Effects of iomeprol,a new nonionic contrast medium,vis a vis iopamidol and nitroglycerin,on coronary diameter and blood flow in chronically instrumented dogs

The effects of an intracoronary administration of iomeprol, a new nonionic tri-iodinated water-soluble contrast medium, on coronary circulation were compared to those of iopamidol and those of nitroglycerin in 6 chronically instrumented conscious dogs. A pair of 10 MHz piezoelectric crystals and an electromagnetic flow probe were placed on the left circumflex coronary artery (LCCA) to measure the epicardial coronary diameter (CD) and coronary blood flow (CBF). Polyethylene tubing for drug administration was inserted into the LCCA proximal to the sonomicrometers. Iomeprol at the dose of 1 ml and 3 ml/min for 1 min significantly increased CD by 0.6±0.1% and 1.4±0.3%, respectively and CBF by 44.5±9% and 70±10%, respectively. Iopamidol at the same rates also significantly increased CD by 0.8±0.1% and 1.5±0.3% and CBF by 50±11% and 82±14%, respectively. There was no statistically significant difference between iomeprol-and iopamidol-induced increases in CD and CBF. However, the duration of the increase in CD was significantly shorter (p<0.05) after iomeprol than after iopamidol. Nitroglycerin (10 μg/kg) significantly increased CD by 4.5±1% and CBF by 105±10%. The increases in CD and CBF in response to iopamidol and iomeprol were significantly smaller (p<0.01) than to nitroglycerin. We conclude that vasodilating effects of iomeprol and iopamidol on the large epicardial coronary artery and coronary blood flow are comparable in conscious dogs and significantly lower than after nitroglycerin in the doses used by us. This study was supported by a grant from the EI-ZA1 Pharmaceutical Co., Tokyo, Japan.     

A prospective randomised controlled trial to determine the early and late reactions after the use of iopamidol 340 (Niopam) and iomeprol 350 (Iomeron) in cardiac catheterisation

A new generation of intravascular contrast agents, the non-ionic monomers have safety profiles that are superior to those of older ionic compounds. There are, however, significant differences between these agents. AIM: The aim of this study was to determine the incidence of early (<24h) and late (>24h to 7 days) reactions to two non-ionic contrast agents currently used during cardiac catheterisation: iopamidol 340 (Niopam Bracco UK Ltd.) and iomeprol 350 (Iomeron Bracco UK Ltd.). METHODS: This was a prospective, randomised, double blinded trial. One thousand nine hundred and eighty-five patients undergoing cardiac catheterisation received one of the following contrast agents on a weekly basis: iopamidol 340 (Niopam) and iomeprol 350 (Iomeron). Reactions that were possibly related to the contrast agents were recorded on predefined data collection forms during the first 24h of the procedure (early reaction) and after 24h to 7 days (late reaction) by means of a questionnaire. RESULTS: The baseline characteristics were matched in both the groups. There was no significant difference in the incidence of heat sensation experienced between the two groups (p=0.1). Early non-heat reactions occurred in 2.7% of patients receiving iopamidol 340 (Niopam) and 4% of those receiving iomeprol 350 (Iomeron) (p=0.1). Significant electrocardiographic changes were recorded in 1.7% of patients who received iopamidol 340 (Niopam), and 1% of those who received iomeprol 350 (Iomeron) (p=0.2). Bradycardia occurred more frequently in the iopamidol 350 group (0.8%) compared to the iomeprol 350 group (0.1%) p=0.02. Late reactions occurred in 16.2% of those receiving iopamidol 340 (Niopam) and 21.7% of those receiving iomeprol 350 (Iomeron) (p=0.02). A total of 23 (3.7%) patients in the iopamidol group and 39 (6.2%) patients in the iomeprol group reported nausea, p=0.01. CONCLUSIONS: The incidence of early adverse reactions was similar with the two non-ionic contrast agents. Although bradycardia was slightly more frequent using iopamidol 340, nausea was reported more commonly 24h after the procedure in patients receiving Iomeron 350 (Iomeron). We conclude that there were only minor clinical differences between these agents; both are safe and well tolerated.     

cAMP and cGMP do not mediate the vasorelaxation induced by iodinated radiographic contrast media in isolated swine renal arteries

Purpose: Vasodilatation is a frequent side effect of radiographic contrast media, partially due to a direct effect on vascular smooth muscles. Our purpose was therefore to examine any possible implication of the cyclic adenosine monophospate (cAMP) and cyclic guanosine monophosphate (cGMP) pathways in contrast media induced vasorelaxation.Material and Methods: Isolated segments of swine renal arteries were precontracted with 10 μM phenylephrine and relaxed with iomeprol before and after blockade of the cAMP and cGMP pathways.Results: 80 mM and 160 mM of iomeprol significantly relaxed about 52% and 68% of the precontracted arterial rings, respectively. 10 μm of IBMX, a phosphodiesterase inhibitor, did not increase the relaxant effect of 80 mM iomeprol but increased the relaxations induced by 400 nM forskolin by about 1.9 times (which stimulates the production of cAMP), and by 1 μm sodium nitroprusside (which stimulates the production of cGMP). 1 μm of H89 (an inhibitor of the cAMP-dependent protein kinase), was able to reduce the relaxation induced by 4 μM forskolin by about 2.5 times but had no significant effect on the relaxation induced by 160 mM iomeprol. 10 μM of ODQ (an inhibitor of the soluble guanylate cyclase), could reduce the relaxation induced by 10 μM of SNP but not the one induced by 160 mM iomeprol. Moreover, the absence of endothelial cells did not alter the relaxation induced by iomeprol.Conclusion: The activation of the cAMP and cGMP pathways are not involved in the in vitro relaxation induced by iomeprol in swine renal arteries.     

Does iodine concentration affect the diagnostic efficacy of biphasic spiral CT in patients with hepatocellular carcinoma?

Background We investigated the effect of iodinated contrast medium concentration on increased neoplastic lesion enhancement and its direct relation to diagnostic efficacy in biphasic spiral computed tomography for detection of hepatocellular carcinoma.Methods A pilot, single-center, randomized, double-blind, crossover, comparative study was performed and included 22 participants. Each patient underwent two separate biphasic contrast-enhanced spiral computed tomographic examinations. Scans were performed with iomeprol containing 400 (iomeprol 400) or 300 (iomeprol 300) mg of iodine per milliliter (Iomeron, Bracco Imaging SpA, Milan, Italy) with a 2- to 12-day window scan; patients were given an equal total dose of 45 g of iodine at a fixed injection rate of 4 mL/s. Comparison included assessment of quantitative and qualitative parameters.Results Lesion density and lesion-to-liver contrast increased more markedly with the higher concentration of contrast medium during the arterial phase (p = 0.0016 and 0.0005, respectively). There was no significant difference in any parameter between the two concentrations during the portal phase. Number of lesions detected during the arterial phase increased from 37 with iomeprol 300 to 42 with iomeprol 400; in the portal phase, the respective numbers were 34 and 36.Conclusion Even though a small number of patients was examined, our study suggests that, in patients with cirrhosis, an increased concentration of iodine improves liver-to-lesion contrast and may improve the detection of hepatocellular carcinoma.     

Effects of low osmolar contrast (iomeprol) on haemorheology and platelet activation in patients with coronary artery disease

Background Non-ionic low osmolar contrast agents are widely used during coronary angiography. As these agents cause activation of thrombotic pathways in vitro, this may have potentially significant clinical impact. However, limited evidence exists as to their in vivo effects from selective coronary cannulation. Methods We initially performed an in vitro experiment to assess the effect of serial contrast (Iomeprol 300, Bracco) dilution on platelet indices [mean platelet count (MPC), platelet volume (MPV), platelet granularity (MPG)]. The in vivo effect of contrast injection on platelet activation markers [soluble P-selectin (sPsel), soluble CD40 ligand (sCD40L)], MPC, MPV, MPG, haemoglobin and haematocrit was subsequently determined in 35 patients (mean age 58 ± 11; 22 males) undergoing cardiac catheterisaton. Results No significant in vitro effect of contrast on MPC or MPV was seen but there was a significant increase in MPG (p = 0.40, 0.10 and 0.01, respectively). In the in vivo study, there was a reduction in mean haemoglobin and haematocrit levels, suggesting an average increase in plasma volume of 6.5 ± 5.8%. The in vivo effect of Iomeprol was associated with an unadjusted reduction in sPsel concentrations (p = 0.04) and MPV (p < 0.05), with denser platelets (p < 0.05). There was no difference in MPC or sCD40L concentration (both p = NS). After adjustment for the haemodilution effect, no significant reduction in P-sel levels was seen with contrast (p = 0.27), although the adjusted post-contrast change in MPG (p = 0.01), MPC (p = 0.01) and sCD40L (p < 0.05) levels were significant. Conclusion Low osmolar contrast led to a minimal effect on soluble and physical indices of platelets within the coronary artery, primarily due to plasma volume expansion.