Validation of the 6 Hz refractory seizure mouse model for intracerebroventricularly administered compounds

•Validation of 6Hz model for blood–brain barrier impermeable compounds.•Seizure evocation in NMRI mice at 49mA with ECT Unit 57800 Ugo Basile stimulator.•Seizure duration as novel, accurate parameter to express results in the 6Hz model.•Levetiracetam decreases seizure duration after i.p. and i.c.v. administration.•I.p. and i.c.v. administered sodium phenytoin does not alter seizure duration.