Antiepileptic Drugs

Question 1

What are the drugs of choice used in the treatment

of status epilepticus?

Answer 1

Phenobarbital, phenytoin, benzodiazepines, thiopental, and
propofol are appropriate choices for initial treatment.
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC,
Ortega R. Clinical Anesthesia. 7th ed. Philadelphia, PA:
Lippincott Williams and Wilkins; 2013: 620.

Question 2

Antiepileptic drugs can cause what adverse
hematologic reactions? Which drugs are usually
associated with these reactions?

Answer 2

Antiepileptic drugs are associated with anemias. The
symptoms are typically mild, but can occasionally produce
aplastic anemia. They are most commonly seen with valproate,
carbamazepine, and phenytoin.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 251.

Question 3

What is the clinical use of phenytoin?

Answer 3

It is used to treat generalized tonic-clonic seizures, as well as
partial seizures.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 408.

Question 4

What physiologic systems are affected by phenytoin?

Answer 4

Phenytoin alters membrane potentials and the concentrations of
the neurotransmitters GABA, norepinephrine, and
acetylcholine. It also interferes with the conductance of sodium,
potassium, and calcium.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 403.

Question 5

List side effects associated with the use of phenytoin.

Answer 5

Gingival hyperplasia, hirsutism, nystagmus, diplopia, ataxia,
hypotension, aplastic anemia, cardiac arrhythmias, Stevens-
Johnson syndrome, and erythema multiforme.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 250.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 409

Question 6

What is phenytoin’s main mechanism of action at

therapeutic concentrations?

Answer 6

Phenytoin exerts its effects through the blocking of sodium
channels and the inhibition of rapidly firing action potentials.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 408.

Question 7

What is the therapeutic blood level of phenytoin?

Answer 7

10-20 mcg/ml
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 408.

Question 8

Describe the result of an intra-arterial injection or

extravasation of phenytoin.

Answer 8

Marked vasoconstriction occurs, which can progress to
compartment syndrome, gangrene, and skin necrosis.
Hines RL, Marschall KE. Anesthesia & Co-Existing Diseases.
6th ed. Philadelphia, PA: Elsevier-Saunders; 2012: 250.

Question 9

What are the clinical uses of carbamazepine?

Answer 9

The original purpose for carbamazepine was in the treatment of
trigeminal neuralgia, however, it is also used for the treatment
of epilepsy and bipolar disorder.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 410.

Question 10

What is carbamazepine’s mechanism of action?

Answer 10

Carbamazepine (Tegretol) blocks sodium channels and inhibits
high-frequency neuronal firing. It also decreases synaptic
transmission.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 409-410.

Question 11

How is carbamazepine administered?

Answer 11

Carbamazepine can only be administered orally.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 11th ed. New York: McGraw-Hill; 2009: 406.

Question 12

What are the most common adverse effects

associated with carbamazepine?

Answer 12

Ataxia and diplopia, both of which are considered to be doserelated.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 410.

Question 13

What is the mechanism of action of Lamotrigine?

Answer 13

Lamotrigine exerts its effects through the depression of rapidly
firing neurons, it decreases the release of glutamate at
synapses, and it also inactivates sodium channels.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 414.

Question 14

List the adverse effects of Lamotrigine.

Answer 14

Nausea, diplopia, dizziness, headache, skin rash, and
somnolence.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 414.

Question 15

How does gabapentin exert its antiepileptic effects?

Answer 15

It decreases the release of glutamate from synapses.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 413.

Question 16

What are the most common adverse effects seen

with the use of gabapentin?

Answer 16

Dizziness, tremor, headache, ataxia, and somnolence
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 413.

Question 17

Does gabapentin cause enzyme induction?

Answer 17

No. Unlike other anticonvulsants, gabapentin does not cause
enzyme induction.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 413.

Question 18

What is the most significant adverse effect of the

antiseizure medication valproate?

Answer 18

It can produce hepatotoxicity. The risk is highest in patients
under 2 years of age and patients taking multiple medications.
Liver enzymes should be monitored closely in patients taking
valproate.
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 419.

Question 19

What is the therapeutic blood level of phenobarbital?

Answer 19

10 mcg/ml to 40 mcg/ml
Katzung BG, Masters, SB, & Trevor AJ. Basic and Clinical
Pharmacology. 12th ed. New York: McGraw-Hill; 2012: 411.