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Pathopharm III > Chapter 15: Drugs for Seizures - Prototype Drugs > Flashcards

Chapter 15: Drugs for Seizures - Prototype Drugs Flashcards

1
Q

Barbiturates Prototype Drug

A

phenobarbital

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2
Q

phenobarbital therapeutic class

A

Antiseizure drug; sedative

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3
Q

phenobarbital pharmacologic class

A

Barbiturate; GABA A receptor Agonist

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4
Q

phenobarbital Actions and Uses

A
  • Acts by changing the action of GABA
    –> Long-acting barbiturate
    –>Enhances the action of GABA –>CNS depression –> reduction of abnormal neuronal discharge
  • management of a variety of seizures
  • sleep promotion
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5
Q

phenobarbital Adverse Effects

A
  • Schedule IV drug –> may cause dependence
    Common side effects
    –> drowsiness
    –> vitamin deficiencies (vitamin D; folate (B9); B12
    –> laryngospasms
    OD
    –> Sever respiratory depression
    –> CNS depression
    –> Coma
    –> Death
  • decreased liver and kidney function
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6
Q

phenobarbital Admin Alerts

A
  • Route: IM, IV
  • IM may produce a local inflammatory reaction
  • IV admin is rarely used d/t risk of extravasation
  • Schedule IV drug
  • Pregnancy Category D
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7
Q

phenobarbital Contraindications

A
  • Hypersensitivity to barbiturates
  • Severe uncontrolled pain
  • Pre-existing CNS depression
  • Porphyrias
  • Severe respiratory disease with dyspnea or obstruction
  • Glaucoma
  • Prostatic hypertrophy
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8
Q

Phenobarbital Interactions

A
  • Alcohol or other CNS depressants
  • Phenobarbital increases the metabolism of many other drugs
  • Kava and valerian may potentiate sedation
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9
Q

Phenobarbital Lab tests

A

Barbiturates may affect bromsulphalein tests and increase serum phosphatase

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10
Q

phenobarbital treatment of OD

A
  • No specific treatment
  • Drug removal
    –> gastric lavage
    –> activated charcoal
    –> hemodialysis
  • treatment is supportive
    –> endotracheal intubation and mechanical ventilation
    –> Treatment of bradycardia and hypotension may be necessary
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11
Q

Benzodiazepines Prototype Drug

A

diazepam

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12
Q

diazepam Actions and Uses

A
  • actions similar to that of barbiturates but safer
    –> binds to GABA receptor-chloride channels through the CNS
  • Short-term seizure control
    –> management of a variety of seizures
    –> calming without strong sedation
    –> skeletal muscle relaxation
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13
Q

diazepam Adverse Effects

A
  • tolerance and dependency
    –> reserved for short-term seizure control or status epilepticus
    -IV
    –> Hypotension
    –> Muscular weakness
    –> tachycardia
    –> Respiratory depression
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14
Q

diazepam Admin Alerts

A

PO
- max therapeutic effects may take form 1-2 weeks
- tolerance may develop after about 4 weeks
- take with food to minimize GI upset

IV
- effects occur in minutes
- Anticonvulsant effects last about 20 minutes
- Monitor respirations every 5-15 minutes
- Airway management and resuscitative equipment accessible

  • do not suddenly stop taking
    –> risk of rebound seizures
  • pregnancy category D
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15
Q

Diazepam Contraindications

A

Injectable form
–> shock
–> coma
–> Depressed vital signs
–> Obstetrical patients
–> Infants less than 30 days of age
Tablet form
–> Infants less than 6 months of age
–> Acute narrow-angle glaucoma or untreated open-angle glaucoma
–> within 14 days of MAOI therapy

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16
Q

Diazepam Interactions

A
  • Alcohol or other CNS depressants
  • cimetidine, oral contraceptives, valproic acid, and metoprolol
    –> potentiate diazepam’s actions
    –> Use reliable contraception
  • levodopa and barbiturates
    –> decreases diazepam action
  • Diazepam increases the levels of phenytoin in the bloodstream
  • Kava and chamomile may cause increased drug effect
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17
Q

diazepam lab tests

A
  • serum level
  • liver and kidney function
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18
Q

diazepam treatment of OD

A
  • administer flumazenil
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19
Q

diazepam Patient teaching

A

Avoid
- alcohol
- nicotine
- OTC drugs
- Herbal medications
- Driving and hazardous activities
Immediately report
- signs of toxicity
- unusual bleeding
- signs of liver of bran disease
- heart block
- Hypoglycemia
- pregnancy
- Mood changes or suicidal thoughts

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20
Q

Hydantoins Prototype Drug

A

phenytoin

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21
Q

phenytoin Actions and Uses

A
  • Desensitizing sodium channels in the CNS responsible for neuronal responsivity
    –> prvents spread of disruptive electrical charges that produce seizures
  • Effective against most types of seizures except absence seizures
    Unlabeled use
  • Digitalis-induced dysrhythmias
  • Antidyrhythmic activity similar to lidocain (class IB)
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22
Q

phenytoin Adverse Effects

A
  • Dysrhythmias
  • Severe hypotension
  • Hyperglycemia
  • Severe CNS reactions
  • peripheral neuropathy w/ long term use
  • severe skin reactions - SJS, exfoliative derm
  • connective tissue reactions
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23
Q

What are the routes for phenytoin? (admin alerts)

A

PO and IV

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24
Q

Can you suddenly stop taking phenytoin and what can happen if you do?

A

Do not suddenly stop taking
- risk for rebound seizures

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25
Q

phenytoin Black Box Warning

A

rate of IV admin should not exceed 50 m g/min in adults and 1-3 m g/min (or 50 m g/min, whichever is slower) in pediatric patients because of risk of severe hypotension and cardiac arrhythmias. Careful cardiac monitoring is needed during and after IV admin

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26
Q

What are contraindications for phenytoin?

A
  • Hypersensitivity to hydantoin products
  • Rash
  • seizures d/t hypoglycemia
  • sinus bradycardia
  • heart block
27
Q

What other types of drugs interact with Phenytoin? (interactions)

A
  • oral anticoagulants
  • glucocorticoids
  • Antituberculin drugs
  • folic acid, calcium, and vitamin D
28
Q

Which drugs impair efficacy of phenytoin? (interactions)

A
  • Digitoxin
  • Doxycycline
  • Furosemide
  • Estrogens and oral contraceptives
  • Theophylline
29
Q

which type of antidepressants can trigger seizures when combined with phenytoin? (interactions)

A

tricyclic antidepressants

30
Q

what are some herbal/food interactions with phenytoin? (interactions

A
  • Herbal laxatives may increase potassium loss
  • Ginkgo may reduce therapeutic effectiveness of phenytoin
31
Q

What are some lab tests to watch for with phenytoin? (lab tests)

A
  • dexamethasone or metyrapone test –> lower than normal values
  • glucose, bromsulphalein and alkaline phosphates –> increased serum levels
  • decreased protein-bound iodine and urinary steroid levels
32
Q

why is it important to do blood testing for therapeutic levels of phenytoin? (lab tests)

A

because it has a very narrow range between the therapeutic dose and toxic dose

33
Q

For OD of phenytoin, what are some drug removal methods?

A
  • gastric lavage
  • Activated charcoal
  • Laxatives
34
Q

Is there a specific treatment for phenytoin OD outside of drug removal methods?

A
  • no specific treatment (supportive)
  • maintain airway and breathing
  • monitor blood levels
  • treat adverse symptoms
35
Q

What is the prototype Drug for Phenytoin-like drugs?

A

Valproic acid

36
Q

what is the MOA of valproic acid?

A

It acts to desensitize sodium channels (same as Phenytoin)

37
Q

What type of seizures is valproic acid used for?

A

used for a wide range of seizures including absence seizures, and mixed type seizures

38
Q

What are other uses for valproic acid outside of seizures?

A

migraine headaches and bipolar disorder

39
Q

What are the adverse effects of valproic acid?

A
  • limited CNS depression (sedation, drowsiness)
  • visual disturbances (photosensitivity)
  • vertigo, headache
  • GI effects (abdominal cramps
  • Hepatotoxicity (can be fatal)
  • Pancreatitis
  • Prolonged bleeding time, bone marrow suppression
  • muscle weakness, tremor, psychomotor agitation
  • weight gain
  • rash, alopecia, pruritus, erythema multiforme
40
Q

What is the route for valproic acid?

A

oral

41
Q

What are some admin alerts of valproic acid regarding GI irritation

A
  • do not chew extended-release tablets b/c mouth soreness will occur
  • Do not mix valproic acid syrup with carbonated beverages b/c it will trigger immediate release of drug and result in severe mouth and throat irritation
  • can open capsules and sprinkle on soft foods if patient cant swallow them
42
Q

What pregnancy category is valproic acid?

A

pregnancy category D

43
Q

What are the contraindications for valproic acid?

A
  • hypersensitivity
  • liver disease
  • bleeding dysfunction
  • Pancreatitis
  • congenital metabolic disorders
44
Q

What is the Black Box Warning for valproic acid?

A
  • May result in fatal hepatic failure, especially in children under the age of 2.
  • Nonspecific symptoms often precede hepatic toxicity; weakness, facial edema, anorexia, and vomiting.
  • Liver function tests should be performed before tx and at specific intervals during the first 6 months of tx.
  • valproic acid can produce life-threatening pancreatitis and teratogenic effects including spina bifida.
45
Q

Which drugs increase valproic acid toxicity?

A

aspirin, cimetidine, chlorpromazine, erythromycin, and felbamate

46
Q

which drugs can cause severe bleeding when used with valproic acid?

A

Warfarin, aspirin, or alcohol use

47
Q

which drugs contribute to CNS depression when used with valproic acid?

A

Alcohol, benzodiazepines, and other CNS depressants

48
Q

What drugs serum levels are increased when used with valproic acid?

A

phenobarbital and phenytoin

49
Q

which drugs lower valproic acid levels?

A

Lamotrigine, phenytoin, and rifampin

50
Q

what is the succinimides prototype drug?

A

ethosuximide

51
Q

What is the MOA of ethosuximide

A

Acts by suppressing calcium influx

52
Q

which type of seizure is ethosuximide the preferred drug for?

A

absence seizures

53
Q

which type of seizures are ethosuximide typically ineffective against?

A

psychomotor or tonic-clonic seizures

54
Q

What are possible Adverse effects for ethosuximide

A
  • psychosis or extreme mood swings, including depression with over suicidal intent (more prominent in patients with hx of psychiatric illness)
  • CNS effects - dizziness, headache, lethargy, ataxia, ADD, hiccups
  • Bone marrow suprression and blood dyscrasias - aplastic anemia, Agranulocytosis, Pancytopenia
  • systemic lupus erythematosus (SLE)
  • Gingival hypertrophy, tongue swelling
  • GI Distress and weight loss
55
Q

What is the route for ethosuximide

A

tablet and flavored syrup forms

56
Q

what type of seizures may be induced if ethosuximide is stopped abruptly?

A

tonic-clonic seizures

57
Q

What pregnancy category is ethosuximide

A

preg cat. C

58
Q

What are the contraindications for ethosuximide?

A
  • hypersensitivity
  • severe liver or kidney disease
  • safety in children younger than 3 had not be established
59
Q

Which drugs should you use with caution when taken with ethosuximide?

A

antiseizure medications, phenothiazines, and antidepressants

60
Q

What serum levels does ethosuximide increase

A

phenytoin serum levels

61
Q

which drug causes ethosuximide serum levels to fluctuate?

A

valproic acid

62
Q

which herbal food may reduce the therapeutic effectiveness of ethosuximide?

A

Ginkgo

63
Q

when treating ethosuximide OD, what are the drug removal methods?

A
  • emesis unless the patient is comatose or convulsing
  • gastric lavage
  • activated charcoal or cathartics

Pathopharm III (9 decks)

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