This Is A Question About A Neurological Drug ( Phenytoin)

This is a question about a neurological drug ( phenytoin) , and titrating down. If a patient is currently taking 800 Mg's phenytoin daily and when tested Chinese on at 31, is it safe to change the daily dose to 500 Mg's in order to get down to just under 20. Patient is , 275# s and currently takes 200 mg am, 200 mg noon and 400 mg evening. So, is it safe to drop the 300 mgs in the evening dose each night for a week then retest to get new level, out, will the large amount cause a seizure as a result of withdrawal?