title: Characterization of in vitro metabolism of capsazepine, a vanilloid transient receptor potential channel antagonist, by liquid chromatography quadrupole ion trap mass spectrometry.
abstract: Capsazepine is an antagonist of the transient receptor potential channel vanilloid 1 (TRPV1), which is known to play an important role in the regulation of pain and inflammation. A selective and sensitive quantitative method for the determination of capsazepine by HPLC-ESI/MS/MS was developed. The method consisted of a protein precipitation extraction followed by analysis using liquid chromatography electrospray quadrupole ion trap mass spectrometry. The chromatographic separation was achieved using a 100 × 2 mm C(18) Waters Symmetry column combined with a gradient mobile phase composed of acetonitrile and 0.1% formic acid aqueous solution at a flow rate of 220 µL/min. The mass spectrometer was operating in full-scan MS/MS mode using two-segment analysis. An analytical range of 10-5000 ng/mL was used in the calibration curve constructed in rat plasma. The inter-batch precision and accuracy observed were 10.1, 6.4 and 6.1% and 100.8, 98.5 and 106.2% at 50, 500 and 5 000 ng/mL, respectively. An in vitro metabolic stability using rat, dog or mouse liver microsomes was performed to determine the intrinsic clearance of capsazepine. The results suggest a very rapid degradation with T(1/2) ranging from 2.6 to 4.3 min and a high clearance, suggesting that drug bioavailability is considerably reduced following extravascular administrations, consequently affecting drug response. Three metabolites were identified by HPLC-MS/MS. S-hydroxylation (M + 16), oxidative desulfuration (M - 16) and desulfuration (M - 32) metabolites of capsazepine were observed following exposure to rat, dog and mouse microsomes.
authors.affiliation: Institut de Chimie Pharmaceutique Albert Lespagnol, Université de Lille 2, Lille, France.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Douat
authors.forename: Pascal
authors.initials: P
authors.lastname: Vachon
authors.forename: Francis
authors.initials: F
authors.lastname: Beaudry
mesh_terms: D000818:Animals; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004285:Dogs; D004355:Drug Stability; D013058:Mass Spectrometry / Q000379:methods*; D051379:Mice; D008862:Microsomes, Liver / Q000378:metabolism; D051381:Rats; D050916:TRPV Cation Channels / Q000037:antagonists & inhibitors*
chemical_list: D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C071423:capsazepine; D002211:Capsaicin