Chapter 15 Antiparkinson Drugs Flashcards
Parkinson’s Disease (PD)
-Chronic, progressive, degenerative disorder
-Affects dopamine-producing neurons in the brain
-Caused by an imbalance of two neurotransmitters
Dopamine
Acetylcholine (ACh)
When do Symptoms occur in Parkinson’s Disease?
- Symptoms occur when about 80% of the dopamine stored in the substantia nigra of the basal ganglia is depleted.
- Symptoms can be partially controlled as long as there are functioning nerve terminals that can take up dopamine.
Parkinson’s Disease Classic Symptoms Include:
Akinesia Bradykinesia Rigidity Tremor Postural instability Staggering gait Drooling `
Akinesia
absense of psychomotor activity resulting in masklike facial expression
Bradykinesia
Slowness of movement
Rigidity
“Cogwheel” rigidity, resistance to passive movement
Tremor
Pill rolling: tremor of the thumb against the forefinger seen mostly at rest and less severe during voluntary activity; usually starts on one side then progresses to the other; is the presenting sign in 70% of cases; also seen as tremor of the hand and extremities
Postural Instibility
Unsteadiness that leads to danger of falling; leaning to one side, even when sitting
The “off–on phenomenon” that some patients with PD experience is best explained as the
variable response to levodopa, resulting in periods of good control and periods of poor control of PD symptoms
Dyskinesia
Difficulty in performing voluntary movements
Two Common types of Dyskinesia
Chorea and Dystonia
Chorea
irregular, spasmodic, involuntary movements of the limbs or facial muscles
Dystonia
abnormal muscle tone leading to impaired or abnormal movements
Rasagiline (Azilect) and Selegiline (Eldepryl)
-Used as monotherapy or used as adjuncts with levodopa
-Contraindications
Known drug allergy
Concurrent use with meperidine
Levodopa Therapy
- Levodopa is a precursor of dopamine.
- Blood–brain barrier does not allow exogenously supplied dopamine to enter but does allow levodopa to enter.
Bromocriptine (Parlodel)
- Works by activating presynaptic dopamine receptors to stimulate the production of more dopamine
- Caution when used for patients with peripheral vascular disease
- Adverse reactions: GI upset, dyskinesias, sleep disturbances
- Drug interactions: erythromycin and adrenergic drugs
Ropinirole (Requip) and Rotigotine (Neupro)
Also used to treat a disorder known as restless legs syndrome, a nocturnal movement of the legs that disrupts sleep
Anticholinergic Therapy
- Anticholinergics block the effects of ACh
- Used to treat muscle tremors and muscle rigidity associated with PD
- These two symptoms are caused by excessive cholinergic activity.
- Does not relieve bradykinesia (extremely slow movements)
SLUDGE
Ach is responsible for causing increased salivation, lacrimation (tearing of the eyes), urination, diarrhea, increased GI motility, and possibly emesis (vomiting)
Benztropine (Cogentin)
- Anticholinergic drug used for PD and extrapyramidal symptoms from antipsychotic drugs
- Caution during hot weather or exercise because it may cause hyperthermia
- Adverse effects: tachycardia, confusion, disorientation, toxic psychosis, urinary retention, dry throat, constipation, nausea, and vomiting
- Anticholinergic syndrome
- Avoid alcohol
Nursing Implications for AntiParkinsons Drugs
- When starting dopaminergic drugs, assist patient with walking because dizziness may occur
- Administer oral doses with food to minimize GI upset
- Encourage patient to force fluids to at least 3000 mL/day (unless contraindicated)
- Taking levodopa with MAOIs may result in hypertensive crisis
