We examined the effects of
laudanosine, one of the principal metabolites of
atracurium, on the electroencephalogram (EEG) in an animal model of induced
epilepsy. Fourteen rabbits were anaesthetized with 4%
halothane in
oxygen, the trachea intubated and the lungs ventilated mechanically with 30%
oxygen and 1%
halothane in
nitrogen. Animals were assigned randomly to receive either an infusion of
laudanosine (
laudanosine group, n = 7) at a rate calculated to produce plasma concentrations similar to those found following the clinical use of
atracurium, or an equal volume of
normal saline (control group, n = 7). To induce an epileptogenic focus,
gelfoam sponges soaked in a pH-adjusted 4%
cefazolin solution were applied bilaterally to the parietal cortical surface. This resulted in the production of spike and burst EEG activity in all animals. However, scoring the frequency of the spikes and bursts revealed no significant differences between the
laudanosine and control groups. We conclude that, in this animal model of
epilepsy, no increased incidence of seizure activity was produced by mean plasma
laudanosine concentrations as great as 0.8 micrograms ml-1. These results suggest that the routine use of
atracurium is unlikely to provoke
seizures, even in the presence of an epileptogenic focus.