The objective of this study was to evaluate the effect of seletracetam (SEL), a potent modulator of synaptic vesicle glycoprotein 2A (SV2A), in patients with photoparoxysmal EEG response (PPR) to intermittent photic stimulation (IPS) as proof-of-principle of efficacy in patients with epilepsy. In this multicenter, single-blind Phase II study, adults with photosensitive epilepsy, with/without concomitant antiseizure medication therapy, underwent IPS under 3 eye conditions (at eye closure, eyes closed and eyes open) after a single oral dose of placebo (day - 1) or SEL (day 1; 0.5, 1, 2, 4, 10, or 20 mg). Complete suppression was a standardized photosensitivity range reduction to 0 over ≥ 1 time points for all eye conditions. Partial suppression was a ≥ 3-point reduction over ≥ 3 testing times vs the same time points on day - 1 in ≥ 1 eye condition. In addition, pharmacokinetics and safety were assessed. Of 27 evaluable patients, 9 reentered to receive a 2nd dosing 1-6 months later, providing a total of 36 individual exposures. At all doses administered - even the lowest -, several subjects reached a complete abolishment of PPR, with a rapid onset of effect. Overall, complete abolishment of PPR was obtained in 40-71 % of the patients; the effect increasing with the dose. In terms of effective doses to suppress PPR, SEL was at least 1,500 times more potent than levetiracetam and 10-20 times more potent than brivaracetam. Adverse events of SEL, including dizziness and somnolence, were mild to moderate. Pharmacokinetics of SEL demonstrated rapid absorption and a linear dose:plasma level relationship. This proof-of-principle study demonstrates that - based on our own experience - SEL is the most potent compound ever tested in the photosensitivity model.
Keywords: Antiseizure medication; Pharmacodynamics; Pharmacokinetics; Photosensitivity model; Safety.
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