ABSTRACT
A simple, sensitive and selective spectrofluorimetric method has been developed for the determination of 3-methylflavone-8-carboxylic acid as the main active metabolite of flavoxate hydrochloride in human urine. The proposed method was based on the measurement of the native fluorescence of the metabolite in methanol at an emission wavelength 390 nm, upon excitation at 338 nm. Moreover, the urinary excretion pattern has been calculated using the proposed method. Taking the advantage that 3-methylflavone-8-carboxylic acid is also the alkaline degradate, the proposed method was applied to in vitro determination of flavoxate hydrochloride in tablets dosage form via the measurement of its corresponding degradate. The method was validated in accordance with the ICH requirements and statistically compared to the official method with no significant difference in performance.
Subject(s)
Flavoxate/analogs & derivatives , Flavoxate/pharmacokinetics , Fluorometry/methods , Calibration , Flavoxate/metabolism , Flavoxate/urine , Humans , Limit of Detection , Reproducibility of Results , Sensitivity and Specificity , Solvents/chemistry , TabletsABSTRACT
A novel water-compatible molecularly imprinted SPE combined with zwitterionic hydrophilic interaction liquid chromatography method for selective extraction and determination of 3-methylflavone-8-carboxylic acid (MFA), the main active metabolite of flavoxate in human urine, was developed and validated. The effects of progenic solvents, pH, cross linker and amount of monomer were studied to optimize the efficiency and selectivity. The molecularly imprinted polymer showed good specific adsorption capacity with an optimum of 200 µmol/g at pH 7.5 and selective extraction of MFA from human urine. The recovery of MFA from human urine was >98%. The lower limit of quantification was 1.20 µg/mL. The proposed method overcomes the matrix effects of endogenous substances generally encountered during direct analysis of urine sample.
Subject(s)
Chromatography, Liquid/methods , Flavoxate/analogs & derivatives , Polymers/chemistry , Solid Phase Extraction/methods , Adsorption , Flavoxate/isolation & purification , Flavoxate/metabolism , Flavoxate/urine , Humans , Hydrophobic and Hydrophilic Interactions , Molecular Imprinting , Polymers/chemical synthesis , Solid Phase Extraction/instrumentationABSTRACT
High performance liquid chromatographic (HPLC) method was presented for the determination of 3-methylflavone-8-carboxylic acid as the main active metabolite of flavoxate hydrochloride (FX) in human urine. The proposed method was based on using CN column with mobile phase consisting of acetonitrile-12 mM ammonium acetate (40:60, v/v) and adjusted to apparent pH 4.0 with flow rate of 1.5 ml min(-1). Quantitation was achieved with UV detection at 220 nm. The proposed method was utilized to the determination of dissolution rate for tablets containing flavoxate hydrochloride. The urinary excretion pattern has been calculated using the proposed method.
Subject(s)
Carboxylic Acids/analysis , Chromatography, High Pressure Liquid/methods , Flavoxate , Parasympatholytics , Acetates/chemistry , Acetonitriles/chemistry , Adult , Calibration , Chromatography, High Pressure Liquid/instrumentation , Drug Stability , Electrocardiography , Flavoxate/analysis , Flavoxate/metabolism , Flavoxate/urine , Humans , Hydrochloric Acid/chemistry , Hydrogen-Ion Concentration , Kidney/physiology , Liver/physiology , Male , Parasympatholytics/analysis , Parasympatholytics/metabolism , Parasympatholytics/urine , Reproducibility of Results , Sensitivity and Specificity , Sodium Hydroxide/chemistry , Solubility , Sonication , Spectrophotometry, Ultraviolet , Tablets/chemistry , Temperature , Time FactorsABSTRACT
The effects of tetraalkylammonium salts and sodium dodecyl sulphate on the migration behaviour of human urinary components and other negatively charged or neutral solutes were investigated. The sulphate acted mainly on hydrophobic and positively charged substances, whereas the ammonium salts acted mainly on negatively charged solutes. By choosing the components of the eluent carefully, the free and conjugate forms of 3-methylflavone-8-carboxylic acid (MFA) in human urine, the major metabolites of flavoxate, could be simultaneously determined without pretreatment, using fenprofen as an internal standard. The calibration curve of MFA was linear in the range 1-50 micrograms/ml and the detection limit was 0.2 microgram/ml, which covered the urine levels encountered in pharmacokinetic studies. The intra-day and inter-day precisions of the method, expressed as the relative standard deviation, were less than 2 and 3%, respectively. This method was successfully applied to an excretion study of MFA in eight healthy volunteers, and the results were in agreement with data in the literature obtained by gas chromatography.