1. Drugs for Neurologic Disorders: Parkinsonism and Alzheimer’s Disease
Chapter 23
Drugs for Neurologic Disorders: Parkinsonism and Alzheimer’s Disease
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2. Parkinsonism Pathophysiology Chronic neurologic disorder
Imbalance of the neurotransmitters dopamine (DA) and acetylcholine (ACh)
Marked by degeneration of neurons of the extrapyramidal motor tract
Reason for the degeneration of neurons is unknown.
Dopamine: an inhibitory neurotransmitter
Acetylcholine: an excitatory neurotransmitter
Dopamine normally maintains control of acetylcholine and inhibits its excitatory response.
In Parkinson’s disease, there is an unexplained degeneration of dopaminergic neurons, and an imbalance between dopamine and acetylcholine occurs.
With less dopamine production, acetylcholine is unopposed, causing excitation and stimulation of neurons that release gamma-aminobutyric acid (GABA).
With increased stimulation of GABA, symptomatic movement disorders occur.
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3. Parkinsonism (Cont.) Characteristics Tremors of head and neck
Rigidity (increased muscle tone)
Bradykinesia (slow movement)
Postural changes
Head and chest thrown forward
Shuffling walk
Lack of facial expression
Pill-rolling motion of hands
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4. Parkinsonism (Cont.) Treatment regimen Anticholinergics Dopaminergics
Block cholinergic receptors
Dopaminergics
Convert to dopamine
Dopamine agonists
Stimulate dopamine receptors
MAO-B inhibitors
Inhibit MAO-B enzyme that interferes with dopamine
COMT inhibitors
Inhibit COMT enzyme that inactivates dopamine
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5. Antiparkinsonism Drugs
Anticholinergics
Parasympatholytic–inhibit the release of acetylcholine
Benztropine (Cogentin)
Trihexyphenidyl HCl (Artane)
Biperiden (Akineton)
Action: inhibit release of acetylcholine
Reduce the rigidity and some of the tremors characteristic of parkinsonism
Minimal effect on bradykinesia
Used to treat drug-induced parkinsonism, or pseudoparkinsonism
Anticholinergics are parasympatholytics that inhibit the release of acetylcholine.
They are said to treat drug-induced parkinsonism (pseudoparkinsonism).
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6. Antiparkinsonism Drugs (Cont.)
Anticholinergics
Nursing Interventions
Monitor vital signs.
Monitor urine output for early detection of urinary retention.
Increase fluid intake, fiber, and exercise to avoid constipation.
Observe for involuntary movements.
Advise patient to avoid alcohol, cigarettes, caffeine, and aspirin to decrease gastric acidity.
Encourage patient to relieve dry mouth with ice chips, hard candy, or sugarless chewing gum.
Suggest use of sunglasses for photophobia.
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7. Nursing Process: Antiparkinson: Anticholinergic Agent
Assessment
Nursing diagnosis
Planning
Nursing interventions
Patient teaching
Cultural considerations
Evaluation
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8. Antiparkinsonism Drugs (Cont.)
Dopaminergics
Carbidopa-levodopa (Sinemet)
Action: converted to dopamine
Increases mobility
Side effects
Fatigue, insomnia
Dry mouth
Blurred vision
Orthostatic hypotension, palpitations, dysrhythmias
Urinary retention
Nausea, vomiting
Dyskinesia, psychosis, severe depression
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9. Dopaminergics Carbidopa-levodopa (Sinemet) Drug interactions
Decrease levodopa effect with:
Anticholinergics
Phenytoin
Tricyclic antidepressants
MAO inhibitors
Benzodiazepines
Phenothiazines
Vitamin B6
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10. Dopaminergics (Cont.) Carbidopa-levodopa Function Advantages
A, When levodopa is used alone, only 1% reaches the brain because 99% converts to dopamine while in the peripheral nervous system. B, By combining carbidopa with levodopa, carbidopa can inhibit the enzyme decarboxylase in the periphery, thereby allowing more levodopa to reach the brain.
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11. Dopamine Agonists Amantadine (Symmetrel)
Also antiviral drug for influenza A
Action
Stimulates dopamine receptors
Taken alone or in combination with levodopa or anticholinergic
Use
Early treatment of parkinsonism as drug tolerance develops
Improvement of symptoms
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12. Antiparkinsonism Drugs (Cont.)
Nursing interventions
Monitor for orthostatic hypotension.
Administer drug with low-protein foods.
Avoid vitamin B6, alcohol, other depressants.
Do not abruptly discontinue.
Warn of harmless brown discoloration of urine and sweat.
Assess for suicidal tendencies.
Assess symptom status and “on-off” phenomenon.
Monitor blood cell counts, liver and kidney function.
Drug may be taken with low-protein foods to decrease GI upset.
Food does slow drug absorption.
High-protein foods interfere with drug transport to CNS.
Foods high in vitamin B6 include lima, navy, kidney beans; cereals.
Vitamin B6 inhibits conversion of levodopa to dopamine.
A conservative amount of vitamin B6 is needed to prevent vitamin B6 deficiency (peripheral neuritis, muscle weakness).
Abrupt discontinuation may cause rebound parkinsonism.
Urine and perspiration discoloration may stain clothing.
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13. Alzheimer’s Disease Pathophysiology Incurable dementia illness
Chronic, progressive neurodegenerative conditions
Marked cognitive dysfunction
Onset usually occurs between ages 45 and 65 years.
Neuritic plaques form.
Neurofibrillary tangles are in neurons.
Cholinergic neurotransmitter abnormality
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14. Alzheimer’s Disease (Cont.)
Pathophysiology
Histologic changes
Histologic changes in Alzheimer’s disease. A, Healthy neuron. B, Neuron affected by Alzheimer’s disease showing characteristic neuritic plaques and cellular neurofibrillary tangles.
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15. Alzheimer’s Disease (Cont.)
Symptoms
Memory loss
Confusion
Inability to communicate
Aggressive behavior
Depression
Psychoses
Progression to loss of memory, logical thinking, and judgment; time disorientation; personality changes; hyperactivity; tendency to wander; inability to express oneself; and later hostility, paranoia
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16. Acetylcholinesterase Inhibitors/Cholinesterase Inhibitors
Tacrine (Cognex), donepezil (Aricept), rivastigmine (Exelon), galantamine (Razadyne)
Action
Allow more acetylcholine in neuron receptors
Increase cognitive function
Use
Mild to moderate Alzheimer’s disease
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17. Acetylcholinesterase Inhibitors/Cholinesterase Inhibitors
Rivastigmine (Exelon)
AChE inhibitor
Prescribed to improve cognitive function for patients with mild to moderate Alzheimer’s disease
Increases the amount of ACh at the cholinergic synapses
Slows the disease process
Fewer drug interactions than donepezil and tacrine
Refer to Table 23-5, Acetylcholinesterase (AChE) Inhibitors for Alzheimer’s Disease.
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18. Acetylcholinesterase Inhibitors/Cholinesterase Inhibitors
Rivastigmine (Exelon)
Side effects: Anorexia, nausea, vomiting, diarrhea, constipation, abdominal pain, GI bleeding, dizziness, depression, peripheral edema, dry mouth, dehydration, restless legs syndrome, nystagmus
Adverse reactions: seizures, bradycardia, orthostatic hypotension, cataracts, myocardial infarction, heart failure
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19. Nursing Process: Rivastigmine (Exelon)
Assessment
Nursing diagnosis
Planning
Nursing interventions
Patient teaching
Cultural considerations
Evaluation
Safety when wandering: remove obstacles from patient’s path so that patient can avoid injury.
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20. Case Study
A patient has been diagnosed with Alzheimer’s disease. The patient’s daughter asks the nurse what the cause of Alzheimer’s disease is. The best response by the nurse is “The cause of Alzheimer’s disease is
a virus.”
a cancer.”
unknown.”
normal aging.”
Answer: C
Rationale: The cause of Alzheimer's disease is unknown.
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21. Case Study
The patient is prescribed rivastigmine (Exelon). The patient’s son wants to know how many times a day his father will need to take this medication. The nurse informs the son that Exelon is usually taken how many times a day? 1 2 3 4
Answer: B
Rationale: Exelon is usually taken twice a day.
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22. Case Study
The nurse should teach the patient’s family to administer the Exelon
without food.
with meals.
at 3:00 am and 3:00 pm.
when the patient is acting most confused.
Answer: A
Rationale: Food decreases absorption rate of Exelon, so it is best administered without food.
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23. Practice Question #1
Which comment to the nurse indicates more teaching is needed for a patient taking carbidopa/levodopa?
“I know I need to take this drug once a day.”
“I know I shouldn’t stop taking this drug abruptly.”
“I understand my urine may become dark and discolored.”
“I know it may take a few weeks or months to control my symptoms.”
Answer: A
Rationale: A statement from the patient such as “I know I need to take this drug once a day” indicates that more teaching is needed because carbidopa/levodopa has a short half-life and must be taken 3 or 4 times per day. The other answers are true.
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24. Practice Question #2
Which side effect/adverse effect of carbidopa/levodopa does the nurse realize is most important to monitor?
Dysphagia
Increased libido
Agranulocytosis
Urinary retention
Answer: C
Rationale: It is most important for the nurse to monitor the patient taking carbidopa/levodopa for agranulocytosis (decreased white blood cells), which is life-threatening. Dysphagia, increased libido, and urinary retention are not life-threatening.
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25. Practice Question #3
Before administering carbidopa-levodopa (Sinemet) for the treatment of parkinsonism, it is most important for the nurse to assess the patient for a history of
pulmonary disease.
diabetes mellitus.
allergy to penicillin.
glaucoma.
Answer: D
Rationale: Contraindications to therapy include narrow-angle glaucoma; severe cardiac, renal, hepatic disease; and suspicious skin lesions (activates malignant melanoma).
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26. Practice Question #4
A patient with Parkinson’s disease is being treated with carbidopa-levodopa (Sinemet). The patient asks the nurse why he needs both agents. The nurse responds,
“The two medicines together are doubly effective.”
“This combination has fewer side effects.”
“You’ll tolerate this better than a single-agent medication.”
“The carbidopa helps the levodopa reach the brain.”
Answer: D
Rationale: Because of the side effects of levodopa and the fact that so much levodopa is metabolized before reaching the brain, an alternative drug, carbidopa, was developed to inhibit the enzyme dopa decarboxylase. By inhibiting the enzyme in the peripheral nervous system, levodopa reaches the brain. The carbidopa is combined with levodopa in a ratio of 1 part carbidopa to 10 parts levodopa.
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27. Practice Question #5
A nurse at an adult day care center notes that many patients are on rivastigmine (Exelon). The nurse knows that the function of this medication is to
increase physical mobility.
cure Alzheimer’s disease.
slow the progression of symptoms of Alzheimer’s disease.
restore full memory to the patients.
Answer: C
Rationale: Rivastigmine tends to slow the disease process. There is no known cure for Alzheimer’s disease.
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.