Carbamazepine-induced hyperammonemia

Abstract

A 26-year-old man with bipolar disorder developed hyperammonemia three weeks after initiating carbamazepine therapy.

Transient hyperammonaemia in a patient with confusion: challenges with the differential diagnosis

“…This is a rare but recognised side effect of carbamazepine with, to our knowledge, only four cases had been reported in the english literature. The mechanism by which carbamazepine causes hyperammonaemia is still unclear 7. In our patient, the only new medications she had started in the preceding 6 months were carbamazepine and lamotrigine for her new-onset epilepsy.…”

“…It is possible that the lamotrigine was responsible for the raised serum ammonia. However, although valproate is a recognised cause of hyperammonaemia,7 there are no reported cases of lamotrigine-induced hyperammonaemia in the literature. We recommend that if a raised serum ammonia is found in a patient with new-onset confusion, the drug history should be carefully examined to exclude iatrogenic hyperammonaemia.…”

Hyperammonemia in review: pathophysiology, diagnosis, and treatment

“…The mechanism by which hyperammonemia develops is unknown, and treatment for the latter is simply to discontinue the anticonvulsant [50][51][52].…”

Hyperammonemic encephalopathy after adjunction of phenobarbital to chronic topiramate and oxcarbazepine therapy

“…However, the exact relationship between symptoms and ammonia levels remains unclear. Among AEDs, hyperammonemia is well documented during VPA therapy, and has been occasionally found after monotherapy with phenytoin, carbamazepine, primidone, but not with PB [1]. Drugs inhibiting carbonic anhydrase, like acetazolamide or TPM, would also increase the blood ammonia level through the induction of metabolic acidosis [2].…”