Antidepressants and seizures: clinical anecdotes overshadow neuroscience

Pharmacological treatment of depression in persons with epilepsy has been an area of controversy because some drugs commonly are perceived specifically to induce or exacerbate seizures in patients with seizure disorders. This prevailing misconception is unjustified by scientific studies, yet it continues to prevent afflicted persons from receiving appropriate therapy. The scientific literature shows that tricyclic antidepressant drugs cause seizures in overdose in both animals and humans. In lower doses, these drugs have anticonvulsant activity in humans and animals. Thus, the antidepressant drugs are like several antiepileptic drugs that can both prevent and cause seizures. The anticonvulsant activity of antidepressant drugs has been studied extensively in animals and almost certainly stems from their capacity to block norepinephrine and/or serotonin reuptake. The pharmacodynamic action responsible for their convulsant effects has not been well studied but may be due to their local anesthetic, antihistaminic, or antimuscarinic activity. The newer, more selective monoamine uptake blockers have very low convulsant liability, and it is suggested that their anticonvulsant activity, which is well documented in animals, be investigated further in humans. If their effects in humans are analogous to those in animals, these drugs can be used safely in epileptic patients with depression, and it is possible that their anticonvulsant activity can be exploited for use in the treatment of epilepsy.