11.2 Anti-Parkinsonian Drugs
3 min read•june 18, 2024
disrupts movement due to dopamine loss in the brain. Anti-Parkinsonian medications aim to restore dopamine function or balance , alleviating motor symptoms like tremors and .
Various drug classes target different aspects of the disease. drugs replenish dopamine, while anticholinergics restore neurotransmitter balance. Understanding these medications is crucial for effective symptom management and improved quality of life.
Overview of Anti-Parkinsonian Medications
Introduction to Parkinson's Disease
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Frontiers | The End Is the Beginning: Parkinson’s Disease in the Light of Brain Imaging View original
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Parkinson's disease, first described by in 1817, is a progressive neurodegenerative disorder affecting movement, balance, and coordination. It primarily results from the loss of dopamine-producing neurons in the , disrupting the and leading to motor symptoms.
Classes of anti-Parkinsonian medications
- Dopaminergic drugs enhance dopamine activity in the brain to alleviate Parkinson's symptoms
- crosses the blood-brain barrier and converts to dopamine in the brain, replenishing depleted levels
- Often combined with to reduce peripheral side effects and increase central nervous system availability
- (, ) directly stimulate dopamine receptors, mimicking dopamine's effects
- (MAO-B) inhibitors (, ) block dopamine breakdown by MAO-B enzyme, prolonging its action
- crosses the blood-brain barrier and converts to dopamine in the brain, replenishing depleted levels
- drugs (, ) block acetylcholine action in the brain, helping restore dopamine-acetylcholine balance
- (COMT) inhibitors (, ) prevent levodopa and dopamine breakdown by COMT enzyme, prolonging levodopa's effects and increasing its bioavailability
Dopaminergic vs anticholinergic drugs
- Dopaminergic drugs provide effective improvement in motor symptoms (, rigidity, ) and are considered first-line treatment
- Risks include (involuntary movements) with long-term use, "on-off" fluctuations in symptom control, nausea, vomiting, and
- drugs help control tremor and rigidity, particularly useful for younger patients with predominant tremor
- Risks include cognitive impairment and confusion (especially in older patients), dry mouth, constipation, urinary retention, and blurred vision
- Limited efficacy compared to dopaminergic drugs
Neurotransmitters in Parkinson's Disease
- Dopamine: Primary neurotransmitter affected in Parkinson's disease, with decreased levels leading to motor symptoms
- Acetylcholine: Imbalance between dopamine and acetylcholine contributes to Parkinson's symptoms
- Glutamate: Excessive glutamate activity may contribute to disease progression
- GABA: Reduced GABA activity in the is associated with motor symptoms
Nursing considerations for Parkinson's medications
- Assess for contraindications and drug interactions before administration
- Monitor for common side effects
- Dopaminergic drugs: nausea, vomiting, orthostatic hypotension, dyskinesias
- Anticholinergic drugs: cognitive impairment, dry mouth, constipation, urinary retention
- Administer medications on time to maintain consistent dopamine levels
- Encourage patients to take medications with food to minimize gastrointestinal side effects
- Monitor for signs of (compulsive gambling, hypersexuality)
- Assess for and on-off phenomena, reporting to the physician for dose adjustments
- Be aware of potential drug interactions
- Levodopa: protein-rich foods, iron supplements, antacids
- : tyramine-rich foods (aged cheeses, cured meats), sympathomimetic drugs, antidepressants
Patient education for Parkinson's treatment
- Emphasize the importance of taking medications as prescribed
- Maintain consistent timing of doses to prevent wearing-off and on-off phenomena
- Do not stop medications abruptly, as this can worsen symptoms
- Provide strategies for managing side effects
- Take medications with food to minimize gastrointestinal issues
- Change positions slowly to prevent orthostatic hypotension
- Practice good oral hygiene to combat dry mouth
- Encourage lifestyle modifications
- Regular exercise (tai chi, yoga) to improve mobility and balance
- Healthy diet with adequate hydration
- Stress management and relaxation techniques (meditation, deep breathing)
- Educate about potential drug interactions and the need to inform all healthcare providers about Parkinson's medications
- Discuss the importance of regular follow-up with the neurologist for medication adjustments
- Provide resources for support groups (Parkinson's Foundation, Michael J. Fox Foundation) and Parkinson's disease organizations
Key Terms to Review (35)
Alpha-synuclein: Alpha-synuclein is a small, presynaptic protein that is primarily found in the neurons of the central nervous system. It is a key player in the pathogenesis of Parkinson's disease and other neurodegenerative disorders, known as synucleinopathies, due to its propensity to misfold and aggregate within cells.
Anticholinergic: Anticholinergics are drugs that block the action of acetylcholine in the nervous system. They are used to treat various conditions, including those affecting the heart and respiratory systems.
Anticholinergic: Anticholinergic drugs are a class of medications that block the action of the neurotransmitter acetylcholine, which is responsible for various physiological functions in the body. This term is particularly relevant in the contexts of anti-Parkinsonian drugs, cardiac emergency drugs, and urinary analgesics, as these medications can exhibit anticholinergic effects.
Basal Ganglia: The basal ganglia are a group of subcortical nuclei in the brain that play a crucial role in the control and regulation of voluntary movement, as well as other important functions such as procedural learning, habit formation, and certain aspects of emotion and cognition. This term is particularly relevant in the context of understanding Parkinson's disease and the development of anti-Parkinsonian drugs.
Benztropine: Benztropine is an anticholinergic medication primarily used in the treatment of Parkinson's disease and other movement disorders. It works by blocking the action of the neurotransmitter acetylcholine, which helps to alleviate the symptoms associated with these conditions.
Bradykinesia: Bradykinesia is a key symptom of Parkinson's disease, characterized by slowness of movement and difficulty initiating voluntary movements. It is a central feature of the motor impairments associated with this neurodegenerative disorder and a primary target for anti-Parkinsonian drug therapies.
Carbidopa: Carbidopa is a medication primarily used in combination with levodopa for the treatment of Parkinson's disease. It works by inhibiting the peripheral conversion of levodopa to dopamine, thereby increasing the amount of levodopa that reaches the brain and enhancing its therapeutic effects.
Carbidopa/levodopa extended release: Carbidopa/levodopa extended release is a combination medication used to treat symptoms of Parkinson’s disease by replenishing dopamine. The extended-release formulation allows for a more consistent delivery of the medication over time.
Catechol-O-methyltransferase: Catechol-O-methyltransferase (COMT) is an enzyme that plays a crucial role in the metabolism and inactivation of catecholamine neurotransmitters, such as dopamine, epinephrine, and norepinephrine. This enzyme is particularly relevant in the context of anti-Parkinsonian drugs, as it is involved in the regulation of these neurotransmitters, which are essential for proper motor function.
COMT Inhibitors: COMT inhibitors are a class of drugs used in the treatment of Parkinson's disease. They work by inhibiting the enzyme catechol-O-methyltransferase (COMT), which is responsible for the breakdown of dopamine and other catecholamines in the body. This action helps to increase the availability of dopamine in the brain, leading to improved motor function and symptom management in Parkinson's patients.
Dopamine Agonists: Dopamine agonists are a class of drugs that mimic the effects of the neurotransmitter dopamine in the brain. They are primarily used in the treatment of Parkinson's disease, as they can help alleviate the motor symptoms associated with the condition by directly stimulating dopamine receptors.
Dopaminergic: Dopaminergic refers to the action or influence of substances, particularly drugs, that affect the neurotransmitter dopamine in the brain. Dopamine is a crucial neurotransmitter involved in various physiological processes, including motor control, reward and motivation, and cognition. Understanding the dopaminergic system is central to the study of anti-Parkinsonian drugs.
Dyskinesias: Dyskinesias are involuntary, uncontrolled movements that can occur as a side effect of certain medications, particularly those used to treat Parkinson's disease. These abnormal movements can affect various parts of the body and can significantly impact a person's quality of life.
Entacapone: Entacapone is a catechol-O-methyltransferase (COMT) inhibitor used in the treatment of Parkinson's disease. It works by inhibiting the enzyme COMT, which is responsible for the breakdown of levodopa, a key medication used to manage the motor symptoms of Parkinson's disease.
Impulse Control Disorders: Impulse control disorders are a group of mental health conditions characterized by the inability to resist urges or temptations to perform harmful or risky behaviors, despite the negative consequences. These disorders can significantly impact an individual's personal, social, and professional life.
James Parkinson: James Parkinson was an English surgeon, apothecary, and paleontologist who is best known for his 1817 essay that first described the condition now known as Parkinson's disease. His groundbreaking work laid the foundation for the understanding and treatment of this neurological disorder.
Levodopa: Levodopa is a medication used to treat the symptoms of Parkinson's disease, a neurodegenerative disorder characterized by motor impairments. It is the primary and most effective pharmacological treatment for managing the motor symptoms associated with Parkinson's disease.
MAO-B Inhibitors: MAO-B inhibitors are a class of drugs that selectively inhibit the monoamine oxidase B (MAO-B) enzyme, which is responsible for the breakdown of neurotransmitters like dopamine in the brain. By inhibiting this enzyme, MAO-B inhibitors help increase the availability of dopamine, making them an important treatment option for Parkinson's disease and other neurological conditions.
Monoamine Oxidase B: Monoamine oxidase B (MAO-B) is an enzyme that catalyzes the oxidative deamination of monoamine neurotransmitters, such as dopamine, in the central nervous system. It plays a crucial role in the metabolism and regulation of these neurotransmitters, which are important for various physiological and neurological processes.
Neurotransmitters: Neurotransmitters are chemical messengers that transmit signals between neurons and target cells in the nervous system. They are responsible for the communication and coordination of various physiological and psychological processes in the body, and their imbalance or dysfunction can contribute to the development of various neurological and psychiatric disorders.
Nigrostriatal Pathway: The nigrostriatal pathway is a crucial neural circuit in the brain that plays a central role in the development and progression of Parkinson's disease. It is a dopaminergic pathway that connects the substantia nigra, a region in the midbrain, to the striatum, a key component of the basal ganglia involved in motor control and coordination.
On-Off Phenomenon: The on-off phenomenon, also known as motor fluctuations, refers to the unpredictable and dramatic shifts between periods of good motor control (on state) and periods of poor motor control and re-emergence of Parkinson's disease symptoms (off state) that can occur in patients with Parkinson's disease who are treated with dopaminergic medications.
Orthostatic Hypotension: Orthostatic hypotension is a sudden drop in blood pressure that occurs when an individual stands up from a sitting or lying position. This condition can lead to dizziness, lightheadedness, and even fainting, and is particularly relevant in the context of various medical conditions and drug therapies.
Parkinson's Disease: Parkinson's disease is a chronic and progressive neurological disorder that primarily affects the motor system. It is characterized by the loss of dopamine-producing neurons in the brain, leading to a variety of symptoms that can significantly impact an individual's quality of life. This term is particularly relevant in the context of understanding the characteristics of drugs used to treat nervous system disorders, as well as the specific anti-parkinsonian drugs that are designed to manage the symptoms of this condition.
Pramipexole: Pramipexole is a dopamine agonist medication primarily used in the treatment of Parkinson's disease and restless leg syndrome. It works by stimulating dopamine receptors in the brain, which helps to alleviate the motor symptoms associated with these neurological conditions.
Rasagiline: Rasagiline is a selective and irreversible monoamine oxidase B (MAO-B) inhibitor used in the treatment of Parkinson's disease. It works by preventing the breakdown of dopamine in the brain, thereby increasing its availability and improving motor symptoms associated with Parkinson's disease.
Rigidity: Rigidity refers to the increased muscle tone and resistance to passive movement observed in individuals with Parkinson's disease. It is a cardinal motor symptom of the disease and is closely associated with the anti-parkinsonian drugs used to manage the condition.
Ropinirole: Ropinirole is a dopamine agonist medication primarily used in the treatment of Parkinson's disease and restless leg syndrome. It works by stimulating dopamine receptors in the brain, mimicking the effects of the neurotransmitter dopamine, which is often deficient in Parkinson's disease.
Selegiline: Selegiline is a selective and irreversible monoamine oxidase (MAO) inhibitor primarily used in the treatment of Parkinson's disease. It works by inhibiting the breakdown of dopamine, norepinephrine, and serotonin, leading to increased levels of these neurotransmitters in the brain and improved motor function in Parkinson's patients.
Substantia Nigra: The substantia nigra is a midbrain structure that plays a crucial role in the pathogenesis of Parkinson's disease and the mechanism of action of anti-Parkinsonian drugs. It is a collection of dopaminergic neurons that are responsible for producing the neurotransmitter dopamine, which is essential for motor control and coordination.
Tolcapone: Tolcapone is a catechol-O-methyltransferase (COMT) inhibitor used in the treatment of Parkinson's disease. It works by blocking the enzyme COMT, which is responsible for the breakdown of dopamine, thereby increasing the availability of dopamine in the brain and improving motor symptoms associated with Parkinson's disease.
Tremor: A tremor is an involuntary, rhythmic shaking movement of a body part, often the hands, head, or voice. Tremors can be a symptom of various neurological and medical conditions, and they can also occur as a side effect of certain medications.
Trihexyphenidyl: Trihexyphenidyl is an anticholinergic medication primarily used to treat the symptoms of Parkinson's disease and other movement disorders. It works by blocking the action of the neurotransmitter acetylcholine, which helps to reduce the involuntary muscle movements and tremors associated with these conditions.
Tyrosine Hydroxylase: Tyrosine hydroxylase is a key enzyme involved in the biosynthesis of catecholamine neurotransmitters, such as dopamine, norepinephrine, and epinephrine. It catalyzes the rate-limiting step in this process, converting the amino acid tyrosine into L-DOPA, which is then further converted into the final neurotransmitters.
Wearing-off: Wearing-off refers to the gradual decrease in the effectiveness of a medication over time, leading to a return of symptoms that the drug was initially used to manage. This phenomenon is commonly observed in the context of anti-Parkinsonian drugs, where the patient experiences a fluctuation in the control of Parkinson's disease symptoms throughout the day.