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Hyperammonemic encephalopathy induced by a combination of valproate and pivmecillinam

C-M Lokrantz1, B Eriksson, I Rosén

  • 1Department of Emergency Medicine, Lund University Hospital, Lund, Sweden.

Acta Neurologica Scandinavica
|March 16, 2004
PubMed

Insights

Valproate (VPA) and pivmecillinam can cause rare hyperammonemic encephalopathy in adults. Combining these medications requires caution due to potential serious neurological side effects.

Area of Science:

  • Neurology
  • Clinical Pharmacology

Background:

  • Valproate (VPA) is an antiepileptic drug used for partial epilepsy.
  • Hyperammonemic encephalopathy is a serious neurological condition characterized by elevated ammonia levels in the blood.

Observation:

  • A 72-year-old woman on VPA monotherapy developed stupor after receiving pivmecillinam for a urinary tract infection.
  • Elevated serum ammonia levels (113 mmol/l) and abnormal EEG findings (bilateral triphasic waves, continuous delta-theta activity) were noted.
  • Liver function tests were normal.

Findings:

  • The patient recovered rapidly after VPA discontinuation and cefuroxime treatment.
  • This case highlights a rare instance of VPA-induced hyperammonemic encephalopathy, particularly with monotherapy.
  • The concurrent use of pivmecillinam, known to decrease carnitine levels, may have contributed to the VPA-induced hyperammonemia.

Implications:

  • Caution is advised when prescribing VPA concurrently with pivmecillinam due to the risk of hyperammonemic encephalopathy.
  • Reduced serum carnitine concentration is a potential mechanism for VPA-induced hyperammonemic encephalopathy.
  • This interaction underscores the importance of monitoring ammonia levels in patients receiving this drug combination.

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