Sensitive column-switching high-performance liquid chromatography method for determination of propiverine in human plasma

A sensitive column-switching high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection was developed for the determination of propiverine in human plasma. Propiverine and internal standard, oxybutynin, were extracted from human plasma that had been made basic with 5N sodium hydroxide into methyl tert-butyl ether. The extracted plasma sample was injected onto the HPLC system consisting of a pretreatment column, a concentrating column, and an analytical column, which were connected with a six-port switching valve. The assay was linear in concentration ranges of 2-200 ng/ml for propiverine in human plasma. This method showed excellent sensitivity (a limit of detection of 0.5 ng/ml), good precision and accuracy. This method is suitable for bioequivalence studies following single dose in healthy volunteers.

Quantification of propiverine by liquid chromatography/electrospray tandem mass spectrometry: Application to a bioequivalence study of two formulations in healthy subjects

Here we report on the development and validation of a sensitive and rapid reversed-phase liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantitative determination of propiverine in human plasma. After adding an internal standard (oxybutynin chloride) to human plasma, samples were extracted using n-hexane/ethylacetate (8:2, v/v). Compounds extracted were analyzed by reversed-phase high-performance liquid chromatography (HPLC) with multiple reaction monitoring (MRM) mode for analyte detection. This method for determination of propiverine proved accurate and reproducible, with a limit of quantitation of 0.5 ng/ml in human plasma. The standard calibration curve for propiverine was linear (r2=0.9988) over the concentration range 0.5-1000.0 ng/ml in human plasma. The intra- and inter-day precision over this concentration range was lower than 8.66% (relative standard deviation, %R.S.D.), and accuracy was between 99.46 and 109.41%, respectively. This method was successfully applied to a bioequivalence study of two propiverine hydrochloride tablet formulations (20 mg) in 24 healthy subjects after a single administration.

Validation of a simple liquid chromatography–tandem mass spectrometric method for the determination of propiverine hydrochloride and its N-oxide metabolite in human plasma

A simple high-performance liquid chromatography (HPLC)-tandem mass spectrometric method has been developed for determination of propiverine hydrochloride and its metabolite, propiverine N-oxide (M-1) in human plasma using stable isotopes, propiverine hydrochloride-d10 and M-1-d10, as internal standards. The analytes were extracted with dichloromethane from 0.2 ml of plasma in neutral condition (pH 7.0) and separated by HPLC on a C18 reversed-phase column using methanol-1% acetic acid (50:50) as a mobile phase, and detected using positive electrospray ionization in selected reaction monitoring (SRM) mode. The method was validated over a concentration range of 2-500 ng/ml for propiverine hydrochloride and 4-1000 ng/ml for M-1 using 0.2 ml of human plasma per assay. The method developed was successfully applied to analysis of propiverine hydrochloride and M-1 in clinical studies.

Increasing sample throughput in pharmacological studies by using dual-column liquid chromatography with tandem mass spectrometry

A robust novel technology of parallel chromatography combined with tandem mass spectrometry was successfully applied to a biological matrix extract for analyte detection. The presented study shows how only by using an additional isocratic pump, a second column and a 10-port valve the throughput is twice of that of a conventional single column system with the same sensitivity. Analytes and matrix were separated and eluting peaks of the first column were detected while the second column was equilibrated. The system was tested and used for the determination of several drugs, metabolites and endogenous compounds (i.e., propiverine, talinolol, scopolamine and leukotrienes).

Evaluation of PET ligands (+)N-[(11)C]ethyl-3-piperidyl benzilate and (+)N-[(11)C]propyl-3-piperidyl benzilate for muscarinic cholinergic receptors: a PET study with microdialysis in comparison with (+)N-[(11)C]methyl-3-piperidyl benzilate in the conscious monkey brain

We developed PET ligands (+)N-[(11)C]ethyl-3-piperidyl benzilate ([(11)C](+)3-EPB) and (+)N-[(11)C]propyl-3-piperidyl benzilate ([(11)C](+)3-PPB) for cerebral muscarinic cholinergic receptors. The distribution and kinetics of the novel ligands were evaluated for comparison with the previously reported ligand (+)N-[(11)C]methyl-3-piperidyl benzilate ([(11)C](+)3-MPB) in the monkey brain (Macaca mulatta) in the conscious state using high-resolution positron emission tomography (PET). At 60-91 min postinjection, regional distribution patterns of these three ligands were almost identical, and were consistent with the muscarinic receptor density in the brain as previously reported in vitro. However, the time-activity curves of [(11)C](+)3-EPB and [(11)C](+)3-PPB showed earlier peak times of radioactivity and a faster clearance rate than [(11)C](+)3-MPB in cortical regions rich in the receptors. Kinetic analysis using the three-compartment model with time-activity curves of radioactivity in metabolite-corrected arterial plasma as input functions revealed that labeling with longer [(11)C]alkyl chain length induced lower binding potential (BP = k(3)/k(4)), consistent with the rank order of affinity of these ligands obtained by an in vitro assay using rat brain slices and [(3)H]QNB. The cholinesterase inhibitor Aricept administered at doses of 50 and 250 microg/kg increased acetylcholine level in extracellular fluid of the frontal cortex and the binding of [(11)C](+)3-PPB with the lowest affinity to the receptors was displaced by the endogenous acetylcholine induced by cholinesterase inhibition, while [(11)C](+)3-MPB with the highest affinity was not significantly affected. Taken together, these observations indicate that the increase in [(11)C]alkyl chain length could alter the kinetic properties of conventional receptor ligands for PET by reducing the affinity to receptors, which might make it possible to assess the interaction between endogenous neurotransmitters and ligand-receptor binding in vivo as measured by PET.

A validated high-performance liquid chromatographic assay for the simultaneous determination of denaverine and its N-monodemethyl metabolite in human plasma

An isocratic reversed-phase high-performance liquid chromatographic method for the simultaneous determination of denaverine and its N-monodemethyl metabolite (MD 6) in human plasma is described. The assay involves the extraction with an n-heptane-2-propanol mixture (9:1, v/v) followed by back extraction into 12.5% (w/w) phosphoric acid. The analytes of interest and the internal standard were separated on a Superspher RP8 column using a mobile phase of acetonitrile-0.12 M NH4H2PO4-tetrahydrofuran (24:17.2:1, v/v), adjusted to pH 3 with 85% (w/w) phosphoric acid. Ultraviolet detection was used at an operational wavelength of 220 nm. The retention times of MD 6, denaverine and the internal standard were 5.1, 6.3 and 10.2 min, respectively. The assay was validated according to international requirements and was found to be specific, accurate and precise with a linear range of 2.5-150 ng/ml for denaverine and MD 6. Extraction recoveries for denaverine and MD 6 ranged from 44 to 49% and from 42 to 47%, respectively. The stability of denaverine and MD 6 in plasma was demonstrated after 24 h storage at room temperature, after three freeze-thaw cycles and after 7 months frozen storage below -20 degrees C. The stability of processed samples in the autosampler at room temperature was confirmed after 24 h storage. The analytical method has been applied to analyses of plasma samples from a pharmacokinetic study in man.

High-performance liquid chromatographic determination of propiverine and its N-oxide in human serum

A high-performance liquid chromatographic method has been developed for the determination of propiverine hydrochloride (P4) and its main metabolite, propiverine N-oxide (P4NO) in human serum. P4 has been shown to be efficacious in those patients who have either idiopathic bladder instability, or neurogenic bladder (detrusor hyperflexia) resulting from spinal cord injuries. In the present method, the analytes were extracted from serum (1 ml, pH 8) into methyl tert.-butyl ether. The separation was performed on a reversed-phase C8 (RP-select B) column using phosphate buffer-acetonitrile (30:70, v/v). UV absorption was used for measuring the analytes, with a limit of quantitation of about 10 ng/ml, which is appropriate for pharmacokinetic studies.

Quantitative capillary column gas chromatographic method for the determination of glycopyrronium in human plasma

A new sensitive and selective capillary column gas chromatographic method for the anti-cholinergic agent glycopyrronium bromide in human plasma is described. The procedure involves preliminary ion-pair extraction of the drug into dichloromethane, followed by concentration and analysis of the ion-pair complex by capillary column gas chromatography using a nitrogen-sensitive detector. The method depends on the thermal dequaternisation of the quaternary ammonium compound and can be used to detect 5 ng/ml in a 3-ml plasma sample. The assay procedure has been applied to the determination of the plasma concentration of glycopyrronium after intravenous administration to an anaesthetised patient.