Clinical Evaluation of Vascoray (Sodium Iothalamate 26%/Methylglucamine Iothalamate 52%)—a New Contrast Medium

Abstract

A clinical comparison and use of a new salt mixture of iothalamate—Vascoray (sodium iothalamate 26%/methylglucamine iothalamate 52%)—with Conray (methylglucamine iothalamate 60%), Conray-400 (sodium iothalamate, 66.8%), Hypaque-M 75% (sodium diatrizoate 25%/methylglucamine diatrizoate 50%) and Angio-Conray (sodium iothalamate 80%) has been carried out. The sodium solutions were found to produce more major and minor side effects, to have the lowest viscosity, and be more irritating to the myocardium, cerebral circulation, and spinal cord. The methylglucamine solutions had fewer side effects, but a greater viscosity for a similar iodine content.

A combination of the sodium and methylglucamine salts of iothalamate and diatrizoate produced fewer side effects in the procedures compared, Table III. The iothalamate compound produced fewer side effects than the diatrizoate compound, Table III.

Vascoray is a sterile solution of 400 mg of organically bound iodine per ml (40% iodine). Each ml contains 260 mg of sodium and 520 mg of methylglu camine as mixed salts of iothalamic acid and not more than 0.15 mg sodium biphosphate as a buffer. This compound was formulated because of the increas ing need for an agent with fewer major and minor side effects for aortography and angiocardiography. It has a viscosity of 14.0 centipoises at 25°C, and 9.0 centipoises at 37.5°C.

The intravenous LD ₅₀ (mice) for methylglucamine iothalamate 60% is 17,000 mg/kg; sodium iothalamate 66.8% is 19,000 mg/kg; sodium iothalamate 26%/ methylglucamine iothalamate 52% is 18,000 mg/kg; and sodium iothalamate 80% is 21,000 mg/kg, Table I. Hayes2 has reported that all standardized toxic ity studies comparing iothalamate preparations and diatrizoate preparations proved the iothalamate preparations to be less toxic than the diatrizoate prepa rations as regards neurotoxicity, nephrotoxicity and cardiopulmonary toxicity. Gensini3 has suggested that the methylglucamine salt may be safer than the sodium salt in the coronary arteries, myocardium and spinal cord tissues. So dium salts are more toxic to the spinal cord, coronary arteries and myocardium than the methylglucamine salts. Methylglucamine salts are generally accepted as less toxic than sodium salts; however, they have a higher viscosity than sodium solutions. The combination of the two salts reduced the side effects while maintaining adequate flow rates, since the sodium solution has a lower viscosity and faster flow rate. This new agent combines the low toxicity-high viscosity of methylglucamine iothalamate with somewhat higher toxicity-lower viscosity of sodium iothalamate.