Pharm: Anti Epileptics

Question 0

What types of seizures do drugs that enhance sodium channel inhibition treat?

Answer 0

Focal and secondary generalized seizures.

NOT absence

Question 1

Define Ictal.

Answer 1

ictal refers to a physiologic state or event such as a seizure.

Question 2

Phenytoin

Answer 2

MOA: acts of Na channels extending the refractory period which leads to inhibition the channel activation.

Indications: focal and tonic clonic seizures

AE: follows zero order kinetics so it needs to be monitored constantly during use

• alters plasma levels of oral contraceptives
• gingival hyperplasia

Question 3

Carbamazepine

Answer 3

MOA: acts of Na channels extending the refractory period which leads to inhibition the channel activation.

Indications: focal seizures

AE: induces its own metabolism by the liver so chronic use involves increasing the dose over time

Question 4

Lamotrigine

Answer 4

MOA: acts of Na channels extending the refractory period which leads to inhibition the channel activation.

Indications: focal seizures

AE: skin rash

Question 5

Lacosamide

Answer 5

MOA: acts of Na channels extending the refractory period which leads to inhibition the channel activation.

Indications: adjunctive therapy for focal seizures

AE: dizziness, headache, nausea, diplopia

Question 6

What types of seizures do drugs that block T-type Calcium channels treat?

Answer 6

Mainly absence seizures

T-type calcium channels are voltage-gated and moderate calcium current in the thalamus and cardiac muscle

Question 7

Ethosuximide

Answer 7

MOA: Block T-type calcium channels

Indications: absence seizures

Question 8

Valproic Acid

Answer 8

MOA: Block T-type calcium channels, also sodium channel blocker, and glutamic acid decarboxylase inhibitor (more GABA)

Indications: absence seizures when ethosuximide is ineffective
-focal seizures as alternate to phenytoin and carbamazepine

AE: hepatotoxicity

Question 9

What types of seizures do drugs that block High Voltage Activated (HVA) calcium channels treat?

Answer 9

All types of seizures EXCEPT absence seizures (focal, secondary generalized, generalized).

(HVA calcium channels are located on presynaptic neurons that, when signals, allow vesicles to release neurotransmitters)

Question 10

Gabapentin

Answer 10

MOA: Blocks HVA calcium channels (anti-seizure)
-also increases GABA content in neural glial cells

Indications: focal, secondary generalized, generalized seizure (NOT ABSENCE)

Question 11

Pregabalin

Answer 11

MOA: blocks HVA calcium channels

Indications: focal seizures, secondary generalized, generalized (NOT ABSENCE)
-useful for patients with liver insufficiency because it is metabolized in the kidneys

Question 12

Diazepam, Lorazepam, Midazolam

Answer 12

MOA: bind GABA-a receptors and enhance chloride current when GABA binds.

Indications: focal and tonic-clonic seizures

Question 13

Clonazepam

Answer 13

MOA: indirect inhibition of T-type calcium channels in the thalamocortical circuits.

Indications: absence seizures

Question 14

Phenobarbital

Answer 14

MOA: binds GABA-a receptor prolonging the activations and opening of the chloride channel, a weak agonist that doesn’t require GABA to bind to have its effect.

Indications: focal and tonic clonic seizure, acute resistant seizures

AE: many due to its weak agonist potential

Question 15

Vigabatrin

Answer 15

MOA: structural analog of GABA that binds and irreversibly inhibits the enzyme GABA transaminase preventing the breakdown of the “real” GABA neurotransmitters.

Indications: infantile spasms and refractory focal epilepsy

AE: bilateral visual field defects and atrophy of peripheral retinal nerve fiber layers
-so any pt. on this medication should have eyes checks periodically

Question 16

Tiagabine

Answer 16

MOA: competitive inhibitor of GABA transporters preventing the re-uptake of GABA into neurons. (“Tidal wave” of GABA)

Indications: potentiates action of GABA-a modulators (BZs, barbs, ethanol)

AE: confusion, sedation, amnesia, ataxia

Question 17

What is the major side effect of all the glutamate receptor antagonists?

Answer 17

Behavioral Adverse Effects

Question 18

Felbamate

Answer 18

MOA: NMDA receptor antagonist

Indications: refractory epilepsy
-potent without the sedative side effects

AE: aplastic anemia and liver failure

Question 19

Rufinamide

Answer 19

MOA: prolongs refractory period of sodium channels, at HIGHER doses inhibits NMDA receptors.

Indications: refractory seizures, focal seizures and drop attacks in Lennox-Gastaut syndrome.

AE: not as severe as felbamate, so an alternative med for refractory epilepsy

Question 20

Describe the treatment procedure for status epilepticus.

Answer 20

1. IV Lorazepam or Diazepam
2. if seizures continue: IV fosphenytoin
3. ” “ : Phenobarbital
4. ” “ : general anesthesia

Question 21

Which of the anti-seizure meds is the most teratogenic?

Answer 21

Valproic Acid