Ppt chapter029

Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins

Introduction to Clinical Pharmacology

Chapter 29-Antiparkinsonism Drugs


Dopaminergic Drugs: Actions Dopaminergic Drugs: Actions

• Symptoms of parkinsonism are caused by depletion of dopamine in CNS

• Amantadine: make more of dopamine available at receptor site; Selegiline: inhibits monoamine oxidase type B, again making more dopamine available

• Combining levodopa with another drug allows more levodopa to reach brain hence provide better pharmacologic effect in patients with Parkinson’s disease

change "patient" to "client"


Dopaminergic Drugs: Uses Dopaminergic Drugs: Uses

• Dopaminergic drugs are used to treat:

– Parkinson’s disease

– Parkinson-like symptoms as a result of injury, drug therapy, or encephalitis

– Restless leg syndrome

– Viral infections


Dopaminergic Drugs: Adverse Reactions, Contraindications, and PrecautionDopaminergic Drugs: Adverse Reactions, Contraindications, and Precaution

• Dry mouth, difficulty in swallowing, anorexia, nausea, and vomiting, abdominal pain, constipation, increased hand tremor headache, dizziness

• Adverse reactions seen with levodopa: choreiform movements, dystonic movements

• Contraindications:

– Dopaminergic drugs: Patients with known hypersensitivity to the drugs



Dopaminergic Drugs: Adverse Reaction Contraindications And Precautions (cont’d)

Dopaminergic Drugs: Adverse Reaction Contraindications And Precautions (cont’d)

– Levodopa: Patients with narrow-angle glaucoma, and those receiving MAOI antidepressants

• Precautions:

– Levodopa is used cautiously in patients with cardiovascular or pulmonary diseases; peptic ulcer disease; renal or hepatic disease; and psychosis

– Dopamine agonist, selegiline, should not be used with opioid meperidine due to antimetabolite conversion



Dopaminergic Drugs: InteractionsDopaminergic Drugs: Interactions

Interactant Drug Effect of Interaction

Tricyclic antidepressants Increased risk of hypertension and dyskinesia

Antacids Increased effect of levodopa

Anticonvulsants Decreased effect of levodopa


Cholinergic Blocking Drugs Anticholinergics: Actions Cholinergic Blocking Drugs Anticholinergics: Actions

• Drugs with cholinergic blocking activity, block Ach in CNS enhancing dopamine transmission

• Antihistimines, such as diphenhydramine are used in elderly patients as they produce fewer adverse effects

change "patient" to 'client"


Cholinergic Blocking Drugs Anticholinergics: Uses and Adverse Reactions

Cholinergic Blocking Drugs Anticholinergics: Uses and Adverse Reactions• Uses:

– Used as adjunctive therapy in all forms of parkinsonism and in control of drug-induced extrapyramidal disorders

• Adverse Reactions:

– Dry mouth; blurred vision; dizziness; mild nausea; nervousness; skin rash; urticaria; urinary retention; dysuria; tachycardia; muscle weakness; disorientation; confusion


Cholinergic Blocking Drugs Anticholinergics: Contraindications and PrecautionsCholinergic Blocking Drugs Anticholinergics: Contraindications and Precautions

• Contraindicated in patients :

– With hypersensitivity to anticholinergic drugs; those with glaucoma; pyloric or duodenal obstruction; peptic ulcers; prostatic hypertrophy; achalasia; myasthenia gravis; megacolon

• Used with caution in patients with:

– Tachycardia; cardiac arrhythmias; hypertension; hypotension; those with a tendency toward urinary retention; those with decreased liver or kidney function; with obstructive disease of urinary system or gastrointestinal tract



Cholinergic Blocking Drugs Anticholinergics: InteractionsCholinergic Blocking Drugs Anticholinergics: Interactions

Interactant drug Effect of interaction

Amantadine Increasedanticholinergic effects

Digoxin Increased digoxin serum levels

Haloperidol Increased psychotic behavior

Phenothiazines Increased anticholinergic effects


COMT Inhibitors: Actions and Uses COMT Inhibitors: Actions and Uses

• Actions:

– Prolong the effect of levodopa by blocking an enzyme, catechol-O-methyltransferase, which eliminates dopamine

– With levodopa- increased plasma concentration and duration of action of levodopa

• Uses:

– COMT inhibitors are used as adjuncts to levodopa/carbidopa in treating Parkinson’s disease


COMT Inhibitors: Adverse Reactions, Contraindications And Precautions COMT Inhibitors: Adverse Reactions, Contraindications And Precautions

• Dizziness, dyskinesias, hyperkinesias, nausea, anorexia, and diarrhea, orthostatic hypotension, sleep disorders, excessive dreaming, somnolence, and muscle cramps, liver failure

• Contraindicated: Patients with hypersensitivity to drugs, during pregnancy and lactation

• Caution: Patients with hypertension; hypotension; decreased hepatic or renal function



COMT Inhibitors: InteractionsCOMT Inhibitors: Interactions

Interactant Drug Effect of Interaction

MAOI antidepressants Increased risk of toxicity of both drugs

Adrenergic drugs Increased risk of cardiac symptoms


Dopamine Receptor Agonists: Actions and Uses Dopamine Receptor Agonists: Actions and Uses

• Actions:

– Act directly on postsynaptic dopamine receptors of nerve cells in brain, mimicking effects of dopamine in brain

• Uses:

– Used for treatment of signs and symptoms of Parkinson’s disease


Dopamine Receptor Agonists: Adverse Reactions, Contraindication, Precautions Dopamine Receptor Agonists: Adverse Reactions, Contraindication, Precautions

• Nausea; dizziness; vomiting; somnolence; hallucinations; confusion; visual disturbances; postural hypotension; abnormal involuntary movements; headache

• Contraindications: Patients with known hypersensitivity to drugs

• Precautions: Used with caution in patients with: dyskinesia; orthostatic hypotension; hepatic or renal impairment; patients with history of hallucinations or psychosis; cardiovascular disease; renal impairment



Dopamine Receptor Agonists: InteractionsDopamine Receptor Agonists: InteractionsInteractant Drug Effect of Interaction

Cimetidine, ranitidine Increased agonist effectiveness

Verapamil, quinidine Increased agonist effectiveness

Estrogen Increased agonist effectiveness

Phenothiazines Decreased agonist effectiveness


Nursing Process: Assessment Nursing Process: Assessment • Preadministration assessment:

– Obtains health history from family member

– Performs physical assessment of patient to provide baseline for future evaluations of drug therapy

• Ongoing assessment:

– Evaluate patient’s response to drug therapy by observing patients for various neuromuscular signs and compare these observations with data obtained during initial physical assessment



Nursing Process: Planning Nursing Process: Planning

• Expected outcomes for patient may include:

– Optimal response to drug therapy

– Support of patient needs related to management of adverse reactions

– Absence of injury

– Understanding of and compliance with prescribed therapeutic regimen



Nursing Process: Implementation Nursing Process: Implementation

• Promoting an optimal response to therapy:

– Carefully monitor drug therapy; provide psychological support; emphasize patient and family teaching

– Requires titration of doses based on patient activities

– Withhold next dose of drug and immediately notify primary health care provider if sudden behavioral changes are noted



Nursing Process: ImplementationNursing Process: Implementation

• Monitoring and managing patient needs:

– Imbalanced nutrition: Less than bodily requirements

•Help patient relieve dry mouth by offering frequent sips of water, ice chips, or hard candy

•Create calm environment; serve small frequent meals; serve foods patient prefers to help improve nutrition

•Monitor patient’s weight daily




• Monitoring and Managing Patient Needs (cont’d):

– Constipation:

•Observe patient with parkinsonism for outward changes that may indicate one or more adverse reactions

•Stress need for diet high in fiber and increasing fluids in diet




• Monitoring and managing patient needs (cont’d):

– Risk for injury:

•Carefully evaluates any sudden changes in patient’s behavior or activity and reports them to primary health care provider

•Assist patient in getting out of bed or a chair, walking, and other self-care activities




• Monitoring and managing patient needs (cont’d):

– Impaired physical mobility:

• If the symptoms occur primary health care provider may order a drug holiday that includes complete withdrawal of levodopa for 5 to 14 days, followed by gradually restarting drug therapy at lower dose




• Educating the patient and family:

– Evaluate patient’s ability to understand therapeutic drug regimen; ability to perform self-care in the home environment; ability to comply with prescribed drug therapy

– Encourages family to create a home environment that is least likely to result in accidents or falls



Nursing Process: Evaluation Nursing Process: Evaluation

• Therapeutic effect is achieved and the symptoms of parkinsonism are controlled

• Adverse reactions are identified, reported, and managed successfully through appropriate nursing interventions

• No evidence of injury is seen

• Patients verbalizes an understanding of treatment modalities, adverse reactions, and importance of continued follow-up care

• Patients and family demonstrate an understanding of drug regimen



End of Presentation

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Ppt chapter029