title: High-performance liquid chromatographic method with amperometric detection employing boron-doped diamond electrode for the determination of sildenafil, vardenafil and their main metabolites in plasma.
abstract: A simple, fast and sensitive HPLC method with electrochemical detection employing boron-doped diamond electrode (BDD) for the determination of sildenafil (Viagra™), vardenafil (Levitra™) and their main metabolites, N-desmethyl sildenafil and N-desethyl vardenafil in human plasma is presented. The assay involved drug extraction by tert-butyl methyl ether and isocratic reversed-phase liquid chromatography with amperometric detection. Complete separation of all analytes was achieved within 12 min. The mobile phase consisted of 20mM sodium dihydrogen phosphate with 40 mM sodium perchlorate/acetonitrile (70:30, v/v), pH 3.5. The electrode working potential was +1520 mV (vs. Pd/H(2)). Calibration curves were linear over the concentration range of 10-400 ng mL(-1). Phloretin was used as an internal standard. The limits of detection (LOD) and quantification (LOQ) for the studied analytes were within the range of 2-4 ng mL(-1) and 7.0-13.4 ng mL(-1), respectively. The developed method was applied to human plasma samples spiked with analytes at therapeutic concentrations. The study confirms the method's suitability for both pharmacokinetic studies and therapeutic monitoring.
authors.affiliation: Department of Analytical Chemistry, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic.
authors.forename: Zdenka
authors.initials: Z
authors.lastname: Bartošová
authors.forename: David
authors.initials: D
authors.lastname: Jirovský
authors.forename: Aleš
authors.initials: A
authors.lastname: Horna
mesh_terms: D001895:Boron / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation* / Q000379:methods; D056148:Chromatography, Reverse-Phase; D018130:Diamond / Q000737:chemistry*; D004566:Electrodes; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000097:blood* / Q000737:chemistry; D016014:Linear Models; D010879:Piperazines / Q000097:blood* / Q000737:chemistry; D011687:Purines / Q000097:blood / Q000737:chemistry; D012680:Sensitivity and Specificity; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000097:blood* / Q000737:chemistry; D014227:Triazines / Q000097:blood / Q000737:chemistry; D000069058:Vardenafil Dihydrochloride
chemical_list: D007093:Imidazoles; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014227:Triazines; D000069058:Vardenafil Dihydrochloride; D018130:Diamond; D000068677:Sildenafil Citrate; D001895:Boron