Acute and chronic toxicity of antiepileptic medications: a selective review

Acute and chronic toxicity complicates all antiepileptic medications (AED) and is idiosyncratic. Acute toxicity can be categorized into 1) acute brain dysfunction or 2) acute organ dysfunction when AED's are started. Despite promising in vitro lymphocyte testing, anticipation of acute reactions cannot be offered. Furthermore, screening for AED toxicity by routine blood and urine tests in asymptomatic patients is of doubtful value and should be abandoned. Patients should be informed of possible reactions and immediately report early symptoms. Treatment for acute reactions is largely unstudied. It is unclear how to reintroduce AED's following acute reactions. Often patients are sensitive to drugs with a similar chemical structure. The "desensitization" protocol of Purvis may be of merit. Three major chronic toxicities of AED's have been noted--soft tissue and gum hypertrophy, progressive ataxia, and peripheral neuropathy. New AED's require careful post-marketing surveillance since long term toxicity data are not yet available.