PRAX-562 (PRAX562) is a novel persistent sodium current (INa) inhibitor, inhibits hNaV1.6 persistent INa induced by ATX-II or SCN8A mutation N1768D with IC50 of 141 and 75 nM, respectively.
PRAX-562 displays similar potency for inhibition of persistent INa expressed by other human NaV isoforms (hNaV1.1, hNaV1.2, hNaV1.5) as well as rat, dog, and mouse orthologs (rNaV1.2, dNaV1.2, mNaV1.6, rNaV1.6), with IC50 values ranging 109-180 nM.
PRAX-562 exhibits tonic block with lower potency (IC50=8470 nM), demonstrating 60-fold preference for persistent INa, also exhibits preference for persistent INa over peak INa tonic block for hNaV1.1 (173-fold).
PRAX-562 reduces intrinsic excitability of hippocampal CA1 pyramidal neurons without compromising action potential (AP) amplitude.
PRAX-562 (3 mg/kg, po) produces dose-dependent protection (increase in latency) of mice against MES-induced tonic hindlimb seizures (EC50=90.1 ng/ml), with complete protection at 10 mg/kg.