<prompt> Most serious side effect of valproate isFulminant hepatitsSpina bifidaWeight gainThrombocytopenia  <response>: Ans. is a i.e., Fulminant hepatits Valproate Valproate acts by multiple mechanism : Prolongation of inactivated Na channel. Inhibition of T type Ca current. Inhibition of degradation of GABA by GABA transminase - facilitation of GABA mediated Cl- channel opening. Its most serious adverse effect is fulminant hepatitis especially in children below 3 years. Used during pregnancy, it has produced spina bifida and other neural tube defects. Uses other than epilepsy -- mania bipolar illness, prophylaxis of migraine, trigeminal neuralgia, tardive dyskinesia. Adverse effect of Valproate Neurological - Ataxia, sedation,tremor Systemic- Hepatotoxicity, thromobocytopenia,GI irritation, weight gain, transient alopecia, hyperammonemia, pancreatitis,coagulation disorder. 