(FDA approved in bold)

• Complex partial seizures (monotherapy and adjunctive)
  
• Simple and complex absence seizures (monotherapy and adjunctive)
  
• Adjunctive therapy for multiple seizure types, including absence seizures
  
• Migraine prophylaxis
  
• Acute mania in bipolar disorder
  
• Cluster headache
  
• Generalized tonic-clonic seizures, including juvenile myoclonic epilepsy
  
• Infantile spasms (West syndrome)
  
• Lennox-Gastaut syndrome
  
• Status epilepticus
  
• Post-hypoxic myoclonus
  
• Landau-Kleffner syndrome (acquired epileptic aphasia)
  
• Spinal muscular atrophy
  
• Acute migraine or status migrainosus
  
• Bipolar depression
  
• Schizophrenia/psychosis

Unknown but there are multiple mechanisms of action

• Activates glutamic acid decarboxylase to increase gamma-aminobutyric acid (GABA) production
  
• Inhibits GABA transaminase and the catabolism of GABA
  
• Sodium channel antagonist
  
• T-type calcium currents in thalamus
  
• May suppress NMDA excitatory neurotransmission

• Seizures – 2 weeks
  
• Migraines – effective within a few weeks but can take up to 3 months to see full effect
  
• Mania – usually effective in days

• Seizures – goal is the remission of seizures. Continue as long as effective and well-tolerated. Consider slowly tapering and stopping after 2 years seizure-free, depending on the type of epilepsy
  
• Migraine – goal is a 50% or greater reduction in migraine frequency or severity. Consider tapering or stopping if headaches remit for more than 6 months or if patient considering pregnancy

• Increase to highest tolerated dose. Check a drug level if compliance an issue
  
• Epilepsy: consider changing to another agent, adding a second agent or referral for epilepsy surgery evaluation. When adding a second agent keep in mind the drug interactions
  
• Migraine: address other issues, such as medication-overuse, other coexisting medical disorders, such as anxiety, and consider changing to or adding a second agent

• Epilepsy: drug interactions complicate multi-drug therapy, especially the older AEDs. Most of the newer drugs, such as gabapentin, topiramate, oxcarbazepine, and zonisamide, are easier to use with DPX
  
• Migraine: consider beta-blockers, antidepressants, natural products, other antiepileptics, and non-medication treatments, such as biofeedback, to improve headache control

• Obtain liver function testing and platelet counts before starting, optional to monitor regularly for the first few months and once or twice a year after that. Test urgently if any symptoms of liver disease or new bleeding or easy bruising
  
• Monitor for weight gain and signs of metabolic syndrome (weight gain, hyperlipidemia, elevated fasting glucose)
  
• Hyperammonemia may occur, even with normal liver function tests. Often asymptomatic. Check a level for any clinically significant symptoms