title: Cyclodextrin-MEEKC for the analysis of oxybutynin and its impurities.
abstract: The development of a cyclodextrin-MEEKC method for the analysis of oxybutynin and five related impurities is described. Experimental design strategies were applied in order to reach baseline separation of the compounds in a short analysis time. Mixture design made it possible to find the best composition for the microemulsion acting as pseudostationary phase, which was constituted by 89.1% 10 mM borate buffer pH 9.2, 1.7% n-heptane, 9.2% SDS/n-butanol in 1:2 ratio. The addition of (2-hydroxypropyl)-beta-cyclodextrin to the background electrolyte was found to improve analysis performance. A Doehlert design, for the factors cyclodextrin concentration and voltage, was carried out and Derringer desirability function led to the identification of 18 mM and 29 kV as the optimal values. Applying the optimum conditions, separation of all the compounds, including the enantiomers of impurity 1, was obtained in less than 12 min. The method was validated according to ICH guidelines for drug assay and determination of impurities and was applied to oxybutynin tablet analysis.
authors.affiliation: Department of Pharmaceutical Sciences, University of Florence, Florence, Italy.
authors.forename: Iacopo
authors.initials: I
authors.lastname: Giannini
authors.forename: Serena
authors.initials: S
authors.lastname: Orlandini
authors.forename: Roberto
authors.initials: R
authors.lastname: Gotti
authors.forename: Sergio
authors.initials: S
authors.lastname: Pinzauti
authors.forename: Sandra
authors.initials: S
authors.lastname: Furlanetto
mesh_terms: D002138:Calibration; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000295:instrumentation / Q000379:methods*; D003505:Cyclodextrins / Q000737:chemistry*; D004655:Emulsions; D008333:Mandelic Acids / Q000032:analysis* / Q000737:chemistry; D015394:Molecular Structure; D018727:Muscarinic Antagonists / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results; D012984:Software; D013237:Stereoisomerism
chemical_list: D003505:Cyclodextrins; D004655:Emulsions; D008333:Mandelic Acids; D018727:Muscarinic Antagonists; C005419:oxybutynin