Valproate-induced stimulation of renal ammonia production and excretion in the rat.

Administration of valproate, a widely used antiepileptic drug, markedly stimulated the production of ammonia by the rat kidney, resulting in an increase in both the renal venous release and the urinary excretion of ammonia. These effects were associated with a diminution of the plasma concentration of urea which was not accompanied by a stimulation of the urinary excretion of urea. These results indicate that the kidneys, together with the liver, might contribute to the hyperammonaemia caused by valproate.