Acute changes of blood ammonia may predict short-term adverse effects of valproic acid.
Valproic acid (VPA) was given to 24 epileptic patients who were already being treated with other antiepileptic drugs. A standardized loading dose of VPA was administered, and venous blood was sampled at 0, 1, 2, 3, and 4 hours. Ammonia (NH3) was higher in patients who, during continuous therapy, complained of drowsiness (7 patients) than in those who were symptom-free (17 patients), although VPA plasma levels were similar in both groups. By measuring VPA-induced changes of blood NH3 content, it may be possible to identify patients at higher risk of obtundation when VPA is given chronically.
D000293:Adolescent; D000328:Adult; D000641:Ammonia / Q000097:blood*; D002648:Child; D003244:Consciousness Disorders / Q000097:blood / Q000139:chemically induced; D004827:Epilepsy / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014635:Valproic Acid / Q000009:adverse effects* / Q000627:therapeutic use
D014635:Valproic Acid; D000641:Ammonia