Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: KEGG:D01817 (Iohexol)
 504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The nonionic iodinated contrast medium, iohexol, introduced for clinical urography, is eliminated from the human organism mainly by glomerular filtration. The aim of this study was to analyze the applicability of iohexol for glomerular filtration rate (GFR) measurement by comparing the plasma clearance of iohexol to the plasma clearance of the traditionally employed substances, chromium-51-EDTA and technetium-99m-DTPA. Iohexol concentration was measured by x-ray fluorescence. To analyze for possible acute effect of iohexol on renal function, additional measurements of 99mTc-DTPA clearance were made prior to the injection of iohexol. In 15 patients having clearance values between 30 and 130 ml/min per 1.73 m2, there were close correlations (r = 0.95-0.98) among iohexol, 51Cr-EDTA, and 99mTc-DTPA clearance. No significant acute renal effect of iohexol was demonstrated. It is concluded that measurement of iohexol clearance provides information about GFR that is as valid as measurements of 51Cr-EDTA and 99mTc-DTPA clearance. Thus, it is possible to perform urography and a determination of GFR using a single injection of iohexol.
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PMID:Measurement of renal function with iohexol. A comparison of iohexol, 99mTc-DTPA, and 51Cr-EDTA clearance. 211 26

A new method for determining the glomerular filtration rate was analysed prospectively. The method uses an x ray fluorescence technique to measure disappearance from the plasma of injected non-ionic iodinated contrast media. Eighty seven patients were studied. Fifty four had an intravenous dose of 100 ml iohexol (Omnipaque) and 33 had 50 ml iohexol. Clearances of chromium-51 labelled edetic acid (51Cr-EDTA) were measured simultaneously. In the patients given 100 ml iohexol there was excellent correlation with 51Cr-EDTA clearance (r = 0.90). The correlation using 50 ml iohexol was also good (r = 0.85). Correlation between creatinine clearance and clearance of 51Cr-EDTA in 33 patients was less satisfactory (r = 0.69). There were no adverse reactions to the contrast media. The equipment used for measuring contrast clearance was robust and simple to operate. Freezing plasma samples in 10 studies and re-examining them weekly for six weeks showed no significant variation in results; hence reproducibility was good. This new and accurate method for determining the glomerular filtration rate merits further study and might find a useful place in routine clinical practice.
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PMID:Accuracy and reproducibility of a new contrast clearance method for the determination of glomerular filtration rate. 308 67

Determination of plasma clearance of contrast agents has been advocated as a means to assess glomerular filtration rate. To evaluate the feasibility of different agents for this purpose, we have compared, in healthy volunteers, the dose dependence of plasma clearance for three contrast media (iohexol, a nonionic agent, and iothalamate and metrizoate, which are ionic substances), with special emphasis on the lower dose range (2-20 mL corresponding to 0.9-12.9 g, depending on dose and agent). Iohexol and iothalamate were cleared at constant rates, irrespective of given dose, whereas metrizoate clearance increased significantly at lower doses. In general, the clearances or iothalamate and metrizoate were, respectively, moderately and markedly higher than that of iohexol. The clearance of different doses of metrizoate (2 mL versus a radiographic dose of 40 mL or more) was also compared with the clearance of [51Cr]EDTA in two groups of patients with reduced renal function. When compared with [51Cr]EDTA in patients with renal dysfunction, metrizoate was cleared significantly faster after a 2-mL dose, whereas clearances were identical when the metrizoate dose was 40 mL or more. These findings indicate that tubular secretion plays an active role in the elimination of metrizoate. The pharmacokinetic properties of iohexol, in combination with its low toxicity, make it a suitable agent for determination of glomerular filtration rate in clinical practice.
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PMID:Contrast media and glomerular filtration: dose dependence of clearance for three agents. 314 28

The pharmacokinetics of iohexol, a new nonionic, water-soluble contrast medium, have been determined after intravenous injection in 20 healthy volunteers, at four different dose levels (125-500 mg I/kg). The apparent volume of distribution was 0.27 1/kg, indicating distribution in the extracellular water. The biologic half-life was 121 minutes, comparable with that of other intravascular contrast media. Iohexol was excreted completely unmetabolized in the urine, with a 100% recovery 24 hours after injection. A comparison of iohexol and chromium-51 (51Cr)-EDTA clearances indicates that iohexol is mainly excreted by glomerular filtration. The 51Cr-EDTA clearance was the same when injected separately and concomitantly with iohexol, indicating that glomerular filtration rate is not affected by iohexol. No dose dependency was observed in the investigated parameters t1/2 alpha, t1/2 beta, Vd, ClT or ClR. Iohexol pharmacokinetics are in correspondence with previously reported data on intravascular contrast media.
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PMID:Human pharmacokinetics of iohexol. A new nonionic contrast medium. 640 18

Twenty-seven patients (15 diabetics and 12 non-diabetics) with normal to moderately reduced renal function underwent femoral angiography with a low-osmolar contrast agent, iohexol (Omnipaque), under perexaminatory hydration. Fourteen patients were randomised to pretreatment with oral felodipine extended release (Plendil) 10 mg and 13 patients to placebo 3-4 h before angiography. GFR measured with [51Cr] EDTA-clearance decreased 24 hours after the angiography in the felodipine group from GFR 52.5 +/- 18.6 (mean +/- SD) to 46.2 +/- 16.5 ml/min (p < 0.01) and in the placebo group from 70.6 +/- 18.6 to 62.6 +/- 26.4 ml/min (p < 0.01). Serum creatinine increased significantly in the felodipine group from 128 +/- 61 to 139 +/- 67 mumol/l (p < 0.05) but not in the placebo group (122 +/- 54 to 125 +/- 51 mumol/l (ns)). The values of serum creatinine returned to baseline levels 7 days after angiography. During hydration there was only a slight reduction of GFR after angiography with iohexol. Thus, felodipine had no major effect on GFR after iohexol but, as baseline GFR tended to be lower in the felodipine pre-treated patients, it might have had some renoprotective effect in patients with more advanced renal failure.
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PMID:Does prophylactic treatment with felodipine, a calcium antagonist, prevent low-osmolar contrast-induced renal dysfunction in hydrated diabetic and nondiabetic patients with normal or moderately reduced renal function? 872 68

The associations among autonomic neuropathy, urinary albumin excretion, and glomerular filtration rate (GFR) measured with 51Cr-EDTA and iohexol clearance were studied in 41 patients with insulin-dependent diabetes mellitus (IDDM) and 15 patients with non-insulin-dependent diabetes mellitus (NIDDM). The study showed that increased urinary albumin excretion was more common in NIDDM than in IDDM. In contrast with IDDM, albuminuria in NIDDM was not related to GFR. Autonomic neuropathy was common in IDDM as well as in NIDDM, and also in patients without nephropathy, but was not connected with hyperfiltration. Low brake index, an ortostatic autonomic index, was associated with nephropathy in NIDDM. Iohexol, a non-ionic contrast medium, was found to be a useful alternative to 51Cr-EDTA for determination of GFR. Moreover, comparison between conventional four-sample plasma clearance and single-sample clearance showed a close correlation. Accordingly, assessment of GFR using a single plasma sample provides reliable results even at high GFR values.
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PMID:Relationships among glomerular filtration rate, albuminuria, and autonomic nerve function in insulin-dependent and non-insulin-dependent diabetes mellitus. 917 1

The plasma clearance of iohexol has recently been proposed as a new method for estimating GFR. The iohexol plasma clearance was compared with that of 51Cr-EDTA in 32 diabetic patients (12 IDDM, 20 NIDDM; age 23-70; diabetes duration 1-35 years) with normal to impaired renal function (serum creatinine: 0.8-6.4 mg/dL). Bolus i.v. injection of 51Cr-EDTA (1 muCi/kg) was followed by 5 mL slow i.v. injection of Omnipaque (Nycomed, Oslo, Norway). Samples for radioactivity and iohexol analysis were drawn at 0, 5, 10, 15, 30, 60, 90, 120, 150, 180, 210, 240, 270, 300 min (+360 and 420 min if serum creatinine > 2.0; +1440 min if > 5.0 mg/dL). Iohexol was assayed in duplicate by HPLC throughout a Nova-Pak C18 column (Waters-Millipore, USA). Only the second peak obtained during elution of iohexol (about 4.5 min) was used for calculation. Dilution tests show highly linear regressions for concentrations between 3.25-650 micrograms/mL (r = 0.99). Imprecision of iohexol assay (the whole procedure from deproteinization to chromatography) was: intra-assay 1.4 +/- 1.5%, mlsd (95% CI: 1.0-1.8%); inter-assay 3.0 +/- 2.7% (1.4-4.6%). Iohexol plasma clearance ranged between 12.9 and 150.9 mL/min, while 51Cr-EDTA plasma clearance between 11.9 and 149.8 mL/min with excellent correlation (iohexol = 0.95 51Cr-EDTA + 2.49; r = O.995). Mean CV between the two methods was 1.7% (range 0-4.9%) with a significant negative correlation (r = 0.5 I, p = 0.007) with the GFR levels. Correlation between repeated measurements, performed in eight patients, was excellent (r = O.994, P = 0.0001). In diabetes, GFR measured by plasma clearance of iohexol shows an excellent agreement with plasma clearance of 51Cr-EDTA throughout a wide range of renal function. Iohexol provides an accurate alternative method for measuring GFR.
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PMID:Iohexol plasma clearance in determining glomerular filtration rate in diabetic patients. 957 53

Glomerular filtration rate (GFR) assesses kidney function. GFR is measured by renal clearance techniques; inulin clearance is the gold standard but is not easily measured. Thus, other methods to determine GFR have been utilized. Endogenous creatinine clearance (CrCl) is the most widely used, but creatinine secretion falsely elevates GFR. Cimetidine inhibits creatinine secretion, such that CrCl equals GFR, provided there are no difficulties with bladder emptying. Estimation of GFR from serum creatinine (e.g. Schwartz formula) is useful clinically; however, such formulae have not been updated for enzymatic creatinine autoanalyzers. Cystatin C, a small protein, is produced at a relatively constant rate and is reabsorbed in the proximal tubule. Cystatin C may be more sensitive than creatinine in detecting a reduction in GFR, but further studies are needed to prove this. Single injection (plasma) clearance techniques are the most precise measures of GFR. Iohexol is an exogenous marker that is comparable to inulin and (51)Cr-EDTA and can be measured by high-performance liquid chromatography (HPLC). Our pilot and the Chronic Kidney Disease in Children (CKiD) North American studies show that iohexol can accurately measure GFR using a four-point plasma disappearance curve national studies show that iohexol can accurately measure GFR using a four-point plasma disappearance curve (10, 30, 120, and 300 min) or, in most cases, a two-point disappearance time (120 and 300 min).
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PMID:Glomerular filtration rate measurement and estimation in chronic kidney disease. 1721 61

(51)Chromium-labeled ethylenediamine tetra-acetic acid ((51)Cr-EDTA) is the gold standard probe for assessing intestinal permeability (IP) in dogs, but exposure to radioactivity is a disadvantage. Iohexol is a safe contrast medium commonly used for medical imaging purposes and has been successfully applied more recently for the assessment of IP in animal models and humans. This study aimed at comparing (51)Cr-EDTA and iohexol as IP blood markers in dogs. A test solution containing (51)Cr-EDTA and iohexol was administered intragastrically to seven healthy laboratory Beagle dogs, and percentage recoveries in serum were calculated. The strong linear association (correlation, r=0.76 and linear regression, y=0.03+5.04x) between (51)Cr-EDTA and iohexol supports the potential usefulness of iohexol as an IP blood marker in dogs.
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PMID:Comparison of 51chromium-labeled ethylenediamine tetra-acetic acid and iohexol as blood markers for intestinal permeability testing in Beagle dogs. 2165 37

Kidney transplantation is the treatment of choice for end-stage renal disease. The evaluation of graft function is mandatory in the management of renal transplant recipients. Glomerular filtration rate (GFR), is generally considered the best index of graft function and also a predictor of graft and patient survival. However GFR measurement using inulin clearance, the gold standard for its measurement and exogenous markers such as radiolabeled isotopes ((51)Cr EDTA, (99m)Tc DTPA or (125)I Iothalamate) and non-radioactive contrast agents (Iothalamate or Iohexol), is laborious as well as expensive, being rarely used in clinical practice. Therefore, endogenous markers, such as serum creatinine or cystatin C, are used to estimate kidney function, and equations using these markers adjusted to other variables, mainly demographic, are an attempt to improve accuracy in estimation of GFR (eGFR). Nevertheless, there is some concern about the inability of the available eGFR equations to accurately identify changes in GFR, in kidney transplant recipients. This article will review and discuss the performance and limitations of these endogenous markers and their equations as estimators of GFR in the kidney transplant recipients, and their ability in predicting significant clinical outcomes.
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PMID:Estimating glomerular filtration rate in kidney transplantation: Still searching for the best marker. 2616 57


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