Anti-Seizure Drugs (Anti-epileptics)

Special Points:

  1. Phenytoin produces Gingival Hyperplasia and Hypertrophy.
  2. Sodium Valproate is a broad spectrum antiepileptic.
  3. Lamotrigin, Topiramate, Zonisamide
  4. Ethosuximide is specific in inhibiting the T-type calcium channels and is specific to treat absence seizure (Petit Mal Epilepsy).
  5. Carbamazepine is drug of choice for Trigeminal Neuralgia.
  6. Phenytoin is known to worsen absence seizure and hence never used for treating absence seizure.
  7. Lorazepam / Diazepam is drug of choice to stop convulsions.
  8. Phenytoin, Carbamazepine, and Barbiturates – all are inducers of CYP3A4 system (Hepatic Microsomal Enzyme System – HMES), whereas Valproate is an inhibitor !!
  9. Contraindication for Barbiturates/Phenobarbitone: Acute Intermittent Porphyria


Seizure: An episode of brain dysfunction due to abnormal electrical discharges of cerebral neurons.

Seizure may be associated WITH or WITHOUT CONVULSIONS.

Sometimes the word “Non-convulsive seizure” may be used to indicate the episode of brain dysfunction (seizure), where there are no convulsions.


Mention adverse effects of Phenytoin sodium (Phenytoin) (Dilantin)

Phenytoin has low therapeutic index. Its adverse effects are as follows:

  1. Gingival Hyperplasia and Hypertrophy, and bleeding gums
  2. Vestibulo-Cerebellar Syndrome manifesting in the form of ataxia (Incoordination of movements), Vertigo (Sensation of moving around), Nystagmus (Involuntary movement of eyeballs), Dysarthria (Difficulty in articulation for speech), Blurring of vision, ocular pain
  3. Coarsening / flattening of facial features, hypertrophy of facial subcutaneous tissue, hypertrichosis (Phenytoin facies)
  4. Hirsutism, Acne
  5. Delusions, hallucinations, behavioral changes
  6. Deficiency of Vitamin D, Osteomalacia
  7. Deficiency of Vitamin B12, folic acid, Vitamin K, Megaloblastic anemia, peripheral neuropathy
  8. Teratogenic Effects: Fetal Hydantoin Syndrome:  CCranio-Facial defects,  Heart defects, Hypoplastic phalanges, Microcephaly, Neural tube defects – Spina bifida. and other malformations 
  9. Phenytoin induces hepatic microsomal enzymes and can increase the metabolism and decrease the effect of many drugs including oral contraceptives, doxycycline, theophylline, warfarin and many others.


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