Anticonvulsants Part 2 (Drugs) Flashcards Preview

Pharmacology > Anticonvulsants Part 2 (Drugs) > Flashcards

Flashcards in Anticonvulsants Part 2 (Drugs) Deck (43)
Loading flashcards...
1
Q

Mechanism of action for carbamazepine (Tegretol)

A

Blocking sodium channels in neurons which blocks propagation of impulses

  • inhibition of high-frequency repetitive firing in neurons
  • decrease in synaptic transmission (presynaptically)
2
Q

Tegretol is highly effective for what seizures?

A

simple and complex partial seizures

3
Q

Other clinical uses for Tegretol

A
  1. Management of bipolar depression
  2. Management of chronic pain
    DENTISTRY: Treatment of trigeminal neuralgia
4
Q

Adverse drug reactions for Tegretol

A
  • CNS effects
  • GI adverse effects
  • Hematologic: causes aplastic anemia (wipes out bone marrow)
  • Dermatologic: rashes, photosensivity, etc.
  • Has potential for inducing serious liver toxicity
  • Congestive heart failure, altered blood pressure
  • XEROSTOMIA
5
Q

Drug interactions of Tegretol

A

“Classic Inducer”
- Decreases effectiveness of warfarin (Coumadin), doxycycline, theophylline (bronchodilator for asthma), oral contraceptives

  • erythromycin-type antibiotics (macrolides) increase carbamazepine blood levels (toxicity)
  • carbamazepine may increase hepatotoxicity of acetaminophen (Tylenol)
6
Q

Mechanism of action for phenytoin (Dilantin)

A

Stabilizes neuronal membranes by decreasing the neuronal membrane passage of sodium ions

  • reduces Na influx and Ca passage through membranes
  • Interferes with calcium mediated release of neurotransmitters
  • Reduces propagation of abnormal impulses in the brain to reduce the frequency of seizures
7
Q

Dilantin is highly effective for what kind of seizures

A
  • all partial seizures (both simple and complex partial)
  • tonic-clonic seizures
  • status epilepticus
8
Q

what is Dilantin not effective against?

A

Absence seizures (petit mal)

9
Q

Dental use of Dilantin

A

trigeminal neuralgia

10
Q

Adverse effects of Dilantin

A

Nausea, vomiting
Loss of taste
Megaloblastic anemia - interferes with B12 metabolism
CNS - confusion, drowsiness, dizziness
Dermatologic: rash, hirsuitism
Vitamin D and folate deficiencies = osteoporosis;
- **FIRST symptom of folate deficiency may be oral mucosal ulceration or glossitis
- *Gyngival hyperplasia - overgrowth of connective tissue

11
Q

Describe more in depth the adverse effect of gingival hyperplasia that Dilantin can have

A

50-60% of patients taking phenytoin experience GH

  • Increased in presence of inflammation
  • **Good oral hygiene reduces extent/severity
  • Slowly regresses after termination of drug therapy
  • May require surgical excision if severe (gingivectomy)
12
Q

Describe the teratogenic effect of Dilantin

A

FDA category D

- Fetal syndrome includes cleft lip, cleft palate, congenital heart disease

13
Q

Describe the drug interactions of Dilantin

A

Many drug interactions

  • phenytoin (Dilantin) causes increases in the metabolism of many drugs
  • Cytochrome P450 “Inducer”
14
Q

Explain the action of GABAmimetic Agents

A

cause release of GABA from presynaptic interneurons

  • encourage GABA fusion with presynaptic neuron
  • **Inhibits the release of acetylcholine from the presynaptic neuron
  • Many seizures are caused by tremendous release of acetylcholine across synapses in cortex
  • GABA = inhibitory neurotransmitter (presynaptically)
15
Q

Mechanism of action for phenobarbital (Luminal)

A

reduces Na and K transport along axonal membranes; potentiates the inhibitory effects of GABA-mediated neurons (GABAmimetic)

16
Q

What is the GENERAL action of Luminal

A

General depressant to CNS

- Limits the spread of seizure discharge in the brain

17
Q

What is the most common barbiturate used as an anticonvulsant?

A

phenobarbital (Luminal sodium)

18
Q

phenobarbital (Luminal sodium) is indicated for what seizure types?

A

tonic-clonic

partial seizure types (both)

19
Q

Most common side effect of phenobarbital (Luminal sodium)

A

Sedation

- Rarely = skin reactions;**Stomatitis may indicate onset of cutaneous reactions, some of which have been fatal

20
Q

Describe the drug interactions of phenobarbital (Luminal sodium)

A

Strong “inducer”
- oral contraceptives, mycins, warfarin

  • Enhances the hepatotoxicity of acetaminophen
  • Additive CNS effects = all CNS depressants, narcotics, alcohol, antidepressants, BDZs = increased risk for respiratory depression
21
Q

Which other anticonvulsant is chemically related to phenobarbital?

A

primidone (Mysoline)

  • primidone metabolized in liver to phenobarbital (precursor to phenobarbital)
  • Much of its actions come from phenobarbital
22
Q

primidone (Mysoline) is used to treat what type of seizures?

A

Partial seizures and tonic-clonic seizures

23
Q

Mechanism of action for valproates?

A

causes increased availability of GABA to neurons

- enhances action of or mimics the effects of GABA presynaptically

24
Q

Valproic acid (Depakene) is used for:

A

Tonic-clonic seizures
Generalized seizures
- Absence (petit mal)
- Myoclonic

25
Q

Adverse reactions to Valproates

A
  • GI
  • CNS effects
  • Hepatotoxicity - not used as often as other drugs; monitor liver function
  • Increases bleeding time= inhibition of platelet aggregation
  • teratogenic
26
Q

Drug interactions with Valproates

A
  • macrolide antibiotics (mycins) = inhibit the metabolism of valproic acid
  • aspirin and other salicylate displace valproic acid from protein-binding sites, leading to acute toxicity
  • additive effect with other CNS depressants
27
Q

What drug is the first choice in absence seizures

A

ethosuximide (Zarontin)

CHILDREN!!!

28
Q

T or F, phenytoin (Dilantin) doesn’t work for absence seizures

A

True

29
Q

Side effects of ethosuximide (Zarontin)

A
  • GI
  • CNS
  • Blood dycrasias
  • Hirsutism
  • Systemic lupus erythematosus
  • *** Oral: gingival hyperplasia; swelling of the tongue
30
Q

clonazepam (Clonipin) is used for what seizures? What is its mechanism of action?

A

Used for ALL types of seizures

- Mechanism of action is unknown

31
Q

What is the drug of choice for local anesthetic induced seizures in dental office

A

diazepam (Valium)

32
Q

Describe mechanism of action of gabapentin (Neurontin)

A

Mechanism is unknown…

- Structurally related to GABA, but does not interact with GABA receptors

33
Q

gabapentin (neurontin) is used for what seizures

A

Partial seizures
tonic-clonic

**Also used for chronic pain; post-herpetic neuralgia (shingles)

34
Q

Main side effect of gabapentin (Neurontin)

A

Oral mucositis

  • Many side effects
35
Q

What is the major advantage of gabapentin (Neurontin)

A

Drug is NOT metabolized

- because it does not affect liver microsomal enzymes, lacks significant drug interactions

36
Q

lamotrigine (Lamictal) is used for what type of seizures?

A

Used for partial seizures and tonic-clonic

37
Q

Mechanism of action for lamotrigine (Lamictal)

A

inhibits the release of glutamate and inhibits voltage-sensitive Na channels, which stabilizes neuronal membranes

-* also weakly inhibits serotonin receptors = used as a part of treatment for bipolar disorder

38
Q

Which drugs is sometimes used before phenytoin to avoid gingival hyperplasia

A

carbamazepine

39
Q

T or F, Seizures may still occur in medicated patients?

A

True, always ask patients when they have had their most recent seizure and if they have known triggers

40
Q

Which drugs are classic P450 inducers?

A

phenytoin (Dilantin) and phenobarbital

41
Q

Liver toxicity is a concern with what drugs

A

carbamazepine (Tegretol) and valproic acid (Depakene) (valproates)

42
Q

T or F, dental light can trigger a seizure

A

True

43
Q

T or F, local anesthetic doesn’t usually have enough effect to trigger a seizure

A

False, it WILL trigger a seizure