Excitative effects in anaesthetized rabbits from subarachnoidally injected iso- and hyperosmolar solutions of iohexol and metrizamide.

Equimolar doses of iohexol and metrizamide (0.48 mmol/kg body weight = 185 mg I/kg), administered in solutions iso- and hyperosmolar to the CSF, were injected subarachnoidally into rabbits under pentobarbital anaesthesia. No excitative effects of iohexol were observed in the behaviour of the rabbits during a 3-h period immediately after the injection. Metrizamide caused significant, severe excitative effects, ranging from hyperexcitability to repeated generalized seizures. The frequency and severity of excitative effects were independent of the osmolality of the metrizamide solutions injected.