Efficacy of verapamil as an adjunctive treatment in children with drug-resistant epilepsy. A pilot study

Purpose: Verapamil, a voltage-gated calcium channel blocker, has been occasionally reported to have some effect on reducing seizure frequency in drug-resistant epilepsy or status epilepticus. We aimed to investigate the efficacy of verapamil as add-on treatment in children with drug-resistant epilepsy. Methods: Seven children with drug-resistant structural-metabolic, unknown or genetic (e.g., Dravet syndrome [DS]) epilepsy received verapamil as an add-on drug to baseline antiepileptic therapy. Verapamil was slowly introduced at the dosage of 1 mg/kg/day and titrated up to 1.5 mg/kg/day. After completing the titration period, patients entered a 14-month maintenance period and were followed up at 3, 8, and 14 months. Heart monitoring was performed at baseline and at each follow-up. The primary outcome measure was the response of seizures to verapamil. Results: Three subjects with genetically determined DS showed a partial (reduction of 50-99%) response for all types of seizures. A patient with DS without known mutation showed a partial control of all types of seizures in the first 13 months; then seizures worsened and verapamil was suspended. Two patients with structural epilepsy and one with Lennox-Gastaut syndrome showed no improvement. Any side effects were recorded. Conclusions: Add-on treatment with verapamil seems to have some effect in controlling seizures in patients with genetically determined DS. Our observations justify further research on the relationship between calcium channels, calcium channel blockers, and channelopathies.