Two-phase and three-phase liquid-phase microextraction of hydrochlorothiazide and triamterene in urine samples.

This paper reports the applicability of two-phase and three-phase hollow fiber based liquid-phase microextraction (HF-LPME) for the extraction of hydrochlorothiazide (HYD) and triamterene (TRM) from human urine. The HYD in two-phase HF-LPME is extracted from 24 mL of the aqueous sample into an organic phase with microliter volume located inside the pores and lumen of a polypropylene hollow fiber as acceptor phase, but the TRM in three-phase HF-LPME is extracted from aqueous donor phase to organic phase and then back-extracted to the aqueous acceptor phase, which can be directly injected into HPLC for analysis. Under optimized conditions preconcentration factors of HYD and TRM were obtained as 128 and 239, respectively. The calibration curves were linear (R(2) ≥ 0.995) in the concentration range of 1.0-100 µg/L for HYD and 2.0-100 µg/L for TRM. The limits of detection for HYD and TRM were 0.5 µg/L. The intra-day and inter-day RSD based on four replicates were obtained as ≤5.8 and ≤9.3%, respectively. The methods were successfully applied for determining the concentration of the drugs in urine samples. Copyright © 2015 John Wiley & Sons, Ltd.

Population-based meta-analysis of hydrochlorothiazide pharmacokinetics.

Hydrochlorothiazide (HCTZ) is a thiazide diuretic used for the treatment of hypertension and edema associated with fluid overload conditions such as congestive heart failure (CHF). A population-based meta-analysis approach in NONMEM® was used to develop a PK model to characterize the time-course of HCTZ concentrations in plasma and excretion into the urine for healthy subjects and CHF patients. Data from healthy subjects receiving 100 mg of oral HCTZ were supplemented with additional plasma concentration and urinary excretion versus time data published in the literature following administration of oral HCTZ doses ranging from 10 to 500 mg to healthy subjects or patients with renal failure, CHF or hypertension. A two-compartment model with first-order oral absorption, using a Weibull function, and first-order elimination best described HCTZ PK. Creatinine clearance (CLCR ) was a statistically significant predictor of renal clearance (CLR ). Non-renal clearance was estimated to be 2.44 l/h, CLR was 18.3 l/h and T1/2,α was 1.6 h and T1/2,ß was 14.8 h for a typical individual with normal renal function (CLCR = 120 ml/min). However, CLR was reduced to 10.5, 5.47 and 2.70 l/h in mild (CLCR = 80 ml/min), moderate (CLCR = 50 ml/min) and severe (CLCR = 30 ml/min) renal impairment, respectively. Model diagnostics helped to demonstrate that the population PK model reasonably predicts the rate of urinary HCTZ excretion over time using dosing history and estimated CLCR , allowing for the convenient assessment of PK-PD relationships for HCTZ when given alone or in combination with other agents used to treat fluid overload conditions.

Simultaneous determination of aliskiren and hydrochlorothiazide in tablets and spiked human urine by ion-pair liquid chromatography.

An alternative method for analysis of aliskiren (ALI) and hydrochlorothiazde (HCT) in combined dosage forms by ion-pair reversed phase high performance liquid chromatography was developed and validated. The pharmaceutical preparations were analyzed using a C18 column (250 mm x 4.6 mm, 3 microm) with a mobile phase consisting of 25% methanol, 50% sodium monobasic phosphate aqueous solution containing 6 mM tetrabutylammonium bromide and 25% water at pH 7.2. Isocratic analysis was performed at a flow rate of 1 mL/min and a column temperature of 30 degrees C under direct UV detection at 210 nm. Paracetamol was used as internal standard. The validation was performed according to the ICH guidelines. The proposed method was linear over the concentration range of 0.250 to 60 and 0.1 to 10 microg/mL for ALI and HCT, respectively. The limits of detection and quantitation (LOD and LOQ) were 0.075 and 0.198 microg/mL, respectively, for ALI and 0.04 and 0.062 microg/mL, respectively, for HCT. The method proved to be specific, sensitive, precise and accurate with mean recovery values of 101.1 +/- 0.32% and 100.9 +/- 0.41% for ALI and HCT, respectively. The method robustness was evaluated by means of an experimental design. The proposed method was applied successfully to spiked human urine samples with mean recoveries of 98.8 +/- 0.36% and 98.1 +/- 0.21% for ALI and HCT, respectively.

Assessment of the drug-drug interactions between fimasartan and hydrochlorothiazide in healthy volunteers.

AIM: Fimasartan is a selective angiotensin II receptor blocker. Hydrochlorothiazide (HCTZ), which is used to treat hypertension and edematous conditions, is coadministered with many antihypertensive agents. METHODS: An open-label, randomized, multiple-dosing, 2-arm, 1-sequence, 2-period study was conducted to assess the effects of fimasartan (240 mg) on HCTZ (25 mg) or vice versa in 18 and 14 healthy male volunteers, respectively. During each drug administration period, drugs were given once daily for 7 days, with a 7-day washout period between the 2 administration periods. RESULTS: The respective geometric mean ratios of fimasartan for AUC τ,ss and C max,ss with HCTZ were 1.30 [90% confidence interval (CI), 0.84-2.01] and 1.17 (90% CI, 0.93-1.47) compared with fimasartan alone. The respective geometric mean ratios of HCTZ for AUC τ,ss and C max,ss with fimasartan were 0.94 (90% CI, 0.84-1.04) and 0.88 (90% CI, 0.80-0.97) compared with HCTZ alone. Plasma renin activity indicated no significant differences between fimasartan monotherapy and coadministered treatment. CONCLUSIONS: Fimasartan administered alone or in combination with HCTZ was well tolerated at the described dosages. Coadministration of fimasartan increased the urinary excretion of HCTZ and urine volume, but these observations are unlikely to have any clinical relevance.

Development and validation of an advanced electrochemical sensor for the fast and cheap determination of hydrochlorothiazide in urine samples using the Monte-Carlo method for uncertainty evaluation.

This work describes the development, optimization, and validation of an electrochemical method for the determination of hydrochlorothiazide (HCTZ) in urine. The method allows fast, cheap and reliable determinations of recent administrations of this diuretic that can be used in doping control in sport. The response of the sensor was determined by differential pulse voltammetry (DPV). The glassy carbon electrode was modified with multiwall carbon nanotubes (MWCNT) and gold nanoparticles. The sensor is calibrated in the analysed sample matrix by the cumulative standard addition method. The method validation was based on the bottom-up evaluation of the measurement uncertainty were components were combined using the Monte Carlo Method (MCM) applicable with no restrictions regarding components uncertainty value and measurement function linearity. The developed metrological models were implemented in MS-Excel spreadsheets. The adequacy of the electrochemical measurements was assessed by comparing their relative standard uncertainty with a target value of 20% and by evaluating the compatibility of measurements with determinations performed by a reference procedure. The tools developed for the construction and optimization of working electrodes are applicable to measurements of other analytes and matrices. The used cumulative standard addition method and respective measurement uncertainty models are applicable to any kind of non-destructive chemical measurement of a solution.

Development and validation of an LC method for simultaneous determination of amiloride hydrochloride and hydrochlorothiazide in human urine.

An HPLC method with photometric detection has been developed for determination of a binary mixture of amiloride hydrochloride and hydrochlorothiazide in human urine using chlorthalidone as the internal standard. Reversed-phase chromatography was performed at room temperature on a cyanopropyl column with the mobile phase consisting of a 10 mM KH2PO4 solution (pH 4.5)-methanol (70 + 30, v/v) at a flow rate of 1 ml/min. The detector was set at 214 nm. The total analysis time was 10 min. The method was validated in terms of accuracy, precision, absolute recovery, freeze-thaw stability, bench-top stability, and re-injection reproducibility. The procedure shows good accuracy, repeatability, and selectivity. Moreover, the method was applied directly to urine that had not undergone prior treatment. The intra- and interday coefficients of variation for all compounds were below 4%, and the method was highly accurate, with a relative error for all compounds that was below 8%. No interference from endogenous compounds in urine samples was found. The proposed method, which is rapid, simple, and does not require any separation steps, has been successfully applied to the assay of human urine containing amiloride hydrochloride and hydrochlorothiazide.

Multiple incidence of the prescription diuretic hydrochlorothiazide in compounded nutritional supplements.

Diuretic agents are prohibited in sports in- and out-of-competition according to the regulations of the World Anti-Doping Agency (WADA) because of their possible masking effects on other doping agents in urine samples, and their ability to produce fast acute weight losses. Despite previous studies reported adverse analytical findings (AAFs) resulting from contaminations at ppm level (µg/g) of medicinal products, and recommended to introduce reporting limits for diuretics in doping controls, these are not adopted in analyses performed by WADA-accredited laboratories. We report the case of an athlete with two AAFs for hydrochlorothiazide (HCTZ) at low urinary concentrations (<10 ng/mL), who declared the use of nutritional supplements prepared in a compounding pharmacy. His nutritional supplements were analyzed revealing HCTZ presence in different concentrations, at the ppm level (µg/g and ng/mL). With the aim of testing the plausibility of the observed urinary HCTZ concentrations with the nutritional supplement ingestion, a urinary excretion study with three healthy volunteers was performed. HCTZ-contaminated powder (6.4 µg/g of HCTZ) was administered to each subject in different dosages, reproducing the possible ingestion pattern occurred. Urine specimens were collected before and after ingestion of the powder, up to 24 hours, and underwent liquid-liquid extraction and liquid chromatography-tandem mass spectrometry determination. Post-administration specimens were found to contain HCTZ at concentrations of 5-230 ng/mL, which supported the accidental inadvertent intake of the prohibited substance by the athlete. This study makes the argument that the introduction of reporting limits for diuretics are warranted in doping control samples, in order to protect against inadvertent AAFs due to contaminated products.

Use of addition calibration technique for determination of acetaminophen and hydrochlorothiazide in human urine by high-performance liquid chromatography.

The quantitation of target analytes in complex matrices such as biological samples requires special calibration approaches to compensate for additional capacity or activity in the matrix samples. A conventional calibration curve, obtained with standard solutions, is one of the most important calibration procedures for quantitation of target analytes in such matrices. However, these technique require a great number of reagents and material, and consume a considerable amount of time throughout the analysis. In this work, a new calibration procedure to analyze urine samples is proposed for the first time in chromatography procedures. The proposed calibration, called the addition calibration technique, was used for the determination of acetaminophen and hydrochlorothiazide in urine samples. The results obtained for the proposed calibration mode were compared to those obtained using standard addition and standard calibration techniques. The proposed addition calibration was validated by statistical studies between results obtained by the addition technique and conventional techniques, using the ANOVA test and linear regression. The results demonstrated good agreement among them. The performance of the analytical method was evaluated. Relative standard deviation, limit of detection, and limit of quantification are respectively 0.5-0.6%, 0.169-0.75 microg/mL, and 0.565-2.5 microg/mL. Linear range falls within the range of 0.3 to 63.8 microg/mL for both compounds. Accuracy ranged between 94% and 101%.

Measurement of glomerular filtration rate in the conscious rat.

INTRODUCTION: Glomerular filtration rate (GFR) is an important parameter for studying drug-induced impairments on renal function in rats. The GFR is calculated from the concentration of creatinine and blood urea nitrogen (BUN) in serum and in urine, respectively. Following current protocols serum and urine samples must be taken from the same animal. Thus, in order to determine time-dependent effects it is necessary to use for each time point one separated group of animals. We developed a statistical test which allows analyzing the GFR from two different groups of animals: one used for repeated serum and the other one used for repeated urine analysis. METHODS: Serum and urine samples were taken from two different sets of rats which were otherwise treated identically, i.e. drug doses, routes of administration (per os or per inhalation) and tap water loading. For each dose group GFR mean, standard deviation and statistical analysis to identify differences between the dose groups were determined. RESULTS: After determination of the optimal time points for measurements, the effect on GFR of the three reference compounds, furosemide, hydrochlorothiazide and formoterol, was calculated. The results showed that the diuretic drugs furosemide and hydrochlorothiazide decreased the GFR and the antidiuretic drug formoterol increased the GFR, as counter regulation on urine loss or urine retention, respectively. DISCUSSION: A mathematical model and the corresponding algorithm were developed, which can be used to calculate the GFR, and to test for differences between groups from two separated sets of rats, one used for urine, and the other one for serum analysis. This new method has the potential to reduce the number of animals needed and to improve the quality of data generated from various groups of animals in renal function studies.

Cyclodextrin Micellar LC for Direct Selective Analysis of Combined Dosage Drugs in Urine.

Two cyclodextrin micellar liquid chromatographic methods were developed and applied to the simultaneous determination of bisoprolol/hydrochlorothiazide and atenolol/chlorthalidone combinations in urine matrices without sample pretreatment. These combined ß-blockers and diuretics chemotherapies are commonly used in the treatment of hypertension and cardiovascular diseases. Hybrid isocratic mobile phases containing hydroxypropyl-ß-cyclodextrin, sodium dodecyl sulfate, phosphate buffer and methanol on a Luna C18 column with 0.5 mL min(-1) flow rate and 25.0°C column temperature were used. The methods were sensitive enough for the determination of analytes at the therapeutic urine levels with limits of detections down to 1.0 µg mL(-1); relative standard deviations and recoveries were ranged between 1.5-4.4% and 98.00-109.52%, respectively. Urinary excretion studies showed that the detection of drugs is possible up to 24 h after their ingestion. The selective proposed separations with less consumption of organic solvents over the hitherto ones could be attributed to the four point competitive interactions among analysts, pseudostationary phases and a real stationary phase.

Electrochemical investigation of the voltammetric determination of hydrochlorothiazide using a nickel hydroxide modified nickel electrode.

The preparation and electrochemical characterization of a nickel hydroxide modified nickel electrode as well as its behavior as electrocatalyst toward the oxidation of hydrochlorothiazide (HCTZ) were investigated. The electrochemical behavior of the modified electrode and the electrooxidation of HCTZ were explored using cyclic voltammetry. The voltammetric response of the modified electrode in the detection of HCTZ is based on the electrochemical oxidation of the Ni(II)/Ni(III) and a chemical redox process. The analytical parameters for the electrooxidation of HCTZ by the nickel hydroxide modified nickel electrode were obtained in NaOH solution, in which the linear voltammetric response was in the concentration range from 1.39×10(-5) to 1.67×10(-4)mol L(-1) with a limit of detection of 7.92×10(-6)mol L(-1) and a sensitivity of 0.138 µA Lmmol(-1). Tafel analysis was used to elucidate the kinetics and mechanism of HCTZ oxidation by the modified electrode.

Estimating compliance with diuretic therapy: urinary hydrochlorothiazide-creatinine ratios in normal subjects.

We gave 21 healthy young men 100 mg of hydrochlorothiazide daily to determine whether or not urinary detection of the drug was feasible as a measure of compliance on a standard antihypertensive regimen. All subjects took the drug daily for 6 days, after which they were divided into four groups with differing patterns of medication administration. Urine hydrochlorothiazide and creatinine measurements were obtained to validate the urinary hydrochlorothiazide-creatinine ratio (UHCR) as an accurate quantitative index of compliance. The subjects achieved a constant level of UHCR of 13 +/- 3.0 within 48 hours of hydrochlorothiazide administration. The UHCR levels decreased to 5.0 +/- 0.8 48 hours after discontinuation of the drug (p less than 0.001). UHCR values in the range of 13 +/- 6 indicate that the subject has ingested hydrochlorothiazide 24 hours previously. The UHCR is a potentially useful means of assessing compliance in hypertensive patients taking hydrochlorothiazide.

Can simple clinical measurements detect patient noncompliance?

Measurement of patient compliance is essential if management of low compliance is to be performed efficiently. We assessed the value of several easily obtained clinical assessments compared to quantitative pill counts among 134 newly treated hypertensive male steelworkers during the first 6 months of their treatment with antihypertensive medication. Patient's self-reports obtained on structured interview correlated best with pill count compliance (r = 0.74, p less than 0.0001). Patients overestimated their compliance by an average of 17% but 90% of those who admitted to being noncompliant were found so. Qualitative urinary chlorthalidone and hydrochlorothiazide levels and changes in serum potassium, uric acid, and blood pressure also correlated with pill count compliance but were less accurate than interviews. Assessment of the patient's "health beliefs" and a variety of sociodemographic and health traits and perceptions did not provide useful information on compliance. Interviewing the patient is a simple and useful approach in assessing compliance with antihypertensive therapy.

Exaggerated natriuretic and calciuric responses to hydrochlorothiazide in renal hypercalciuria but not in absorptive hypercalciuria.

Patients with hypercalciuria have been reported to have an exaggerated response to hydrochlorothiazide (HCTZ), implying a renal tubular defect in solute reabsorption. To determine whether this disturbance is generalized or unique to a particular pathogenetic type of hypercalciuria, we measured the increments in urinary sodium (delta Na), calcium (delta Ca), and magnesium after a 100-mg dose of oral HCTZ in 10 normal subjects and 31 patients with different types of hypercalciuric nephrolithiasis. Eleven patients with renal hypercalciuria had significantly greater delta Na (P less than 0.005) and delta Ca (P less than 0.005) than the normal subjects. Ten patients with absorptive hypercalciuria and 10 patients with fasting hypercalciuria without parathyroid stimulation had delta Na and delta Ca indistinguishable from those of normal subjects. In all groups, urinary HCTZ and basal 24-h urinary Na did not differ. The results suggest that the unique natriuretic and calciuric responses to HCTZ occur only in renal hypercalciuric patients with secondary hyperparathyroidism. The data support a renal tubular defect in renal hypercalciuric in contrast to other diagnostic categories of hypercalciuric nephrolithiasis.

Influence of time intervals for cholestyramine dosing on the absorption of hydrochlorothiazide.

Ten healthy adult men participated in a study to evaluate appropriate dosing schedules of cholestyramine to minimize its effect on the absorption of hydrochlorothiazide (HCTZ). A single 8 gm dose of cholestyramine 2 hours before or after HCTZ, 75 mg po, significantly decreased the amount of HCTZ excreted unchanged in the urine over 24 hours (Ae(0-24)) by 65% (P less than 0.01) and 26% (P less than 0.05), respectively, in four subjects. Six subjects randomly received three different schedules: control, single dose of cholestyramine 4 hours after HCTZ, and multiple doses of cholestyramine (-24, -12, and +4 hours) after HCTZ. There were no significant differences in HCTZ kinetics between the control group and the subjects who received a single dose of cholestyramine. Multiple doses of cholestyramine significantly altered HCTZ kinetics, including reductions in Ae(0-24) by 35% (P less than 0.02), AUC(0-infinity) by 32% (P less than 0.01), and Cmax by 31% (P less than 0.01). We conclude that the best dosing schedule for cholestyramine is 4 hours after HCTZ, but there will still be at least a 30% to 35% decrease in the absorption of HCTZ.

Bioequivalence study of a new tablet formulation of triamterene and hydrochlorothiazide.

A three-treatment, single-dose, crossover bioequivalence study was conducted in healthy volunteers to compare urinary drug recovery following administration of hydrochlorothiazide tablets, the currently marketed capsule formulation of triamterene and hydrochlorothiazide (Dyazide), and a new tablet preparation of these active ingredients (Maxzide). No significant differences were observed in the urinary recovery of hydrochlorothiazide after the administration of hydrochlorothiazide tablets and Maxzide tablets. However, only about one-half as much hydrochlorothiazide was recovered following the administration of Dyazide capsules. Similarly, the urinary recovery of triamterene and the sulfate ester of hydroxy-triamterene after administration of Dyazide capsules was approximately one-half the levels observed after giving the new tablet formulation. The clinical consequences of the limited bioavailability of the active ingredients of Dyazide are discussed.

Malabsorption of hydrochlorothiazide following intestinal shunt surgery.

Hydrochlorothiazide 775mg was administered orally to 5 patients who had undergone intestinal shunt operations for obesity 1.5 to 6 years previously. Postoperative weight loss averaged 53.4kg. The concentrations of hydrochlorothiazide in plasma and urine were determined with gas/liquid chromatography. The mean area under the plasma concentration time curve during 9h in 4 of the patients was 889ng/ml.h. Mean total urinary recovery of hydrochlorothiazide amounted to 23.0mg in the 5 patients, which corresponds to approximately half that seen in healthy volunteers. The gastrointestinal hydrochlorothiazide appears to be substantially reduced after intestinal shunt surgery.

Quantitative determination of thiazides in urine by a sensitive colorimetric method.

Chloriothiazide and hydrochlorothiazide may be determined in urine by the Bratton-Marshall reaction after extracting with ethyl acetate and treating the extract with Florisil. Such treatment reduces the background color of the urine sample and eliminates interferences. The modified procedure is thus sensitive enough to determine both drugs in 24 hour urine specimens from patients receiving therapeutic doses orally.

Correlation of urinary excretion with in vitro dissolution using several dissolution methods for hydrochlorothiazide formulations.

Four different hydrochlorothiazide formulations were prepared, and cumulative urinary hydrochlorothiazide excretion was determined in a crossover study using six volunteers. A comparison of in vivo results showed that one formulation (Forumulation D) was significantly different from the others at 2, 3, 4, 5, 8, and 14 hr. A dissolution study was conducted on each formulation using the flask, USP basket, and magnetic basket methods at agitation speeds of 50, 100, and 150 rpm. Formulation D was significantly different from other formulations when determined using the USP basket method at 150 rpm and a sampling time of 10 min; the USP basket method at 100 rpm and a sampling time of 100 min; the flask method at 100 rpm and sampling times of 30, 40, 60, and 120 min; and the flask method at 150 rpm and sampling times of 30 and 40 min. Significant in vitro and in vivo correlations were found using a regression analysis and F test. With a correlation coefficient and 95% confidence intervals, it was established that the USP basket method at 150 rpm was the best predictor of urinary hydrochlorothiazide excretion among the dissolution methods tested.

Pharmacokinetics of hydrochlorothiazide in fasted and nonfasted subjects: a comparison of plasma level and urinary excretion methods.

The bioavailability of hydrochlorothiazide from 50-mg oral tablet doses was examined in healthy male volunteers under fasting and nonfasting conditions. Bioavailability was examined from plasma levels and urinary excretion of unchanged drug. The pharmacokinetics of hydrochlorothiazide in plasma could be described in terms of a triexponential function, and the mean drug half-lives determined from the three exponents were 1.0, 2.2, and 9.0 hr. Changing the accompanying fluid volume has no significant effect on hydrochlorothiazide absorption in fasted subjects. Plasma drug levels were significantly reduced in non-fasted individuals, compared with those in fasted individuals. A similar trend was observed in the urinary excretion of hydrochlorothiazide, but differences between treatments were not significant (p greater than 0.05). Mean 48-hr urinary recovery of hydrochlorothiazide was 70.5% of the dose in nonfasted subjects, and 73.5 and 75.0% of the dose in fasted subjects receiving the drug with 20 and 250 ml of water, respectively. The cumulative urinary excretion of hydrochlorothiazide correlated poorly (r = 0.27) with areas under plasma drug level curves, although the correlation between the means of these values for each of the three treatments was high (r = 0.996).. Close similarity was observed between urinary excretion rates of hydrochlorothiazide and the time course of drug concentrations in plasma.