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Pulmonary angiography with iopamidol and Renografin 76 in normal and pulmonary hypertensive dogs.

The cardiovascular response produced during pulmonary angiography performed with the standard ionic agent diatrizoate (Renografin 76) and a new non-ionic agent iopamidol was compared. Nine dogs were evaluated while ventilated on room air and on 10% O2 which significantly elevated pulmonary arterial pressure. Iopamidol produced similar changes in mean aortic and pulmonary arterial pressures compared with normal saline (less than 20% change). Renografin 76, however, produced a significantly greater elevation in mean pulmonary arterial pressure (a 41% increase) and depression in mean aortic pressure (a 40% reduction) than either saline or iopamidol (p less than 0.01). These results were similar for dogs being ventilated with room air and oxygen. The results indicate that iopamidol should be better tolerated and therefore a safer contrast agent for pulmonary angiography than diatrizoate.

Animals↗

Iopromide. A new non-ionic contrast medium.

The new non-ionic contrast agent, iopromide (Schering) is comparable in osmolality and viscosity to the other recently developed low osmolality media, ionic and non-ionic. Its chemotoxicity, as assessed by protein binding, enzyme inhibition and effects on the coagulation cascade is significantly less than that of the conventional media and very similar to that of another established new non-ionic agent, iopamidol (Niopam, Bracco/Merck).

Animals↗

Attenuation changes of the normal and ischemic canine kidney. Dynamic CT scanning after intravenous contrast medium bolus.

The potential of CT scanning to explore total and regional renal blood flow was evaluated in a dog model with unilateral renal artery stenosis (n = 7, reduction of renal blood flow: 32-75% of base line flow). Attenuation versus time curves were generated for the renal cortex and medulla, as well as for the aorta and renal vein. A fast CT scanner was used which allowed for up to 24 scans/minute at the same level (slice thickness: 10 mm). A total of 10 ml contrast medium was injected into a peripheral vein for each scan series taken. During baseline conditions, the curve of the renal cortex and medulla demonstrated 2 peaks. The first peak was mainly related to early vascular enhancement, whereas the second peak corresponded mainly to the appearance of contrast medium in the distal convolutes and collecting ducts. Ischemia of the kidney resulted in a reduction of the first peak and a flattening of the leading edge slope. Transport of contrast medium through the extravascular compartments of the kidney was delayed during ischemia. Relative renal blood flow was obtained from the CT data by dividing peak enhancement by rise-time as assessed from the cortical curve. All measurements were related to baseline flow and validated by flow measurements using radioactive labeled microspheres (n = 5). Correlation was found to be r = 0.97.

Animals↗

Contrast media osmolality and plasma volume changes.

A theoretical and experimental study of the plasma volume expansion consequent on the hyperosmolality of contrast media is presented. In the case of the ratio 1.5 media theory and experiment coincide closely but in the case of the ratio 3 media the observed changes exceed the predicted. It is proposed that this is due partly to the slower diffusion of the ratio 3 media out of the intravascular space and partly due to the fact that the osmotic load presented by these media is greater than would be expected from a study of their commercial solutions in which osmolality is reduced by molecular aggregation. The implications for the relative haemodynamic effects of different contrast media are discussed. The osmotic effects of contrast media also play a part in determining the image quality achievable in intravenous digital subtraction angiography (IV-DSA). It is predicted that ratio 3 contrast media will give better quality images in IV-DSA than ratio 1.5 media.

Contrast Media↗

Effect of contrast media on the formation of prostacyclin in isolated rat lungs.

The synthesis of prostacyclin (PGI2) was studied in isolated perfused rat lungs during the infusion of radiographic contrast media into the pulmonary circulation. At the same molar concentration, diatrizoate, iopamidol, and NaCl fairly equally stimulated the generation of PGI2. A bolus injection of histamine also enhanced the formation of PGI2. A high dose of ionic diatrizoate and hypertonic saline (0.4 mol/l) caused considerable pulmonary edema, which was less marked with non-ionic iopamidol. Experiments with 125I-labeled contrast media indicated rapid efflux of contrast media from the lungs. The present investigation indicates that different contrast media stimulate the synthesis of prostacyclin mainly because of chemical irritation of the pulmonary endothelium. The enhanced formation of endothelium-derived prostacyclin may mediate some systemic and local side effects seen temporarily during intravascular contrast medium examinations.

6-Ketoprostaglandin F1 alpha↗

Iohexol and iopamidol: second-generation nonionic radiographic contrast media.

Iohexol and iopamidol are new second-generation nonionic contrast media. We review their physical/chemical properties and describe the improvements made over the first-generation nonionic prototype, metrizamide, and conventional ionic contrast media. The significance of low osmolar solutions is discussed and the relationship between osmolality and adverse reactions is emphasized. The convenience of a ready-to-use stable solution that offers an advantage over the lyophilized metrizamide in practical application is suggested. Clinical studies using randomized, double-blind comparison techniques are cited. An attempt is made to define the exact role for iohexol and iopamidol.

Biopharmaceutics↗

Comparative neurotoxicity of angiographic contrast media.

The neurotoxic effects in cerebral angiography of three iodinated ionic contrast media, nonionic iopamidol, 25% mannitol, and saline controls were compared in 25 rabbits. Diatrizoate sodium meglumine was the most toxic agent, followed by diatrizoate and meglumine, iothalamate meglumine, and mannitol in terms of blood-brain barrier (BBB) disruption and coupled perfusion decline. HIPDm distribution was more sensitive than trypan blue extravasation for monitoring brain dysfunction. Iopamidol and saline controls exhibited no visual BBB breakdown or alteration in regional uptake of I-125 HIPDm, confirming the safety of nonionic iopamidol as compared with presently used ionic contrast media.

Animals↗

The unreliability of mammalian glomerular markers in teleostean renal studies.

1. The assumption that (3H) methoxy inulin, (14C) polyethylene glycol (PEG) and (125) iothalamate (glofil) are reliable volume and glomerular markers in teleosts was tested. 2. PEG occupied smaller volumes than inulin and glofil in sea-water-adapted Salmo gairdneri. Ureteral clearances of PEG were about 22% higher than those of inulin and glofil, and urine-to-plasma ratios were significantly greater for PEG than for the other two markers. 3. After introduction into the urinary bladder the three macro-molecules appeared in the plasma, PEG at the lowest rates. 4. These observations indicate that mammalian glomerular markers can penetrate the bladder and possibly the ureters and renal tubules. Therefore, their clearances may not give a true measure of glomerular filtration rates in teleosts.

Animals↗

[Suppressive effects of iodinated contrast media on human platelet aggregation].

Suppressive effects of several iodinated contrast media on stimulus-induced aggregation of human platelets were demonstrated. All contrast media, including ionic (iothalamate and ioxaglate) and non-ionic ones (iohexol, ioversol and iopamidol), suppressed the collagen- and thrombin-induced aggregation in a concentration-dependent manner. The effects of the former were much stronger than those of the latter. With ioxaglate, a similar inhibitory effect was also observed on PAF- and U46619-stimulated aggregation. The suppressive effect of ioxaglate on collagen-stimulated aggregation almost disappeared upon dilution of the medium with the platelet-poor plasma, suggesting that the effect is reversible.

Collagen↗