Feasibility of reversing benzodiazepine tolerance with flumazenil.

To examine whether the benzodiazepine antagonist flumazenil can reverse tolerance to benzodiazepines but without precipitating withdrawal seizures, the antiepileptic effect of flumazenil itself and its ability to reverse tolerance at a dose that would leave sufficient receptors free for the binding of benzodiazepines were investigated. Electroencephalographic studies in 6 patients with partial and 6 with generalised seizures showed that flumazenil had a short (20 min) non-dose-dependent suppressant effect on epileptic discharges in those with partial seizures. Receptor occupancy studies in 12 patients showed that 1.5 mg flumazenil given intravenously occupied 55% receptors, whereas 15 mg occupied nearly all receptors. When 3 patients with partial seizures who had become tolerant to clonazepam were given 1.5 mg flumazenil, they were seizure-free for 6-21 days after the injection. The value of intermittent therapy with a benzodiazepine antagonist for preventing or reversing tolerance to benzodiazepine agonists ought to be investigated further.