Parkinson’s Disease

Parkinson's Disease is a chronic, progressive autoimmune disorder common in males over 50. It primarily affects the basal ganglia, specifically the substantia nigra, leading to decreased dopamine production. Dopamine is an inhibitory neurotransmitter, and its deficiency, coupled with increased acetylcholine (an excitatory neurotransmitter), causes an imbalance that impairs complex body movements.

The imbalance in neurotransmitters manifests as characteristic symptoms: tremors (resting tremors, often described as 'pill-rolling'), rigidity (cogwheel rigidity, like a jerky motion), bradykinesia (slow movements, an early sign that can progress to akinesia or absence of movement), and postural changes (shuffling gait, stooped posture, leading to an increased risk of falls). Other symptoms include micrographia (small handwriting) due to impaired fine motor skills, a mask-like face, dysphagia (difficulty swallowing), drooling, and slow peristalsis, which can cause constipation and risk of aspiration.

The primary medication for Parkinson's is levodopa, which crosses the blood-brain barrier and converts into dopamine. Carbidopa is given concurrently to prevent levodopa from being converted to dopamine outside the brain by the decarboxylase enzyme. This ensures more levodopa reaches the brain, where it's needed, maintaining its efficacy. Medications like Sinemet combine both levodopa and carbidopa.

COMT inhibitors, such as Entacapone, are also used. COMT is an enzyme that destroys both levodopa and dopamine. By inhibiting COMT, more levodopa remains available to be converted into dopamine, increasing dopamine levels in the brain. Some medications, like Stalevo, combine levodopa, carbidopa, and entacapone. Additionally, anticholinergic medications like Benztropine (Cogentin) and Trihexyphenidyl (Artane) are prescribed to counteract the relative excess of acetylcholine.

Nurses must monitor for side effects of levodopa, which include expected effects like dark urine, orthostatic hypotension, and anticholinergic effects. More critical concerns indicative of toxicity or overdose are hallucination/psychosis (requiring safety precautions due to potential auditory hallucinations) and dyskinesia (involuntary movements like winking, lip smacking, and facial gazing), which are permanent side effects. It's crucial to differentiate between perception (hallucination) and delusion (thought process issues). Patients should avoid MAO inhibitors (due to risk of hypertensive crisis), tyramine-rich foods, high-protein diets (protein can decrease levodopa absorption), and B6 supplements (pyridoxine decarboxylase), as these can interfere with levodopa's effectiveness.