Central Nervous System Pharmacology Part 2

Front 1

What are the main mechanisms of action of antiepileptic drugs?

Back 1

-to limit sustained repetitive firing of neurons by slowing the rate of recover in sodium channels.
-by enhancing GABA-mediated synaptic inhibition.
-by limiting the activation of calcium channels.

Front 2

This drug helps prevent seizures without producing general CNS depression.

Back 2

Phenytoin.

Front 3

What order of elimination does phenytoin have at a therapeutic concentration?

Back 3

Zero-order elimination kinetic at therapeutic concentrations.

Front 4

Acute toxicity of this drug after oral administration results in ataxia, nystagmus, drowsiness, and diplopia.

Back 4

Phenytoin.

Front 5

Acute toxicity of this drug after rapid IV infusion can result in cardiovascular collapse and/or CNS depression.

Back 5

Phenytoin.

Front 6

What is Fosphenytoin?

Back 6

A soluble pro-drug of phenytoin, that decreases, but does not eliminate, acute IV phenytoin toxicity.

Front 7

Chronic toxicity of this drug is characterized by behavioral changes, gingival hyperplasia, GI-disturbances, megaloblastic anemia, hirsutism, depression of serum folate and vitamin K levels.

Back 7

Phenytoin.

Front 8

What type of seizures is phenytoin effective for?

Back 8

All types except absence seiaures.

Front 9

How does phenobarbital work to prevent seizures?

Back 9

Phenobarbital's activity can be achieved at doses lower than those that cause sedative or hypnotic activities. Phenobarbital potentiates GABA inhibitory transmission and decreases glutamate excitation, elevates the seizure threshold, and limits the seizure spread.

Front 10

What is the half-life of phenobarbital?

Back 10

3-4 days.

Front 11

What effect does phenobarbital have on anesthesia and other CNS depressants?

Back 11

Has an additive effect, prolonging sedation, etc..

Front 12

What type of seizures can be treated with phenobarbital?

Back 12

Grand mal, psychomotor, and focal seizures.

Front 13

This drug is structurally and pharmacologically similar to phenobarbital but is less potent?

Back 13

Primidone.

Front 14

What are some adverse effects of carbamazepine?

Back 14

Diplopia, blurred vision, drowsiness, dizziness, nausea, vomiting, ataxia, liver toxicity, blood dyscrasias, skin reactions, including STEVENS-JOHNSON SYNDROME

Front 15

What type of seizures is carbamazepine used for?

Back 15

Psychomotor, grand mal, and cortical focal seizures.
Also used for neuropathic pain, bipolar disorder.

Front 16

This is a newer drug that is chemically similar to carbamazepine except it is less likely to cause severe skin reactions and hematologic toxicity?

Back 16

Oxcarbazepine.

Front 17

Ethosuximide is used to treat what type of seizures?

Back 17

Commonly used to treat absence seizures.

Front 18

What is the mechanism of action of ethosuximide?

Back 18

Ethosuximide increases neuronal refractory period by decreasing the conductance in calcium channels.

Front 19

What is the half-life of Ethosuximide?

Back 19

About 30 hours in children and about 60 hours in adults.

Front 20

What are the signs and symptoms of ethosuximide toxicity?

Back 20

Nausea, vomiting, and drowsiness are all dose-related. Parkinsonism, blood dyscrasias, urticaria, and Stevens-Johnson syndrome.

Front 21

This drug is used in patients who don't respond to any drug, regardless of seizure type?

Back 21

Valproic Acid.

Front 22

What is the mechanism of action of valproic acid?

Back 22

Valproic acid works via several mechanisms. Valproic acid blocks the recovery in sodium channels, hyperpolarizes cells via an action on potassium channels and perhaps by acting on the GABA systems.

Front 23

What if valproic acid is combined with other anticonvulsants?

Back 23

Valproate inhibits the metabolism of phenobarbital, carbamazepine, and ethosuximide.

Front 24

Name 4 benzodiazepines.

Back 24

Diazepam, clonazepam, lorazepam, chlorazepate.

Front 25

What is believed to be the mechanism of action of benzo's?

Back 25

May facilitate GABA-mediated pre and post synaptic inhibition.

Front 26

These two benzo's are preferred for status epilepticus?

Back 26

Diazepam or lorazepam.

Front 27

This benzo is used for akinetic, myoclonic, and absence seizures.

Back 27

Clonazepam.

Front 28

This benzo is used as an adjunct for treatment of complex partial seizures.

Back 28

Chlorazepate.

Front 29

This is a new drug that was approved for use in adults with partial seizures and in children with seizures associated with Lennox-Gastaut Syndrome.

Back 29

Felbamate.

Front 30

Lamotrigine, gabapentin, topiramate, tiagabine, zonisamide, and levetiracetam have all been approved for what?

Back 30

Add-on/adjunct treatment of partial seizures.

Front 31

This adjunct to partial seizure treatment should be avoided in patients allergic to sulfonamides.

Back 31

Zonisamide.

Front 32

This adjunct to partial seizure treatment is also effective in the treatment of neuropathic pain and possibly effective in a variety of other neurologic conditions.

Back 32

Gabapentin.

Front 33

What is the mechanism of action of lamotrigene?

Back 33

Acts by slowing the recovery in sodium channels and perhaps by inhibiting glutamate release.

Front 34

Name two other possible uses for topiramate.

Back 34

Treatment of tremors and prevention of migraines.

Front 35

What is the mechanism of action of tiagabine?

Back 35

Tiagabine acts by inhibiting the reuptake of GABA.

Front 36

The most common side effects of this drug include: weakness, diplopia, ataxia, nausea, irritability, life-threatening rash, Stevens-Johnson syndrome.

Back 36

Lamotrigene.

Front 37

What are the adverse reactions of gabapentin?

Back 37

Somnolence, dizziness, ataxia, fatigue, and nystagmus.

Front 38

Adverse reactions of this drug include: difficulty concentrating, drowsiness, dizziness, ataxia, and an increase in the incidence of kidney stones. It also inhibits carbonic anhydrase and metabolic acidosis may result.

Back 38

Topiramate.

Front 39

What are the adverse reactions to tiagabine?

Back 39

cognitive problems, dizziness, headache, somnolence, tremor, and depression.

Front 40

This drug may cause somnolence, asthenia, agitation, depression, or psychosis.

Back 40

Levetiracetam.

Front 41

The most common side effects of this drug include: weakness, diplopia, ataxia, nausea, irritability, life-threatening rash, Stevens-Johnson syndrome.

Back 41

Lamotrigene.

Front 42

What are the adverse reactions of gabapentin?

Back 42

Somnolence, dizziness, ataxia, fatigue, and nystagmus.

Front 43

Adverse reactions of this drug include: difficulty concentrating, drowsiness, dizziness, ataxia, and an increase in the incidence of kidney stones. It also inhibits carbonic anhydrase and metabolic acidosis may result.

Back 43

Topiramate.

Front 44

What are the adverse reactions to tiagabine?

Back 44

cognitive problems, dizziness, headache, somnolence, tremor, and depression.

Front 45

This drug may cause somnolence, asthenia, agitation, depression, or psychosis.

Back 45

Levetiracetam.

Front 46

Define status epilepticus.

Back 46

A state of continuous seizure activity without recovery of consciousness. Some causes include sudden withdraw of CNS depressants or antiepileptic agents, or drug poisoning.

Front 47

When is multiple drug therapy warranted?

Back 47

Only if more than one seizure type is present or a single drug fails to provide adequate control at a near toxic level.

Front 48

True/False: The therapeutic concentration of most anticonvulsant drugs is close to toxic level?

Back 48

True.

Front 49

Are antiepileptic safe for use during pregnancy?

Back 49

No. There is an increased incidence of birth defects associated with several antiepileptic drugs.

Front 50

What is the goal of anticonvulsant therapy in the pregnant patient?

Back 50

Drug therapy should be aimed at the lowest dosage consistent with seizure control and supplementary vitamin K and folic acid are required for both the newborn and the pregnant mother.