The effects of clonidine, an adrenergic a2 agonist hypotensive agent, and methoxital, a short-acting barbiturate anesthetic, on epileptiform discharges detected by presurgical magnetoencephalography (MEG) were investigated in 14 patients with medically intractable focal epilepsies treated at the University of Erlangen-Nuernberg, Germany. Oral premedication with clonidine increased focal epileptiform discharges in 9 and induced complex partial seizures in 2 patients. Methoxital increased total number of epileptic MEG discharges and the number of spikes contributing to MEG source localizations in 8 patients. Both drugs have proconvulsant effects and may be used as activating agents for localization of epileptogenic foci in EEG, electrocorticography, and MEG. [1]

COMMENT. Clonidine is a second line treatment for children with ADHD, and is especially indicated in those with tics or sleep disorders secondary to methylphenidate. The most frequent side-effect is drowsiness, and an epileptogenic effect in patients has not previously been reported.

Laboratory studies in animals with experimental seizures have demonstrated both anticonvulsant and convulsant effects with clonidine, dependent on the dose. Low doses are anticonvulsant while higher doses decrease seizure thresholds. In children receiving clonidine for ADHD, the lowest effective dose should be employed. In those with a history of seizures and/or epileptiform EEG, clonidine should be introduced with caution and in conjunction with an antiepileptic medication.