Acute Mental Status Changes and Hyperchloremic Metabolic Acidosis with Long‐Term Topiramate Therapy

Abstract

Mental status changes and metabolic acidosis may occur with topiramate therapy. These adverse events were reported during dosage titration and with high dosages of the drug. A 20-year-old man receiving topiramate, valproic acid, and phenytoin experienced acute-onset mental status changes with hyperchloremic metabolic acidosis. He had been receiving a modest dose of topiramate 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. This case illustrates the need for close evaluation of patients who experience acute-onset mental status changes during topiramate therapy.

Effect of Long-term Topiramate Therapy on Serum Bicarbonate and Potassium Levels in Adult Epileptic Patients

“…This includes anorexia or paresthesia, whereas the chronic condition is associated with increased risk for kidney stones, osteomalacia, or osteoporosis. [1][2][3][4]8 Occurrence of lower bicarbonate levels in patients taking TPM has been described in several case reports [10][11][12][13] and some clinical studies. 6,[15][16][17] However, no significant correlation was observed previously between the length of TPM therapy and bicarbonate or potassium levels.…”

“…1,3,4,8,9 Several case reports have indicated that TPM can cause metabolic acidosis in patients. [10][11][12][13][14] Also, a number of clinical trials have shown that TPM decreases serum bicarbonate levels. 6,[15][16][17] Metabolic acidosis was previously observed in 48% of patients treated with TPM in a retrospective cohort study.…”

Blockage of a fluid administration set

“…The most common side-effects are not dose related and usually involve the central nervous system [2]. Metabolic acidosis has been reported after topiramate overdose, in children and during longterm therapy [3]. The early metabolic adverse effect of topiramate in our case suggests that the acidosis may be an idiosyncratic reaction or related to the rapid increment in dose.…”

Predisposition to metabolic acidosis induced by topiramate

“…), this is a well documented adverse event induced by TPM [2][3][4][5] . Metabolic acidosis is probably due to the carbonic anhydrase inhibitory effect of TPM, which increases the bicarbonate lost in the urine, and consequently, decreases CO 2 serum levels 2 .…”