Phenobarbital improves survival in theophylline-intoxicated rabbits

As in humans, theophylline intoxication in rabbits causes seizures and death. We studied whether the administration of phenobarbital or phenytoin following a toxic dose of theophylline would improve survival in rabbits. New Zealand white rabbits were infused intravenously with theophylline, 115 mg/kg over 50 minutes. Upon completion of the infusion, rabbits were randomized to receive either saline (control) (N = 60) or saline containing phenobarbital 20 mg/kg (N = 60), or phenytoin 12 mg/kg (N = 30), infused over 30 minutes. The number (and percentage) of rabbits surviving 24 hours in each group was: control 12 (20%), phenobarbital 30 (50%), and phenytoin 7 (23%) [X2; p less than 0.005; two-tailed]. In all fatal cases, death was preceded by a seizure; rabbits that survived did not seize. These results show that phenobarbital administered intravenously to theophylline-intoxicated rabbits prevented seizures and improved survival whereas phenytoin administration had no significant effect.