High-performance liquid chromatographic determination of ethacrynic acid in human plasma.

A high-performance liquid chromatographic method for the determination of ethacrynic acid (EA) in human plasma is described. Plasma was prepared for analysis by addition of 4-(2,4-dichlorophenoxy)-butyric acid as an internal standard followed by acidification with hydrochloric acid and extraction with ethyl acetate. Separation was by isocratic reversed-phase chromatography, the column effluent was monitored at 280 nm and quantitation was performed using peak-area ratios. The linear range for EA determination was from 0.5 to 25 micrograms/ml with a lower limit of detection of 0.1 microgram/ml. The reported method is convenient, sensitive and reproducible, illustrating its usefulness for pharmacokinetic studies.     

High-performance liquid chromatographic determination of pilocarpine in plasma.

A high-performance liquid chromatographic procedure requiring neither derivatization nor complex sample work-up is reported for reproducibly and sensitively determining pilocarpine in plasma. Following stabilization of pilocarpine against in vitro hydrolysis using sodium fluoride, plasma samples were extracted and the extracts chromatographed on a 5-microns, low-carbon-load (6%) C18 reversed-phase column. The assay was linear between 10 and 300 ng/ml (r = 0.998). It had sufficient sensitivity to quantitate pilocarpine at concentrations as low as 10 ng/ml (signal-to-noise ratio > or = 4) using a 500-microliters sample. The assay appears to be the first published specifically for plasma determinations and has proven capable of supporting pharmacokinetics studies of pilocarpine disposition in the anesthetized dog.     

High-performance liquid chromatographic determination of ganciclovir in plasma.

A rapid, selective and sensitive isocratic reversed-phase high-performance liquid chromatographic method for the determination of ganciclovir in plasma samples was developed. This method, which was applied to the analysis of plasma ganciclovir from heart transplant patients under ganciclovir therapy for cytomegalovirus infections, represents a suitable analytical tool for drug monitoring and pharmacokinetic investigations.     

High-performance liquid chromatographic determination of fluvoxamine and fluvoxamino acid in human plasma.

A high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of fluvoxamine and its major metabolite fluvoxamino acid in plasma. Fluvoxamine and fluvoxamino acid in plasma were extracted using a C18 bonded-solid phase cartridge, followed by C4 reversed-phase HPLC separation.Fluvoxamine, fluvoxamino acid and moperone as an internal standard were detected by ultraviolet absorbance at 254 nm. It was possible to determine both fluvoxamine and fluvoxamino acid in the concentration range of 25.0-200.0 ng/mL, respectively. The detection limits of both fluvoxamine and fluvoxamino acid were 10.0 ng/mL, respectively. The mean recoveries of fluvoxamine and fluvoxamino acid added to plasma were more than 94.0% and 96.5%, with a coefficient of variation of less than 7.6% and 8.2%, respectively. This method has been used for the simultaneous determination of steady-state plasma concentration (Css) of fluvoxamine and fluvoxamino acid in depressive patients treated with 200 mg of oral fluvoxamine dosed as 100 mg twice-daily. The Css values of fluvoxamine and fluvoxamino acid in twelve Japanese patients were showed individual variations, which were in the range of 48.3-532.9 ng/ml and 35.6-307.1 ng/ml, respectively.     

High-performance liquid chromatographic determination of iothalamic acid in human plasma and urine.

A simple, rapid and sensitive method for the determination of iothalamic acid (IA) in both plasma and urine is reported. After extraction with ethyl acetate, IA was determined by strong anion-exchange high-performance liquid chromatography with ultraviolet detection at 254 nm. The lower limit of detection was 0.5 micrograms/ml. The average recovery was 73 and 57% from plasma and urine, respectively. Linearity was found over the investigated concentration range (up to 500 micrograms/ml for plasma and up to 10.0 mg/ml for urine). The reproducibility of the technique was good (coefficient of variation less than 6%) as was the precision and accuracy (coefficient of variation less than 2.5%). No interference from endogenous substances or any of the common drugs tested was found.     

High-performance liquid chromatographic determination of pentaerythritol in plasma

A sensitive analysis of pentaerythritol in plasma has been devised, based on the formation or its tetra-p-methoxybenzoate derivative and high-performance liquid chromatography employing an ultraviolet photometric detector. The method permits analysis of pentaerythritol in the ppm range.     

High-performance liquid chromatographic determination of ambroxol in human plasma.

Ambroxol has been determined in biological fluids using a rapid and sensitive high-performance liquid chromatographic method. The samples prepared from plasma by liquid-liquid extraction were analysed on reversed-phase silica gel by competing-ion chromatography with ultraviolet detection. The method was applied to the determination of ambroxol levels in twelve healthy volunteers after oral administration of 90 mg of ambroxol in tablets of Mucosolvan and Ambrosan.     

High-performance liquid chromatographic determination of busulfan in plasma

Summary Busulfan (Myleran; 1,4-bis-(methanesulfonyloxy) butane; BU) is a bifunctional alkylating agent used in clinical practice since 1959. It is currently included at high doses in conditioning regimens for bone marrow transplantation, usually in combination with cyclo-phosphamide. A high-performance liquid chromatographic method has been developed for the determination of BU in plasma. The basis of the assay is a derivatization with sodium diethyldithiocarbamate at 32°C in the presence of 1-bromo-1-deoxy-3,6-anhydrogalactitol as internal standard. Analysis is performed on a cyano column with heptane-isopropanol-glacial acetic acid as mobile phase and UV detection at 280 nm. The calibration graph was linear in the concentration range 0.18–46.40 μM BU in plasma. The limit of detection was 0.1 μM. The precision and accuracy were between the limits required by good laboratory practice. Presented at Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, september 1–3, 1999     

High-performance liquid chromatographic determination of bromazepam in human plasma

An assay using high-performance liquid chromatography has been developed for the determination of bromazepam in plasma. After a single-step extraction from basified samples with dichloromethane, using decarboxyloflazepate as an internal standard, samples were analysed using a reversed-phase Nova Pak 5-microns column with a mobile phase of methanol - phosphate buffer (60 + 40) adjusted to pH 7.6. The drugs were detected at 239 nm and the limit of detection was found to be 3 micrograms l-1 for bromazepam. The method is simple, rapid and sensitive and permits bromazepam levels in clinical and pharmacokinetic studies to be monitored.     

High-performance liquid chromatographic determination of benzodiazepines in human plasma

A simple and sensitive method for determination of benzodiazepines in plasma has been developed using high-performance liquid chromatography in a reverse-phase mode. The method is illustrated by application to plasma samples containing diazepam and N-desmethyldiazepam at concentrations which would be encountered during therapy, with limits of detection of 10 ng/ml and 2 ng/ml for diazepam and N-desmethyldiazepam, respectively.