Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0023380 (lethargy)
 5,697 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

All individuals receiving valproic acid therapy in an institution for the mentally retarded were evaluated for hyperammonemia. Of these 19 adults, 6 had persistent and 5 others had intermittent hyperammonemia. The hyperammonemic patients were asymptomatic, except that 2 had occasional lethargy. Hyperammonemia was detected more often in younger adults and in those treated with multiple anticonvulsants, especially phenytoin. Valproate-induced hyperammonemia is probably the result of depletion of mitochondrial acetyl CoA and decreased production of N-acetylglutamate, the obligatory activator of the first enzyme of the urea cycle, carbamyl phosphate synthetase I. Anticonvulsant-mediated microsomal enzyme induction may also contribute.
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PMID:Valproic acid-induced hyperammonemia in mentally retarded adults. 642 25

A 24-year-old patient had symptoms of lethargy, convulsions and hyperammonaemia during valproic acid therapy. Cessation of valproic acid treatment brought about an improvement both of the symptoms and of the hyperammonaemia. However, enzymatic analysis after the cessation of valproic acid therapy revealed a complete absence of carbamoylphosphate synthetase (CPS) activity in liver biopsy. A unique polypeptide band, corresponding to the control CPS protein in molecular weight ('CPS-like' protein), was found in normal amounts in the patient's liver on sodium dodecyl sulphate-polyacrylamide gel electrophoresis. This CPS-like protein seemed to be more labile than the control, because the polypeptide band became faint after freeze-thawing. Intravenous administration of L-alanine resulted in a significant increase of serum urea and a transient increase of blood ammonia concentrations. These results strongly suggest that the patient has a labile CPS protein with no activity in vitro but some activity in vivo. We consider that valproic acid may have disrupted some metabolic adaptation by reducing N-acetylglutamate in the liver, which in combination with CPS deficiency induced severe hyperammonaemia.
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PMID:Carbamoylphosphate synthetase deficiency in an adult: deterioration due to administration of valproic acid. 848 2