in water as the mobile phases to resolve EZ. The mass analysis was performed in a triple quadrupole mass spectrometer using multiple reaction monitoring (MRM) with positive scan mode. The results show that the linear range of EZ is 4.88-10,000.00 nM. The intra-day variance is less than 12.43% and the accuracy is between 88.88 and 108.00%. The inter-day variance is less than 12.87% and accuracy is between 89.27 and 115.89%. Protein precipitation was performed using methanol to extract EZ from plasma and brain tissues. Only 40 μL of plasma is needed for analysis due to the high sensitivity of this method, which could be completed in less than three minutes. This method was used to study the pharmacokinetics of EZ in SD rats, and the transport of EZ in Caco-2 and MDCK-MDR1 overexpressing cell culture models. Our data show that EZ is not a substrate for p-glycoprotein (P-gp) and its entry into the brain may not limited by the blood-brain barrier.
authors.affiliation: Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, The University of Houston, 1441 Moursund Street, Houston, TX 77030, USA. Electronic address: sgao3@uh.edu.
authors.forename: Song
authors.initials: S
authors.lastname: Gao
authors.affiliation: Department of Neurobiology & Anatomy, The University of Texas Health Science Center at Houston, P.O. Box 20708, Houston, TX 77225, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, The University of Houston, 1441 Moursund Street, Houston, TX 77030, USA.
authors.forename: Taijun
authors.initials: T
authors.lastname: Yin
authors.affiliation: Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, The University of Houston, 1441 Moursund Street, Houston, TX 77030, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, The University of Houston, 1441 Moursund Street, Houston, TX 77030, USA.
authors.forename: Beibei
authors.initials: B
authors.lastname: Xu
authors.affiliation: Department of Neurobiology & Anatomy, The University of Texas Health Science Center at Houston, P.O. Box 20708, Houston, TX 77225, USA.
authors.forename: Anthony N
authors.initials: AN
authors.lastname: Moore
authors.affiliation: Department of Neurobiology & Anatomy, The University of Texas Health Science Center at Houston, P.O. Box 20708, Houston, TX 77225, USA.
authors.forename: Pramod K
authors.initials: PK
authors.lastname: Dash
authors.affiliation: Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, The University of Houston, 1441 Moursund Street, Houston, TX 77030, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Hu
mesh_terms: D061605:Administration, Intravenous; D000818:Animals; D001923:Brain Chemistry; D018938:Caco-2 Cells; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D005016:Ethoxzolamide / Q000008:administration & dosage / Q000032:analysis* / Q000737:chemistry / Q000493:pharmacokinetics*; D006801:Humans; D016014:Linear Models; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D005016:Ethoxzolamide
keywords: Absorption; CNS distribution; Ethoxzolamide; Pharmacokinetics; UPLC-MS/MS