Anticonvulsive effect of dapsone (4,4′-diaminodiphenyl sulfone) on amygdala-kindled seizures in rats and cats

Dapsone (4,4′-diaminodiphenyl sulfone; DDS), an established anti-leprosy drug, showed anticonvulsive effects in the amygdaloid kindling model of epilepsy. Single doses of the drug in rats (6.25–12.5 mg/kg i.p.) suppressed the kindled seizures in a dose-dependent manner without overt behavioral toxicity. With repeated oral administration in cats, relatively higher initial doses (13–23 mg/kg) were required to obtain seizure suppression, and neurotoxic signs occurred within a few days with serum drug levels of approximately 20 μg/ml. Although dapsone showed anticonvulsive effects in both animal species, the effective serum levels overlapped the toxic levels reported in the clinical treatment of leprosy. In the majority of the cats, however, seizure suppression was maintained even after the discontinuation of dapsone with lower serum levels than those observed at the beginning of the seizure suppression. Therefore, dapsone would be useful as an antiepileptic drug only when long-term anticonvulsive efficacy is demonstrated using smaller doses comparable to those used in the treatment of leprosy.