Drug Topics - October 22, 2007 - (Page 27)

27 Alternatively, some researchers theorize that Parkinson’s disease may result from exposure to an environmental toxin or injury. Such exposures to rural living, well-water consumption, and pesticides or herbicides have all been linked to increased risk of Parkinson’s disease. However, there is no conclusive evidence that any one environmental factor can be considered the sole cause of the disease. Most experts agree that Parkinson’s is caused by a combination of genetic and environmental factors. Parkinson’s disease may result from other causes such as brain tumors near the basal ganglia, atherosclerosis of the cerebral blood vessels, or head trauma. Most commonly, however, drugs such as antipsychotics, some antiemetics, and other agents cause clinical manifestations of the disease. (See Table 1.) GOAL To provide pharmacists and technicians with an overview of Parkinson’s disease and the pharmacotherapy involved in its treatment CREDIT This lesson provides two hours of CE credit and requires a passing grade of 70%.* OBJECTIVES Upon completion of the article, pharmacists and technicians should be able to: Describe the etiologies and pathophysiology associated with Parkinson’ s disease (PD) List the common clinical manifestations associated with PD. Compare and contrast the advantages and disadvantages of the available pharmacologic agents for PD Recommend an appropriate drug regimen for a given patient with PD Discuss the pharmacist’ s role in PD *To receive credit you must score 70% or higher on the quiz and complete the evaluation. Upon successful completion, the University of Florida College of Pharmacy will mail Statements of Credit for written quizzes within 10 working days. Participants completing the program on-line may print a Statement of Credit after successfully completing the program. side of the body, but they remain most apparent on the original side of occurrence. While a resting tremor is one of the cardinal symptoms of PD, some may never experience it. One of the most disabling symptoms of Parkinson’s disease is rigidity, or an increase in muscle resistance to passive movement. For example, a person who presents with rigidity may not be able to swing his or her arms when ambulating, have a stooped posture with flexed elbows, and have facial fixity. Rigidity can affect both the distal joints (i.e., elbow, knee, or wrist) and the proximal joints (i.e., neck, shoulders, or hips). If a patient has a coexisting tremor, the smooth plastic nature of rigidity may be broken up by rhythmic catches (“cogwheel” phenomenon). Those without a coexisting tremor will have a lead-pipelike rigidity characterized by inflexibility. Lack of facial expression (hypomimia)—or masklike appearance—may be noticeable and should not be misinterpreted in a Parkinson’s patient as lack of interest, cognitive impairment, or indifference. Rigidity commonly causes aching and muscle cramping, which may be mistaken for arthritis. Akinesia and bradykinesia are defined as absence and slowness of movement, respectively. Movement is often slowed Pathophysiology overview Regardless of the exact etiology, much is known about the resulting primary pathology of Parkinson’s disease. Dopamine is an inhibitory neurotransmitter of acetylcholine, an excitatory neurotransmitter. Dopamine is synthesized and stored in the substantia nigra, then transported to the striatum. Under normal conditions and through a complex sequence of stimulatory and inhibitory neuronal pathways, striatal neurons communicate with neurons of the thalamocortical pathway. However, through mechanisms unknown, there takes place a reduction in striatal dopamine, which leads to overactivity of acetylcholine. The resulting increased cholinergic activity causes the motor movement complications associated with Parkinson’s disease. Clinical presentation Since the definitive diagnosis of PD is confirmed only during postmortem examination, diagnosis relies solely on one’s clinical presentation. However, the symptoms do not become apparent until 70%-80% of the dopamine-producing cells in the substantia nigra are depleted. Four cardinal features characterize PD: a resting tremor, akinesia or bradykinesia, muscle rigidity, and postural instability. While these symptoms alone are rather nonspecific, in combination they constitute parkinsonism. One way to remember these symptoms is through the use of the acronym TRAP (tremors, rigidity, akinesia/bradykinesia, and postural instability). Initially, the symptoms vary in combination and typically begin unilaterally, but as the disease progresses, the symptoms become bilateral. Additional characteristics include ‘freezing” and nonmotor symptoms. A unilateral tremor in the hand or foot is the first presenting symptom in about 70% of those diagnosed with PD. It is commonly referred to as a “resting tremor” because it becomes visible only when a person’s muscles are relaxed or in stressful situations and usually subsides when the person performs a purposeful movement. Often, hand tremors cause a back-andforth rubbing of a patient’s thumb and forefinger referred to as “pill-rolling.” While the hands and feet are most commonly affected, the jaw, forearms, and legs may also be involved. In the later stages of the disease, the tremors may spread to the other

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Drug Topics - October 22, 2007 Contents Latebreakers Legislative Victory Builds Momentum for Pharmacy Month Letters Health-System Edition R.Ph.s Brace for Payment Denial for Hospital-Acquired Conditions Topical Human Thrombin Helps Arrest Bleeding FDA Panels Fail to Set Target Levels for Renal Patients’ Hemoglobin Warning Letters Raise Patient Safety Concerns for Fentora Ending/Reversing Weight Gain Man Given Fatal Drug Overdose at Staten Island Hospital Pharmacists Playing More Important Role in Dialysis Treatment AHA President R.Ph.'s Here's How You Can Increase Your Value Premier Launches Comprehensive Quality Improvement Project FDA Approves Dexrazoxane for Treatment of Extravasation New Federal, State Reforms to Ease Disaster Relief Kinks 150 Years of American Pharmacy Ten Tips for MTM Success Independent Superstars: The Ones to Watch The New Dynamic Duo A Parkinson's Disease Primer Classified New Products Advertisers Index Viewpoint

Drug Topics - October 22, 2007

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