Download - Ppt chapter029
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Introduction to Clinical Pharmacology
Chapter 29-Antiparkinsonism Drugs
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nursing Process: ImplementationNursing Process: Implementation
• 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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nursing Process: ImplementationNursing Process: Implementation
• 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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nursing Process: ImplementationNursing Process: Implementation
• 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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
Nursing Process: ImplementationNursing Process: Implementation
• 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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
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
Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins
End of Presentation