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Valproic acid induced hyperammonaemic encephalopathy.
Saima Amanat1, Naila Shahbaz, Yasmin Hassan
1Department of Neurology, Dow University of Health Sciences and Civil Hospital, Karachi. dr.saimakashif@gmail.com
JPMA. the Journal of the Pakistan Medical Association
|July 20, 2013
Summary
Valproic acid can cause hyperammonaemia leading to encephalopathy, even at therapeutic doses. Monitoring is crucial for patients on valproic acid experiencing neurological symptoms.
Area of Science:
- Neurology
- Clinical Pharmacology
Background:
- Valproic acid is a widely used antiepileptic drug.
- Hyperammonaemic encephalopathy is a potential adverse effect of valproic acid therapy.
Purpose of the Study:
- To investigate the clinical and laboratory features of valproic acid-induced hyperammonaemic encephalopathy.
- To identify the incidence and characteristics of this adverse event in patients treated with valproic acid.
Main Methods:
- An observational study involving ten patients presenting with encephalopathic symptoms while on valproic acid therapy.
- Comprehensive laboratory investigations including serum ammonia, serum valproic acid levels, liver function tests, and neuroimaging were performed.
- Exclusion of other causes of encephalopathy was confirmed through clinical and laboratory assessments.
Main Results:
- All ten patients exhibited hyperammonaemia concurrent with encephalopathic symptoms.
- Elevated serum ammonia levels were observed independently of valproic acid dosage or serum concentration.
- Eighty percent of patients had normal liver function tests; 60% improved with L-Carnitine, 30% with valproic acid withdrawal.
Conclusions:
- Valproic acid can induce symptomatic hyperammonaemia and encephalopathy, even within therapeutic ranges.
- Continuous monitoring for hyperammonaemia is essential in all patients taking valproic acid who develop encephalopathic symptoms.
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