Sequential Electrochemical Reduction, Solvent Partition, and Automated Thiol Colorimetry for Urinary Captopril and its Disulfides

Kadin, Harold; Poet, Raymond B.

doi:10.1002/jps.2600711014

Cited by 25 publications

(8 citation statements)

References 12 publications

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“…To minimise oxidation of captopril to disulphides in urine after collection, a solution of the very effective metal chelator, diethylenetriamine pentaacetic acid (DTPA), was mixed into freshly voided urine followed shortly by a lowering of the pH by addition of a solution of citric and oxalic adds. The urine samples were then refrigerated until assayed (Kadin & Poet 1982). The order of addition for DTPA, citric and oxalic acids is important because DTPA is more effective as a chelator at pH 5.…”

Section: Assay Methodsmentioning

confidence: 99%

Pharmacokinetics of Captopril in Healthy Subjects and in Patients with Cardiovascular Diseases

Duchin

McKinstry

Cohen

et al. 1988

Clinical Pharmacokinetics

130

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Captopril, the first orally active inhibitor of angiotensin-converting enzyme, is used widely in the treatment of hypertension and congestive heart failure. The pharmacokinetics of this agent have been studied extensively in healthy subjects and in patients with hypertension, congestive heart failure, and chronic renal failure. Captopril contains a sulphydryl group and binds readily to albumin and other plasma proteins. The drug also forms mixed disulphides with endogenous thiol-containing compounds (cysteine, glutathione), as well as the disulphide dimer of the parent compound. These components in blood and urine are measured collectively as total captopril. Because of the reversibility of the formation of these inactive disulphides, total captopril may serve as a reservoir of the pharmacologically active moiety, and thus contribute to a duration of action longer than that predicted by blood concentrations of unchanged captopril. To measure free or unchanged captopril concentrations, a chemical stabiliser must be added to the biological samples to prevent the formation of captopril disulphides ex vivo. In healthy subjects given captopril intravenously, the body clearance of captopril and steady-state volume of distribution were about 0.7 L/h/kg and 0.8 L/kg, respectively. The elimination half-life of unchanged captopril was approximately 2 hours. The primary route of elimination of captopril is the kidney. The renal clearance of unchanged captopril exceeds the glomerular filtration rate, due to active tubular secretion of the drug. In healthy subjects, about 70 to 75% of an oral dose is absorbed and the bioavailability of captopril is approximately 65%. Peak blood concentrations are reached about 45 to 60 minutes after oral administration. The bioavailability of captopril is not altered by age or concomitant medications including diuretics, procainamide, allopurinol, cimetidine or digoxin. However, the co-administration of food or antacids, or probenecid with captopril has been shown to diminish the bioavailability of the latter and decrease its clearance, respectively. The decreased bioavailability of captopril when taken with meals does not significantly alter clinical responses to the drug. Over a wide range of oral (10 to 150 mg) and intravenous doses (2.5 to 10 mg) captopril had linear kinetics in healthy volunteers. In healthy subjects with normal renal function and patients with congestive heart failure given captopril 3 times daily, blood concentrations of total captopril accumulated, whereas those of unchanged captopril did not. Severe renal insufficiency was associated with an accumulation of both unchanged and total captopril.(ABSTRACT TRUNCATED AT 400 WORDS)

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Section: Assay Methodsmentioning

confidence: 99%

Pharmacokinetics of Captopril in Healthy Subjects and in Patients with Cardiovascular Diseases

Duchin

McKinstry

Cohen

et al. 1988

Clinical Pharmacokinetics

130

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“…4 Therefore, the determination of CAP is important from a physiological point of view as well as for the purposes of quality control. Several methods have been proposed for the determination of CAP including highperformance liquid chromatography with pre-or post-column derivatization, [5][6][7][8][9][10] colorimetry, 11 fluorimetry, [12][13][14] chemiluminescence, [15][16][17] capillary electrophoresis, 18 spectrophotometry [19][20][21][22][23] and electrochemical methods. [24][25][26][27][28][29][30][31][32][33][34][35] Carbon nanotubes (CNTs) continue to receive remarkable attention in electrochemistry.…”

Section: Introductionmentioning

confidence: 99%

Electrocatalytic oxidation of captopril on a vinylferrocene modified carbon nanotubes paste electrode

et al. 2012

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The study of electrochemical behavior and determination of captopril, as an angiotensin-converting enzyme inhibitor using a vinylferrocene modified multiwalled carbon nanotubes paste electrode (VFMCNTPE) is reported. The cyclic voltammetric results indicate that the VFMCNTPE system can remarkably enhance electrocatalytic activity toward the oxidation of captopril in aqueous buffer solution pH 8.0. Under the best experimental conditions selected, the calibration curve for captopril was linear in the concentration range from 0.2 to 400 mmol L À1 and a detection limit of 0.08 mmol L À1 was obtained. The influence of pH and potential interfering substances on the determination of captopril were studied. Electrochemical impedance spectroscopy was used to study the charge transfer properties at the electrode-solution interface. Finally, the sensor was examined as a selective, simple, and precise new electrochemical sensor for the determination of captopril in real samples, such as drugs and urine. Satisfactory results were obtained.Scheme 1 Structure of CAP.

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“…Several methods have been applied to the determination of CAP, including high-performance liquid chromatography [6][7][8][9], gas chromatography [10,11], spectrophotometry [12,13], fluorimetry [14][15][16], radioimmunoassay [17], chemiluminescence [18][19][20], atomic absorption spectrophotometry [21], Raman spectroscopy [22], capillary electrophoresis [23,24], and electrochemical methods [25][26][27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Voltammetric Determination of Captopril Using Chlorpromazine as a Homogeneous Mediator

Bahramipur

Jalali

2011

International Journal of Electrochemistry

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Chlorpromazine was used as a homogeneous electrocatalyst in the oxidation of captopril. The anodic peak current of chlorpromazine was increased substantially in the presence of low concentrations of captopril (pH 4). Cyclic voltammetry and chronoamperometry were used to study the kinetics of the catalytic electron transfer reaction. The values of electron transfer coefficient () and catalytic rate constant () were estimated to be 0.34 and , respectively. Linear sweep voltammetry was used for the determination of captopril in the presence of chlorpromazine. A linear calibration curve was obtained in the concentration range of captopril of 10.0–300.0 μM, with a limit of detection of 3.65 μM. The relative standard deviation (RSD%) for 5 replicate measurements of captopril (100 μM) was 1.96%. The method was applied to the determination of captopril in pharmaceutical formulations and blood serum samples with satisfactory results.

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Sequential Electrochemical Reduction, Solvent Partition, and Automated Thiol Colorimetry for Urinary Captopril and its Disulfides

Cited by 25 publications

References 12 publications

Pharmacokinetics of Captopril in Healthy Subjects and in Patients with Cardiovascular Diseases

Pharmacokinetics of Captopril in Healthy Subjects and in Patients with Cardiovascular Diseases

Electrocatalytic oxidation of captopril on a vinylferrocene modified carbon nanotubes paste electrode

Voltammetric Determination of Captopril Using Chlorpromazine as a Homogeneous Mediator

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