topiramate and Hyponatremia

Central pontine myelinolysis (CPM) develops due to acute hypernatremia from a normal baseline serum sodium in the setting of electrolyte abnormalities induced by topiramate use. Topiramate is a commonly used medication with several indications including migraines, myoclonic jerks and seizures. It has been reported to cause renal tubular acidosis and severe electrolyte abnormalities, which in turn predispose patients to neuropathology via renal concentration defects and osmotic shifts. Our patient is a 55-year-old woman with a history of multiple sclerosis and myoclonus on topiramate for several years who presented with weakness and was found to be profoundly hypokalemic. She went on to develop changes in mental status, motor deficits and evidence of CPM on MRI during her hospitalisation. Surprisingly, the patient never had hyponatremia; however, she had an acute rise in serum sodium from a normal baseline after fluid resuscitation with normal saline for hypotension during her admission.

Topics: Electrolytes; Female; Humans; Hypernatremia; Hyponatremia; Magnetic Resonance Imaging; Middle Aged; Myelinolysis, Central Pontine; Topiramate

Topics: Acidosis; Adverse Drug Reaction Reporting Systems; Anticonvulsants; Carbamazepine; Communication; Cooperative Behavior; Drug Monitoring; Drug-Related Side Effects and Adverse Reactions; Fructose; Humans; Hyponatremia; Topiramate

Ongoing refinements in pharmacology continue to provide new medications for the treatment of seizure disorders and other neurologic conditions. The authors present the cases of two children who developed relatively uncommon adverse effects to new anticonvulsant medications, including metabolic acidosis with topiramate and hyponatremia with oxcarbazepine. In one of our two patients, intraoperative acidosis related to topiramate was noted. Appropriate investigation with documentation of normal serum lactate resulted in the exclusion of other potentially serious causes of acidosis and in the identification of topiramate as the causative agent. In our second patient, hyponatremia and status epilepticus resulted from therapy with oxcarbazepine. Prompt recognition of hyponatremia, fluid restriction, and cessation of oxcarbazepine therapy resulted in prompt correction of the hyponatremia. We review previous reports of these adverse effects with topiramate and oxcarbazepine, describe the pathophysiology of these metabolic alterations, provide treatment strategies, and make suggestions for monitoring patients during therapy with these anticonvulsant medications.

Topics: Acidosis; Anticonvulsants; Blood Gas Analysis; Carbamazepine; Child; Child, Preschool; Female; Fructose; Humans; Hyponatremia; Intraoperative Complications; Lactic Acid; Male; Topiramate