McKenna's Pharmacology for Nursing, 2e

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C H A P T E R 2 4 Antiparkinsonism agents

ANTICHOLINERGIC AGENTS Anticholinergics (Table 24.2) are drugs that oppose the effects of acetylcholine at receptor sites in the substantia nigra and the corpus striatum, thus helping to restore chemical balance in the area. Anticholinergics used to treat Parkinson’s disease include benztropine ( Benztrop , • Often, this drug is combined with another drug, which allows the correct levels of levodopa to reach the brain. • People who take this drug must have their individual dose needs adjusted over time. Common effects of this drug include: • Fatigue, weakness and drowsiness : Try to space activities evenly through the day; allow rest periods to avoid give drug with food; administer with carbidopa; have person void before each dose. Provide support and reassurance to deal with disease and drug effects. Instruct the person regarding drug dose, effects and adverse symptoms to report. Evaluation Evaluate drug effects: relief of signs and symptoms of Parkinson’s disease. Monitor for adverse effects: CNS effects; renal changes, urinary retention; GI effects (constipation); increased sweating or flushing. Monitor for drug–drug interactions: hypertensive crisis with MAO inhibitors, decreased effects with vitamin B 6 or phenytoin. Evaluate the effectiveness of the teaching program. Evaluate the effectiveness of comfort and safety measures. TEACHING FOR S.S. • The drug that has been prescribed is called levodopa. It increases the levels of dopamine in the central areas of the brain and helps to reduce the signs and symptoms of Parkinson’s disease.

Cogentin ), biperiden ( Akineton ) (not available in New Zealand) and benzhexol ( Artane ) (not available in New Zealand) . Therapeutic actions and indications The anticholinergics used to treat parkinsonism are syn- thetic drugs that have been developed to have a greater • Tell any doctor, nurse or other healthcare provider involved in your care that you are taking this drug. • Keep this drug and all medications out of the reach of children. • Do not overexert yourself when you begin to feel better. Pace yourself. • Take this drug exactly as directed, and schedule regular medical checkups to evaluate its effects. these side effects. Take safety precautions and avoid driving or operating dangerous machinery if these conditions occur. • Dizziness, fainting : Change position slowly to avoid dizzy spells. • Increased sweating, darkened urine : This is a normal reaction. Avoid very hot environments. • Headaches, difficulty sleeping : These usually pass as the body adjusts to the drug. If they become too uncomfortable and persist, consult with your healthcare provider. • Report any of the following to your healthcare provider: uncontrolled movements of any body part, chest pain or palpitations, depression or mood changes, difficulty in voiding, or severe or persistent nausea and vomiting. • Be aware that vitamin B 6 interferes with the effects of levodopa. If you feel that you need a vitamin product, consult with your healthcare provider about using an agent that does not contain vitamin B 6 . • Avoid eating large quantities of health foods that contain vitamin B 6 , such as grains and brans. If you are taking a carbidopa–levodopa combination, these precautions are not as important.

TABLE 24.2

DRUGS IN FOCUS Anticholinergic agents

Drug name

Dosage/route

Usual indications

benzhexol (Artane)

1–10 mg PO daily in 3–4 divided doses

Adjunctive treatment of parkinsonism and drug-induced extrapyramidal reactions Adjunctive treatment of parkinsonism, and drug-induced parkinsonism resulting from drug effects Adjunctive treatment of parkinsonism, and drug-induced parkinsonism resulting from drug effects

benztropine (Cogentin)

0.5–6 mg/day PO may be needed; 1–2 mg IM or IV; reduce dose in older people

1–4 mg PO t.d.s. or q.i.d

biperiden (Akineton)