Anti-epileptics

Question 1

What is the MOA of phenytoin?

Answer 1

Inhibit VG fast Na+ channel in inactivated state on presynaptic glutamate neuron (same as local anesthetics and Class Ib anti-arrhythmia drugs)

Question 2

What are the dose-related ADRs of phenytoin in adults?

Answer 2

Diplopia, ataxia, dizziness, nystagmus, tremor, sedation

Question 3

What are the non-dose-related / chronic use ADRs of phenytoin (unique to phenytoin) in adults?

Answer 3

Gingival hyperplasia and hirsutism

Question 4

OD of phenytoin is what type of elimination?

Answer 4

Zero-order elimination

Question 5

What is the definition of zero-order and first-order elimination?

Answer 5

Zero-order elimination is a constant rate of metabolism independent of drug concentration (concentration, same plasma conc. / time, linear line). First-order elimination is rate of metabolism proportional to drug concentration where half life is constant (percentage, different conc. / time, exponential / curved line).

Question 6

What are the zero-order elimination drugs?

Answer 6

Phenytoin, high-dose aspirin, and alcohol

Question 7

Which type of elimination allows for the drug to accumulate in the body because it is not efficient?

Answer 7

Zero-order elimination

Question 8

What is the MOA of carbamazepine?

Answer 8

Inhibit inactivated VG fast Na+ channel

Question 9

What are the ADRs of carbamazepine in adults?

Answer 9

SIADH, SJS, and agranulocytosis (reduced WBC)

Question 10

Besides convulsion, carbamazepine is used to treat _____ and _____.

Answer 10

Trigeminal Neuralgia, mania

Question 11

What are the ADRs of carbamazepine in the fetus?

Answer 11

Cleft lip / palate and spina bifida

Question 12

What are the ADRs of phenytoin in the fetus?

Answer 12

Fetal Hydantoin Syndrome (signs include microcephaly, growth delay, mental retardation, developmental delay, and craniofacial dysmorphic features; hydantoin old name for phenytoin)

Question 13

What are the 3 MOAs for valproic acid?

Answer 13

1. Inhibit VG fast Na+ channels in inactive state 2. Blocks GABA ransaminase (decrease degradation, increase GABA) 3) blocks VG T-type (transient) Ca2+ channel in Thalamus (glutamate neuron)

Question 14

Which drug is known to be the universal treatment for seizures since it can treat all types?

Answer 14

Valproic acid

Question 15

What are the 2 uses of Valproic acid in addition to treating seizures?

Answer 15

Treatment of mania, migraine prevention

Question 16

What ADR in the fetus occurs if mother takes Valproic acid (like all anti-convulsants)?

Answer 16

Spina bifida

Question 17

To prevent spina bifida in a woman trying to get pregnant, what do you do?

Answer 17

Give her folate supplements 1 month before and 3 months after the pregnancy.

Question 18

When do you use ethosuximide?

Answer 18

Absence seizure

Question 19

How do you ID an absent seizure on EEG?

Answer 19

3 HZ spike with slow wave about 3-4 seconds

Question 20

What is the MOA of ethosuximide?

Answer 20

Blocks VG T-type (transient) Ca2+ channel in Thalamus (glutamate neuron)

Question 21

What is the ADR of ethosuximide?

Answer 21

swollen joints, depression, liver damage, kidney damage, drug reation (thiol)

Question 22

What is the MOA of lamotrigine?

Answer 22

AMPA receptor (glutamate) antagonist

Question 23

What is the ADR of lamotrigine?

Answer 23

SJS

Question 24

Lamotrigine is used to treat _____ seizures.

Answer 24

General tonic-clonic (grand-mal)

Question 25

Besides Valproic acid, what other two anti-convulsants can be used to prevent migraines?

Answer 25

Lamotrigine and Topiramate

Question 26

What is the MOA of felbamate?

Answer 26

NMDA (glutamate) receptor blocker (potentiate GABA A receptor)

Question 27

Though all the all anti-convulsant drugs can cause aplastic anemia, which one is considered to be the #1 worst offender of the ADR?

Answer 27

Felbamate

Question 28

What other ASR, besides aplastic anemia, can be caused by Felbamate?

Answer 28

Liver toxicity

Question 29

What is the mechanism of Gabapentin?

Answer 29

N-type presynaptic VG Ca2+ channel blocker (glutamate neuron, increase GABA release)

Question 30

Other than treating convulsions, what can Gabapentin be used for?

Answer 30

Postherpetic neuralgia (shingles)

Question 31

Which anti-convulsant drugs inhibit P450?

Answer 31

Valproic acid

Question 32

Which anticonvulsant drugs induce P450?

Answer 32

All of them EXCEPT Valproic acid

Question 33

Which drugs cause alopecia?

Answer 33

Valproic acid

Question 34

Which drugs anti-convulsant, anti-cancer, anti-HIV, and anti-PCP/PCJ cause pancreatitis respectively?

Answer 34

Valproic acid, asparginase, didanosine, Pentamidine

Question 35

Which drugs cause spina bifida and which one has higher incidence?

Answer 35

valproic acid > carbamazepine

Question 36

Which drugs treat absence seizure?

Answer 36

ethosuximide and valproic acid

Question 37

Which drugs first to treat status epilepticus (work fast to stop immediately)?

Answer 37

Diazepam and Lorazepam (BZDs)

Question 38

What are the drugs for maintained treatment (long term use)?

Answer 38

Barbituates and Phenytoin

Question 39

What drugs are used in children with febrile convulsion?

Answer 39

First Diazepam to stop convulsion then second acetaminophen to reduce fever

Question 40

What drugs for general tonic clonic seizure?

Answer 40

Valproic acid, carbamazepine

Phenytoin, lamotrigine, topiramate

Question 41

What are the ADRs of Pentamidine?

Answer 41

Reduces blood Ca2+ causing painful muscle spasm and acute pancreatitis

Question 42

What methods should you do to reduce a fever causing febrile convulsion in a child if acetaminophen is not used?

Answer 42

Warm water bath, 30% alcohol bath, or put in air conditioned room