92b/93b - Epilepsy and Anticonvulsants Flashcards
Which 1st generation AEDs are enzyme inducers?
- Phenobarbital
- Phenytoin
- Carbamazepine
Which AED is the drug of choice for abscence seizures?
Ethosuximide
What is the mechanism of the benzodiazepines?
Which seizures do they treat?
Increased frequency of Cl- channel opening
Effective for myoclonic seizures
Rescue medication for status epilepticus
Describe the general mechanisms of seizure generation
- Too much excitation
- Ionic: too much inward Na+, Ca2+
- NeuroT: Too much glutamate, aspartate
- Too little inhibition
- Ionic: too little inward Cl-, outward K+
- NeuroT: Not enough GABA
What is the mechanism of ethosuximide?
What is it used for?
Blocks T-type Ca2+ currents in the thalamus
Drug of choice for abscence seizures
What is the most concerning possible side effect of lamotrigine?
Steven-Johnson syndrome
- But broadly, lamotrigine is a good broad-spectrum AED that is safe in pregnancy
Which AED can also be used for migraine prophylaxis and neuropathic pain?
Topiramate
Describe the signs of a myoclonic seizure
Myoclonic = generalized
- Myoclonus
- Brief, shock-like jerk of a muscle or group of muscles
- Bilateral, synchronous
- vs. clonus which is repeated rhythmic jerking
- If several myoclonic jerks occur in rhythmic succession, it is a clonic seizure
- Consciousness NOT impaired
Which AEDs are safe in pregnancy?
Lamotrigine
But need frequent adjustment in dose b/c serum levels fall in the 3rd trimester
Describe the signs of a tonic seizure
Tonic = generalized
- Symmetric, tonic muscle contraction of extremities
- Tonic flexion of waist and neck
- Lasts 2-20 seconds
- EEG
- Sudden attenuation, generalized polyspike waves
- (similar to atonic)
Which kind of epilepsy is characterized by focal seizures with impaired consciousness with automatisms?
Temporal lobe epilepsy
- Automatisms = lip smacking, swallowing, fumbling, picking at clothes
What is the mechanism of Levetiracetam?
What is it used for?
What is its notable side effect?
- Mechanism
- Binds to synaptic vescicle protein SV2A to regulate neurotransmitter release
- Also reduces activity through high-voltage Ca2+ channels
- Use
- Broad spectrum - used as monotherapy or adjunctive
- Side effect
- CNS depression and irritability
What EEG changes are associated with abscence seizures?
3 Hz spike-wave discharges in every channel
Lasts for 3-10 seconds
- Abscence seizures are generalized
- Sudden onset, sudden resolution
- No post-ictal confusion
What is the mechanism of carbamazepine?
What is it used for?
Inhibits Na+ channels
Tricyclic
Used to treat epilepsy w/predominantly focal seizures
Will worsen abscence seizures
Which kind of epilepsy is characterized by seizures that originate in the hippocampus and/or amygdala?
Mesial temporal lobe epilepsy
- Focal seizures evolve into a bilateral, convulsive seizure early on
In which populations should valproate be avoided?
- Pregnant women
- High risk of neural tube defects
- Neonates
- Hepatic toxicity due to elevated liver enzymes
Which AEDs can be used for neuropathic pain?
Gabapentin
Carbamazepine
Pregabalin
Which 1st generation AED is an enzyme inhibitor?
Valproate