Anti-Seizure Drugs Flashcards
What drug is used as 1st line treatment for silent (absence) seizures?
Ethosuximide
What is the mechanism of ethosuximide?
Blocks thalamic T-type Ca2+ channels –> irregular rhythmic cortical discharge of absence attack
What are the major side effects of Ethosuximide?
(EFGHIJ) Ethosuximide causes fatigue, GI distress, headache, itching, Stevens-Johnson syndrome
What do benzodiazepines do & which ones are used for status epilepticus? P.S. what are benzos also used for?
Benzos increase GABAa action - Diazepam and lorazepam - they are also used for eclampsia seizures (first line is MgSO4)
What are the side effects of Benzodiazepines? (4)
Sedation, tolerance, dependence, respiratory depression
What is the mechanism of Phenytoin?
Increase Na+ channel inactivation & decrease release of glutamate; zero-order kinetics (give more –> more effect)
What is the 1st line use of Phenytoin? What is the prophylactic use of Phenytoin?
1st line: tonic-clonic seizure; prophylaxis: status epilepticus
What is the parenteral form of Phenytoin?
Fosphenytoin
What is the acute use of Phenytoin? (2)
Simple & complex partial (focal) seizures
What are the side effects of Phenytoin?
Nystagmus, diplopia, ataxia, gingival hyperplasia, hirsutism, peripheral neuropathy, teratogenesis (fetal hydrantoin syndrome), megaloblastic anemia, SLE-like syndrome, induction of P-450, lymphadenopathy, Steven’s Johnson syndrome, osteopenia
When does sedation occur in Phenytoin use?
only @ HIGH levels of Phenytoin use!
What is Carbamazepine used for?
1st line treatment for simple and complex partial (focal) seizures & tonic-clonic seizures <– first line along with Phenytoin and Valproic acid
What is the mechanism of Carbamazepine?
Increases Na+ channel inactivation & decreases release of Glutamate
What else other than anti-seizure is Carbamazepine used for?
1st line for trigeminal neuralgia - brief episodes of sudden & severe unilateral “electric shock like” and “stabbing” pain (V2, V3)
Valproic Acid mechanism?
Increase Na+ channel inactivation; also increases GABA concentration by inhibiting GABA transaminase
What are the uses of Valproic acid? (5)
1st line for tonic-clonic seizures (1st line along with Phenytoin and Carbamazepine)
- Acutely for simple partial (focal) seizures
- Acutely for complex partial (focal) seizures
- Acutely for myoclonic seizures (along with Phenobarbital and Levetiracetam)
- Acutely for absence seizures
Side effects of Valproic acid?
GI distress, rare but fatal hepatotoxicity (must measure LFTs), neural tube deficits in fetus (spina bifida) so contraindicated in pregnancy, tremor, weight gain, hair loss
Other than anti-seizure, what is Valproic acid also used for?
Bipolar disorder as a mood stabilizer
Which anti-seizure drugs are highly bound to plasma protein?
Phenytoin & Valproic acid
What are the side effects of Carbamazepine?
- Diplopia
- Ataxia
- Blood dyscrasias (agranulocytosis, aplastic anemia so CBC should be monitored)
- Liver toxicity
- Teratogenesis
- Induction of cyt P-450 so may metabolize other drugs
- SIADH
- Stevens-Johnson syndrome
What is Stevens-Johnson syndrome?
Prodrome of malaise and fever followed by rapid onset of erythematous/purpuric macules in oral region, ocular region, and genitals)
Skin lesions progress to epidermal necrosis & sloughing
What is the mechanism of Gabapentin?
Gabapentin primarily inhibits high-voltage-activated Ca2+ channels; designed as GABA analog
What are the uses for Gabapentin? (3) *NOTE: HIGH doses needed
Used acutely for the following:
- Simple partial (focal) seizure
- Complex partial (focal) seizure
- Tonic-clonic seizure
What are the side effects of Gabapentin?
Sedation, ataxia
Other than anti-seizure, what else is Gabapentin used for?
Gabapentin is also used for peripheral neuropathy, postherpetic neuralgia, migraine prophylaxis, and bipolar disorder
What is the action of Phenobarbital?
Increased GABAa action (like Benzos and alcohol)
What is phenobarbital used for?
Phenobarbital is acutely used for the following:
- Simple partial (focal) seizure
- Complex partial (focal) seizure
- Tonic-clonic seizure
- Status epilepticus
What are the side effects of Phenobarbital?
Sedation, tolerance, dependence, induction of cyt p450, cardiorespiratory depression
Is phenobarbital used in neonates?
Yes as first line in neonates to treat seizures
What is topiramate used for?
Topiramate is used acutely for:
- Simple partial (focal) seizures
- Complex partial (focal) seizures
- Tonic-clonic seizures
What are the side effects of Topiramate?
Sedation, mental dulling, kidney stones, weight loss, myopia, glaucoma
What is the mechanism of Topiramate?
Topiramate blocks Na+ channels; also increases GABA action
What is the other use for Topiramate other than anti-seizure?
Topiramate is also used for migraine prevention
What is the mechanism of Lamotrigine?
Lamotrigine blocks voltage-gated Na+ channels
What is the major side effect of Lamotrigene?
Stevens-Johnson syndrome, so Lamotrigene must be titrated slowly
*NOTE: pediatric patients are @ high risk of Stevens-Johnson syndrome
What is the mechanism of Levetiracetam?
Unknown; may modulate GABA and Glu release; it is a synaptic vesicle protein
What is the mechanism of Tiagabine?
It increases GABA by inhibiting re-uptake of GABA (blocks GABA transporter called GAT-1)
What is the mechanism of Vigabatrin?
Vigabatrin increases GABA by irreversible inhibiting GABA transaminase in presynaptic neuron
What is the mechanism of Felbamate?
Felbamate blocks the NMDA receptor
What are the symptoms of Felbamate toxicity?
Aplastic anemia, severe hepatitis
A patient wants prophylaxis for status epilepticus. What do you prescribe?
Phenytoin!
What do you prescribe for an acute attack of status epilepticus?
Benzodiazepines (diazepam, lorazepam)
Someone has an absence seizure. What do you prescribe as first line drug?
Ethosuximide
Someone has a tonic-clonic seizure. What are your options for first-line treatment?
Phenytoin, carbamazepine, valproic acid
Someone has a simple partial (focal) seizure. What do you prescribe as first-line treatment?
Carbamazepine
Someone has a complex partial (focal) seizure. What do you prescribe as 1st line treatment?
Carbamazepine
What is status epilepticus?
One continuous seizure or recurrent seizures without regaining consciousness between seizures for greater than 30 minutes (can be convulsive or non-convulsive)
Which anti-epileptic drugs are contraindicated in pregnancy? (5)
Valproic acid, phenobarbital, phenytoin, carbamazepine, benzodiazepines
What do you prescribe to treat infantile spasms?
ACTH/vigabatrin
What do you prescribe to treat benign occipital seizures?
Carbamazepine, oxcarbazepine
What do you prescribe to treat juvenile myoclonic seizures?
Valproic acid
