metrizamide and iopromide

The authors investigated the effect on the brain of red blood cells that had been modified by contrast media. Rat blood was mixed with an equivolume of contrast media, and up to 200 microL of the mixture was infused to the internal carotid artery of the rat. Evans blue was administered intravenously to assess the integrity of the blood-brain barrier (BBB). Immediately after the death of the animal, or 2.5 hours after the infusion, the brain was removed for evaluation of the degree of BBB destruction and edema. Extensive destruction of the BBB, cerebral edema, and death of the animals were induced by infusion of blood mixed with an ionic contrast medium, such as diatrizoate and iothalamate, which deformed red blood cells. Microscopic observation showed atrophy and necrosis of nerve cells and decomposition of nerve fibers in the affected area of the brain. Cerebral damage was not observed in rats injected with blood mixed with a nonionic contrast medium such as iopamidol, iopromide, or metrizamide, which had less effect on red blood cells. Cerebral damage also was observed in the rats injected with blood mixed with a hyperosmotic solution of mannitol, as well as washed red blood cells mixed with an ionic contrast medium. This study's results indicate that hyperosmotic ionic contrast media affect red blood cells and cause disturbance in cerebral circulation.

Topics: Animals; Blood-Brain Barrier; Brain Edema; Cerebral Angiography; Contrast Media; Diatrizoate Meglumine; Erythrocyte Deformability; Iohexol; Iopamidol; Iothalamate Meglumine; Male; Metrizamide; Osmolar Concentration; Rats; Rats, Inbred Strains

The non-ionic X-ray contrast media metrizamide, iopamidol, iohexol, and iopromide do not bind calcium and are less hyperosmolar than the conventional ionic contrast media, for instance amidotrizoate (diatrizoate), iothalamate, or ioglicate. Hence the use of non-ionic contrast media is associated with less undesirable side-effects that are attributable to hypertonicity such as an increase in circulating plasma volume, decreased deformability of red blood cells, damage of vascular endothelium with consequent activation of blood coagulation, the complement system and fibrinolysis, increased release of bradykinin and histamine, cardiac arrhythmias, diuresis, vasodilation and decreased blood pressure, pain and heat sensation. Because of less dilution the quality of imaging is also better. According to the intravenous LD50 in experimental animals the acute toxicity of non-ionic contrast media is lower than that of ionic media. With respect to contrast quality and the rate of side-effects the various non-ionic contrast media appear to be equivalent. Despite their higher price and higher viscosity it is probable that the non-ionic contrast media will replace the classical ionic media, especially in angio- and myelography.

Topics: Animals; Calcium; Contrast Media; Epilepsy; Humans; Iohexol; Iopamidol; Iothalamic Acid; Membrane Potentials; Metabolic Clearance Rate; Metrizamide; Neurons; Structure-Activity Relationship; Triiodobenzoic Acids; Viscosity

Topics: Animals; Complement Activation; Contrast Media; Erythrocytes; Female; Histamine Release; Humans; Iodobenzoates; Iohexol; Iopamidol; Iothalamic Acid; Male; Metrizamide; Mice; Muramidase; Rats; Triiodobenzoic Acids