21) Anti-Epileptic Drugs Flashcards
What is epilepsy?
Episodic discharge of abnormal high frequency electrical activity in brain leading to seizure
How can a diagnosis of epilepsy be determined?
Evidence of recurrent seizures, unprovoked by identifiable causes
How are seizures classified?
Partial (simple and complex)
Generalised
What are some dangers of severe epilepsy?
Physical injury
Hypoxia
SUDEP
Brain dysfunction
What is primary epilepsy?
No identifiable cuase
What is secondary epilepsy?
Medical condition affecting the brain e.g. vascular disease or tumour
What are some precipitants to epilepsy?
Sensory stimuli Brain disease/trauma Metabolic - hypoglycemia, hypocalcemia, hyponatremia Infections Therapeutics
What are the targets of anti-epileptic drugs?
Voltage gated sodium channel blockers
Enhancement of GABA
Inhibition of Ca2+ channel function
Inhibition of glutamate
What are some examples of drugs that prolong VG sodium channel inactivation state?
Carbamezepine
Phenytoin
Lamotrigine
For what types of seizures is carbamezepine indicated?
Tonic clonic
Partial
What are the side effects of carbamezepine?
Dizziness, ataxia, numbness, rashes, hyponatremia, motor disturbance
Rare: neutropenia
For what types of seizures is phenytoin indicated?
Tonic clonic
Partial
What are the side effects of phenytoin?
Dizziness, ataxia, headache, nystagmus, gingival hyperplasia. Stevens-Johnson
How is phenytoin monitored?
Monitor free concentration in plasma
Salivary levels
For what types of seizures is lamotrigine indicated?
Partial
Tonic clonic
Absence
What are the side effects of lamotrigine?
Dizziness, ataxia, sleepiness, nausea, skin rashes
Why does enhancing GABA help in treating seizures?
Post synaptic inhibition and a natural anti-convulsant
What is the mechanism of action of valproate?
Inhibits GABA inactivation, stimulates GABA synthesis, VGSCB
What are the side effects of valproate?
Sedation, ataxia, tremor, weight gain
Rare: hepatic failure
For what types of seizures is valproate indicated?
Partail, tonic clonic and absence
What are the side effects of benzodiazepines?
Sedation, tolerance, confusion, aggression, withdrawal, resp and CNS depression
How is benzodiazepine overdose treated?
IV flumazenil
Give examples of benzodiazepines:
Lorazepam/diazepam - status epilepticus
Clonazepam - absence
How can anti-epileptic drugs affect the fetus?
Congenital malformations
Facial and digit hypoplasia
Neural tube defects (valproate)
How do anti-epileptic drugs affect contraception?
Failure rate of contraception is 4x as high when using carbamazepine or phenytoin
How should anti-epileptics be used in pregnancy?
Single agent at lowest dose
Use lamotrigine
High dose folate supplements and vit K (trimester 3)
What is status epilepticus?
Prolonged seizure of any type - single convulsion lasting more than 30 mins or convulsions back to back with no recovery
What is the treatment for status epilepticus?
ABCDE, O2, terminate seizure
Lorazepam IV
IV phenytoin
If no response - midazolam, propofol and ITU admission
