The Excretion of Iodipamide

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Abstract
Iodipamide, the one intravenous cholangiographic agent in present use, is certainly of great value, although room for improvement in visualization of the bile ducts still exists. Too often the ducts are so faintly visualized as not to permit optimal study or no opaque material is seen at all. Poor or unrecognized liver function can be blamed for some failures, but better cholangiography might be sought in a knowledge of the normal pharmacology of iodipamide and attempts to enhance the biliary excretion of this agent. Precise information on the excretion of iodinated substances into the bile is meager, and there has been relatively little interest in modifying biliary excretion of contrast agents. Measurements of iodipamide in blood, bile, and urine in the dog over a range of intravenous doses is the subject of this paper. Iodipamide was originally introduced as the disodium salt of N, Nadipyl-bis (3-amino-2, 4, 6 triiodobenzoic acid), supplied as a 20 per cent solution. More recently the methylglucamine salt has been introduced as a 52 per cent solution. The usual recommended dose of 20 ml affords 5.2 g of iodine. The trade name for the agent in Europe is Biligrafin, in America Cholografin. Plan of Experiment Determinations of iodipamide excretion at different dose levels in the same animal were considered superior to single acute experiments in multiple subjects. In this way, the animal was his own control, and variations in individual animals were minimized. The advantages of repeated studies in essentially healthy animals without evidence of biliary tract obstruction or infection and in good nutritional and electrolytic balance are obvious. The indwelling T-tube is known to be safe from the standpoint of infection and does not produce biliary obstruction or loss of bile, and therefore nutritional status is maintained. The bile collection when the long limb of the T-tube is open probably approximates the total flow quantitatively (20), and the collected bile has the same composition as that which passes into the duodenum. Prior cholecystectomy of the animals excludes the gallbladder mucosa from influencing bile composition. Other factors, such as exercise, digestion, and absorption of foods and fluid, known to influence bile flow were eliminated or kept constant. Studies were not begun until the dogs had convalesced for at least seven days. During this time the T-tube was clamped and protected by an abdominal bandage. Penicillin was given the first few postoperative days. The dogs were healthy and maintained their weights. Individual experiments were conducted in dogs fasted overnight, but allowed water. The animal was placed in a canvas sling, thus standardizing the position and activity of the animal. The T-tube was opened on the morning of the experiment, and bile was allowed to flow freely for a time.