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Questions and Answers
Which of the following is a notable side effect associated with ropinirole?
Which of the following is a notable side effect associated with ropinirole?
What is the starting dose for pramipexole in treating early Parkinson's disease?
What is the starting dose for pramipexole in treating early Parkinson's disease?
What therapeutic effect does selegiline have when administered with levodopa?
What therapeutic effect does selegiline have when administered with levodopa?
Which of the following medications is FDA approved for restless leg syndrome?
Which of the following medications is FDA approved for restless leg syndrome?
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What does the term ‘wearing off’ effect refer to?
What does the term ‘wearing off’ effect refer to?
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How does pramipexole compare to ropinirole in terms of potency?
How does pramipexole compare to ropinirole in terms of potency?
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Which of the following is a common side effect of advanced doses of levodopa?
Which of the following is a common side effect of advanced doses of levodopa?
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What is the primary reason for neuronal death in parkinsonism related to glutamate?
What is the primary reason for neuronal death in parkinsonism related to glutamate?
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What symptom is characteristic of the later stages of untreated Parkinson's disease?
What symptom is characteristic of the later stages of untreated Parkinson's disease?
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Which drug is primarily known for causing drug-induced temporary parkinsonism due to dopaminergic blockage?
Which drug is primarily known for causing drug-induced temporary parkinsonism due to dopaminergic blockage?
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What was a significant breakthrough in the treatment of Parkinson's disease in 1967?
What was a significant breakthrough in the treatment of Parkinson's disease in 1967?
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Which area of the brain is primarily affected in Parkinson's disease?
Which area of the brain is primarily affected in Parkinson's disease?
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Which condition is a rare cause of Parkinsonism due to chronic copper poisoning?
Which condition is a rare cause of Parkinsonism due to chronic copper poisoning?
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What effect does reserpine have on dopamine in the brain?
What effect does reserpine have on dopamine in the brain?
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What is a common manifestation accompanying Parkinson's disease?
What is a common manifestation accompanying Parkinson's disease?
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What does an 'all or none' response in patients indicate regarding their condition?
What does an 'all or none' response in patients indicate regarding their condition?
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Which of the following statements is true regarding the use of peripheral decarboxylase inhibitors?
Which of the following statements is true regarding the use of peripheral decarboxylase inhibitors?
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What is typically the starting dose of levodopa for a patient?
What is typically the starting dose of levodopa for a patient?
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How does pyridoxine affect the therapeutic effect of levodopa?
How does pyridoxine affect the therapeutic effect of levodopa?
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What might the combination of carbidopa and levodopa lead to regarding patient symptoms?
What might the combination of carbidopa and levodopa lead to regarding patient symptoms?
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For which condition is cautious use of levodopa especially important?
For which condition is cautious use of levodopa especially important?
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What typically occurs to systemic dopamine levels with the use of levodopa?
What typically occurs to systemic dopamine levels with the use of levodopa?
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What is the approximate usual daily dose of levodopa?
What is the approximate usual daily dose of levodopa?
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What happens to levodopa's half-life in the periphery when doses are reduced?
What happens to levodopa's half-life in the periphery when doses are reduced?
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What response may exemplify the progression of a disorder in patients on levodopa?
What response may exemplify the progression of a disorder in patients on levodopa?
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What is the role of Levodopa in treating Parkinson's Disease?
What is the role of Levodopa in treating Parkinson's Disease?
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Which of the following is a side effect associated with the use of Glutamate antagonists such as Amantadine?
Which of the following is a side effect associated with the use of Glutamate antagonists such as Amantadine?
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How do D1 like receptors primarily affect neuronal signaling?
How do D1 like receptors primarily affect neuronal signaling?
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Which MAO-B inhibitor is commonly used in the management of Parkinson's Disease?
Which MAO-B inhibitor is commonly used in the management of Parkinson's Disease?
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What characterizes D2 like receptors in the dopamine receptor family?
What characterizes D2 like receptors in the dopamine receptor family?
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Which of the following central anticholinergics is used to manage extrapyramidal symptoms?
Which of the following central anticholinergics is used to manage extrapyramidal symptoms?
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What is a major concern when using COMT inhibitors like Entacapone?
What is a major concern when using COMT inhibitors like Entacapone?
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Which of the following statements about MPTP-like chemicals is accurate?
Which of the following statements about MPTP-like chemicals is accurate?
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Which drug is associated with an 'awakening' effect in hepatic coma?
Which drug is associated with an 'awakening' effect in hepatic coma?
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What is a direct consequence of using antihistaminics like Promethazine in treating neurological conditions?
What is a direct consequence of using antihistaminics like Promethazine in treating neurological conditions?
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What is an advantage of using ropinirole or pramipexole over levodopa in Parkinson's treatment?
What is an advantage of using ropinirole or pramipexole over levodopa in Parkinson's treatment?
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Which specific type of MAO does selegiline inhibit?
Which specific type of MAO does selegiline inhibit?
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What is the primary route of metabolism for ropinirole?
What is the primary route of metabolism for ropinirole?
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How long is the terminal half-life of ropinirole?
How long is the terminal half-life of ropinirole?
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What is the main effect of the drug bromocriptine in Parkinson’s disease?
What is the main effect of the drug bromocriptine in Parkinson’s disease?
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What condition is associated with the use of levodopa that newer DA agonists attempt to mitigate?
What condition is associated with the use of levodopa that newer DA agonists attempt to mitigate?
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What percentage of ropinirole is bound to plasma proteins after oral absorption?
What percentage of ropinirole is bound to plasma proteins after oral absorption?
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Which of the following is true regarding the side effects associated with levodopa compared to DA agonists?
Which of the following is true regarding the side effects associated with levodopa compared to DA agonists?
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What is the implication of using ropinirole or pramipexole for Parkinson's patients considering neuronal degeneration?
What is the implication of using ropinirole or pramipexole for Parkinson's patients considering neuronal degeneration?
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What is the purpose of differentiating between MAO-A and MAO-B in pharmacology?
What is the purpose of differentiating between MAO-A and MAO-B in pharmacology?
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Study Notes
Parkinsonism
- Parkinsonism is an extrapyramidal motor disorder, characterized by rigidity, tremor, and hypokinesia
- Secondary symptoms include impaired posture and gait, a mask-like face, and excessive saliva production (sialorrhoea)
- Dementia is sometimes associated with parkinsonism
- Untreated, symptoms progressively worsen over several years, leading to a rigid state, difficulty breathing, and susceptibility to infections or embolisms
- Parkinson's Disease (PD) is a progressive degenerative disorder primarily affecting the elderly. It was first described in 1817.
- Most cases are idiopathic, some are arteriosclerotic, and postencephalitic cases are now rare.
- Wilson's disease, a rare cause, is due to chronic copper poisoning.
- The main pathological feature of Parkinson's Disease is neuronal degeneration in the substantia nigra pars compacta and the nigrostriatal dopaminergic pathway.
- This causes a dopamine deficiency in the striatum, which subsequently creates an imbalance between inhibitory dopaminergic and excitatory cholinergic systems controlling muscle tone and coordination.
Antiparkinsonian Drugs - Classification
-
Drugs affecting brain dopaminergic system include:
- Dopamine precursors (e.g., levodopa)
- Peripheral decarboxylase inhibitors (e.g., carbidopa, benserazide)
- Dopamine agonists (e.g., bromocriptine, ropinirole, pramipexole)
- MAO-B inhibitors (e.g., selegiline, rasagiline)
- COMT inhibitors (e.g., entacapone, tolcapone)
Levodopa
- Levodopa is a specific and effective treatment for PD
- It's a precursor to dopamine, and crosses the blood-brain barrier to alleviate dopamine deficiency
- Levodopa is decarboxylated in peripheral tissues (primarily the gut and liver) into dopamine
- About 1-2% of administered levodopa crosses to the brain converting to DA, stored as a neurotransmitter.
Actions of Levodopa
- Levodopa primarily improves symptoms in Parkinsonian patients, especially hypokinesia and rigidity, then tremor
- It normalizes secondary symptoms, such as posture, gait, speech, facial expression, mood, and self-care
- While effective initially, its effect gradually diminishes as the disease progresses
Adverse Effects of Levodopa
- Common side effects include nausea, vomiting, postural hypotension (often asymptomatic)
- Cardiac arrhythmias, exacerbation of angina are also possible
- Alterations in taste sensation are possible from levodopa therapy
Classification of Dopaminergic Agonists
- Non-ergot dopamine agonists (e.g., ropinirole, pramipexole): fewer gastrointestinal side effects, better tolerated compared to bromocriptine
- Ergot dopamine agonists (e.g., bromocriptine): effective but more likely to produce side effects such as nausea, vomiting, hallucinations, hypotension.
Other Drugs used in Parkinsonism
- Peripheral decarboxylase inhibitors (carbidopa/benserazide): combined with levodopa to increase levodopa bioavailability
- MAO-B inhibitors: selegiline and rasagiline prolong the effects of levodopa and may have mild neuroprotective benefits
- COMT inhibitors (entacapone and tolcapone): enhance levodopa action by inhibiting COMT, the enzyme that breaks down levodopa, prolonging its effects
Anticholinergics
- These drugs reduce the unbalanced cholinergic activity in the striatum of Parkinsonian patients
- Commonly used drugs include Trihexyphenidyl, Procyclidine, Biperiden, Orphenadrine, Promethazine
- Side effects mimicking atropine-like effects are possible, but less severe than levodopa or MAO inhibitors
MAO-B Inhibitors
- Selegiline and rasagiline selectively inhibit MAO-B, reducing the breakdown of dopamine
- This can be beneficial in early-stage PD and sometimes in combination with levodopa
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Description
Explore the symptoms, causes, and progression of Parkinsonism, a motor disorder characterized by rigidity, tremor, and hypokinesia. This quiz covers the pathophysiology behind Parkinson’s Disease, including neuronal degeneration and the role of dopamine. Test your knowledge on this progressive condition and its associated factors.
