Simple determination of hydrochlorothiazide in human plasma and urine by high performance liquid chromatography

Spectrophotometric and Multivariate Calibration Techniques for Simultaneous Determination of Different Drugs in Pharmaceutical Formulations and Human Urine: Evaluation of Greenness Profile

Eco-friendly, rapid, and cost-effective two spectrophotometric methods were developed and validated for the determination of atenolol, paracetamol, hydrochlorothiazide, and levofloxacin. The first method is the newly developed extended derivative ratio (EDR) and the second method is multivariate curve resolution-alternating least squares (MCR-ALS). In the EDR method, the extended derivative ratio amplitudes at 281.6, 237.6, 279.2, and 282.8 nm were used for quantification of atenolol, paracetamol, hydrochlorothiazide, and levofloxacin, respectively. In the MCR-ALS method, calibration model was developed and correlation constraint was employed. External validation data set composed of seven mixtures was used, and different figures of merits such as root mean square error of prediction, standard error of prediction, bias, and relative error of prediction were calculated, and satisfactory results were obtained. Both methods provided comparable results. The methods were validated and applied for the determination of the target analytes in dosage forms, spiked and real human urine. Thereafter, the obtained results were statistically compared to the published methods and revealed no significant difference regarding accuracy and precision. Furthermore, the greenness profile of the methods was evaluated using the National Environmental Methods Index "NEMI" and Analytical Eco-Scale. The developed methods can be used as a valid eco-friendly and simple cost-effective alternative to the commonly used chromatographic methods for the routine analysis of the studied drugs in dosage forms and human urine.

Simultaneous determination of losartan, EXP-3174 and hydrochlorothiazide in plasma via fully automated 96-well-format-based solid-phase extraction and liquid chromatography–negative electrospray tandem mass spectrometry

An automated, sensitive and high-throughput liquid chromatographic/electrospray tandem mass spectrometric (LC-MS/MS) assay was developed for the simultaneous determination of losartan (LOS), its major circulating metabolite EXP-3174 and hydrochlorothiazide (HCTZ) in human plasma. LOS and HCTZ coexist in the same drug formulation, and this is the first method that enables the simultaneous determination of both drugs along with the active metabolite of LOS. Since these drugs have different physicochemical properties, the employment of a liquid-liquid extraction (LLE) protocol was precluded. A fully automated solid-phase extraction (SPE) protocol, based on 96-well format plates, was used to isolate these compounds and furosemide (internal standard, IS) from plasma. Washing and elution steps were amended accordingly in order to minimize any matrix effect from components of the plasma without reducing the elution of the molecules of interest. The compounds were eluted from a C18 column and detected with an API 3000 triple-quadrupole mass spectrometer using negative electrospray ionization and multiple reaction monitoring (MRM). The assay was linear over the range 1.00-400 ng/mL for LOS and EXP-3174 and 0.500-200 ng/mL for HCTZ, respectively, when 200 microl of plasma was used in the extraction. The overall intra- and interassay variations were within acceptance limits. The analysis time for each sample was 4 min, and more than 300 samples could be analyzed in one day by running the system overnight. The assay was simple, highly sensitive, selective, precise, fast, and it enables the reliable determination of LOS, EXP-3174 and HCTZ in pharmacokinetic or bioequivalence studies after per os administration of a single tablet containing both drugs.

Sensitive quantification of chosen drugs by reversed-phase chromatography with electrochemical detection at a glassy carbon electrode

Reversed-phase-high-performance liquid chromatographic method with electrochemical detection has proven to be a highly sensitive and selective method for determination of trace components in complex biological samples, and the electrochemical detector becomes an important alternative tool to ultraviolet and fluorescence detectors. A rapid and sensitive method for the accurate determination of metoclopramide, hydrochlorothiazide, imipramine and diclofenac in serum or plasma samples is described. The method is based on liquid-liquid extraction. The compounds were separated on C-18 column as stationary phase with a different binary mixture as mobile phase. Proposed method was validated with respect to specificity, linearity range, limit of detection and quantitation, precision, accuracy and successfully applied in a pharmacokinetic studies.

Sensitive liquid chromatography-tandem mass spectrometry method for quantification of hydrochlorothiazide in human plasma

A simple, rapid, sensitive and specific liquid chromatography-tandem mass spectrometry method was developed and validated for quantification of hydrochlorothiazide (I), a common diuretic and anti-hypertensive agent. The analyte and internal standard, tamsulosin (II) were extracted by liquid-liquid extraction with diethyl ether-dichloromethane (70:30, v/v) using a Glas-Col Multi-Pulse Vortexer. The chromatographic separation was performed on a reversed-phase column (Waters symmetry C18) with a mobile phase of 10 mm ammonium acetate-methanol (15:85, v/v). The protonated analyte was quantitated in negative ionization by multiple reaction monitoring with a mass spectrometer. The mass transitions m/z 296.1 solidus in circle 205.0 and m/z 407.2 solidus in circle 184.9 were used to measure I and II, respectively. The assay exhibited a linear dynamic range of 0.5-200 ng/mL for hydrochlorothiazide in human plasma. The lower limit of quantitation was 500 pg/mL, with a relative standard deviation of less than 9%. Acceptable precision and accuracy were obtained for concentrations over the standard curve ranges. A run time of 2.5 min for each sample made it possible to analyze a throughput of more than 400 human plasma samples per day. The validated method has been successfully used to analyze human plasma samples for application in pharmacokinetic, bioavailability or bioequivalence studies.

Simultaneous determination of valsartan and hydrochlorothiazide in tablets by first-derivative ultraviolet spectrophotometry and LC

First-derivative ultraviolet spectrophotometry and high-performance liquid chromatography (HPLC) were used to determine valsartan and hydrochlorothiazide simultaneously in combined pharmaceutical dosage forms. The derivative procedure was based on the linear relationship between the drug concentration and the first derivative amplitudes at 270.6 and 335 nm for valsartan and hydrochlorothiazide, respectively. The calibration graphs were linear in the range of 12.0-36.1 microg x ml(-1) for valsartan and 4.0-12.1 microg x ml(-1) for hydrochlorothiazide. Furthermore, a high- performance liquid chromatographic procedure with ultraviolet detection at 225 nm was developed for a comparison method. For the HPLC procedure, a reversed phase column with a mobile phase of 0.02 M phosphate buffer (pH 3.2)-acetonitrile (55: 45; v/v), was used to separate for valsartan and hydrochlorothiazide. The plot of peak area ratio of each drug to the internal standard versus the respective concentrations of valsartan and hydrochlorothiazide were found to be linear in the range of 0.06-1.8 and 0.07-0.5 microg x ml(-1), respectively. The proposed methods were successfully applied to the determination of these drugs in laboratory-prepared mixtures and commercial tablets.

Liquid extraction and HPLC-DAD assay of hydrochlorothiazide from plasma for a bioequivalence study at the lowest therapeutic dose

The main parameters considered in optimizing the liquid extraction and quantitative assay were the yield, precision, limit of quantification, time required for extraction and concentration, and quantity of solvent. The influence on these parameters of the following factors was examined: nature of the extracting solvent, quantity of solvent, co-extraction solvent, and duration of stirring. Instead of equilibrium parameters of the involved thermodynamic system, a kinetic approach was preferred in terms of the effective partition 'constant', which is not really constant but a function of time and extraction conditions. The final selected method, considered to be rapid and simple, was applied to determine the pharmacokinetics of hydrochlorotiazide (HCT) after administration of Capozide (Bristol-Myers Squibb) tablets containing 50 mg Captopril and 25 mg HCT, to 4 healthy volunteers. The results obtained were in accordance with the pharmacokinetic parameters of HCT reported in the literature.

Simple method for determination of hydrochlorothiazide in human urine by high performance liquid chromatography utilizing narrowbore chromatography

A simple high performance liquid chromatographic (HPLC) method utilizing narrowbore chromatography was developed for the determination of hydrochlorothiazide in human urine. A mobile phase of 0.1% aqueous acetic acid--acetonitrile (93:7, v/v) pH 3 was used with a C18 analytical column and ultraviolet detection (UV). The method demonstrated linearity from 2 to 50 micrograms ml-1 using 50 microliters of urine with a detection limit of 1 microgram ml-1. The method was utilized in a study evaluating if racial differences are present in the pharmacokinetic and pharmacodynamic effects of hydrochlorothiazide.

New sensitive method for the determination of hydrochlorothiazide in human serum by high-performance liquid chromatography with electrochemical detection

A HPLC method with a very sensitive electrochemical detection has been developed for determining the diuretic agent hydrochlorothiazide (HCT) in serum of volunteers to whom a single dose of the fixed combination of 12.5 mg HCT and 25 mg triamterene was administered. In the present method samples (0.2 ml serum, pH 7) were purified by extraction of HCT into 5 ml tert.-butyl-methyl ether. The separated organic phase was spiked with p-aminobenzoic acid (PABA) standard. The separation was performed on a reversed-phase C18 column using phosphate buffer-acetonitrile (90:10). A coulometric cell was used to measure HCT and an ultraviolet detector for PABA. The limit of quantitation for serum samples of only 200 microliters was 5 ng/ml (i.e. 60 pg HCT/injection) with a good reproducibility (1-8%). Short retention times were found: 1.2 min for PABA and 5.8 min for HCT.

Fully automated methods for the determination of hydrochlorothiazide in human plasma and urine

LC assays utilizing fully automated sample preparation procedures on Zymark PyTechnology Robot and BenchMate Workstation for the quantification of hydrochlorothiazide (HCTZ) in human plasma and urine have been developed. After aliquoting plasma and urine samples, and adding internal standard (IS) manually, the robot executed buffer and organic solvent addition, liquid-liquid extraction, solvent evaporation and on-line LC injection steps for plasma samples, whereas, BenchMate performed buffer and organic solvent addition, liquid-liquid and solid-phase extractions, and on-line LC injection steps for urine samples. Chromatographic separations were carried out on Beckman Octyl Ultrasphere column using the mobile phase composed of 12% (v/v) acetonitrile and 88% of either an ion-pairing reagent (plasma) or 0.1% trifluoroacetic acid (urine). The eluent from the column was monitored with UV detector (271 nm). Peak heights for HCTZ and IS were automatically processed using a PE-Nelson ACCESS*CHROM laboratory automation system. The assays have been validated in the concentration range of 2-100 ng ml-1 in plasma and 0.1-20 micrograms ml-1 in urine. Both plasma and urine assays have the sensitivity and specificity necessary to determine plasma and urine concentrations of HCTZ from low dose (6.25/12.5 mg) administration of HCTZ to human subjects in the presence or absence of losartan.

Interaction of allopurinol and hydrochlorothiazide during prolonged oral administration of both drugs in normal subjects. II. Kinetics of allopurinol, oxipurinol, and hydrochlorothiazide

The kinetics of allopurinol and hydrochlorothiazide were investigated in seven healthy male subjects during prolonged coadministration of two drugs. Subjects were maintained on an isoenergetic, purine-free formula diet with RNA supplementation for 24 days. Allopurinol (300 mg) was given orally on days 1-24. Hydrochlorothiazide (50 mg daily) was added to days 11-21. On day 43 a single oral dose of 50 mg hydrochlorothiazide was administered. Plasma concentration-time profiles of allopurinol and its main metabolite oxipurinol were obtained on days 1, 10, and 21; hydrochlorothiazide profiles were assessed on days 21 and 43. In addition, 24-h plasma concentrations of oxipurinol were measured repetitively, and 24 h urine samples were collected for the determination of allopurinol, oxipurinol, and hydrochlorothiazide. For oxipurinol, mean Cmax was not altered on hydrochlorothiazide treatment (13.8 +/- 1.4 micrograms/ml and 14.7 +/- 2.6 micrograms/ml, respectively); mean AUC0-24 was 259 and 290 micrograms h-1 ml-1, respectively. The small difference in AUC0-24 values does not explain the increase in plasma uric acid concentration during hydrochlorothiazide treatment, nor do the variations in allopurinol and hydrochlorothiazide kinetics.