Determination of pirlindole in plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic method is described for the analysis of pirlindole [2,3,3a,4,5,6-hexahydro-8-methyl-1H-pyrazino(3,2,1-jk)carbazole hydrochloride], a new antidepressive drug. The drug was extracted from plasma into dichloromethane, and the analysis was carried out on a reversed-phase column, the effluent being monitored by fluorescence detection. The method is selective and sensitive (limit of detection 1-2 ng/ml plasma). Urine analysis was done by direct injection of the diluted sample. The method was applied to the analysis of plasma and urine samples of eight healthy male volunteers who received a 75-mg oral dose of a tablet formulation of pirlindole. The method was also applied to a study in three beagle dogs which received pirlindole (1 mg/kg) by infusion (0.1 mg/kg/min) and orally (10 mg/kg) to estimate the absolute bioavailability of the drug.     

Determination of amdinocillin in plasma and urine by high-performance liquid chromatography

A rapid, sensitive and specific high-performance liquid chromatographic (HPLC) assay was developed for the determination of amdinocillin (formerly mecillinam) in human plasma and urine. The assay is performed by direct injection of a plasma protein-free supernatant or a dilution of urine. A 10 micrometer muBondapak phenyl column with an eluting solvent of water--methanol--1 M phosphate buffer, pH 7 (70:30:0.5) was used, with UV detection of the effluent at 220 nm. Azidocillin potassium salt [potassium-6-(D-(-)-alpha-azidophenyacetamido)-penicillanate] was used as the internal standard and quantitation was based on peak height ratio of amdinocillin to that of the internal standard. The assay has a recovery of 74.4 +/- 6.3% (S.D.) in the concentration ranges of 0.1-20 microgram per 0.2 ml of plasma with a limit of detection equivalent to 0.5 microgram/ml plasma. The urine assay was validated over a concentration range of 0.025-5 mg/ml of urine, and has a limit of detection of 0.025 mg/ml (25 microgram/ml) using a 0.1-ml urine specimen per assay. The assay was applied to the determination of plasma and urine concentrations of amdinocillin following intravenous administration of a 10 mg/kg dose of amdinocillin to two human subjects. The HPLC and microbiological assays were shown to correlate well for these samples.     

Determination of trichlormethiazide in human plasma and urine by high-performance liquid chromatography

Summary This paper describes a high-performance liquid chromatographic (HPLC) assay method for the determination of trichlormethiazide (TCM) in human plasma and urine. After extraction and separation on an ODS column TCM from plasma was detected by oxidation in an electrochemical detector (ECD) by a porous graphite electrode. The sensitivity was better than HPLC with UV detection, enabling the determination of 2 ng ml^–1 TCM in human plasma. This method also allows determination of TCM at higher concentrations by exchanging the UV for the electrochemical detector. To study the pharmacokinetics, TCM in plasma and urine was assayed with coefficients of variation in the range 2–3%. The method has the advantages of high sensitivity for plasma assay and high precision with a simple procedure for both plasma and urine samples. Small samples of 0.5 ml plasma per assay also reduced the total volume of plasma needed.     

Determination of 2-mercaptopropionylglycine in plasma and urine by high-performance liquid chromatography

Methods for quantitative analysis of total and non-protein-bound 2-mercaptopropionylglycine (2-MPG) in plasma, and total 2-MPG in urine, have been developed. By reduction of urine, plasma or deproteinized plasma samples with tributylphosphine, 2-MPG is liberated from its disulphides, and after clean-up of the sample, 2-MPG is derivatized with N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide (DACM). The 2-MPG-DACM derivative is then quantified by high-performance liquid chromatography (HPLC) with fluorimetric detection. Both ion-suppression and ion-pair HPLC gave satisfactory chromatograms. The precision of the methods was satisfactory (coefficient of variation 3.1-5.8%), analytical recovery was quantitative (85-99%) and the two HPLC techniques were well correlated (r = 0.99). Five healthy subjects receiving 500 mg of 2-MPG showed maximal total plasma concentration of 13.8-26.9 mumol/l at 3-5 h after intake, and their non-protein-bound 2-MPG was, at the same time, 62-77% of the total 2-MPG. The urinary excretion was 27.8 +/- 3.8% (mean +/- S.D.) of the given dose, most of it excreted within 12 h after intake.     

Determination of piquindone in canine plasma and urine by high-performance liquid chromatography

This report describes a rapid, sensitive and selective method for the determination of piquindone in canine plasma and piquindone and the N-demethyl metabolite of piquindone in canine urine, utilizing normal-phase high-performance liquid chromatography (HPLC) with isocratic elution at ambient temperature and monitoring the ultraviolet absorbance of the eluent at 254 nm. The trimethyl analogue of piquindone is used as the internal standard in the HPLC assay of plasma. The assay was applied to the measurement of concentrations of piquindone in the plasma and urine of a dog following single intravenous and oral administration of 5 mg/kg doses of piquindone hydrochloride dihydrate.     

Determination of cefotaxime and desacetylcefotaxime in plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic method is described for the analysis of the anti-bacterial agent cefotaxime and desacetylcefotaxime in physiological fluids. Plasma or serum samples were mixed with chloroform--acetone to remove proteins and most lipid material. The aqueous phase was then freeze-dried, reconstituted in mobile phase and chromatographed on a reversed-phase column using UV detection at 262 nm. Urine was analysed directly after centrifugation to remove particulate matter. The detection limit was 0.5--1.0 micrograms/ml for serum and 5 micrograms/ml for urine. The method has been applied to the analyses of cefotaxime and desacetylcefotaxime in plasma, serum, urine, cerebrospinal fluid, saliva, and pus from infected wound secretions. Two additional metabolites, which are lactones in which the beta-lactam ring has been opened, could be separated by this method.     

Determination of picotamide in human plasma and urine by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the determination of picotamide in human plasma and urine is described. After addition of an internal standard (bamifylline), the plasma and urine samples were subjected to liquid-liquid extraction and clean-up procedures. The final extracts were evaporated to dryness and the resulting residues were reconstituted in 100 microliters of methanol-water (50:50, v/v) and chromatographed on a LiChrosorb RP-SELECT B reversed-phase column coupled to an ultraviolet detector monitored at 230 nm. Chromatographic analysis takes about 10 min per sample. The assay was linear over a wide range and has a limit of detection of 0.005 and 0.1 micrograms/ml in plasma and urine, respectively. It was selective for picotamide, accurate and robust and thus suitable for routine assays after therapeutic doses of picotamide.     

Determination of tamarixetin and kaempferide in rat plasma and urine by high-performance liquid chromatography

Tamarixetin and kaempferide, the major bioactive constituents of Xiheliu extract, have been simultaneously/quantitatively determined in rat plasma and urine by a sensitive high performance liquid chromatography method after oral administration the total flavonoids from Xiheliu. In this study, the biological samples were prepared by solid-phase extraction, then simultaneously detected at 254 nm and successfully separated and quantified using a reversed-phase C₁₈ column with methanol-formic acid aqueous gradient solution, at a flow rate of 1 mL/min. Good linearity (r > 0.989) of tamarixetin was observed in plasma and urine with the calibration ranges both at 1.6–80 μg/mL. For kaempferide, the correlation coefficient reached 0.994 in plasma at 1.4–70 μg/mL. The RSD of intra- and inter-day were 1.9–6.5% for tamarixetin and 1.3–9.0% for kaempferide in plasma; in urine, the intra- and inter-day RSD for not only tamarixetin but also kaempferide was no more than 7.4 and 5.8%, respectively. The lowest extraction recovery was 87.6% for kaempferide and 93.2% for tamarixetin in plasma and urine for both low and high concentrations. Due to the high sensitivity (the LOQ for tamarixetin was 1.2 μg/mL and for kaempferide 1.4 μg/mL), accuracy, precision, and good selectivity, the assay was successfully applied to pharmacokinetic studies of both flavonols in rats. The half-lives of tamarixetin and kaempferide were 17.8 ± 1.4 and 92.5 ± 1.6 min, and the c _max were 3.1 ± 0.2 and 2.5 ± 0.4 μg/mL, respectively.     

Determination of pemoline in plasma, urine and tissues by reversed-phase high-performance liquid chromatography

A simple and selective high-performance liquid chromatographic method with ultraviolet detection at 215 nm for the determination for pemoline in rat plasma, urine and tissues is described. Pemoline in the samples was extracted with methylene chloride at pH 10 and the organic phase was evaporated after adding 5-methyl-5-phenylhydantoin used as an internal standard. Pemoline and the internal standard were separated on a Kaseisorb LC C8-60-5 reversed-phase column. The limits of determination of pemoline in 0.1-0.2 ml of plasma, urine and tissue homogenates were 2, 100 and 20 ng, respectively. The method should be useful for studies of the pharmacokinetics and distribution of pemoline in small animals.     

Determination of captopril and its mixed disulphides in plasma and urine by high-performance liquid chromatography

A high-performance liquid chromatographic method has been developed which enables sensitive determination of captopril and its mixed disulphides in plasma and urine after oral administration of a new antihypertensive agent, 1-(D-3-acetylthio-2-methylpropanoyl)-L-prolyl-L-phenylalanine (DU-1219, I). Captopril is derivatized with a new reagent, N-(4-benzoylphenyl)maleimide and the derivative is extracted with chloroform and assayed using a liquid chromatograph equipped with an ultraviolet detector at 254 nm. Mixed disulphides of captopril with thiol compounds such as cysteine, glutathione and plasma proteins are reduced with tributylphosphine to form captopril, followed by derivatization with N-(4-benzoylphenyl)maleimide. Accurate determinations are possible over a concentration range of 10-500 ng/ml captopril in plasma, and 100-2500 ng/ml captopril in urine. The coefficients of variation of captopril in plasma (200 ng/ml) and urine (500 ng/ml) are 3.7% and 2.6%, respectively, and those of mixed disulphides of captopril are similar to those of captopril. Plasma levels and urinary excretion of captopril and its mixed disulphides in healthy volunteers following single oral administration of I (50 mg) have also been determined.     

Determination of teicoplanin in human plasma and urine by affinity and reversed-phase high-performance liquid chromatography

A sensitive, highly selective and simple high-performance liquid chromatographic method for the determination of teicoplanin, a novel glycopeptide antibiotic, composed of six components, in human plasma and urine is described. After an isolation step by affinity chromatography, the antibiotic substances were chromatographed on a Nucleosil C18 column with phosphate buffer-acetonitrile according to a gradient profile. All the components were detected by their UV absorption at 240 nm. The concentration of teicoplanin was determined by using the external standard procedure. This method was applied to the sum of the six major components as well as to each of them separately. The linearity of the method was checked between 0.5 and 50 micrograms/ml for plasma and between 2 and 50 micrograms/ml for urine. The limit of detection was 0.1 microgram/ml for both biological fluids. The coefficients of variation of the between-day assays did not exceed 8.6 and 8.9% in plasma and urine, respectively. The application of the method to a pharmacokinetic study of teicoplanin after a single intravenous therapeutic dose in a patient is reported. This rapid technique also appears to be suitable for drug monitoring.