Objective: The present study aimed to determine if adjunctive use of verapamil, as a P-glycoprotein (P-gp) inhibitor, is efficacious in decreasing seizure frequency in patients with refractory temporal lobe epilepsy.
Materials and methods: This was an open-label pilot study. Adult patients with refractory temporal lobe epilepsy were studied. Baseline seizure type and seizure count were determined. Patients were divided randomly into two groups. Group A received verapamil 120 mg/day (n=13), and group B received 240 mg/day (n=6). All patients were followed for eight weeks. The proportion of responders, which consist of patients with more than 50% reduction in seizure frequency from baseline, was tabulated.
Results: Nineteen patients were studied. Seven patients (36.84%) reached the responder rate. Three patients (50%) in group B were among the responders; two of these patients achieved seizure freedom. Four patients (30.7%) in group A responded favorably to verapamil.
Conclusion: Developing new means of improving the effectiveness of existing antiepileptic drugs is a desirable way of tackling the dilemma of medically refractory epilepsy. Hypothetically, P-gp inhibitors (e.g., verapamil) might be used to counteract the removal of AEDs from the epileptogenic tissue. Such a strategy was adopted in this non-placebo-controlled, open-label, pilot study. We observed a significant achievement in seizure control associated with adjunctive use of verapamil in patients with refractory temporal lobe epilepsy.
Keywords: P-gp inhibitor; Seizure reduction; Temporal lobe epilepsy; Verapamil.