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Nursing Knowledge
Parkinson’s disease (PD) occurs when the brain cells that produce dopamine stop working or die, leading to imbalanced dopamine and acetylcholine levels.
Insufficient dopamine results in tremors, muscle rigidity, and abnormal movements.
Drug therapies are aimed at restoring dopamine levels and/or inhibiting the effects of acetylcholine. Drug therapy does not cure PD, but helps slow the progression of debilitating symptoms.
Note: Do not abruptly stop PD medications due to risk of neuroleptic malignant syndrome. PD medications become less effective over time.
Examples of MAO-B inhibitors are rasagiline or selegiline.
MAO-B inhibitors inhibit MAO-B, blocking dopamine breakdown. They are used with levodopa to prolong action and reduce dosage.
MAO-B inhibitors can interact with tyramine-rich foods, antidepressants, and cold medications. Contraindications include cardiac issues, ulcers, and dementia.
An example of an NMDA-type glutamate antagonist is amantadine.
NMDA-type glutamate antagonists mimic dopamine in the brain. They work longer, but are less effective than levodopa.
NMDA-type glutamate antagonists can interact with CNS stimulants and anticholinergics. Contraindications include glaucoma, kidney or liver disease, enlarged prostate, and epilepsy.
Dopamine antagonists include pramipexole, ropinirole, rotigotine.
Dopamine antagonists mimic dopamine in the brain. They work longer, but are less effective than levodopa.
Antipsychotics and CNS depressants can interact with dopamine antagonists. Contraindications include cardiac or renal disease, mental illness, and sleep apnea.
The best-known dopamine prodrug is levodopa/carbidopa.
Levodopa crosses the blood–brain barrier and is converted into dopamine. Carbidopa prevents the breakdown of levodopa before it reaches the brain.
Dopamine prodrugs can interact with 1st-generation antipsychotics, MAO inhibitors. A high-protein diet can influence their effect as well.
Contraindications include glaucoma, a history of melanoma, diabetes, ulcers, cardiac or liver disease, and mental illness.
A prominent example of a COMT inhibitor is opicapone.
COMT inhibitors protect levodopa from breakdown by the COMT enzyme.
Interactions include MAOs, antihypertensives, CNS depressants. Contraindications include mental illness, sleep apnea, and liver or kidney disease.
An example of an anticholinergic is benztropine.
Anticholinergics block the action of acetylcholine. This helps decrease muscle stiffness, sweating, saliva production, and difficulty walking.
Substances that can interact with anticholinergics include lisinopril, levothyroxine, antidepressants, antipsychotics, alcohol, and many other drugs.
Contraindications are glaucoma, enlarged prostate, liver disease, and urinary blockage.
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