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• Classification of Antiseizure Drugs (ASDs)

  • Sodium Channel Blockers
  • Hydantoins
  • Tricyclic
  • Branched-Chain Fatty Acid
  • Phenyltriazine
  • Calcium Channel Blockers
  • GABA Analogs
  • SV2A Receptor Blocker
  • Gabaergic Drugs
  • Barbiturates
  • Benzodiazepines (BZDs)
  • GABA Transaminase Inhibitor
  • GAT-1 Inhibitor
  • Monosaccharide Derivatives
• Sodium Channel Blockers


  Block voltage-gated Na+ channels → inhibits generation of action potentials (high-frequency firing of neurons)
• Hydantoins


  • Phenytoin
  • Fosphenytoin
  • Mephenytoin
  • Ethotoin
• Phenytoin


  • Extensively bound to albumin (~90%), Dose-dependent elimination
  • Also alters K+, Ca2+, Glutamate, GABA
  • DOC for generalized tonic-clonic seizures and Partial seizures
  • Status epilepticus (less sedating)
  • Antiarrhythmic drug (GROUP 1B)
  • Early Diplopia, Nystagmus, and ataxia common dose dependent AE
  • Gingival hyperplasia, Hirsutism, Vitamin D metabolism abnormalities, Teratogen
  • Potent enzyme inducer
  • Fosphenytoin is a water-soluble prodrug of phenytoin
  • Non-sedating at therapeutic doses
  • Phenytoin has an affinity for thyroid binding globulin
• Tricyclic


  • Carbamazepine
  • Oxcarbazepine
  • Eslicarbazepine
• Carbamazepine


  • Auto-induction, highly protein bound (~75%)
  • Carbamazepine is metabolized to carbamazepine-10-11-epoxide (antiseizure effect)
  • Also affects voltage-gated K+ channels
  • DOC for trigeminal neuralgia
  • DOC for generalized tonic-clonic seizures and partial seizures
  • Manic phase (bipolar disorder)
  • Dose-dependent GIT abnormalities, dizziness, blurred vision, diplopia, ataxia
  • Steven-Johnson syndrome, Teratogen (Spina bifida, craniofacial abnormalities)
  • Hyponatremia (Oxcarbazepine)
  • Oxcarbazepine induces enzymes to a lesser extent (less drug interactions) and is not converted to an active epoxide metabolite
• Branched-Chain Fatty Acid


  • Valproic acid
  • Sodium valproate
• Valproic acid


  • Blocks NMDA receptors; Increases GABA levels
  • DOC for bipolar disorder (acute mania)
  • DOC for generalized tonic-clonic seizures and DOC for absence seizures
  • Partial seizures, myoclonic seizures
  • Prophylactic for migraine
  • GI upset, weight gain, hair loss
  • Drowsiness, Fine tremor
  • Idiosyncratic hepatotoxicity (< 2y.o) and thrombocytopenia, Teratogen (NTD – spina bifida)
  • NTD-Neural Tube Defect
  • Potent enzyme inhibitor
• Phenyltriazine


  • Lamotrigine
  • Zonisamide
• Lamotrigine, Zonisamide


  • DOC for Partial seizures
  • Generalized tonic-clonic seizure, myoclonic seizures, absence seizures, bipolar disorder
  • Dizziness, Ataxia, Nausea
  • Steven-Johnson syndrome
• Calcium Channel Blockers


  • Ethosuximide
  • Phensuximide
  • Methsuximide
• Ethosuximide, Phensuximide, Methsuximide


  • Blocks voltage-gated T-type Ca2+ channels in the thalamus
  • DOC for generalized absence seizure
  • GI upset (Nausea, Vomiting)
  • Lethargy, Headache
  • Behavioral changes (euphoria)
• GABA Analogs


  • Gabapentin
  • Pregabalin
• Gabapentin, Pregabalin


  • Blocks Ca2+ channels → Prevents glutamate release
  • DOC for Neuropathic pain (postherpetic neuralgia)
  • Partial seizures, Migraine
  • Dizziness, Sedation, Ataxia, Nystagmus, Tremor
• Levetiracetam


  • Selectively binds and inhibits synaptic vesicular protein SVA2 receptor → Stimulation of SVA2 receptor promotes synaptic vesicle exocytosis
  • Generalized tonic-clonic seizures, Partial seizures, Juvenile myoclonic epilepsy
  • Dizziness, Sedation, Ataxia, Weakness, Irritability, Hallucinations, Psychosis
• Gabaergic Drugs


  • Barbiturates
  • Benzodiazepines (BZDs)
• Barbiturates (Phenobarbital, Primidone)


  • Binds to GABAa receptor sites (distinct from BZD) → increases the duration of Cl- channel opening → hyperpolarization → ↓ neuronal firing
  • Generalized tonic-clonic seizures, Partial seizures, Status epilepticus, Insomnia
  • DOC for infants
  • Unwanted daytime sedation, Extension of CNS depressant action, Tolerance, Dependence
  • Potent enzyme inducer
  • Primidone is metabolized by oxidation to phenobarbital
• Benzodiazepines (Clonazepam, Lorazepam, Diazepam, Clorazepate)

  • Binds to GABAa receptor sites → increases the frequency of Cl- channel opening → hyperpolarization → ↓ neuronal firing
  • Absence seizure, Myoclonic seizure, Infantile spasms, Lennox-Gastaut syndrome (Clonazepam)
  • Status epilepticus (Lorazepam, Diazepam, Clorazepate)
  • Anterograde amnesia, Decrease psychomotor skills, Unwanted daytime sedation, Tolerance, Dependence
  • Potent enzyme inducer
• Vigabatrin


  • Irreversibly inhibits GABA-T → sustained increase in the extracellular concentration of GABA
  • Infantile spasms associated with tuberous sclerosis
• Tiagabine


  • Selectively binds and inhibits GAT-1 → prevents GABA termination via reuptake → ↑ GABA levels
  • Adjunct therapy for focal seizures
• Topiramate, Felbamate


  • Multiple actions on synaptic function
  • Na+ channels
  • GABAa receptor subtypes
  • AMPA or Kainate receptors
  • ASD with the greatest number of mechanisms of action
• Epileptic Seizure Classifications


  • Focal Onset Seizures
  • Generalized Onset Seizures
  • Simple Partial Seizures/ Focal Aware Seizures
  • Complex Partial Seizures/ Focal Impaired Awareness Seizures
  • Grand Mal/ Tonic-Clonic Seizure
  • Petit Mal/ Generalized Absence Seizure
• Psychotic disorders


  • Manic phase of bipolar disorder
• Anti-emetics


  Promethazine and Prochlorperazine
• Chlorpromazine


  Prototype of all antipsychotics
• Piperidine antipsychotics


  • Thioridazine
  • Fluphenazine
  • Perphenazine
  • Trifluoperazine
• Piperidine antipsychotics


  Schizophrenia and other psychotic disorders
• Piperidine antipsychotics


  • Corneal and lens deposit (Phenothiazine)
  • Cardiotoxicity - QT prolongation arrhythmia (Piperidine - Thioridazine)
  • Decrease seizure threshold (Piperidine)
• Butyrophenone antipsychotics


  • Haloperidol
  • Droperidol
• Butyrophenone antipsychotics


  • Schizophrenia and other psychotic disorders
  • Bipolar disorder (Manic Phase)
  • Tourette's Syndrome
  • Less sedating among typical antipsychotics
• Atypical antipsychotics


  Mechanism of action: Blocks 5-HT2 receptors >> D2 receptors
• Clozapine


  • Schizophrenia (drug of choice for refractory and suicidal schizophrenia)
  • Extrapyramidal symptoms (less)
  • Hyperprolactinemia (less)
  • Postural Hypotension
  • Weight gain
  • Hyperglycemia
  • Hyperlipidemia
  • Agranulocytosis
• Because of the risk of agranulocytosis, patients taking clozapine must have a weekly blood count for 6 weeks
• Clozapine and Olanzapine have the highest tendency to cause weight gain
• Quetiapine and Clozapine are amongst the atypicals that are least likely to cause tardive dyskinesia
• Olanzapine


  • Schizophrenia
  • Bipolar Disorder
  • Anorexia Nervosa
  • Depression
  • Safe in pregnancy
• Quetiapine


  • Schizophrenia
  • Bipolar Disorder
  • Sleep promotion and maintenance
  • Extrapyramidal symptoms (less)
  • Hyperprolactinemia (less)
  • Postural Hypotension (less)
  • Weight gain (less)
  • Hyperglycemia (less)
  • Hyperlipidemia (less)
  • Somnelence
  • Fatigue
  • Sleep paralysis
  • Hypnagogic hallucinations
  • Cataracts
  • Priapism
  • QT prolongation arrhythmia
• Risperidone


  • Schizophrenia
  • Bipolar Disorder
  • Tourette syndrome
  • Depression
  • Intractable Hiccups
  • Extrapyramidal symptoms
  • Highest propensity to cause hyperprolactinemia (Amenorrhea, Galactorrhea)
  • Postural Hypotension
  • Weight gain (less)
  • Hyperglycemia (less)
  • Hyperlipidemia (less)
• Risperidone is the only antipsychotic approved for schizophrenia in the youth
• Ziprasidone


  • Schizophrenia
  • Bipolar disorder (Acute mania)
  • Extrapyramidal symptoms
  • Postural Hypotension (less)
  • QT prolongation arrhythmia
  • Little to no tendency to cause hyperglycemia, hyperprolactinemia, or weight gain