ABSTRACT
A high-performance liquid chromatographic method for the determination of tenoxicam in plasma has been developed. Tenoxicam was extracted from buffered plasma (pH 3 or 4, respectively) with dichloromethane and the evaporated extracts were analysed on a C18 reversed-phase column using a methanol-phosphate buffer mobile phase and with UV detection at 371 nm. The detection limit was 20 ng/ml using a 0.5-ml sample. The method is selective with respect to the 5'-hydroxy metabolite, which is present in plasma after multiple administration of tenoxicam; this metabolite may also be determined using this procedure.
Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/blood , Piroxicam/analogs & derivatives , Thiazines/blood , Chromatography, High Pressure Liquid , Drug Stability , Humans , Hydrogen-Ion Concentration , Indicators and Reagents , Light , Time FactorsABSTRACT
A high-performance liquid chromatographic method for the determination of bromazepam in plasma and of its main metabolites in urine is described. The unchanged drug is extracted from plasma with dichloromethane, using Extrelut 1 extraction tubes. The residue from this extract is subsequently analysed by reversed-phase high-performance liquid chromatography with ultraviolet detection (230 nm). The limit of detection is 6 ng/ml of plasma, using a 1-ml specimen. For the determination of the metabolites, the urine samples are incubated to effect enzymatic deconjugation and are then extracted with dichloromethane. Following two clean-up steps (back extractions), the final residue is analysed on the same reversed-phase system as the plasma samples. The limit of detection for the two metabolites is 200 ng/ml.
Subject(s)
Anti-Anxiety Agents/metabolism , Bromazepam/metabolism , Animals , Bromazepam/analogs & derivatives , Bromazepam/urine , Cattle , Chromatography, High Pressure Liquid/methods , Glucuronidase/metabolism , Half-Life , Humans , Hydroxylation , Liver/enzymology , Pyridines/urine , Spectrophotometry, UltravioletABSTRACT
Selective high-performance liquid chromatographic methods for the determination of tiapamil and its two main metabolites in plasma and urine are described. Tiapamil together with its metabolites is extracted at alkaline pH into dichloromethane. Separation is carried out using normal-phase high-performance liquid chromatography with ultraviolet detection (278 nm). The unchanged drug and the desmethyl metabolite are analysed simultaneously. The second metabolite is analysed separately under more polar conditions. The sensitivity limits are 50 ng/ml for tiapamil, 100 ng/ml for the desmethyl metabolite and 75 ng/ml for the second metabolite, using 0.5 ml of plasma. The sensitivity limits in urine are 100 ng/ml for all three compounds using a 0.5 ml specimen. The method has been applied to the analysis of human plasma and urine after intravenous (70 mg) and oral (400 mg) administration of tiapamil.
