Anti-Convulsants

Question 1

Carbamazepine mechanism

Answer 1

Increases Na+ channel inactivation

Question 2

Clonazepam mechanism

Answer 2

Increases GABA action (benzo)
Used for:
- absence seizures 
- myoclonic seizures 
- infantile spasms

Question 3

Diazepam mechanism & use

Answer 3

Increases GABA action (benzo)

First line for acute status epilepticus

Question 4

Ethosuximide mechanism

Answer 4

Blocks thalamic T-type Ca2+ channels; used for treating absence seizures

Question 5

Felbamate Toxicity

Answer 5

Causes aplastic anemia and severe hepatitis at unexpectedly high rates–> recommended to use it only for refractory cases

Question 6

Gabapentin mechanism

Answer 6

Designed as GABA analog, but primarily inhibits high voltage-activated Ca2+ channels

Question 7

Lamotrigine mechanism

Answer 7

Blocks voltage-gated Na+ channels

Question 8

Lamotrigine Toxicity

Answer 8

Life-threatening dermatitis (steven-johnson syndrome)

Question 9

Phenobarbital mechanism

Answer 9

Increases GABA action (barbituate)

Question 10

Phenytoin mechanism and use

Answer 10

Increases Na+ channel inactivation

Good alternatives are available so it is no longer used as a first line drug

Question 11

Topiramate mechanism

Answer 11

Blocks Na+ channels and increases GABA action

Question 12

Valproic acid mechanism

Answer 12

Increases Na+ channel inactivation and increases GABA concentration

Question 13

Tonic-Clonic Grand-Mal Seizure

Answer 13

prolonged duration with loss of consciousness

Question 14

Absence Seizures

Answer 14

loss of consciousness and amnesia (from less than 10s to 45 seconds)

Question 15

Myoclonic seizures

Answer 15

brief shock-like muscle contractions in extremities

Question 16

Simple Partial

Answer 16

focal onset in cerebral cortex; seizures lasting from 30s to 60s with no loss of consciousness. Basically this is an aura.

Question 17

Complex Partial

Answer 17

focal onset in cerebral cortex; seizures lasting from 30s to 2 min with loss of consciousness

Question 18

3 ways that anti-convulsants work:

Answer 18

1. Enhances GABAergic transmission in the CNS
2. Reduces excitatory/glutamatergic transmission in the CNS
3. Reduces neuronal excitability by targeting ion channels

Question 19

Gabapentin Toxicity/SEs

Answer 19

Can exacerbate myoclonic seizures

Causes somnolence, dizziness, and ataxia

Question 20

Topiramate SEs

Answer 20

somnolence, fatigue, dizziness, cognitive slowing, psychiatric symptoms, and WEIGHT LOSS.

Question 21

Ethosuximide Toxicity

Answer 21

EFGH:
-Ethosuximide
-Fatigue
-GI distress
-Headache
Rare cases--> rash, Steven-Johnson Syndrome, and bone marrow depletion

Question 22

Valproic Acid Use

Answer 22

Used for:

• partial seizures (simple and complex)
• tonic-clonic (first line w/ carbamazepine & phenytoin)
• absence seizures (ethosuximide is first line)
• myoclonic seizures

Question 23

Valproic Acid Toxicity

Answer 23

Hepatotoxicity (rare, but fatal within 4 months– measure LFTs)
Birth defects (spina bifida, cardiovascular, orofacial, and digital defects)
Weight gain & tremor

Question 24

Anti-convulsants and Oral Contraception

Answer 24

Majority of anticonvulsant medications that induce liver enzymes (e.g. phenytoin, carbamazepine, phenobarbital) do reduce the efficacy of oral contraceptives

Question 25

Anti-convulsants and Vitamin K

Answer 25

vitamin K supplements during the last 2-4 weeks of gestation recommended to decrease the risk of coagulation problems and cerebral hemorrhage in the newborn

Question 26

Phenytoin Toxicity

Answer 26

Nystagmus, diplopia, ataxia, sedation, gingival hyperplasia, hisutism, megaloblastic anemia, teratogenesis (fetal hydantoin syndrome), SLE-like syndrome, induction of Cytochrome P450, lymphadenopathy, SJS, and osteopenia

Question 27

What drugs may exacerbate absence seizures?

Answer 27

Phenytoin, Phenobarbital, and Carbamazepine

Question 28

Carbamazepine Toxicity

Answer 28

Diplopia, ataxia, blood dyscrasias (agranulocytosis, aplastic anemia), liver toxicity, teratogenesis, induction of cytochrome P450, SIADH, SJS
–> Blood counts and LFTs should be done often!

Question 29

Phenobarbital Toxicity

Answer 29

Sedation, tolerance, dependence, induction of cytochrome P450
Tolerance–> toxicity (often in children)

Question 30

What anti-convulsant is contraindicated in pregnancy?

Answer 30

Valproic Acid due to risk of neural tube defects