Which one of the following statements about phenytoin is accurate?

high frequency discharges are inhibited with little effect on normal low frequency discharges which allow Na+ channels to recover even when inactivation is prolonged. This effect has been noted at therapeutic concentration of phenytoin, while other effects like reduction in Ca2+ influx, inhibition of glutamate and facilitation of GABA responses have been demonstrated at higher I toxic concentrations. Intracellular accumulation of Na+ that occurs during repetitive firing is prevented. REF KD TRIPATHI 8TH ED.