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Ppt chapter029

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  • 1. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Introduction to Clinical Pharmacology Chapter 29- Antiparkinsonism Drugs
  • 2. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 3. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 4. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Dopaminergic 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
  • 5. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 6. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Dopaminergic 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
  • 7. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 8. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 9. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Cholinergic 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
  • 10. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Cholinergic Blocking Drugs Anticholinergics: Interactions Interactant drug Effect of interaction Amantadine Increased anticholinergic effects Digoxin Increased digoxin serum levels Haloperidol Increased psychotic behavior Phenothiazines Increased anticholinergic effects
  • 11. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 12. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 13. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins COMT Inhibitors: Interactions Interactant Drug Effect of Interaction MAOI antidepressants Increased risk of toxicity of both drugs Adrenergic drugs Increased risk of cardiac symptoms
  • 14. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 15. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 16. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Dopamine Receptor Agonists: Interactions Interactant Drug Effect of Interaction Cimetidine, ranitidine Increased agonist effectiveness Verapamil, quinidine Increased agonist effectiveness Estrogen Increased agonist effectiveness Phenothiazines Decreased agonist effectiveness
  • 17. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 18. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 19. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 20. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing 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
  • 21. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing 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
  • 22. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing 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
  • 23. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing 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
  • 24. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins Nursing 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
  • 25. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins 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
  • 26. Copyright © 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins End of Presentation