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Questions and Answers
What is a primary characteristic of parkinsonism?
What is a primary characteristic of parkinsonism?
What can excessive amounts of glutamate cause in neuronal cells?
What can excessive amounts of glutamate cause in neuronal cells?
What drug was found in 1967 to produce significant improvement in Parkinson's disease?
What drug was found in 1967 to produce significant improvement in Parkinson's disease?
In Parkinson’s disease, where does degeneration primarily occur?
In Parkinson’s disease, where does degeneration primarily occur?
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What type of disorder is Parkinson’s disease classified as?
What type of disorder is Parkinson’s disease classified as?
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What condition is associated with chronic copper poisoning?
What condition is associated with chronic copper poisoning?
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What effect does reserpine have on dopamine?
What effect does reserpine have on dopamine?
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Which of the following is a potential consequence of untreated Parkinson's disease?
Which of the following is a potential consequence of untreated Parkinson's disease?
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What effect does dopaminergic action in the striatum have on SN-PR and GP-I?
What effect does dopaminergic action in the striatum have on SN-PR and GP-I?
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What results from the imbalance between dopamine and acetylcholine in Parkinson's disease?
What results from the imbalance between dopamine and acetylcholine in Parkinson's disease?
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Which hormone's release is inhibited by endocrine dopamine acting on pituitary mammtropes?
Which hormone's release is inhibited by endocrine dopamine acting on pituitary mammtropes?
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How is levodopa primarily absorbed in the body?
How is levodopa primarily absorbed in the body?
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What is NOT a side effect at the initiation of levodopa therapy?
What is NOT a side effect at the initiation of levodopa therapy?
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What happens to levodopa when gastric emptying is slow?
What happens to levodopa when gastric emptying is slow?
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Which factor does NOT affect the bioavailability of levodopa?
Which factor does NOT affect the bioavailability of levodopa?
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What characterizes the therapeutic effect of levodopa in patients taking it over time?
What characterizes the therapeutic effect of levodopa in patients taking it over time?
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What is the primary effect of Selegiline when added to levodopa therapy?
What is the primary effect of Selegiline when added to levodopa therapy?
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Which side effect is associated with Tolcapone?
Which side effect is associated with Tolcapone?
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How is Entacapone typically administered with levodopa-carbidopa?
How is Entacapone typically administered with levodopa-carbidopa?
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What is a common side effect of Selegiline?
What is a common side effect of Selegiline?
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What interaction might Selegiline have with pethidine?
What interaction might Selegiline have with pethidine?
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What distinguishes Rasagiline from Selegiline?
What distinguishes Rasagiline from Selegiline?
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Which of the following medications is not hepatotoxic?
Which of the following medications is not hepatotoxic?
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Why has the use of Tolcapone been restricted in Europe and Canada?
Why has the use of Tolcapone been restricted in Europe and Canada?
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Which of the following drugs has a greater affinity for D3 receptors?
Which of the following drugs has a greater affinity for D3 receptors?
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What is the usual daily maintenance dose of levodopa?
What is the usual daily maintenance dose of levodopa?
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Which dopamine agonists are frequently used as monotherapy for early Parkinson's disease (PD)?
Which dopamine agonists are frequently used as monotherapy for early Parkinson's disease (PD)?
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How long can dose titration for maximum improvement take?
How long can dose titration for maximum improvement take?
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What is the standard combination of carbidopa to levodopa in treatment?
What is the standard combination of carbidopa to levodopa in treatment?
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Which of the following medications is better tolerated with fewer gastrointestinal symptoms compared to bromocriptine?
Which of the following medications is better tolerated with fewer gastrointestinal symptoms compared to bromocriptine?
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Which drug formulation comprises benserazide and levodopa?
Which drug formulation comprises benserazide and levodopa?
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What percentage of patients treated with ropinirole needed supplemental levodopa?
What percentage of patients treated with ropinirole needed supplemental levodopa?
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What is the fixed dose of entacapone and tolcapone used in PD treatment?
What is the fixed dose of entacapone and tolcapone used in PD treatment?
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What is a characteristic side effect associated with the use of central anticholinergics?
What is a characteristic side effect associated with the use of central anticholinergics?
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How many years of additional life quality does drug therapy typically provide to PD patients?
How many years of additional life quality does drug therapy typically provide to PD patients?
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Which side effect is generally associated with anticholinergic drugs?
Which side effect is generally associated with anticholinergic drugs?
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What effect do both entacapone and tolcapone have on levodopa therapy?
What effect do both entacapone and tolcapone have on levodopa therapy?
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Which of the following combinations can accentuate side effects of anticholinergic drugs?
Which of the following combinations can accentuate side effects of anticholinergic drugs?
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What is the primary action of central anticholinergics in treating PD?
What is the primary action of central anticholinergics in treating PD?
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Based on current understanding, does levodopa therapy accelerate the progression of PD?
Based on current understanding, does levodopa therapy accelerate the progression of PD?
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What percentage improvement in parkinsonian symptoms is typically produced by anticholinergics after a single dose?
What percentage improvement in parkinsonian symptoms is typically produced by anticholinergics after a single dose?
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Which symptom is most benefited by anticholinergic treatment?
Which symptom is most benefited by anticholinergic treatment?
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What is a common side effect of anticholinergics in the elderly, particularly males?
What is a common side effect of anticholinergics in the elderly, particularly males?
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Which medication is often combined with levodopa during the deterioration phase of therapy?
Which medication is often combined with levodopa during the deterioration phase of therapy?
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When is it generally advisable to use anticholinergics or newer direct DA agonists?
When is it generally advisable to use anticholinergics or newer direct DA agonists?
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What is a characteristic of the side effect profile of anticholinergics?
What is a characteristic of the side effect profile of anticholinergics?
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Which newer direct DA agonist is commonly employed for early cases of parkinsonism?
Which newer direct DA agonist is commonly employed for early cases of parkinsonism?
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Which of the following statements is true about the use of levodopa therapy?
Which of the following statements is true about the use of levodopa therapy?
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Study Notes
Parkinsonism
- Parkinsonism is an extrapyramidal motor disorder, marked by rigidity, tremor, and hypokinesia
- Secondary symptoms include poor posture, gait issues, a mask-like face, and excessive saliva production
- Dementia is sometimes associated with parkinsonism
- Untreated, parkinsonism progresses to a rigid, immobile state with difficulty breathing, often leading to death from infection or embolisms
- Parkinson's disease (PD) is the most common form
- Idiopathic cases are the majority, with some cases linked to arteriosclerosis and very rarely post-encephalitis
- Wilson's disease, a rare cause, is related to chronic copper poisoning
- A key characteristic lesion in PD is the degeneration of substantia nigra pars compacta neurons and the nigrostriatal (dopaminergic) tract
- This leads to dopamine (DA) deficiency in the striatum, which controls muscle tone and coordination
- An imbalance arises between dopaminergic (inhibitory) and cholinergic (excitatory) systems.
- Excessive glutamate can trigger excitotoxic neuronal death via NMDA receptors
- Drug-induced parkinsonism, often from neuroleptics, is common today, while reserpine-related cases are less frequent now.
Antiparkinsonian Drugs
- Levodopa (l-dopa) is a breakthrough treatment for PD. It's the precursor to dopamine; however, dopamine itself cannot cross the blood-brain barrier.
- Peripheral decarboxylase inhibitors (e.g., carbidopa, benserazide) are used with levodopa to enhance its effectiveness by preventing premature dopamine conversion outside the brain
- Dopamine agonists (e.g., bromocriptine, ropinirole, pramipexole) are potential alternatives, sometimes used as adjuvants or replacements for levodopa
- Monoamine oxidase-B (MAO-B) inhibitors (e.g., selegiline, rasagiline) can protect dopamine from breakdown
- Catechol-O-methyl transferase (COMT) inhibitors (e.g., entacapone, tolcapone) slow the breakdown of levodopa in the periphery, making more levodopa available to the brain
- Amantadine (a glutamate antagonist) is another dopamine facilitator, which sometimes provides benefit
- Central anticholinergics (e.g., trihexyphenidyl, procyclidine, biperiden) help reduce the imbalance of cholinergic neurotransmitters
Classification of Antiparkinsonian Drugs
- Drugs affecting the brain dopaminergic system
- Dopamine precursors
- Peripheral decarboxylase inhibitors
- Dopamine agonists
- MAO-B inhibitors
- COMT inhibitors
- Drugs affecting the brain cholinergic system
- Central anticholinergics
- Antihistaminics
Actions and Pharmacokinetics of Levodopa
- Levodopa significantly improves motor symptoms in patients with PD, but its effects on behavior can be complex.
- The drug's effectiveness primarily depends on dopamine production within the brain, hence the use of peripheral decarboxylase inhibitors.
- It has rapid absorption from the intestines, and is metabolized in the liver and periphery to an extent that only a small percentage is available for usage in the brain.
- Several factors affect the bioavailability of levodopa, including food intake, other medications, and gastric emptying.
Adverse Effects of Antiparkinsonian Drugs
- Some medications can cause nausea, vomiting, postural hypotension, cardiac arrhythmias, and exacerbation of angina
- Alteration in taste sensation, abnormal movements (dyskinesias), behavioral effects (anxiety, hallucinations) and excessive daytime sleepiness are notable long-term side effects.
- Certain drugs require careful dose adjustment to minimize these adverse effects
- Pyridoxine (vitamin B6) can lessen the therapeutic effectiveness of levodopa.
- Anticholinergics and phenothiazines, anticholinergics and other related drugs, and MAO inhibitors need careful attention.
Classification and Action of Other Antiparkinsonian Drugs
- Anticholinergic drugs: reduce the imbalance in neurotransmitter activity in the striatum, particularly beneficial for tremor.
- Dopamine agonists: act on dopamine receptors in the striatum to improve motor control.
- MAO-B inhibitors: prolong the duration of levodopa's effect by decreasing dopamine breakdown.
- COMT inhibitors: increase the amount of levodopa available in the brain by inhibiting its metabolism.
- Amantadine: a glutamate antagonist that can improve motor control but tolerability reduces over time.
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Description
Explore the key aspects of parkinsonism, an extrapyramidal motor disorder characterized by rigidity, tremor, and hypokinesia. This quiz covers the symptoms, progression, and underlying neurobiological changes associated with Parkinson's disease and other types. Test your understanding of causes, symptoms, and implications of this condition.
