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Chapter 10: Drugs to Treat Myasthenia Gravis and Alzheimer’s Disease

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Chapter 10: Drugs to Treat Myasthenia Gravis and Alzheimer’s Disease

12 problems · 0 figures

Case Study 10.2.1 §10.2 source ↗

Table 10.4 in the book ↗
Vital Signs Physical Examination
Temperature: 98.2°F

• Head, eyes, ears, nose, and throat (HEENT): Normocephalic, left eyelid droop, minimal facial expressions. Ears, nose, and throat unremarkable. Vision 20/25 in both eyes via Snellen chart. Near vision poor using Rosenbaum card.

• Cardiovascular: Audible S1, S2. Rhythm regular. No murmurs, rubs, or gallops. No peripheral edema bilaterally. Radial and dorsalis pedis pulses 2+.

• Respiratory: Lungs clear bilaterally in all fields.

• GI: Abdomen round, soft, and nontender. Bowel sounds present in all four quadrants.

• Musculoskeletal: Limited range of movement (ROM) in bilateral upper extremities and 3/5 muscle strength. Lower extremities with full ROM and 5/5 muscle strength.
Heart rate: 72 beats/min
Respiratory rate: 18 breaths/min
Blood pressure: 112/64 mm Hg
Oxygen saturation: 96% on room air
Height: 5'6"
Weight: 138 lb

Read the following clinical scenario to answer the questions that follow.

Rae Lennon is a 38-year-old assistant professor at a small university. In November, they noticed that their vision was blurry, especially when grading papers. Rae said that they were seeing double. At first, they just assumed they were tired because their sleeping pattern had changed over the past 2 weeks and they were not getting enough sleep.

About a month after that, while drying their hair, Rae observed their left eyelid was drooping and it was becoming difficult to hold the hairdryer due to weakness in the arms. Over the Christmas break, Rae visited the primary care provider, who referred Rae to a local neurologist based on the symptoms. During Rae’s appointment with the neurologist, a thorough history and physical assessment were carried out. In addition, blood tests results revealed elevated levels of acetylcholine receptor antibodies. Based on these results, Rae was diagnosed with MG.

History
Overactive bladder

Current Medications
Oxybutynin 5 mg, 4 times daily

Which class of medication will the neurologist prescribe Rae to improve their symptoms?
  1. a.
    Cholinergic agonist
  2. b.
    Cholinergic antagonist
  3. c.
    Indirect-acting reversible cholinesterase inhibitor
  4. d.
    Indirect-acting irreversible cholinesterase inhibitor

Answer

C. Indirect-acting reversible cholinesterase inhibitor
These drugs prevent the enzyme cholinesterase from breaking down ACh, allowing more of this neurotransmitter to accumulate in the synapses and continuing to stimulate the cholinergic receptors at the NMJ. This stimulation causes increased skeletal muscle contraction.

Case Study 10.2.2 §10.2 source ↗

Table 10.4 in the book ↗
Vital Signs Physical Examination
Temperature: 98.2°F

• Head, eyes, ears, nose, and throat (HEENT): Normocephalic, left eyelid droop, minimal facial expressions. Ears, nose, and throat unremarkable. Vision 20/25 in both eyes via Snellen chart. Near vision poor using Rosenbaum card.

• Cardiovascular: Audible S1, S2. Rhythm regular. No murmurs, rubs, or gallops. No peripheral edema bilaterally. Radial and dorsalis pedis pulses 2+.

• Respiratory: Lungs clear bilaterally in all fields.

• GI: Abdomen round, soft, and nontender. Bowel sounds present in all four quadrants.

• Musculoskeletal: Limited range of movement (ROM) in bilateral upper extremities and 3/5 muscle strength. Lower extremities with full ROM and 5/5 muscle strength.
Heart rate: 72 beats/min
Respiratory rate: 18 breaths/min
Blood pressure: 112/64 mm Hg
Oxygen saturation: 96% on room air
Height: 5'6"
Weight: 138 lb

Read the following clinical scenario to answer the questions that follow.

Rae Lennon is a 38-year-old assistant professor at a small university. In November, they noticed that their vision was blurry, especially when grading papers. Rae said that they were seeing double. At first, they just assumed they were tired because their sleeping pattern had changed over the past 2 weeks and they were not getting enough sleep.

About a month after that, while drying their hair, Rae observed their left eyelid was drooping and it was becoming difficult to hold the hairdryer due to weakness in the arms. Over the Christmas break, Rae visited the primary care provider, who referred Rae to a local neurologist based on the symptoms. During Rae’s appointment with the neurologist, a thorough history and physical assessment were carried out. In addition, blood tests results revealed elevated levels of acetylcholine receptor antibodies. Based on these results, Rae was diagnosed with MG.

History
Overactive bladder

Current Medications
Oxybutynin 5 mg, 4 times daily

What is the main cause of this disease?
  1. a.
    Abnormal tau protein and neurofibrillary tangles
  2. b.
    Antibodies attacking the nicotinicN receptors
  3. c.
    Beta-amyloid plaques and oxidative stress
  4. d.
    Destruction of the myelin sheath

Answer

B. Antibodies attacking the nicotinicN receptors
MG is an autoimmune disease in which the client produces antibodies that destroy functional receptors at the NMJ, causing muscle weakness.

10-1 §10.RQ source ↗

Donepezil is an acetylcholinesterase (AChE) inhibitor. Which of the following is consistent with the action of this drug?
  1. a.
    The drug is used to treat mild and severe forms of Alzheimer’s disease.
  2. b.
    The drug cannot cross the blood–brain barrier.
  3. c.
    The drug must be taken 30 minutes before meals.
  4. d.
    The drug requires twice-daily dosing due to a short half-life.

Answer

A. The drug is used to treat mild and severe forms of Alzheimer’s disease.
The drug will cross the blood–brain barrier, has a 70-hour half-life, and is unaffected by oral intake.

10-2 §10.RQ source ↗

In Alzheimer’s disease, which pharmacologic action within the brain will reduce the symptoms seen with this progressive disease?
  1. a.
    Decreased sensitivity of cholinergic receptors on the postsynaptic neuron
  2. b.
    Decreased action of acetylcholinesterase (AChE)
  3. c.
    Inhibition of the release of acetylcholine (ACh) from presynaptic neurons
  4. d.
    Increased amount of available acetylcholinesterase (AChE)

Answer

B. Decreased action of acetylcholinesterase (AChE)
Because a decreased level of ACh is present in this disease, decreasing the action of AChE can help reduce the symptoms because less ACh will be broken down.

10-3 §10.RQ source ↗

A nurse is teaching a 74-year-old client how to properly apply a rivastigmine transdermal patch. Which of the following statements from the client requires additional teaching?
  1. a.
    “The patch needs to be changed weekly.”
  2. b.
    “I should apply the patch over a clean, hairless, and intact area of the skin.”
  3. c.
    “The old patch must be removed before a new patch is put on.”
  4. d.
    “Sites should be rotated and the same site should not be used for 14 days.”

Answer

A. “The patch needs to be changed weekly.”
The patch needs to be changed every 24 hours, not weekly. All the other options are correct statements.

10-4 §10.RQ source ↗

The client asks the nurse how the drug memantine works in the body. What is the nurse’s best response to the client’s question?
  1. a.
    “It inhibits the cholinesterase enzyme so that less ACh will be broken down into choline and acetone.”
  2. b.
    “The drug binds to the magnesium site on the glutamate receptor to slow calcium influx into the cell.”
  3. c.
    “The drug binds directly to the cholinergic receptors and blocks calcium from entering the cell.”
  4. d.
    “It will bind directly to the centrally acting muscarinic receptors to enhance cognitive function.”

Answer

B. “The drug binds to the magnesium site on the glutamate receptor to slow calcium influx into the cell.”
Memantine is an NMDA receptor antagonist. When too much calcium enters the cell, it makes it extremely excitable, interfering with cognition. Too much calcium is toxic. Normally, glutamate binds to the NMDA receptors for a brief period, allowing the calcium channel to open. Glutamate then dissociates from the receptors and magnesium binds to the NMDA receptors, closing the calcium channel and preventing further calcium from entering.

10-5 §10.RQ source ↗

A client taking donepezil has been prescribed a new drug. Which drug prescription should the nurse question?
  1. a.
    Second-generation H1RAs
  2. b.
    Acetaminophen
  3. c.
    Propranolol
  4. d.
    Selective serotonin reuptake inhibitors (SSRIs)

Answer

C. Propranolol
Propranolol is a nonselective beta blocker; therefore, one would be concerned about extremely low heart rate plus bronchoconstriction.

10-6 §10.RQ source ↗

Which AChE inhibitor should be stopped immediately if the client notices a rash?
  1. a.
    Donepezil
  2. b.
    Galantamine
  3. c.
    Pyridostigmine
  4. d.
    Neostigmine

Answer

B. Galantamine
There is a potential for serious and life-threatening skin rashes when using this drug. Stevens–Johnson syndrome, a disorder of the skin and mucous membranes characterized by a painful rash that disseminates, is one example. Blisters form, and eventually the top skin layer will die and shed.

10-7 §10.RQ source ↗

A client has just been diagnosed with mild Alzheimer’s disease. The health care provider prescribes donepezil oral disintegrating tablet 5 mg daily. What key point should the client be taught about how to take this drug?
  1. a.
    “You may crush the pill and mix with food if you have problems swallowing the whole pill.”
  2. b.
    “This medication should only be taken in the morning with your breakfast.”
  3. c.
    “Allow the drug to completely dissolve on your tongue. Do not swallow it whole.”
  4. d.
    “The drug is soft enough that you can chew it if you are afraid of choking.”

Answer

C. “Allow the drug to completely dissolve on your tongue. Do not swallow it whole.”
The drug was prescribed as a disintegrating tablet, so it must completely dissolve on the tongue. It is not to be chewed, crushed, or swallowed whole.

10-8 §10.RQ source ↗

What indicates an optimal dosage of acetylcholinesterase (AChE) inhibitors for clients with myasthenia gravis?
  1. a.
    Muscle relaxation
  2. b.
    Pupil constriction
  3. c.
    Increased intestinal motility
  4. d.
    Increased ability to raise eyelids

Answer

D. Increased ability to raise eyelids
The AChE inhibitors prescribed for myasthenia gravis increase muscle strength and muscle relaxation. Since clients may have drooping of the eyes due to muscle weakness, the ability to raise the eyelids independently is evident of increased muscle strength.

10-9 §10.RQ source ↗

The nurse is assigned to a client with a diagnosis of myasthenia gravis. The client was taking pyridostigmine 1000 mg daily. Due to the exacerbation of their symptoms, the provider increased the dose to 1500 mg daily. What condition should the nurse be assessing?
  1. a.
    Sinus tachycardia
  2. b.
    Hypertension
  3. c.
    Fluid volume deficit
  4. d.
    Fluid volume overload

Answer

C. Fluid volume deficit
Because the client’s dose was increased, they are at risk for cholinergic crisis. This is characterized by increased urine output, diarrhea, vomiting, excess salivation, and diaphoresis.

10-10 §10.RQ source ↗

The nurse should be prepared to administer which drug to a client experiencing a cholinergic drug overdose?
  1. a.
    Epinephrine
  2. b.
    Atropine
  3. c.
    Propranolol
  4. d.
    Pilocarpine

Answer

B. Atropine
If there is cholinergic toxicity, an anticholinergic should be given to counteract the signs and symptoms. For instance, atropine will increase the heart rate and decrease intestinal motility and inhibit contraction of the detrusor muscle.

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Problems and answers are adapted from Pharmacology for Nurses by Tina Barbour-Taylor, Leah Mueller (Sabato), Donna Paris and Dorie Weaver, OpenStax, and are used under the CC BY-NC-SA 4.0 licence. Access for free at https://openstax.org/books/pharmacology/pages/1-introduction. Illustrations: Copyright Rice University, OpenStax, under CC BY-NC-SA 4.0 license. This adaptation is released under the same licence, is non-commercial, and is neither affiliated with nor endorsed by OpenStax or Rice University.