Summary Purpose sec-Butyl-propylacetamide (SPD) is a one-carbon homologue of valnoctamide (VCD), a CNS-active amide derivative of valproic acid (VPA) currently in phase II clinical trials. The current study evaluated the anticonvulsant activity of SPD in a battery of rodent seizure and epilepsy models and assessed its efficacy in rat and guinea pig models of status epilepticus (SE) and neuroprotection in an organotypic hippocampal slice model of excitotoxic cell death. Methods SPD’s anticonvulsant activity was evaluated in several rodent seizure and epilepsy models including: maximal electroshock (MES), 6Hz psychomotor, subcutaneous (s.c.) metrazol-, s.c., picrotoxin, s.c. bicuculline, audiogenic and corneal and hippocampal kindled seizures following intraperitoneal administration. Results obtained with SPD are discussed in relationship to those obtained with VPA and VCD. SPD was also evaluated for its ability to block benzodiazepine-resistant SE induced by pilocarpine (rats) and soman (rats and guinea pigs) following intraperitoneal administration. SPD was tested for its ability to block excitotoxic cell death induced by the glutamate agonists N-methyl-D-Aspartate (NMDA) and kainic acid (KA) using organotypic hippocampal slices and SE-induced hippocampal cell death using FluoroJade B staining. The cognitive function of SPD-treated rats that were protected against pilocarpine-induced convulsive SE was examined 10-14 days post SE using the Morris water maze (MWM). The relationship between the pharmacokinetic profile of SPD and its efficacy against soman-induced SE was evaluated in two parallel studies following SPD (60 mg/kg, i.p.) administration in the soman SE rat model. Key Findings SPD was highly effective and displayed a wide protective index (PI=TD50/ED50) in the standardized seizure and epilepsy models employed. SPD’s wide PI values demonstrate that it is effective at doses well below those that produce behavioral impairment. Unlike VCD, SPD also displayed anticonvulsant activity in the rat pilocarpine model of SE. Thirty minutes after the induction of SE, the calculated rat-ED50 for SPD against convulsive SE in this model was 84mg/kg. SPD was not neuroprotective in the organotypic hippocampal slice preparation; however, it did display hippocampal neuroprotection in both SE models and cognitive sparing in the MWM which was associated with its antiseizure effect against pilocarpine-induced SE. When administered 20 and 40min after SE onset, SPD (100-174mg/kg) produced long-lasting efficacy (e.g., 4-8hr) against soman-induced convulsive and electrographic SE in both rats and guinea pigs. SPD-ED50 values in guinea pigs were 67mg/kg and 92mg/kg at when administered at SE onset or 40min after SE onset, respectively. Assuming linear PK, the PK-PD results (rats) suggests that effective SPD plasma levels ranged between 8-40mg/L (20 min post onset of soman-induced seizures) and 12-50mg/L (40 min post onset of soman-induced seizures). The time to peak (tmax) pharmacodynamic effect (PD-tmax) occurred after the PK...

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Spreading depolarizations are implicated in a diverse set of neurologic diseases. They are unusual forms of nervous system activity in that they propagate very slowly and approximately concentrically, apparently not respecting the anatomic, synaptic, functional, or vascular architecture of the brain. However, there is evidence that spreading depolarizations are not truly concentric, isotropic, or homogeneous, either in space or in time. Here we present evidence from KCl-induced spreading depolarizations, in mouse and rat, in vivo and in vitro, showing the great variability that these depolarizations can exhibit. This variability can help inform the mechanistic understanding of spreading depolarizations, and it has implications for their phenomenology in neurologic disease.

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