Neural tolerance of the non-ionic dimers iodixanol and iotrolan and the non-ionic monomer iopamidol during myelography in non-anaesthetised rabbits

PURPOSE: The neural tolerance of the recently introduced dimer iodixanol (320 g I/l) was compared with that of the dimer iotrolan (300 g I/l) and of the monomer iopamidol (300 g I/l), both used in clinical myelography.MATERIAL AND METHODS: Non-anaesthetised rabbits were injected into the cisterna magna with Ringer's solution (control) or contrast media (CM) at doses of 1.0 or 0.5 ml/kg b.w. The behaviour of the animals (10 in each of 7 groups) was evaluated for signs of excitation and depression during the first 3 hours after injection.RESULTS: At the dose level of 1.0 ml/kg b.w., iodixanol produced no seizures but did cause focal twitching in 4/10 rabbits. Iopamidol produced grand mal seizures in 2/10 and hyperexcitability in 4/10 rabbits. Iotrolan produced generalised grand mal seizures in 8/10 rabbits, an incidence of excitation significantly greater than that of iodixanol (p < 0.01) and iopamidol (p < 0.05). The excitative effects of iodixanol were not significantly different from those of iopamidol and Ringer's solution. All 3 CM produced similar depressive effects on rabbit behaviour. Ringer's solution caused no depressive effects (p < 0.01). A clear dose response was produced with all 3 CM after treatment with a lower dose of 0.5 ml/kg b.w.CONCLUSION: The results indicate that the neural tolerance in the rabbit of iodixanol is higher than that of iotrolan, and is at least equal to that of iopamidol