Chapter 19: Antiseizure Drugs Flashcards
A seizure disorder that results from abnormal electric discharges from the cerebral neurons characterized by a loss or disturbance of consciousness and usually involuntary, uncontrolled movements.
Active Epilepsy
Occur when there is a disruption in the electrical functioning of the brain due to an imbalance in the excitation and inhibition of electrical impulses
Seizures
Why is there excessive amount of excitation discharges?
- Defect in neuronal membrane
- Degree of sodium influx
- Decrease in GABA inhibitory action
Useful in diagnosing epilepsy
EEG, MRI, CT
What are drugs used for epileptic seizures called?
Antiseizure drugs
Anticonvulsants
Antiepileptic drugs
How do antiseizure drugs work?
Stabilize nerve cell membranes and suppress the abnormal electric impulses in the cerebral cortex
Mechanism of Action of Antiseizure Drugs
- Suppress sodium influx through binding to the sodium channel when it is inactivated, which prolongs the channel inactivation and thereby prevents neuron firing
- Suppressing the calcium influx, which prevents the electric current generated by the calcium ions to the T-type calcium channel
- By increasing the action of GABA, which inhibits neurotransmitters throughout the brain
Drugs that suppress sodium influx
Phenytoin, Fosphenytoin, Carbamazepine, oxcarbazepine, valproic acid, topiramate, zonisamide, lamotrigine
Seizures involve both cerebral hemispheres of the brain
Generalized Seizure
Drugs that suppress Calcium influx
Ethosuximide, valproic acid
Drugs that enchance Gaba
Barbiturate, benzodiazepine, tiagabine
Gabapentin - promotes GABA release
Tonic-Clonic seizure
Grand mal seizure
Tonic phase - skeletal muscles contract or tighten in a spasm that lasts 3-5 seconds
Clonic - dysrhythmic muscular contractions with jerkiness of legs and arms for 2-4 minutes
Sustained muscle contraction
Tonic
Dysrhythmic muscle contraction
Clonic
Absence seizure Petit mal seizure
Brief loss of consciousness lasts less than 10 seconds, less than 3 spikes on EEG
Usually occurs in children
Absence seizure
Myoclonic seizure
Isolated clonic contraction or jerks that last 3–10 seconds may be limited to one limb (focal myoclonic) or may involve the entire body (massive myoclonic); may be secondary to a neurologic disorder such as encephalitis or Tay-Sachs disease.
Atonic Seizure
Head drop, loss of posture, and sudden loss of muscle tone occurs. If lower limbs are involved, the patient could collapse.
Muscle spasms for babies
Infantile Spasm
Partial seizure
Involves one hemisphere of the brain; no loss of consciousness occurs in simple partial seizures, but there is a loss of consciousness in complex partial seizures.
Simple Seizure
Occurs in motor, sensory, autonomic, and psychic forms; no loss of consciousness occurs.
Motor Seizure
Formerly called the Jacksonian seizure, this type involves spontaneous movement that spreads; it can develop into a generalized seizure.
Sensory seizure
Visual, auditory, or taste hallucinations
Autonomic response of seizures
Paleness, flushing, sweating, vomitting
