Drugs for Neurologic Disorders: Parkinsonism and Alzheimer’s Disease Chapter 23 Drugs for Neurologic Disorders: Parkinsonism and Alzheimer’s Disease Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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). Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Nursing Process: Antiparkinson: Anticholinergic Agent Assessment Nursing diagnosis Planning Nursing interventions Patient teaching Cultural considerations Evaluation Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Dopaminergics Carbidopa-levodopa (Sinemet) Drug interactions Decrease levodopa effect with: Anticholinergics Phenytoin Tricyclic antidepressants MAO inhibitors Benzodiazepines Phenothiazines Vitamin B6 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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). Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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.