Determination Of Furosemide In Plasma Research Articles

Determination of furosemide in plasma and urine using monolithic silica rod liquid chromatography

In the present study we developed a fast and reliable HPLC assay for the determination of the loop diuretic furosemide in plasma and urine, using a Chromolith ® RP 18e (100 mm × 4.6 mm) monolithic silica rod HPLC column. After liquid–liquid extraction with diethylether, plasma or urine samples were separated with a gradient consisting of solvent A (20% acetonitrile) and solvent B (80% acetonitrile), both in 0.25% acetic acid. The flow rate was 3.5 ml/min and the effluent was monitored by fluorescence with excitation at 230 nm and emission at 410 nm. The retention times for the internal standard (naproxen) and for furosemide were 2.1 and 3.7 min, respectively, and total run time was 8 min. The calibration curves were linear between 7.8 and 1000 ng/ml, and within-assay and between-assay coefficients of variation were <6.5% and <10%, respectively. The proposed assay for furosemide in plasma and urine using monolithic silica rod chromatography is fast, sensitive, and reliable, and, thus, well suited for pharmacokinetic studies.

High-performance liquid chromatographic determination of furosemide in plasma and urine and its use in bioavailability studies

A sensitive, selective and efficient reversed-phase high-performance liquid chromatographic (HPLC) method is reported for the determination of furosemide in human plasma and urine. The method has a sensitivity limit of 5 ng/ml in plasma, with acceptable within- and between-day reproducibilities and good linearity ( r 2>0.99) over a concentration range from 0.05 to 2.00 μg/ml. The one-step extract of furosemide and the internal standard (warfarin) from acidified plasma or urine was eluted through a μBondapak C 18 column with a mobile phase composed of 0.01 M potassium dihydrogenphosphate and acetonitrile (62:38, v/v) adjusted to pH 3.0. Within-day coefficients of variation (C.V.s) ranged from 1.08 to 8.63% for plasma and from 2.52 to 3.10% for urine, whereas between-day C.V.s ranged from 4.25 to 10.77% for plasma and from 5.15 to 6.81% for urine at three different concentrations. The minimum quantifiable concentration of furosemide was determined to be 5 ng/ml. The HPLC method described has the capability of rapid and reproducible measurement of low levels of furosemide in small amounts of plasma and urine. This method was utilized in bioavailability/pharmacokinetic studies for the routine monitoring of furosemide levels in adults, children and neonate patients.

Quantitative determination of furosemide in plasma, plasma water, urine and ascites fluid by high-performance liquid chromatography.

A high-performance liquid chromatographic method using spectrofluorometric detection is described for the determination of furosemide in plasma, plasma water, urine and ascites fluid. The extraction procedure decreases interference from endogenous substances. The detection limit of furosemide is 10 ng in 0.5 ml of biological sample. The method is sufficiently sensitive for pharmacokinetic study of furosemide with normal subjects and patients with liver cirrhosis and/or renal disease after oral administration of furosemide in a retard capsule, and for study of protein binding of furosemide in patients with various diseases.

External‐Standard High‐Performance Liquid Chromatographic Method for Quantitative Determination of Furosemide in Plasma by Using Solid‐Phase Extraction and On‐Line Elution

AbstractA rapid and simple external‐standard high‐performance liquid chromatographic (HPLC) method has been developed for the determination of the concentration of furosemide in plasma. The analyte is extracted with a C‐2 ethyl sorbent. On‐line elution of the analyte into the HPLC system is accomplished with an advanced automated sample processor (Varian). Furosemide is quantified by fluorescence detection within a linear range of 25 to 1000 ng/mL (average correlation coefficient, 0.9998), with a limit of detection of 1.8 ng/mL. Both internal‐ and external‐standard procedures were evaluated, and the external‐standard procedure demonstrated superior characteristics. The external‐standard procedure was precise to within a relative standard deviation of 8% and accurate with <3% error throughout the concentration range studied. The external‐standard HPLC method was used to analyze the concentration of furosemide in >1000 plasma samples obtained from patients with either normal kidney function or renal failure who had received furosemide either orally or intravenously in an experimental setting.

Routine methods in toxicology and therapeutic drug monitoring by high performance liquid chromatography: III. A rapid microscale method for determination of furosemide in plasma and urine.

A highly specific, sensitive, and rapid microscale method is described for determining furosemide levels in plasma and urine. Monitoring furosemide levels has been recommended in patients with impaired renal function and in premature infants since furosemide has been known to cause ototoxicity. The method described here is simple, easy to run, takes only 7 min per sample, and can be set up for routine monitoring of furosemide by clinical laboratories. The method uses ion-pairing high performance liquid chromatography and detection of furosemide by fluorescence, which gives excellent separation and high sensitivity with minimal sample preparation. The method requires only 25 microliters of plasma or urine and, thus, is suitable for use in newborn intensive care units.

An Improved HPLC Method for the Determination of Furosemide in Plasma and Urine

Abstract A sensitive HPLC method with minimal sample preparation and good reproducibility for the determination of furosemide in plasma and urine is described. Acidified plasma samples were extracted using CH2Cl2 containing desmethylnaproxen as internal standard (IS). Fresh urine samples were incubated with β-gluc-uronidase for 15 minutes and then treated with CH3CN containing IS. Chromatography was performed on a C18 column with 10 mcl sample injection, Mobile phases were: a) for plasma: 0.01 M NaH2PO4, pH 3.5 - CH3OH (65:35), and b) for urine: acetic acid, pH 3.5 - CHS3OH (60:40) at 3 ml/min and fluorescence detection at Ex 235/Em 389 nm. The plasma standard curve was linear from 0.01 to 15.0 mcg/ml and the urine from 0.5 to 200.0 mcg/ml. The within run CV's were 3,2% at 0.74 mcg/ml plasma and 2.0% at 10.7 mcg/ml urine. Recovery from plasma was 69.9% at 2.0 mcg/ml and 98.6% from urine at 5.0 mcg/ml. The stability of furosemide and its glucuronide were studied. Both methods have been applied to the analy...

Determination of furosemide in rat plasma using HPLC and liquid scintillation

A rapid and convenient HPLC method for the determination of furosemide in plasma is described. The method uses a buffered mobile phase containing 22% (v/v) acetonitrile. The precision, detection limit and the correlation between the HPLC method and a liquid scintillation determination of furosemide are satisfactory. A pharmacokinetic study of furosemide in the rat is described.

Comparison of extraction and precipitation methods for the HPLC determination of furosemide in plasma and urine

Comparisons have been made between an ether extraction method and an acetonitrile precipitation method for the HPLC determination of furosemide (frusemide) in human plasma and urine. Recoveries of furosemide were 81-89% (ether extraction method for plasma), 73-103% (acetonitrile precipitation method for plasma) and 62-89% (ether extraction method for urine) for the concentration ranges studied. Values of correlation coefficients were 0.9998, 0.9991 and 0.9997 for standard curves for the three methods, respectively. Accuracy and precision (RSD) were: 92.4-114% +/- 3.57-20% for ether-extracted plasma; 98.1-103% +/- 3.47-19.9% for acetonitrile-precipitated plasma; and 103-107% +/- 4.03-13.2% for ether-extracted urine. Because of carryover of endogenous urine components, the acetonitrile-precipitation assay was unacceptable for urine. Furosemide was stable in frozen plasma for at least 113 days and in frozen urine for at least 204 days. No artifactual appearance of the hydrolysis product of furosemide, 4-chloro-5-sulfamoylanthranilic acid (CSA), was detected by the ether-extraction method under normal assay conditions.

Quantitative determination of furosemide in plasma, plasma water, urine and ascites fluid by high-performance liquid chromatography

A high-performance liquid chromatographic method using spectrofluorometric detection is described for the determination of furosemide in plasma, plasma water, urine and ascites fluid. The extraction procedure decreases interference from endogenous substances. The detection limit of furosemide is 10 ng in 0.5 ml of biological sample. The method is sufficiently sensitive for pharmacokinetic study of furosemide with normal subjects and patients with liver cirrhosis and/or renal disease after oral administration of furosemide in a retard capsule, and for study of protein binding of furosemide in patients with various diseases.

Improved method for the analysis of furosemide in plasma by high-performance liquid chromatography

Modifications of existing rapid high-performance liquid chromatographic procedures for the determination of furosemide in plasma were made in order to achieve greater sensitivity. To a small volume of plasma was added an internal standard structurally related to furosemide. Then, following previously described procedures, acetonitrile was added to precipitate the proteins and the clear supernatant was separated. However prior to injection of the supernatant the pH and composition of the sample were adjusted. This modification of the sample enabled an injection volume of up to 300 μl of the supernatant to be injected onto the chromatographic column. The effluent was monitored spectrofluorimetrically. A standard linear calibration curve with a mean precision of ± 4.4% was obtained for plasma samples containing 20–900 ng/ml of furosemide. Two structurally related compounds were used as internal standards in the furosemide assay.

A simplified assay of furosemide in plasma and urine by high-pressure liquid chromatography

A simplified high-pressure liquid chromatographic method for determination of furose-mide in plasma and urine has been developed using a fluorometric detector directly coupled to the column effluent. The method includes an ether extraction from acidified biologic samples. The mobile phase used for chromatography on a reversed-phase column (C 18 hydro-carbon permanently bonded to silica particles) is sufficiently acidic to induce fluorescence of furosemide. The methylester of furosemide is employed as an internal standard. The sensitivity is 0.1 and 0.25 μg per ml plasma and urine, respectively. The applicability to pharmacokinetic studies of furosemide is shown.

Gas chromatographic determination of furosemide in plasma using an extractive alkylation technique and an electron capture detector

Gas chromatographic determination of furosemide in plasma using an extractive alkylation technique and an electron capture detector