Comparison of iodixanol with iohexol for delayed pelvic venous opacification: a preliminary study of potential use for CT venography

OBJECTIVE: The goal of this prospective randomized study was to determine whether isosmolar contrast material offers an advantage over low-osmolar contrast material for delayed venous opacification in CT venography. SUBJECTS AND METHODS. We prospectively enrolled 200 adult outpatients. Patients were randomized to receive either the low-osmolar (hyperosmolar to blood) nonionic contrast medium, iohexol, or the nonionic isosmolar contrast medium, iodixanol. Images were obtained before contrast administration and 180 sec after contrast administration through the pelvis at the level of the external iliac vessels. Opacification of the external iliac vessels was assessed both objectively and subjectively. RESULTS: The arterial and venous densities before contrast administration were approximately 45 H for both groups. On delayed images obtained after contrast administration, the mean venous density was 95.2 H for iohexol and 101.4 H for iodixanol. Changes in venous density due to administration of iohexol and iodixanol were 49.8 and 56.1 H, respectively. This 12.5% difference was highly significant (p = 0.002). Sixty-six percent of the images in the iodixanol group were rated either 4 (good) or 5 (excellent), whereas only 36% of the iohexol group achieved a similar rating on our subjective rating scale. This difference was statistically significant (chi(2) = 16.4, p < 0.001, df = 1). CONCLUSION: Our study shows that isosmolar contrast material provides significant improvement in delayed opacification of the external iliac vessels in comparison with conventional low-osmolar contrast medium (hyperosmolar to blood).     

Diagnostic efficacy of excretory urography with low-dose, nonionic contrast media.

A prospective, randomized, physician-blinded study was conducted to determine whether a smaller dose of low-osmolar, nonionic contrast medium can provide diagnostic information on excretory urograms equivalent to that obtained with higher doses of ionic and nonionic contrast agents. One hundred fifty adult patients who underwent excretory urography received a high-dose ionic contrast medium (diatrizoate sodium), high-dose nonionic contrast medium (iohexol), or low-dose nonionic contrast medium (iohexol). All urograms were scored for diagnostic quality. No difference in urographic quality was detected among the different doses of contrast media. The lower dose of low-osmolar nonionic contrast medium provided equivalent diagnostic information. The quality of the nephrotomograms, ureteral image, and overall image was slightly greater with diatrizoate than with a small dose of iohexol, but the difference was not significant. This study suggests that excretory urograms obtained in relatively healthy, well-prepared patients with smaller, less expensive doses of a nonionic contrast agent are at least diagnostically equivalent to those obtained with typical higher doses of ionic and nonionic agents.     

Iodixanol and iohexol in cardioangiography. A comparative vectorcardiographic study

Purpose: The non-ionic dimeric contrast medium (CM) iodixanol is isotonic with blood through the addition of electrolytes. In this study, we evaluated computerised dynamic vectorcardiography (VCG) as a tool in CM research by comparing the electrophysiological effects of iodixanol with those of the low-osmolar CM iohexol.Material and Methods: A total of 119 patients referred for cardioangiography were included in this double-blind, randomised, parallel comparison of iodixanol (320 mg I/ml) and iohexol (350 mg I/ml). VCG was recorded and different VCG parameters were analysed. General tolerability, safety and radiographic efficacy were also assessed.Results: Iodixanol induced less changes than iohexol in all VCG parameters and the sensation of warmth was significantly milder after iodixanol, but both CM were well tolerated. VCG might be useful in future studies to analyse electrophysiological effects caused by CM.     

Anticoagulant effects of contrast materials: in vitro study of iohexol, ioxaglate, and diatrizoate

It has been reported that clot formation may occur when blood is mixed directly with nonionic contrast medium in a syringe during angiography. To investigate this possibility, we performed three in vitro experiments to determine the anticoagulant properties of a low-osmolar, nonionic contrast medium (iohexol); a low-osmolar, ionic medium (ioxaglate); and a high-osmolar, ionic medium (diatrizoate). In the first experiment, human arterial blood was incubated at room temperature in an angiographic syringe with each of the three media for 60 min, after which the mixture was filtered for clots. In the second experiment, the clotting times of venous blood in heparinized saline or serial dilutions of the three agents were determined. In the third experiment, the partial thromboplastin time of platelet-poor plasma in heparinized saline or serial dilutions of the three agents was measured. No clots were observed in any of the arterial blood samples. Iohexol prolonged the normal 15-min clotting time of venous blood to 160 min, compared with a clotting time of at least 330 min for ioxaglate and diatrizoate. Iohexol prolonged the normal 36-sec partial thromboplastin time of platelet-poor plasma to 40 sec, compared with 50 sec for diatrizoate and 54 sec for ioxaglate. Our data show that iohexol, like ioxaglate and diatrizoate, inhibits clot formation when mixed with blood in a syringe. It prolongs the clotting time to approximately the same degree as 600 U/l of heparinized saline, but to a lesser degree than the other two media. All three media have a minimal effect on the partial thromboplastin time. Our results do not show any risk of clot formation in the usual clinical setting in which there is inadvertent mixing of blood with iohexol, ioxaglate, or diatrizoate in an angiographic syringe.     

Comparison of the side-effects of low-osmolar contrast media in intravenous urography

The subjective side-effects of almost equivalent intravenous iodine doses of the three new low-osmolar contrast media, ioxaglate (Hexabrix), iopamidol (Niopam) and iohexol (Omnipaque) have been recorded and are found to be generally comparable. Urticaria occurred more frequently with ioxaglate than with the other contrast media and there was a tendency for ioxaglate to cause more nausea. Pain at the injection site occurred less often with ioxaglate than with iohexol. If low-osmolar contrast media are to be used in intravenous urography the relative cost of each is important, there being as yet insufficient data concerning the relative incidences of major reactions.     

Ioversol for intravenous urography: A comparison study

A new nonionic, low-osmolar iodinated contrast media, ioversol, was compared with another low-osmolar, nonionic contrast media, iohexol, in 80 patients undergoing intravenous urography. There were 40 patients in each contrast group. Patients were assessed for changes in vital signs, patient tolerance (heat and pain), and other adverse effects. Double-blind evaluation was also performed for comparison of the urogram image quality. There were no severe, life-threatening reactions for either contrast group. Ten patients (25%) receiving ioversol and seven (17.5%) receiving iohexol perceived body heat related to the injection of contrast material. Two patients (5%) in each group experienced mild nausea. Two patients (5%) of each group experienced noted unpleasant taste, and two patients (5%) of the iohexol group complained of headache. Vital signs remained stable without significant change in both groups, and image quality was considered equivalent. The results indicate that the two contrast agents are equivalent in image quality, safety, and incidence of adverse effects.     

A comparison of iohexol and diatrizoate-meglumine in children undergoing cardiac catheterization

Iohexol (Omnipaque) and meglumine and sodium diatrizoate (Renografin-76) were compared in a double-blind, randomized study for their efficacy, safety, and hemodynamic effects as angiographic contrast agents in children. Forty-four children were randomly allocated to receive either iohexol or diatrizoate as a component of their routine or emergency cardiovascular evaluation. Following age stratification, baseline physiologic parameters were not significantly different between patients receiving either iohexol or diatrizoate. After systemic ventricular injection, iohexol produced significantly less hemodynamic alteration in systemic systolic blood pressure, systemic ventricular end-diastolic pressure, and dP/dt. Less alteration in heart rate and significantly less effect on the QT interval were seen with iohexol. Image quality was comparable, although significantly more patient mobility was associated with diatrizoate-meglumine. This study shows that iohexol, a nonionic contrast medium, causes less hemodynamic disturbance than diatrizoate-meglumine in children. Therefore, its use to be preferred in these potentially high-risk patients.     

Effect of an iso-osmolar contrast medium on pulmonary arterial pressure at pulmonary angiography

A clinical comparison of the effects on pulmonary arterial pressure induced by contrast media with various osmolalities, iohexol 140 mg I/ml (300 mosm/kg H2O), iohexol 300 mg I/ml (690 mosm/kg H2O), and diatrizoate 292 mg I/ml (1480 mosm/kg H2O) following selective pulmonary angiography was made in 12 patients with normal pulmonary arterial pressure. A double-blind crossover study was performed and the contrast media were administered in random order. The pulmonary arterial pressure was recorded continuously before, during, and for 3 min after the injection. The effect of iohexol 140 on the pulmonary arterial pressure was significantly less marked than that of diatrizoate 292, whereas no statistical significance was shown between iohexol 140 and iohexol 300. These results indicate that iso-osmolar contrast medium (iohexol 140), as well as iohexol 300, would be better tolerated than diatrizoate 292, and is therefore a safer contrast medium for selective pulmonary angiography.     

Effect of iohexol and diatrizoate on pulmonary arterial pressure following pulmonary angiography. A clinical comparison in man

A clinical comparison of the effects on pulmonary arterial pressure produced by iohexol and diatrizoate, following selective pulmonary angiography, was made in 17 patients with a normal pressure before the injection of the contrast medium. A double blind crossover study was performed and each contrast medium was administered in random order. The pulmonary arterial pressure was continuously recorded before, during and after the injection for 3 minutes. The effect of iohexol on the pulmonary arterial pressure was significantly less than that of diatrizoate. The results indicated that iohexol should be better tolerated than diatrizoate and therefore a safer contrast medium for selective pulmonary angiography.     

Iohexol compared with metrizoate in urography

Urography was performed in 20 patients using the new non-ionic contrast medium iohexol (Omnipaque) and in 22 patients using the conventional ionic medium metrizoate (Isopaque) in a randomized, double blind comparison. Iohexol caused significantly less subjective reactions and less tachycardia than metrizoate. No significant difference between the contrast media was observed regarding the influence on blood pressure, hematologic parameters, or clinical chemical parameters in blood and urine. Urographic films of similar and high quality were obtained with both contrast media.     

Neuroangiography with iohexol

Iohexol is a new, nonionic water-soluble contrast agent undergoing early clinical trials in the United States. Using a double-blind, parallel format, iohexol was compared with meglumine iothalamate (60 patients) for selective cerebral angiography, and with sodium meglumine diatrizoate (40 patients) for arch aortography. Iohexol produced significantly less pain than meglumine iothalamate or sodium meglumine diatrizoate. There were no significant differences in terms of heart rate, blood pressure, or electrocardiogram (ECG) changes. Both produced a transient tachycardia and hypotension after arch aortography, but significantly less so with iohexol. No significant complications occurred. Film quality was comparable between contrast agents except for diminished motion artifacts with iohexol. Iohexol appears to be a superior neuroangiographic contrast agent to current ionic drugs.     

Contrast media and pain in patients with acute ureteral stone obstruction. A comparative study with iohexol and metrizoate

A randomized study was conducted in 43 patients who were in pain due to acute ureteral obstruction. Emergency urography was performed in all patients, using either a low osmolar non-ionic (iohexol) or a high osmolar ionic (metrizoate) contrast medium. Increase of pain following injection of contrast media was found in 56 percent of all patients. Increase of pain occurred with both contrast media without any difference between the degree of pain nor the number of patients who experienced an increase of pain. Delayed excretion was considered the only reliable indicator of the degree of obstruction in the present study. Nineteen (68%) of the 28 patients with a delayed excretion greater than 10 min experienced increased pain while the incidence of pain increase was significantly lower (33%) in patients without that sign of ureteral obstruction (p less than 0.05). The increase of pain was not associated with a simultaneous increase of the mean arterial blood pressure.     

Effect on thrombus growth and thrombolysis of two types of osmolar contrast media in rabbits

Thromboembolic complications have been reported after diagnostic or interventional radiological procedures. However, contrast media inhibit platelet function and blood coagulation in vitro. To investigate these characteristics in vivo, we determined the effect of nonionic and ionic low osmolar contrast media on thrombus growth and thrombolysis in rabbits in a randomized study design. Rabbits received either ionic low osmolar contrast medium (ioxaglate), nonionic low osmolar contrast medium (iohexol) or saline. Thrombus growth was determined by the accretion of 125I-labeled fibrinogen on to autologous, nonradioactive, preformed thrombi in rabbit jugular veins. Thrombolysis was assessed by measurement of the decrease in radioactivity of standard sized preformed 125I-fibrinogen labeled thrombi. Ioxaglate significantly inhibited thrombus growth (60% inhibition, P less than 0.005 vs. saline), in contrast to iohexol, which had no significant effect (33% inhibition, P less than 0.2 vs. saline). Neither ioxaglate nor iohexol affected thrombolysis.     

Iohexol does not influence the levels of blood serum cation electrolytes during intravenous pyelography

PURPOSE: The influence of the nonionic contrast agent iohexol on blood pH and the cation electrolytes Ca, Na, K and Mg was studied in vivo in humans during the intravenous pyelography. MATERIAL AND METHODS: A population of 28 patients without renal function impairment or electrolyte imbalance was divided into two equal groups. The first group received an intravenous injection of 0.6 mL Omnipaque per kg of body weight (0.388g iohexol/kg and 0.18 g iodine/kg). The second group received a double dose of Omnipaque (1.2 mL iohexol/kg; 0.776g iohexol/kg and 0.36g iodine/kg). Blood samples (5 mL) were taken before the injection of the contrast medium and 5, 10 and 20 minutes (marking the end of the examination) after the injection. Blood pH was also determined immediately after each sample collection, while electrolytes were measured in the laboratory. Systolic and diastolic blood pressure were also determined simultaneously with each sample collection using a mercury manometer. RESULTS: Iohexol in simple and double doses did not have any statistically significant effect either on blood pH or on blood serum electrolytes during intravenous pyelography. Blood pressure, both systolic and diastolic, remained stable in all the patients during the examination. CONCLUSIONS: Our results show that the nonionic contrast medium iohexol at the doses used in routine intravenous pyelography does not have any influence on blood pH and serum cardioactive cation electrolytes in humans. An electrolyte imbalance is always a risk factor that may contribute to the development of cardiovascular side effects. This factor is eliminated when iohexol is administered intravenously instead of an ionic agent.     

A comparison between iohexol and metrizamide, two nonionic contrast media, in aorto-femoral angiography

Iohexol, a recently developed non-ionic contrast medium, is shown to be well tolerated on aorto-femoral angiography. The aortic injection of 40 ml of iohexol (350 mg I/ml) was usually associated with a moderate sensation of heat and an absence of pain. A transient fall in blood pressure, no different from that resulting from metrizamide, was associated with some increase in heart rate.     

Comparative study between iohexol and iopromide for aortofemoral arteriography

A double-blind clinical trial was performed on 50 patients in order to compare omnipague (iohexol) and Ultravist-300 (iopromide) for peripheral arteriography. Both contrast media were well tolerated, but there was less body heat and pain in the Ultravist group. There were no idiosyncratic reactions or significant changes in blood pressure before and after the injection.     

Comparison of the image quality of intravenous urograms using low-osmolar contrast media

Almost equivalent, intravenous iodine doses of the three new low-osmolar contrast media, ioxaglate (Hexabrix), iopamidol (Niopam) and iohexol (Omnipaque) have been compared for image quality on the intravenous urogram. Generally good radiographic images were obtained. Iohexol gave better results for the nephrogram and pelvicalyceal distension compared with the other contrast media, but only the nephrogram results were statistically significant. Pyelographic density and ureteric distension and density were similar with all three contrast media. In patients where low-osmolality contrast media need to be used for intravenous urography, we suggest that iohexol gives the best radiographic images. Other factors, such as cost and the relative incidence of side-effects of the low-osmolar contrast media also need to be taken into consideration.     

Iohexol compared to Urografin Meglumine in cerebral angiography

Summary In a double blin cross-over study the non ionic, water soluble contrast medium iohexol has been compared to Urografin Meglumine by angiography in common carotid artery and vertebral artery. More subjective adverse effects were generally seen with Urografin than with iohexol and statistically there were significantly less changes in heart rate after iohexol but no significant changes in the intra-arterial recorded blood pressure.     

In vivo comparative antithrombotic effects of ioxaglate and iohexol and interaction with the platelet antiaggregant clopidogrel

RATIONALE AND OBJECTIVES: Experiments were designed to (1) compare the effects of iodinated contrast media (CM) on a rat model of arterial thrombosis, (2) evaluate which element of the ioxaglate solution supports its antithrombotic activity, and (3) investigate the interaction of ionic and non-ionic CM with the antiplatelet agent clopidogrel. MATERIALS AND METHODS: Carotid thrombosis was induced in rats by extravascular application of a filter paper soaked in FeCl3 (35% vol/wt), proximal to an ultrasonic flow probe. (1) The antithrombotic potential of low-osmolar ionic (ioxaglate Na/meglumine) or nonionic contrast media (iohexol and iodixanol) (all 1600 mg iodine/kg, IV) was assessed by measuring the time to occlusion (TTO) of the carotid artery and the thrombus weight (TW). (2) Isotonic saline and iso-osmolar (280 mOsm/kg) and hyperosmolar (560 mOsm/kg) solutions of meglumine hydrochloride, meglumine ioxaglate (560 mOsm/kg), sodium ioxaglate (600 mOsm/kg) and sodium and meglumine ioxaglate (commercial solution) were tested under similar conditions. (3) Interaction with clopidogrel was tested by injecting lower dose of CM (960 mg iodine/kg) 2 hours after clopidogrel (2 mg/kg per os). RESULTS: (1) Ioxaglate prolonged TTO when compared with saline (30.0 +/- 1.1 minute vs. 19.6 +/- 2.4 minutes, P< 0.001), whereas iohexol had no effect (21.3 +/- 1.3 minutes). Ioxaglate's effect was associated with a reduction in TW with ioxaglate versus saline (2.6 +/- 0.4 mg and 4.7 +/- 0.7 mg, respectively, P< 0.05) whereas TW remained unchanged in the iohexol group (4.2 +/- 0.4 mg). The nonionic dimer iodixanol induced a direct vasoconstrictor effect on the carotid artery and was consequently excluded from the study. (2) Neither iso-osmolar nor hyperosmolar solutions of meglumine had any effect on TTO whereas both sodium and meglumine salts of ioxaglic acid prolonged TTO, suggesting that the antithrombotic effect of ioxaglate is mediated by the ioxaglic acid moiety alone as neither meglumine, osmolality or sodium played a significant role. (3) A synergistic effect on TTO was found when ioxaglate was associated with clopidogrel whereas no such effect was observed with iohexol. CONCLUSIONS: These data show a greater in vivo antithrombotic potential for the ionic contrast medium ioxaglate than for the non-ionic contrast medium iohexol and, for the first time, a synergistic effect between a contrast medium and a platelet antiaggregant drug in vivo.     

Addition of sodium to the nonionic contrast medium iohexol during coronary angiography in man. Lack of electrocardiographic or hemodynamic effects.

It has recently been claimed that lack of sodium in nonionic contrast media may increase the risk of ventricular arrhythmias during coronary angiography. Thus, the influence of sodium addition to the nonionic contrast medium iohexol was studied in 75 patients with severe coronary heart disease. The study design was randomized, parallel and double-blind, and iohexol was given either with or without addition of NaCl (28 mmol/l). Both formulations induced a transient drop in arterial blood pressure, and prolongation of the QT interval and QRS duration at 10 s only (p less than 0.01). The electrical QRS axis was significantly changed by the coronary artery injections after 10 s, but not later. No differences between iohexol with and without NaCl were observed for any of the variables studied. No serious arrhythmias were observed. Thus, the addition of NaCl (28 mmol/l) to iohexol did not influence the electrocardiographic or hemodynamic changes induced by iohexol during coronary angiography.