DIET-INDUCED AND VALPROATE-INDUCED TRANSIENT HYPERAMMONEMIA - EFFECT OF L-CARNITINE

Hyperammonemia is an adverse effect of valproate (VPA) treatment, In p articular, transient hyperammonemia has been reported to occur in VPA- treated patients after protein-rich meals, This phenomenon may occur s econdary to a VPA-mediated carnitine insufficiency, We sought to confi rm that protein ingestion would result in transient hyperammonemia and to determine whether supplementation with L-carnitine mould prevent t his effect, We studied the effect of consumption of a standardized pro tein-rich meal (45 g protein) before (phase I) and after (phase II) ad ministration of L-carnitine 50 mg/kg/day for 7 days in 11 epileptic ch ildren (13.3 +/- 2.3 years of age) receiving VPA, Venous blood was obt ained during fasting (baseline) and at 2 and 4 hours after the protein -rich meal for analysis of ammonia (NH3), and VPA concentrations, Mean VPA trough concentrations did not differ significantly at any time, A fter protein ingestion, 2-hour NH3, concentration increased by 86% (P <.05) from baseline in phase I as compared with a 38% increase in phas e II, In both phases I and II, 4-hour NH3 concentrations decreased tow ard baseline values, We conclude that (1) modest protein ingestion can result in significant transient increases in NH3 in VPA-treated child ren, (2) significant increases may occur in patients with normal fasti ng NH3 concentrations, (3) these increases can be significantly attenu ated by L-carnitine supplementation, and (4) these changes do not appe ar to be related to changes in VPA concentration. (C) 1997 by Elsevier Science Inc. All rights reserved.