EXAM #3: ANTICONVULSANTS II

Question 1

What two drugs are Hydantoins?

Answer 1

Phenytoin

Fos-phenytoin

Question 2

What is the difference between Phenytoin and Fos-phenytoin?

Answer 2

Fos-phenytoin is a prodrug that is more soluble, making it available for IV and IM preparations

Question 3

What is the effect of Phenytoin on metabolism?

Answer 3

Induction of cytochome p450

Question 4

What type of elimination does Phenytoin undergo?

Answer 4

Zero-order i.e. system can become SATURATED

Question 5

What is the mechanism of action of Phenytoin?

Answer 5

1) Blocks Na+ channels by binding the voltage gated Na+ channel in the inactivated state
2) Enhances GABA release
3) Decreases glutamate release
4) Prevents seizure propagation

Question 6

What are the clinical indications for Phenytoin?

Answer 6

1) Grand mal seizure
2) Patrial seizure
3) Status epilepticus

Question 7

What is the unique adverse effect that is strongly associated with Phenytoin?

Answer 7

Gingival Hyperplasia

Question 8

What is Fetal Hydantoin Syndrome?

Answer 8

Teratrogenic syndrome including cleft lip and palate cause by Phenytoin ingestion during pregnancy

Question 9

What class of drug is Carbamazepine?

Answer 9

Tricyclic

Question 10

What is the mechanism of action of Carbamazepine?

Answer 10

Inhibition of voltage-gated Na+ channels

Question 11

What is the effect of Carbamazepine on metabolism?

Answer 11

Potent induction of CYP p450

Question 12

What is Oxacarbazepine?

Answer 12

New drug with similar structure to Carbamazepine that has FEWER side effects

Question 13

What are the clinical indications for Carbamazepine?

Answer 13

1) General tonic-clonic seizures
2) Partial seizures
3) Trigeminal neuralgia
4) Bipolar disorder (manic phase)

Question 14

What is the drug of choice for trigeminal neuralgia?

Answer 14

Carbamazepine

Question 15

What is the unique side effect of Carbamazepine?

Answer 15

SIADH i.e “Syndrome of Inappropriate ADH Secretion” leading to fluid retention and hyponatremia

Also, like Phenytoin, a potent Teratogen

Question 16

What is the mechanism of action of Phenobarbital?

Answer 16

Increases the duration of opening of GABA receptors on the post-synpatic cell

Question 17

What is Phenobarbital commonly clinically used for?

Answer 17

1) Neonatal seizures
2) Seizures in pregnancy
3) Status epileptics

Question 18

What is Primidone?

Answer 18

Prodrug of Phenobarbital

Question 19

What type of seizure is Ethosuximide used to treat?

Answer 19

Petite mal

Question 20

What is the mechanism of action of Ethosuximide?

Answer 20

Blocks pre-synpatic T-type Ca++ channels

Question 21

What is the second drug used to treat Petite Mal seizures?

Answer 21

Valproic acid

Question 22

What is the mechanism of action of Valproic acid ?

Answer 22

1) T-type Ca++ channel blocker

2) Inhibition of GABA transaminase (increase GABA in synapse)

Question 23

What are the unique side effects of Valproic acid ?

Answer 23

1) Hepatotoxic syndrome

2) Teratogenic risk

Question 24

What is the preferred initial agent for status epilepticus?

Answer 24

Diazepam

Note that this is relatively short acting and requires an additional drug to maintain cessation of seizure activity*

Question 25

What is the difference between Lorazepam and Diazepam?

Answer 25

Lorazepam is longer acting in status epilepticus

Question 26

What is the mechanism of action for Diazepam?

Answer 26

Increases the frequency of GABA-A channel opening

Question 27

What is the mechanism of action of Gabapentin?

Answer 27

Synthetic GABA analog that BLOCKS pre-synapatic Ca++ channels (Counter-intuitive)

Question 28

What are the clinical indications for Gabapentin?

Answer 28

1) Grand mal seizure | 2) Neuropathic pain

Question 29

What is Pregablin?

Answer 29

Lyrcia, a newer GABA analog

Question 30

What is the mechanism of action of Lamotrigine?

Answer 30

Blocks pre-synaptic Na+ and Ca++ channels

Question 31

What is the unique adverse effect associated with Lamotrigine?

Answer 31

Stevens Johnson Syndrome

Question 32

What is the mechanism of action of Felbamate?

Answer 32

Blocks Na+ and glutamate receptors

Question 33

What adverse effects as associated with Felbamate?

Answer 33

- Aplastic anemia | - Liver failure

Question 34

What is the mechanism of action of Tiagabine?

Answer 34

Inhibits GABA uptake

Question 35

What are the two major drugs we discussed as muscle-relaxants?

Answer 35

1) Diazepam | 2) Baclofen

Question 36

What is the mechanism of action of diazepam as a muscle relaxant?

Answer 36

Increases frequency of central GABA-A receptor opening to increase central inhibitor effect

Question 37

What is the difference GABA-A and GABA-B receptors?

Answer 37

``` A= Cl- ion channel B= GPRC that increases K+ conductance ```

Question 38

What is the mechanism of action of Baclofen?

Answer 38

GABA-B receptor agnoist that increases K+ conductance

Question 39

Clinically, what is the difference between Diazepam and Baclofen?

Answer 39

Baclofen causes less sedation