Aspartame and phenylalanine do not enhance theophylline-induced seizures in rats.

Oral administration of the artificial sweetener aspartame, 1 g/kg, or of an equimolar dose of its metabolite phenylalanine, to fasted rats 1 hour before slow i.v. infusion of theophylline until the onset of maximal seizures had no significant effect on the total dose and the serum and cerebrospinal fluid concentrations of theophylline at the pharmacologic endpoint. These findings indicate that consumption of aspartame is not a potential risk factor for theophylline-induced neurotoxicity.