Pharmacology: Seizures and Epilepsy

Definitions:

Convulsion: abnormal motor phenomena (jerking, movements, tics, rigors)
Seizure: a sudden, excessive synchronous electrical discharge of neurons in the brain that can spread to other foci
Epilepsy: group of chronic neurological disorders characterized by recurring seizures

Main Types of Seizures:

Simple Partial: discrete motor, sensory, autonomic and psychoillusionry symptoms. No loss of consciousness. Persists 20-30 seconds.
Tonic-Clonic: major convulsions characterized by a period of muscle rigidity (tonic phase) followed by synchronous muscle jerks (clonic phase). Immediate loss of consciousness. Followed by postictal state. Lasts 90 seconds or less.

Therapeutic Goals:

  • Enable patient to live a normal life.
  • Ideally eliminate seizures, but may not be possible

How do Anti-Epileptic Drugs Work?

  • suppress discharge of neurons within a seizure focus
  • suppress the spread of seizure activity from the focus to other areas of the brain
  • decrease in sodium influx, decrease in calcium influx, increase in potassium influx

Traditional AED’s

  • Phenytoin (Dilantin): Therapeutic range: 10-20mcg/mL, can cause gingival hyperplasia and nystagmus
  • Carbamazepine (Tegretol): Also treats trigeminal neuralgia and bipolar disorder. Contraindicated if patient has bone marrow depression or hypersensitivity. Avoid grapefruit juice!
  • Valproic Acid (Depakote): Also treats migraines and bipolar disorder. Therapeutic range: 50-100mcg/mL. Highly teratogenic! Can cause hepatotoxicity, pancreatitis and hypersensitivity.
  • Ethosuximide (Zarontin): Treats absence seizures. Therapeutic range: 40-100mcg/mL. Generally devoid of adverse effects.
  • Phenobarbital: Older drug, long-acting. Toxicity can cause nystagmus and ataxia. Overdose can cause respiratory depression and possibly death. Has a sedative effect, cognitive/learning impairment, CNS depression and drug dependence. May make children hyper.

Status Epilepticus

A MEDICAL EMERGENCY in which a patient is continually having tonic-clonic seizures for 20-30 minutes and is not conscious the whole time.

Immediate treatment includes: turning patient to the side, administering oxygen, removing objects that could potentially harm, having padded bedrails, suction secretions, and DO NOT restrain the patient or put anything in their mouth. Administer one of the following medications:

  • Diazepam (Valium): Used for emergency treatment of status epilepticus. Short half-life. May develop physical dependence and withdrawal symptoms.
  • Lorazepam (Ativan): Drug of choice used in status epilepticus because of prolonged effects. A rectal gel is available for out of hospital use.

Source: Lehne Pharmacology for Nursing Care, 9th Edition, Chapter 24💎



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