Osmotic effect and solubility of amipaque (metrizamide) in the gastrointestinal tract

Loops of small intestine in seven rabbits were resected with intact pedicle and ligated at both ends after instillation of 0.5 ml of Gastrografin, Urografin 76%, Amipaque 370 mg I/ml, Amipaque 170 mg I/ml or physiologic saline. After half an hour, the amount of fluid in the loops containing Gastrografin and Urografin 76% increases about twice as much as in the loops containing Amipague with the same iodine concentration because of their greater osmolality. The differences between the loops with isotonic Amipaque (170 mg I/ml) and physiologic saline are not significant. Precipitation occurs when sodium and meglumine salts of diatrizoate, metrizoate, iothalamate, iocarmate and ioglycamate are mixed with 0.05 N HCl. No precipitation occurs with Amipaque, not even when the HCl concentration is as high as 1.2 N. Precipitation occurs when Gastrografin is added to gastric juices with low pH, but is not seen with Amipaque should be a suitable contrast medium for gastrointestinal examinations because of its low osmolality and toxicity and good solubility in gastric juice.