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PubMed1984

Simple and micro high-performance liquid chromatographic method for simultaneous determination of p-aminohippuric acid and iothalamate in biological fluids.

A simple, rapid and micro high-performance liquid chromatographic method was developed for separate or simultaneous determination of p-aminohippuric acid and iothalamate in plasma and urine using p-aminobenzoic acid as an internal standard. The method involved deproteinizing samples with two volumes of acetonitrile followed by injection of 5 microliters of deproteinized supernatant onto a C18 reversed-phase column. The mobile phase contained 3.5% acetonitrile in 0.04% phosphoric acid and flowed at a rate of 1.5 ml/min. The column effluent was monitored by an ultraviolet detector at 254 nm. Retention times for p-aminohippuric acid, iothalamate and p-aminobenzoic acid were approximately 4.5, 6 and 8 min, respectively. This method requires as little as 5 microliters of sample and can be used to measure accurately down to 1 microgram/ml p-aminohippuric acid and 0.5 microgram/ml iothalamate in plasma samples. The coefficients of variation of the assay with or without the use of internal standard were generally low (below 7%). No interferences from endogenous substances or any drugs tested were found.

4-Aminobenzoic Acid↗
PubMed2000

High-performance liquid chromatographic determination of p-aminohippuric acid and iothalamate in human serum and urine: comparison of two sample preparation methods.

A high-performance liquid chromatography method applied to determine p-aminohippuric acid (PAH) and iothalamate (IOT) in serum and urine samples of patients was evaluated according to recovery, reproducibility and linearity utilizing narrow-bore columns. The mobile phase consisted of 0.15 M sodium dihydrogenphosphate with 1.2 mM tetrabutylammonium sulphate, the pH was adjusted to pH 4.6, acetonitrile was added to a final ratio of 95:5 (v/v), the flow-rate was set at 0.3 ml/min. The separation was achieved on a ODS Hypersil column (200 x 2.1 mm I.D.). The UV detector was set at 254 nm. PAH and IOT are used for evaluation of kidney function [effective renal plasma flow (ERPF) and glomerular filtration rate (GFR)]). Under the described chromatographic conditions two sample preparation techniques, ultrafiltration and acetonitrile precipitation were compared. The results demonstrate the accuracy of both methods in evaluation of ERPF and GFR. Due to its cost-effectiveness we recommend the acetonitrile precipitation method in clinical routine.

Chromatography, High Pressure Liquid↗
PubMed1998

Simultaneous determination of p-aminohippuric acid, acetyl-p-aminohippuric acid and iothalamate in human plasma and urine by high-performance liquid chromatography.

A sensitive and specific high-performance liquid chromatographic assay was developed for the simultaneous determination of p-aminohippuric acid (PAH), acetyl-p-aminohippuric acid (aPAH), and iothalamate in human plasma and urine. Plasma samples were prepared by protein precipitation with acetonitrile followed by evaporation, reconstitution in mobile phase, and injection onto a C18 reversed-phase column. Urine samples were diluted with 3 volumes of mobile phase prior to injection. Column effluent was monitored by UV detection at 254 nm. The lower limits of quantification in plasma were 0.5 mg/l for PAH and aPAH, and 1.0 mg/l for iothalamate. The within-day and between-day coefficients of variation in plasma and urine were < or =7.8% for all analytes. This method is well suited for renal function studies using iothalamate and PAH, whether administered as a bolus dose or by continuous infusion, to measure glomerular filtration rate and effective renal plasma flow, respectively.

Acetonitriles↗
PubMed1994

Modified radioiodination and quality control methods for [125I]sodium iothalamate.

[125I]Sodium iothalamate can be prepared by the isotope-exchange method with the use of a contrast medium preparation (i.e. iothalamate sodium injection, USP, 80%). The initial isolation and purification of iothalamate from the contrast medium solution for radioiodination is tedious and time-consuming (i.e. 1 1/2 h for purification and overnight for drying). The new method uses iothalamic acid to replace iothalamate sodium injection as a starting material and reduces the heating time and multiple acid-washing steps during radioiodination to expedite the radiolabelling process. The radiochemical purity (RCP) of [125I]sodium iothalamate obtained from the new method was 98.9 +/- 1.3% (n = 30) versus RCP value of 99.2 +/- 1.0% (n = 25) from the old method with no significant differences between the two groups of RCP values. An RCP chromatographical system to separate and migrate the radiochemical species of [125I]sodium iothalamate from the origin is described in this paper.

Iodine Radioisotopes↗
PubMed1990

Preparation and evaluation of radiopaque hydrogel microspheres based on PHEMA/iothalamic acid and PHEMA/iopanoic acid as particulate emboli.

Highly porous poly(2-hydroxyethyl methacrylate) (PHEMA) microspheres prepared by suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) in presence of polymeric diluents such as poly(methyl methacrylate) (PMMA) in toluene and poly(tetramethylene glycol) (PTMG) were made radiopaque by esterification of the reactive hydroxyl groups with iothalamic acid and iopanoic acid, two radiopaque substances clinically used. Of the various solvents and catalysts examined, tetrahydrofuran (THF) and N,N'-dimethyl paratoluidine (DMPT) were found to be best for obtaining a high degree of conversion. More than 30 wt% iodine could be bound to the microspheres which made them sufficiently radiopaque to be imaged radiographically. Microspheres retained their porosity, swelling ability, hydrophilicity, and surface morphology to a significant extent after iodination. Preliminary implantation studies of such microspheres subcutaneously in rats have shown no adverse tissue reactions over a 6-month period. It is suggested that these microspheres would prove to be useful as particulate emboli in endovascular embolization.

Animals↗
PubMedDate not supplied

Uptake of contrast materials by experimental acute myocardial infarctions: a preliminary report.

The concentration of iodine within infarcted and normal myocardium after intravenous administration of contrast material was determined by fluorescence excitation analysis in seven dogs at 48 hours after coronary arterial ligation. The iodine concentration of infarcted myocardial tissue was several times greater than normal myocardium after administration of meglumine/sodium diatrizoate, iodipamide, and an experimental polymer of iothalamic acid.

Acute Disease↗
PubMed1984

High-performance liquid chromatographic analysis of cefotetan epimers in human plasma and urine.

Cefotetan, a new broad-spectrum 7 alpha-methoxycephalosporin antibiotic, was assayed in plasma and urine by means of reversed-phase high-performance liquid chromatography. Commercially available cefotetan exists in two epimeric forms. The procedure described allows the separation and quantitation of both epimers. For the first time a different pharmacokinetic behaviour (t1/2 = 3 h versus 4 h) for each epimer after intravenous injection to healthy volunteers is demonstrated. It is assumed that one epimer is bound to a greater extent to serum proteins and is therefore responsible for the differences observed. As both epimers exhibit similar antibacterial activity, it seems doubtful whether these differences would have clinical significance. Iothalamic acid was determined simultaneously as a marker of kidney function.

Biological Assay↗
PubMedDate not supplied

Solute excretion during intravenous urography: a comparison of sodium and methylglucamine iothalamates.

The sodium and methylglucamine salts of iothalamic acid were compared as urographic agents. The two drugs were administered intravenously to dogs at a dose of 600 mgI/kg. The outputs and concentrations of the major urinary solutes and the injected solutes were measured to define the differences in renal excretion of sodium and methylglucamine iothalamates. The action of methylglucamine as a relatively inert osmotic diuretic was reconfirmed. When sodium iothalamte was adminstered the tubular reabsorption of sodium and chloride was greater than when methylglucamine iothalamate was used. It is suggested that this reabsorption explains the advantage of sodium-linked agents over methylglucamine-linked agents in urography.

Animals↗
PubMed2001

A simple method for the identification and assay of iopamidol and iothalamate meglumine in pharmaceutical samples based on proton nuclear magnetic resonance spectroscopy.

A proton nuclear magnetic resonance (PMR) spectroscopic method is described for the direct assay and identification of the triiodinated radiographic contrast agents iopamidol (nonionic type) and iothalamate meglumine (ionic type) in commercial solutions and as a bulk material. Samples were prepared by simply diluting an injectable solution with or dissolving a powdered sample in D2O. Sodium acetate was added to serve as an internal standard. Quantitations were based on the resonance signals for the protons of the CH3-CO-group at 1.58 ppm (iopamidol) or 2.25 ppm (iothalamate), CH3-N-group at 2.38 ppm (meglumine) and CH3-CO-group at 1.92 ppm (acetate). The mean +/- SD (n = sets of 10 samples each) recovery of iopamidol, iothalamic acid and meglumine from synthetic mixtures with the internal standard were 99.6 +/- 0.63, 99.7 +/- 0.66 and 99.9 +/- 1.18%, respectively; with the values ranging from 98.7-100.9% for iopamidol and iothalamate, and from 98.3-100.8% for meglumine.

Contrast Media↗
PubMed1989

[Enoxacin concentration in seminal fluid, in prostate secretions and in prostatic adenoma tissue following oral administration or intravenous infusion].

In eleven volunteers and 39 patients undergoing transurethral resection of the prostate or bladder tumor, concentrations of enoxacin were measured in seminal fluid (volunteers), in prostatic fluid (volunteers, patients) and in prostatic adenoma tissue (patients) after oral (400 mg) administration and intravenous (428 mg) infusion (60 min) of enoxacin. Simultaneously 2.534 g of iothalamic acid was i.v. injected to identify possible urinary contamination. The concentrations of enoxacin in seminal fluid after 2-4 h and in prostatic tissue after about 1-4 h and 14-16 h exceeded plasma concentrations more than two-fold. The concentrations in prostatic fluid after 1-4 h were about half the plasma concentrations. Venous blood samples were taken after intravenous infusion at intervals of up to 24 h in a total of 14 patients. The mean plasma concentration of enoxacin decreased from its maximum of 6.9 mg/l at the end of infusion to 0.5 mg/l at 12 h after administration. A terminal half life of 6.65 h was calculated according to an open two-compartment model.

Administration, Oral↗
PubMed1982

Renal radiopharmaceuticals--an update.

Noninvasive radionuclide procedures in the evaluation of renal disease have been accepted increasingly as effective and valuable alternatives to older clinical methods. The development of suitable radiopharmaceuticals labeled with high photon intensity radionuclides and with 99mTc in particular has stimulated this modality during the last few years. Currently several nearly ideal agents are available for anatomical and functional studies of kidney imparting very low absorbed radiation doses. These include 99mTc-GHA and 99mTc-DMSA for renal morphology and differential function evaluation, 99mTc-DTPA for GFR and 123I orthoiodohippurate for ERPF measurements. A suitable agent as a replacement for the latter labeled with 99mTc is actively being sought. Computer-assisted processing of dynamic renal function studies enables the observer to obtain a wealth of information related to the renal extraction, uptake, parenchymal transit and pelvic transit parameters of the agent administered into the bloodstream. Each of these parameters either globally or differentially contributes to a detailed evaluation of renal disease states. Several of these procedures have been validated against classical techniques clinically but more detailed information is being sought with the recently introduced radiopharmaceuticals. With the detailed validation and increasing recognition of the clinical utility of several of the radionuclidic procedures at many centers, it is hoped that radionuclide assessment of renal disorders ultimately will be made available routinely at all medical facilities.

Carbon Radioisotopes↗
PubMed2002

Functional effects of renal artery stent placement on treated and contralateral kidneys.

BACKGROUND: This study examined the effects of stent placement for renal artery stenosis on the function of treated and contralateral kidneys. METHODS: Eighteen patients who underwent stent placement for unilateral renal artery stenosis presenting with hypertension and/or renal failure were studied before angiography and stent placement and at their one-year follow-up. Renal vein blood samples were taken at both sides, at each side simultaneously with a sample from the aorta, to measure the plasma renin concentration and the concentrations of 131I-hippuran and 125I-thalamate during constant systemic infusion of these radiochemicals. This allowed an assessment of the single-kidney contributions to the total renin secretion, effective renal plasma flow (131I-hippuran clearance) and glomerular filtration rate (125I-thalamate clearance). RESULTS: At the one-year follow-up, the vein-to-artery renin ratio at the treated side had decreased to normal, from 1.65 +/- 0.131 to 1.23 +/- 0.076 (mean +/- SEM; P = 0.011), indicating an improved renal blood flow. Contralaterally it rose from 1.09 +/- 0.042 to 1.17 +/- 0.029 (P = 0.055) at follow-up. The extraction ratio of 131I-hippuran improved at the treated side (0.48 +/- 0.049 to 0.62 +/- 0.034; P = 0.003) and contralaterally (0.67 +/- 0.033 to 0.73 +/- 0.026; P = 0.043). The extraction ratio of 125I-thalamate, which equals filtration fraction, improved at both sides (0.12 +/- 0.014 to 0.17 +/- 0.012 at the treated side, P = 0.001; 0.18 +/- 0.013 to 0.22 +/- 0.011 contralaterally, P = 0.002). Two-kidney effective renal blood flow and glomerular filtration rate remained unchanged. CONCLUSION: Renal artery stenting was capable of causing improvement of glomerular filtration rate of the treated kidney, although the overall glomerular filtration rate did not change.

Aged↗