title: Investigation of ex vivo stability of fesoterodine in human plasma and its simultaneous determination together with its active metabolite 5-HMT by LC-ESI-MS/MS: Application to a bioequivalence study.
abstract: Fesoterodine is a non-selective muscarinic-receptor antagonist, used in the treatment of overactive bladder syndrome. A highly sensitive, selective and rapid method has been developed for the simultaneous determination of fesoterodine and its active metabolite, 5-hydroxymethyl tolterodine (5-HMT) in human plasma by liquid chromatography-tandem mass spectrometry (LC-ESI-MS/MS). Due to rapid conversion of parent drug to 5-HMT, ex vivo stability of fesoterodine in human plasma was extensively studied to optimize the extraction protocol. The analytes and their deuterated analogs were quantitatively extracted from 100μL human plasma by liquid-liquid extraction in methyl tert-butyl ether: n-hexane. The chromatographic separation of analytes was achieved on a Kromasil C18 (100mm×4.6mm, 5μm) column under isocratic conditions. The method was validated over a dynamic concentration range of 0.01-10ng/mL for both the analytes. Ion-suppression effects were investigated by post-column infusion of analytes. The precision (% CV) values for the calculated slopes of calibration curves, which would reflect the relative matrix effect, were less than 1.5% for both the analytes. The intra-batch and inter-batch precision (% CV) across quality control levels varied from 1.82 to 3.73% and the mean extraction recovery was >96% for both the analytes. The method was successfully applied to a bioequivalence study of 8mg fesoterodine tablet formulation (test and reference) in 12 healthy Indian subjects under fasted and fed condition. The assay reproducibility estimated by reanalysis of incurred samples showed a change of ±12.0%.
authors.affiliation: Chemistry Department, Kadi Sarva Vishwavidyalaya, Sarva Vidyalaya Campus, Sector 15/23, Gandhinagar 382015, Gujarat, India.
authors.forename: Jignesh M
authors.initials: JM
authors.lastname: Parekh
authors.forename: Mallika
authors.initials: M
authors.lastname: Sanyal
authors.forename: Manish
authors.initials: M
authors.lastname: Yadav
authors.forename: Pranav S
authors.initials: PS
authors.lastname: Shrivastav
mesh_terms: D000328:Adult; D001559:Benzhydryl Compounds / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D002853:Chromatography, Liquid / Q000379:methods*; D003408:Cresols / Q000097:blood* / Q000737:chemistry / Q000493:pharmacokinetics; D018592:Cross-Over Studies; D004355:Drug Stability; D006801:Humans; D016014:Linear Models; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D053719:Tandem Mass Spectrometry / Q000379:methods; D013810:Therapeutic Equivalency
chemical_list: C109909:5-hydroxymethyl tolterodine; D001559:Benzhydryl Compounds; D003408:Cresols; C526675:fesoterodine