Grainger R G
Br J Radiol. 1980 Aug;53(632):739-46. doi: 10.1259/0007-1285-53-632-739.
All current intravascular radiological contrast media are salts and produce solutions of very high osmolality--five to eight times that or tissue cells, plasma or tissue fluid (all of which have an osmolality of 300 mosmols per kg water). Erythrocytes and vascular endothelium are adversely affected by the high osmolality of intravascular contrast media, resulting in tissue anoxia and increased capillary permeability, the latter causing damage to the blood-brain barrier. Vasodilatation, systemic hypotension and osmotic hypervolaemia are generalized manifestations of the high osmolality of contrast media. New low osmolality contrast media have been synthesized, utilizing a non-ionizing radical (such as amide or amine) instead of the carboxyl group of a tri-iodinated substituted benzoic acid. Such examples are metrizamide (Amipaque) and Iopamidol (both non-ionic amides) and Hexabrix (salts of a mono-acid dimer). Early clinical evaluation suggests that these low osmolality solutions have major advantages in reducing pain, heat sensation and adverse reactions of angiography.
目前所有的血管内放射造影剂都是盐类，会产生高渗溶液，其渗透压是组织细胞、血浆或组织液（渗透压均为每千克水300毫渗摩尔）的五到八倍。血管内造影剂的高渗性会对红细胞和血管内皮产生不利影响，导致组织缺氧和毛细血管通透性增加，后者会破坏血脑屏障。血管扩张、全身性低血压和渗透性高血容量是造影剂高渗性的普遍表现。新型低渗造影剂已被合成，它们使用非离子基团（如酰胺或胺）取代了三碘代取代苯甲酸的羧基。例如甲泛葡胺（阿米培克）、碘帕醇（均为非离子酰胺）和六异泛影葡胺（单酸二聚体的盐类）。早期临床评估表明，这些低渗溶液在减轻血管造影的疼痛、热感和不良反应方面具有主要优势。
