Neurotolerability of Nonionic X-Ray Contrast Media

Abstract

RATIONALE AND OBJECTIVES Because small quantities of x-ray contrast agents can cross the blood-brain barrier, the authors evaluate the properties that contribute to neurotoxicity. METHODS The acute toxicity of various monomer and dimer contrast media was assessed after intracerebroventricular (ICV) injection to mice and intracisternal (ICI) injection to rats. RESULTS In mice, median lethal dose (LD₅₀) values for monomer contrast media apart from iohexol were higher than those for dimer contrast media. In rats, iopentol and iopromide were more neurotoxic than all other contrast media. The signs of toxicity for all contrast media included convulsions, dyspnea, hypoactivity, and sedation. Hypertonic D-mannitol solution was tolerated as well as artificial cerebrospinal fluid. Neither the hydrophilicity of the molecules nor the physicochemical properties of their solutions explain the toxicities satisfactorily. CONCLUSIONS Neurotoxicity of monomer or dimer contrast media depends more on chemical structure characteristics other than hydrophilicity than on the physicochemical characteristics of their solutions.