Acute mental status changes and hyperchloremic metabolic acidosis with long-term topiramate therapy

Mental status changes and metabolic acidosis may occur with topiramate ther apy. These adverse events were reported during dosage titration and with hi gh dosages of the drug. A 20-year-old man receiving topiramate, valproic ac id, and phenytoin experienced acute-onset mental status changes with hyperc hloremic metabolic acidosis. He had been receiving a modest dose of topiram ate for 9 months. He was weaned off topiramate over 5 days, and his mental status returned to baseline within 48 hours of discontinuing the agent. Thi s case illustrates the need for close evaluation of patients who experience acute-onset mental status changes during topiramate therapy.