Anti-seizure

• Antiseizure drugs


  Drugs used for epileptic seizures, also called anticonvulsants or antiepileptic drugs
• How antiseizure drugs work

  1. Suppressing sodium influx

  2. Suppressing calcium influx

  3. Increasing the action of gamma-aminobutyric acid (GABA)
• Hydantoins


  The first antiseizure drug used to treat seizures was phenytoin, a hydantoin discovered in 1938 and still commonly used for controlling seizures
• Hydantoins


  • Inhibit sodium influx, stabilize cell membranes, reduce repetitive neuronal firing, and limit seizures
  • Act as an antidysrhythmic by increasing the electrical stimulation threshold in cardiac tissue
  • Have a slight effect on general sedation and are non-addicting
  • Should not be used during pregnancy due to teratogenic effect on the fetus
• Barbiturates


  • Phenobarbital, a long-acting barbiturate, is prescribed to treat tonic-clonic, partial, and myoclonic seizures and status epilepticus
  • Reduce seizures by enhancing the activity of GABA, an inhibitory neurotransmitter
  • Therapeutic serum range of phenobarbital is 20 to 40 mcg/mL
  • Risks include sedation and tolerance, and discontinuance should be gradual to avoid recurrence of seizures
• Succinimides


  • Used to treat absence seizures
  • Act by decreasing calcium influx through the T-type calcium channels
  • Therapeutic serum range of ethosuximide is 40 to 100 mcg/mL
  • Adverse effects include blood dyscrasias, renal and liver impairment, and systemic lupus erythematosus
• Benzodiazepines


  • Clonazepam is effective in controlling absence and myoclonic seizures, but tolerance may occur 6 months after drug therapy starts
  • Clorazepate dipotassium is administered for treating partial seizures
  • Diazepam is administered by IV to treat status epilepticus, but has a short-term effect so other antiseizure drugs must be given during or immediately after
• Iminostilbenes


  • Carbamazepine, an iminostilbene, is used to control tonic-clonic and partial seizures
  • Also used for psychiatric disorders, trigeminal neuralgia, and alcohol withdrawal
  • Therapeutic serum range of carbamazepine is 4 to 12 mcg/mL
  • A potentially toxic interaction can occur when grapefruit juice is consumed
• Carbamazepine


  An iminostilbene used to control tonic-clonic and partial seizures, also used for psychiatric disorders, trigeminal neuralgia, and alcohol withdrawal
• Carbamazepine


  • Therapeutic serum range is 4 to 12 mcg/mL
  • Potentially toxic interaction can occur when grapefruit juice is taken with carbamazepine, drug concentrations must be carefully monitored
• Valproic acid


  Prescribed for tonic-clonic, absence, and mixed types of seizures, safety and efficacy not established for children younger than 2 years, hepatotoxicity is a possible adverse reaction, therapeutic serum range is 50 to 100 mcg/mL
• Status epilepticus


  A continuous seizure state, considered a medical emergency. Diazepam administered by IV or lorazepam followed by IV administration of phenytoin are the choices of pharmacologic agents. For continued seizures, midazolam or propofol and then high-dose barbiturates are used. These drugs should be administered slowly to avoid respiratory depression.