Prolonged vertical nystagmus after pentobarbital sodium administration

Of 17 healthy adults without nystagmus who ingested 100 mg of pentobarbital sodium, six had up-beating, gaze-evoked vertical nystagmus 12 hours later. Three of them had nystgmus 36 hours later, but none of them had it 60 hours later. Therefore, one should be reluctant to ascribe this type of nystagmus to a disease of the central nervous system in patients who received a barbiturate within several days of examination.