18 Questions
What is the reason for taking levodopa on an empty stomach?
To avoid interference with the transport of levodopa into the CNS
What is the primary reason why the therapeutic response to levodopa declines over time?
The number of neurons capable of converting levodopa to dopamine decreases
What is the effect of pyridoxine on levodopa therapy?
It reduces the effect of levodopa
What is the mechanism of action of carbidopa in enhancing the effects of levodopa?
Inhibiting dopamine decarboxylase in peripheral tissues
What is the primary advantage of coadministering carbidopa with levodopa?
Reduced side effects due to decreased metabolism in peripheral tissues
What is the consequence of combining MAO inhibitors with levodopa?
Hypertensive crisis
What is the effect of levodopa on the heart?
It causes tachycardia
What is the fate of administered levodopa in the absence of carbidopa?
It is metabolized in peripheral tissues and GI tract, leading to undesirable side effects
What is the primary mechanism of action of levodopa in the treatment of Parkinson's disease?
Converting to dopamine in the CNS, which is then released from synaptic vesicles
What is the reason for the brownish color of saliva and urine in patients taking levodopa?
Due to the presence of melanin pigment
What is the primary reason for administering levodopa with carbidopa?
To inhibit the metabolism of dopamine in the periphery
What is the effect of levodopa on the iris?
Mydriasis
What is the primary reason why dopamine does not cross the blood-brain barrier?
It is unable to cross the blood-brain barrier due to its chemical structure
What is the result of the rapid absorption of levodopa from the small intestine?
Fluctuations in plasma concentration
What is the benefit of combining levodopa with carbidopa in the treatment of Parkinson's disease?
It decreases the dose of levodopa needed by four- to fivefold
What is the effect of peripheral dopamine formation on the body?
It causes nausea, vomiting, cardiac arrhythmias, and hypotension
What is the typical response of patients with Parkinson's disease to levodopa-carbidopa therapy?
A decline in response during the 3rd to 5th year of therapy
Why is gradual withdrawal from levodopa therapy necessary?
To prevent rebound symptoms
This quiz covers the effects of levodopa on the central nervous system in patients with Parkinson's disease, including its therapeutic response, motor control fluctuations, and symptomatic relief.
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