Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Iohexol”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1990

Measurement of renal function with iohexol. A comparison of iohexol, 99mTc-DTPA, and 51Cr-EDTA clearance.

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.

Adult↗
PubMed1998

Iohexol, platelet activation and thrombosis. I. Iohexol-induced platelet secretion does not affect thrombus formation in native blood.

BACKGROUND: The nonionic monomer iohexol triggers in vitro platelet secretion of beta-thromboglobulin (beta-TG). This iohexol platelet activation may promote intravascular thrombosis. We studied this relationship by employing a human model of collagen-induced platelet thrombus formation at arterial flow. The ionic dimer ioxaglate, the nonionic dimer iodixanol, and glucose were included. METHODS AND RESULTS: In vitro platelet activation as measured by beta-TG secretion following a 1-min incubation of native blood with 50 vol% of iohexol was significant. Glucose solutions of 300, 580 and 825 mosmol, corresponding to the osmolalities of respectively iodixanol, ioxaglate and iohexol, increased the beta-TG secretion in parallel with the osmolalities. Ioxaglate and iodixanol were virtually inert. Continuous infusion of iohexol or 580 or 825 mosmol glucose (40 vol%) into flowing native blood at an arterial wall shear rate of 2600 s-1 in an ex vivo collagen-induced platelet thrombus formation device triggered pronounced secretion of beta-TG. However, the platelet thrombus formation in blood mixed with iohexol was within the same range as that observed with ioxaglate or iodixanol. Increasing glucose osmolality induced increasing beta-TG secretion, which paralleled gradually decreasing platelet thrombus formation. CONCLUSION: Iohexol and 580 or 825 mosmol glucose trigger platelet secretion of beta-TG. This secretion is not associated with enhanced collagen-induced platelet thrombus formation at high arterial shear.

Blood Donors↗
PubMed1992

Effects of vasoconstrictors on isolated rabbit coronary arteries exposed to isotonic iohexol. Potassium chloride-, histamine-, endothelin-, and prostaglandin-F2 alpha-induced contractions on arteries exposed to iohexol without and with osmotic additions (sodium chloride or glucose).

RATIONALE AND OBJECTIVES: A major effect of contrast media (CM) on coronary vessels is vasodilatation, but occasionally, both ionic and nonionic media may cause coronary artery spasm. The influence of CM on the actions of vasoactive substances is not well known. To investigate the effects on rabbit coronary arteries of an iso-osmolar nonionic CM, iohexol (140 mg I/mL) the vasoconstrictors potassium chloride (KCl), histamine, endothelin, and prostaglandin-F2 alpha (PGF2 alpha) were used. The effects of iohexol with 30 to 150 mM sodium chloride (NaCl) or with 25-50 g/L glucose also were investigated. METHODS: Coronary artery segments were mounted between two L-shaped prongs in tissue baths with buffer solution. Before each investigation, buffer was exchanged with iohexol solution. Increasing concentrations of a vasoconstrictor were added, and the constriction of the vessels was recorded. RESULTS: Iohexol caused a comparatively small inhibition of the contractile effects of histamine and endothelin. This meant little reduction in maximal contraction (Emax), and the concentration of constrictory substance resulting in half maximal contraction (EC50) compared with buffer solution. Iohexol also caused a small reduction in Emax of KCl, but EC50 was significantly lower. Adding NaCl or glucose to iohexol decreased Emax and increased EC50. Iohexol inhibited most of the contractile effect of PGF2 alpha, but adding NaCl increased Emax slightly. CONCLUSIONS: The effects caused by a nonionic CM on coronary arteries cannot be attributed to osmolality alone. The CM influenced the effects of vasoconstrictors to differing degrees, but the inhibition of the CM per se was usually small.

Animals↗
PubMed1998

Iohexol, platelet activation and thrombosis. II. Iohexol-induced platelet secretion does not affect collagen-induced or tissue-factor-induced thrombus formation in blood that is anticoagulated with heparin and aspirin.

BACKGROUND: There is a dispute about the potential effects of radiographic contrast media (CM) on thrombogenesis. The nonionic CM iohexol triggers platelet beta-thromboglobulin (beta-TG) secretion, and thus may activate the platelets and promote thrombosis. We addressed this topic in a study employing a human model of arterial thrombus formation in the presence of aspirin and heparin. This was a follow-up to our initial study (on thrombus formation in native blood) which did not include antithrombotic drugs. The nonionic CM iohexol (monomer) and iodixanol (dimer) and the ionic CM ioxaglate (dimer) were compared. METHODS AND RESULTS: Thrombus formation was triggered by a surface rich in either collagen or tissue factor, positioned in a parallel-plate perfusion chamber device at an arterial wall shear rate of 2600 s-1. Blood from healthy volunteers, following ingestion of 1 g aspirin, was mixed with 40 vol% CM and 2.0 IU/ml heparin and passed over the surfaces. Thrombus formation in the presence of either CM showed no difference, despite the fact that iohexol triggered a pronounced platelet beta-TG secretion; iodixanol or ioxaglate were virtually inert. CONCLUSION: There was no association between iohexol-induced beta-TG secretion and thrombus formation on collagen (platelet-driven) or on tissue factor (thrombin-driven) in the presence of a standard antithrombotic regimen of aspirin and heparin as used in the clinic. The notion of a thrombotic risk due to platelet activation by iohexol was thus not substantiated by this study.

Anticoagulants↗
PubMed1993

Oral contrast media in CT of the abdomen. A double-blind randomized study comparing an aqueous solution of amidotrizoate, an aqueous solution of iohexol and a viscous solution of iohexol.

In a double-blind randomized study 3 different preparations of oral contrast media for bowel opacification at CT of the abdomen have been compared. Plain aqueous solutions of amidotrizoate (9 mg I/ml) and iohexol (9 mg I/ml) were used as well as a preparation of iohexol (9 mg I/ml) to which a viscosity-increasing agent had been added. The distribution of the contrast media in the intestine, transit time and patient tolerance were evaluated. No significant differences were found regarding the distribution between the 3 preparations of contrast media, while there was a tendency for the transit time to be increased when the viscous preparation of iohexol was used. The aqueous solution of iohexol had the best taste, while the viscous preparation was markedly more difficult to drink. Aqueous solutions of iohexol and amidotrizoate were equal for bowel opacification and the addition of the viscosity-increasing agent did not improve the distribution of the contrast medium in the intestine.

Administration, Oral↗
PubMed1992

Comparison of iohexol-240 versus iohexol-300 in abdominal CT.

Forty patients without evidence of liver, kidney, or significant cardiac disease were prospectively divided into two groups of 20, receiving either iohexol-240 or iohexol-300. A contrast load of 150 ml was administered in conjunction with a rapid scanning technique at a preselected, fixed level to include liver, renal cortex, and aorta. Peak enhancement was calculated as change in Hounsfield units (HU) over baseline for each area of interest. Mean peak enhancement and standard deviation were calculated for each organ, and the difference between the means for the two contrast agents was compared using the Student's t test. Differences were not statistically significant with all p values greater than 0.05. Our results suggest iohexol-240 is preferred to iohexol-300 for body computed tomography (CT) due to its lower cost and iodine load without statistically significant change in diagnostic quality of the examination.

Evaluation Studies as Topic↗
PubMed1986

Ascending lower-limb phlebography: a comparative study of Hexabrix 320, iohexol 300 and iohexol 240.

A prospective, randomised study on 60 legs in 45 patients examined by ascending lower-limb phlebography was conducted to compare Hexabrix 320 (May and Baker Ltd), iohexol 300 and iohexol 240. The quality of opacification of the veins, side-effects, cost and amount of contrast agent used were compared. All three agents produced adequate examinations. Iohexol 300 was preferred for its denser opacification. Iohexol 240 was associated with the lowest incidence of side-effects and Hexabrix 320 cost the least per examination.

Female↗
PubMed1991

A single plasma sample method for estimation of the glomerular filtration rate in infants and children using iohexol, I: Establishment of a body weight-related formula for the distribution volume of iohexol.

This study was performed in order to develop a method for estimation of the glomerular filtration rate (GFR) from a single plasma sample based upon the plasma disappearance rate of the non-ionic contrast medium iohexol. The apparent distribution volume for iohexol was measured in 100 infants and children and used for establishment of a weight-related empirical formula for the distribution volume. Using the distribution volume obtained by this formula, a preliminary GFR was calculated from the iodine concentration measured in a plasma sample taken 3 h after injection of iohexol. When this estimate was corrected by another empirically established correction factor, a high degree of agreement was found between a GFR reference method and the 3-h single plasma sample method. In another group of 13 children the 3-h single plasma sample GFR was estimated twice with a 2-day interval, and the day-to-day variations were found to be similar to those obtained with other standard methods.

Adolescent↗
PubMed1994

Cost-effective use of low-osmolality contrast media for CT of the liver: evaluation of liver enhancement provided by various doses of iohexol.

OBJECTIVE: Because of pending efforts to reform health care in the United States, judicious use of low-osmolality contrast media is important. We studied the effects of using various concentrations and volumes of iohexol, compared with the conventional dose and concentration of diatrizoate meglumine used for CT, to determine if a more cost-effective dose results in diagnostically efficacious liver enhancement. SUBJECTS AND METHODS: A total of 902 patients received one of nine different doses of IV contrast media. Eight doses of iohexol were used: 125 ml of iohexol 350 (350 mg l/ml, 44 g l/dose), 100 ml of iohexol 350 (35 g l/dose), 150 ml of iohexol 300 (300 mg l/ml, 45 g l/dose), 120 ml of iohexol 300 (36 g l/dose), 100 ml of iohexol 300 (30 g l/dose), 175 ml of iohexol 240 (240 mg l/ml, 42 g l/dose), 150 ml of iohexol 240 (36 g l/dose), and 125 ml of iohexol 240 (30 g l/dose). A single dose (150 ml) of diatrizoate meglumine 60% (w/v) was used (42 g l/dose). Contrast material was injected at a rate of 2 ml/sec. Scanning began 35-45 sec after injection. Quantitative analysis of enhancement was performed by obtaining region-of-interest measurements through the liver on scans obtained before and after injection of contrast material. Mean and maximum changes in hepatic density and mean time to maximum enhancement were measured. Mean time-density curves were subsequently derived for each dose of contrast material. Qualitative analysis of enhancement was performed by using subjective, previously defined criteria. All studies were interpreted in a double-blind fashion. RESULTS: Mean hepatic enhancement was greater with 125 ml of iohexol 350 and 150 ml of iohexol 300 than with other doses of contrast material (p < .05). Both 125 ml of iohexol 350 and 150 ml of iohexol 300 produced actual hepatic enhancement of more than 50 H for over 60 sec. The greatest maximum increase in hepatic density occurred with 125 ml of iohexol 350. When analyzed qualitatively, 150 ml of iohexol 300 resulted in the highest percentage of optimum enhancement. CONCLUSION: According to quantitative analysis, 125 ml of iohexol 350 administered at a rate of 2 ml/sec produces the best enhancement, whereas according to qualitative analysis, 150 ml of iohexol 300 produces the best enhancement. All doses of iohexol 240 provide poor enhancement compared with a conventional dose of contrast material of 150 ml of diatrizoate meglumine 60% or 150 ml of iohexol 300. A moderate cost savings can be achieved by using 125 ml of iohexol 350 for dynamic sequential CT.

Cost-Benefit Analysis↗
PubMed1996

Determination of residual renal function with iohexol clearance in hemodialysis patients.

Residual renal function (RRF) may contribute significantly to the total dialysis prescription. Conventional quantitation of RRF in hemodialysis (HD) patients is measured by urea clearance and requires a 24-hour urine collection which is often difficult to perform and inaccurate. The renal clearance of iohexol was evaluated as an alternative method for RRF assessment (iohexol-derived RRF) in hemodialysis patients. An intravenous bolus of iohexol (12 ml; 300 mg iodine/ml) was administered to 42 hemodialysis patients following routine HD. A single blood sample was obtained approximately 44 hours later (pre-HD) to determine the plasma clearance of iohexol using x-ray fluorescence methods. Total body clearance of iohexol (CTBio) and non-renal clearance of iohexol (CNRio) 2.87 +/- 0.3 ml/min (mean +/SEM) were used to calculate iohexol-derived RRF (CTBio-CNRio). Iohexol-derived RRF determinations were then compared to urea clearance-derived RRF measurements. The RRF contribution to the dialysis prescription was also calculated utilizing iohexol-derived RRF compared to urea-derived RRF. Iohexol-derived RRF did not differ from urea-derived RRF (2.48 +/- 0.3 vs. 2.64 +/- 0.4 ml/min, P = 0.21). The RRF contribution to the weekly dialysis prescription (Kt/V) did not differ when iohexol-derived RRF was compared to urea-derived RRF (0.94 +/- 0.1 vs. 0.93 +/- 0.1, P = 0.9). Additionally, the effect of iohexol on RRF was assessed in 17 HD patients. Urea-derived RRF determinations one week after iohexol exposure did not differ from those measured one week prior to iohexol exposure (3.17 +/- 0.6 vs. 2.91 +/- 0.5 ml/min, respectively). Thus, renal clearance of iohexol can be an accurate and safe measure of RRF in HD patients and potentially simplify delivery of the dialysis prescription.

Adult↗
PubMed2003

Evaluation of iohexol clearance used to estimate glomerular filtration rate in clinically normal foals.

OBJECTIVE: To determine whether pharmacokinetic analysis of data derived from a single i.v. dose of iohexol could be used to predict creatinine clearance and evaluate simplified methods for predicting serum clearance of iohexol with data derived from 2 or 3 blood samples in clinically normal foals. ANIMALS: 10 healthy foals. PROCEDURE: Serum disposition of iohexol and exogenous creatinine clearance was determined simultaneously in each foal (5 males and 5 females). A 3-compartment model of iohexol serum disposition was selected via standard methods. Iohexol clearance calculated from the model was compared with creatinine clearance. Separate limited-sample models were created with various combinations of sample times from the terminal slope of the plasma versus time profile for iohexol. Correction factors were determined for the limited-sample models, and iohexol clearance calculated via each method was compared with exogenous creatinine clearance by use of method comparison techniques. RESULTS: Mean exogenous creatinine clearance was 2.17 mL/min/kg. The disposition of iohexol was best described by a 3-compartment open model. Mean clearance value for iohexol was 2.15 mL/min/kg and was not significantly different from mean creatinine clearance. A method for predicting serum iohexol clearance based on a 2-sample protocol (3- and 4-hour samples) was developed. CONCLUSIONS AND CLINICAL RELEVANCE: Iohexol clearance can be used to predict exogenous creatinine clearance and can be determined from 2 blood samples taken after i.v. injection of iohexol. Appropriate correction factors for adult horses and horses with abnormal glomerular filtration rate need to be determined.

Animals↗
PubMedDate not supplied

Relationship between plasma iohexol clearance and urinary exogenous creatinine clearance in dogs.

The objective of this study was to determine if plasma iohexol clearance, computed by a 1-compartment model defined by 3 plasma samples. was an accurate measure of glomerular filtration rate (GFR) in dogs. Twenty-two adult Beagle dogs of both genders were studied. Ten dogs had intact kidneys, and 12 dogs had surgically reduced renal mass. A bolus injection of iohexol was made, and blood was obtained for plasma iohexol assay after 120, 180, and 240 minutes. Plasma was analyzed for iohexol concentration by means of 3 assay methods: chemical, high-performance liquid chromatography (HPLC), and inductively coupled plasma emission spectroscopy (ICP). Urinary clearance of exogenous creatinine was used to measure GFR for three 30-minute periods occurring between 150 and 240 minutes after iohexol injection. Plasma clearance of iohexol and renal clearance of creatinine were compared by linear regression analysis and by limits of agreement techniques. Plasma iohexol clearance and urinary exogenous creatinine clearance were significantly correlated (chemical R2 = .90; HPLC R2 = .96; and ICP R2 = .96). The 1-compartment iohexol clearance:exogenous creatinine clearance ratios were 1.04 +/- 0.17, 1.05 +/- 0.14, and 1.10 +/- 0.15 for the chemical, HPLC, and ICP methods of assay, respectively, indicating that plasma iohexol clearance slightly overestimated GFR. Assuming a +/- 2 standard deviation interval for error, corrected plasma iohexol clearance measured GFR with +/-34% accuracy for the chemical, +/-26% accuracy for the HPLC, and +/-27% accuracy for the ICP method. These results indicate that plasma iohexol clearance should have utility for detection of renal dysfunction earlier in the course of progressive renal disease than is possible with measurement of plasma creatinine or urea concentrations.

Animals↗
PubMed2003

Iohexol-induced neutrophil myeloperoxidase release and activation upon contact with vascular stent-graft material: a mechanism contributing to the postimplantation syndrome?

PURPOSE: To investigate whether the contrast medium iohexol alone or in combination with vascular stent-graft material induces neutrophil degranulation. METHODS: Human whole blood or isolated human neutrophils were incubated with or without iohexol and vascular stent-graft material. Samples were also drawn from 5 patients undergoing diagnostic angiography using iohexol. Myeloperoxidase and lactoferrin concentrations were determined by enzyme immunoassays. RESULTS: Both in vitro and in the patients, iohexol induced neutrophil degranulation with considerable individual variation in dose sensitivity and timing. The in vitro effect was independent of the type of anticoagulant used (ethylenediamine tetra-acetic acid, heparin, lepirudin). Experiments using isolated neutrophils showed that degranulation was independent of complement activation or platelet-derived mediators. The dose for maximal response varied from 5 to 50 mg I/mL (10.7-107.6 mg/mL iohexol). In vitro, vascular stent-graft material alone did not induce neutrophil degranulation. As compared to iohexol alone, incubation with iohexol and vascular stent-graft material in combination substantially increased the release of myeloperoxidase. CONCLUSIONS: Iohexol induces neutrophil degranulation, which is greatly enhanced when combined with vascular stent-graft material. Thus, iohexol-induced neutrophil activation may contribute to an inflammatory response following stent-graft implantation. We speculate that neutrophil activation during other procedures combining catheters and iohexol (e.g., angiography) may induce inflammation, which might have detrimental effects.

Blood Vessel Prosthesis↗
PubMed1998

Iohexol plasma clearance in determining glomerular filtration rate in diabetic patients.

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.

Adult↗
PubMed1996

Iohexol clearance for assessment of glomerular filtration rate in diabetic pregnancy.

BACKGROUND: Plasma clearance of iohexol (Omnipaque) is well suited for determination of glomerular filtration rate (GFR) during pregnancy. OBJECTIVE: To settle guidelines for the use of iohexol clearance in diabetic pregnancy. STUDY DESIGN: Prospective comparative. MATERIAL AND METHODS: Iohexol (5 ml) was injected intravenously and plasma concentrations determined by high pressure liquid chromatography after 180-240 min in 44 diabetic pregnant women. RESULTS: Iohexol clearance was normal in most cases of nephropathy or albuminuria. Iohexol clearance correlated negatively with blood pressure, S-Urate, and S-Creatinine. When S-Urate was < 232 mumol/l or S-Creatinine < 70 mumol/l, iohexol clearance was always normal (sensitivity = 1.0). When, in combination, S-Urate was > 345 mumol/l, and S-Creatinine > 70 mumol/l, iohexol clearance was always subnormal (sensitivity = specificity = Kappa index = 1.0). CONCLUSIONS: In diabetic pregnancy, nephropathy or albuminuria cannot solely be used for selection of candidates for iohexol clearance determination. A S-Urate < 230 mumol/l (3.9 mg/dl) or S-Creatinine < 70 mumol/l (0.92 mg/dl) was reassuring for a normal GFR. We suggest iohexol clearance determinations in diabetic pregnancies when S-Urate is > 350 mumol/l (5.9 mg/dl) and/or S-Creatinine > 70 mumol/L.

Adult↗
PubMed1986

Use of iohexol in the radiographic diagnosis of ischemic bowel.

This study evaluates the use of iohexol as a radiographic diagnostic contrast agent in normal animals and those with experimental bowel ischemia and obstruction. Eighteen rats and 12 rabbits were gavaged with iohexol in a dose of 7.5 mL/kg using concentrations of 140 mg I/mL (isotonic with blood) or 300 mg I/mL. In addition, four rabbits had intraperitoneal iohexol injection and three were given gastrografin gavage. Experimental groups included normal bowel controls, bowel injury induced by ischemia and alcohol contact, bowel obstruction by ligature, and intraperitoneal injection. Serial abdominal radiographs and plasma concentrations of iohexol were obtained. Iohexol remained stable throughout the gastrointestinal tract, retained its intensity, and was well visualized up to four days after administration. Bowel images were fair at concentrations of 140 mg I/mL and excellent at 300 mg I/mL. Gastrografin caused bowel distention and poor visualization related to dilution. It also precipitated in the stomach. Iohexol was rapidly absorbed from the peritoneal cavity and excreted by the kidneys, without causing peritonitis. Rat plasma iohexol levels were three times controls in obstructed bowel and 80 times controls if there was mucosal injury without perforation. Rabbit peak plasma levels were 30 times greater following intraperitoneal injection than with gastric gavage. These observations suggest that iohexol may be useful as a gastrointestinal contrast agent. Measuring plasma iohexol levels may be helpful in the evaluation of suspected bowel ischemia or perforation in the clinical setting.

Animals↗
PubMed1996

Ionic mechanisms contributing to the vasorelaxant properties of iodinated contrast media: a comparison of iohexol and iodixanol in the rabbit isolated aorta.

1. We have used rings of rabbit thoracic aorta to investigate the vasorelaxant properties of two different classes of non-ionic iodinated radiographic contrast media (IRCM) and the mechanisms, underlying their mode of action. Iohexol (a triiodinated monomer) was compared with iodixanol (a hexaiodinated dimer). 2. Iohexol and iodixanol both relaxed phenylephrine (0.3 microM) constricted rabbit aorta in a concentration-dependent manner that did not depend on the presence of an intact endothelium. When expressed as a function of iodine concentration, iodixanol caused significantly less relaxation than iohexol. However, the extent of relaxation was similar for both IRCM when expressed on a molar basis. Furthermore, increasing the molarity of the buffer to comparable levels with mannitol evoked only a small (approximately 15%) relaxation of phenylephrine-induced tone. 3. Ouabain (10 microM) significantly inhibited both iohexol- and iodixanol-induced relaxations by approximately 30%. 5-(N-Ethyl-N-isopropyl)-amiloride (EIPA, 100 nM) significantly inhibited iohexol-induced relaxation to the same extent as ouabain, but did not alter the vasorelaxant effect of iodixanol. Co-incubation with ouabain and EIPA had an additive effect in the case of iohexol, increasing inhibition of relaxation to approximately 60%, whereas inhibition of iodixanol-induced relaxation by the combination of ouabain plus EIPA did not differ from that of ouabain alone. 4. Replacing NaCl with N-methyl-D-glucamine (NMDG) to lower extracellular [Na+] and thereby inhibit Na(+)-Ca2+ exchange, attenuated the relaxation evoked by iohexol or by iodixanol (by approximately 25%) in each case. 5. We conclude that iohexol- and iodixanol-induced vasorelaxation in rabbit aorta is mediated through a direct action on vascular smooth muscle that is not simply a consequence of altered osmolality. It involves modulation of the Na(+)-K+ ATPase and, in the case of iohexol, Na(+)-H+ exchange. Both agents also appear to modulate Na(+)-Ca2+ exchange, through direct and/or indirect mechanisms. This is the first study to show specific pharmacological differences between monomeric and dimeric contrast media in vascular smooth muscle.

Animals↗
PubMed1992

Comparison of iohexol 300 and diatrizoate meglumine 60 for body CT: image quality, adverse reactions, and aborted/repeated examinations.

Six hundred patients were prospectively randomized and given either diatrizoate meglumine 60 or iohexol 300 during dynamic contrast-enhanced body CT in order to compare image quality, contrast reactions, and the number of aborted studies or studies in which images had to be repeated. Three hundred two patients received iohexol 300, and 298 patients received diatrizoate meglumine 60. Thirty-nine percent (119/302) of the patients given iohexol 300 and 63% (188/298) of the patients given diatrizoate meglumine 60 had at least one adverse reaction thought to be related to contrast material during, or within 24 hr of, the body CT scan. When reactions of discomfort (heat or warmth, flushing, bad taste) were excluded, 16% (48/302) of the patients who received iohexol and 33% (99/298) of the patients who were given diatrizoate meglumine 60 had at least one adverse reaction. The differences in both types of reactions between the two agents were significant (p less than .001). Among scans evaluated for study quality, 71% (214/302) of the iohexol 300 group and 62% (184/298) of the diatrizoate meglumine 60 group had optimal enhancement (p = .02). However, when the optimal and adequate categories were combined, 301 of 302 patients given iohexol 300 and 292 of 298 patients given diatrizoate meglumine 60 had diagnostic-quality studies (no statistical difference). Studies were not terminated nor were images repeated in 97% (292/302) of the patients given iohexol 300 and in 94% (280/298) of those given diatrizoate meglumine 60. The CT study was repeated because of movement during the contrast injection or aborted because of contrast-related reactions in 0.7% of the patients given iohexol 300 and in 3.0% of the patients given diatrizoate meglumine 60. This difference was statistically significant (p = .04). Our results suggest that the difference in image quality, number of adverse reactions, and number of aborted/repeated CT scans performed with iohexol 300 or diatrizoate meglumine 60 are not sufficiently different to warrant conversion to nonionic agents for body CT scans.

Diatrizoate Meglumine↗