Improved Control of Epilepsy by Monitoring Plasma Ethosuximide

Plasma ethosuximide level was monitored in 70 patients with absence (petit mal) seizures. Levels were linearly related to administered dose. Of 37 ambulatory patients with uncontrolled attacks, 38% (14) had levels below the 95% tolerance limit in contrast to 9% (5) of the controlled group. This difference, due to noncompliance with therapy, was eliminated by regular monitoring. Appropriate adjustment of plasma ethosuximide levels resulted in a reduction of seizures in 48% (18) of previously uncontrolled patients. Practical control of epilepsy increased from 64% (45) to 81% (57). Monitoring of plasma ethosuximide increases the effectiveness of therapy by the recognition of noncompliance and the individualization of drug requirements.