Anti-Parkinson Drugs Chapter 15

Drug Profiles

• Amantadine, benztropine mesylate, bromocriptine, carbidopa-levodopa, entacapone, ropinirole, rasagiline, and selegiline are key antiparkinson medications.

Objectives

• Understanding the role of acetylcholine and dopamine in the brain is crucial for managing Parkinson's disease.
• Parkinson's disease involves a unique pathophysiology characterized by dopamine deficiency.
• Various classes of medications exist for Parkinson's management, each with distinct mechanisms and side effects.
• Nursing care plans must encompass all phases of patient care for effective management of antiparkinson drugs.

Adjunctive Drugs

• Adjunctive drugs enhance therapy when combined with primary drugs, offering either additive or independent effects.

Akinesia

• Defined as the loss of movement, leading to characteristics such as a masklike facial expression and impaired postural reflexes.

Chorea

• Involves involuntary, rapid movements like finger flexing and shoulder lifting, presenting as purposeless motions.

Dyskinesia

• Refers to abnormal involuntary movements and loss of control over motor functions.

Dystonia

• Characterized by distorted voluntary movements affecting areas like the head, neck, or feet.

On-Off Phenomenon

• Patients frequently experience alternating periods of symptom control ("on" time) and lesser control ("off" time) with Parkinson's treatment.

Parkinson's Disease

• A progressive neurodegenerative disorder marked by resting tremors, masklike facial expression, shuffling gait, and muscle rigidity.

Presynaptic Drugs

• These are antiparkinson medications that exert effects before reaching the nerve synapse.

Rigidity

• Defined as muscle resistance to passive movement, resulting in a specific "cogwheel" rigidity often seen in Parkinson's patients.

TRAP

• A mnemonic summarizing the classic symptoms: Tremor, Rigidity, Akinesia, Postural instability.

Tremor

• Characterized by shakiness, especially noticeable in the extremities during rest.

Wearing-Off Phenomenon

• Patients may experience a gradual increase in parkinsonian symptoms as medication effectiveness diminishes, even at maximum doses.

Pathophysiology of Parkinson's Disease

• The disease results from a dopamine deficit in the substantia nigra, located within the basal ganglia, which is crucial for motor control.

Extrapyramidal System

• This system is involved in motor function, muscle tone, posture, and smooth muscle activity, heavily influenced by dopamine.

Lower Neuron Motor Movements

• The thalamus acts as a relay for brain impulses, while the cerebellum coordinates muscle movements.

Key Neurotransmitters

• Dopamine functions as an inhibitory neurotransmitter, whereas acetylcholine acts as an excitatory neurotransmitter, both essential for motor regulation.

Imbalance Causes

• The imbalance between acetylcholine and dopamine in Parkinson's is primarily due to the failure of substantia nigra nerve terminals to produce sufficient dopamine.

Dopamine's Role

• Acts within the basal ganglia to control movements, and its destruction leads to depletion and unopposed cholinergic activity.

Neurodegenerative Diseases

• Alzheimer's disease and Parkinson's disease are the two most common neurodegenerative conditions.

Facts About Parkinson's Disease

• Onset typically occurs between ages 45 to 65, and incidence rates are expected to rise with an aging population.
• There is a 2% lifetime risk of developing the disease, with a higher prevalence in men (3:2 ratio).

Classic Symptoms

• Key symptoms include bradykinesia, postural instability, rigidity, and tremors, frequently used for diagnosis.

Mnemonic: TRAP

• A valuable tool to remember the major symptoms of Parkinson's disease: Tremor, Rigidity, Akinesia, Postural instability.