Pathophysiology: Increased GABA therefore CNS depression and in higher doses leads to mitochondrial toxicity by depleting L-carnitine. 

Clinical:

• CNS depression - sedation, coma, ataxia, tremor; can lead to cerebral edema which is what can kill these patients.
• Cardiac - can lead to cardiac arrest
• GI - nausea and vomiting.
• Levels can peak at 18 hours so this is not your usual observe for 6-8 hour ingestion; can also have delayed presentation from ER preps or bezoar formation.

Labs:

• Hypernatremia - secondary to the sodium load in "sodium valproate"
• Hypoglycemia, hypocalcemia
• Transaminitis and Hyperammonemia which can worsen the encephalopathy. 
• Metabolic acidosis

Evaluation:

• EKG and continous monitoring given overdose
• Labs:
• CBC, Chem7, VBG, Lactate 
• Valproic Acid Level
• LFTs and NH4
• Acetaminophen and Salicylates
• Imaging: consider CTH for the undifferentiated altered mental status and/or to monitor for cerebral edema. 

Management:

• Symptomatic and supportive care is the mainstay. 
• Toxicology or Poison Center Consult 
• May recommend GI decontamination such as Activated Charcoal (beware of airway protection) or Whole Bowel Irrigation
• L-carnitine - mixed data 
• Naloxone - case reports that helps improve mentation transiently. 
• Hemodialysis - usually at level > 800; nephrology consult. 
• Carbapenems - ask your toxicologist about using Carbapenem as it can increase hepatic metabolism and increase distribution of Valproate in erythrocytes.