A patient has been given a prescription for levodopa-carbidopa for a new diagnosis of Parkinson's disease. The patient asks the nurse, "Why are there two drugs in this pill?" The nurse's best response reflects which fact?
Carbidopa prevents the breakdown of levodopa in the periphery.
Carbidopa is the biologic precursor of dopamine and can penetrate into the central nervous system.
Carbidopa allows for larger doses of levodopa to be given.
There are concerns about drug-food interactions with levodopa therapy that do not exist with the combination therapy.
The Correct Answer is A
A. Carbidopa prevents the breakdown of levodopa in the periphery, specifically in the gastrointestinal tract and peripheral tissues, allowing more levodopa to reach the brain and be converted to dopamine. This enhances the effectiveness of levodopa therapy in managing the symptoms of Parkinson's disease.
B. Carbidopa is not the biologic precursor of dopamine. It is a peripheral decarboxylase inhibitor that does not cross the blood-brain barrier.
C. Carbidopa does not directly allow for larger doses of levodopa to be given. However, by
inhibiting the peripheral breakdown of levodopa, it enhances the availability of levodopa to the central nervous system, potentially improving therapeutic efficacy.
D. While levodopa-carbidopa combination therapy may have fewer drug-food interactions compared to levodopa alone, the primary reason for combining these medications is to enhance the effectiveness of levodopa by preventing its peripheral breakdown.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. Acetaminophen is generally considered safe for patients with a history of peptic ulcer disease.
It does not irritate the gastrointestinal mucosa like nonsteroidal anti-inflammatory drugs (NSAIDs).
B. Patients with a history of liver disease should not receive acetaminophen or should use it with caution and under close supervision, as acetaminophen is metabolized in the liver. Liver
impairment can lead to decreased metabolism of acetaminophen, potentially resulting in drug accumulation and hepatotoxicity.
C. Acetaminophen is commonly used to relieve mild to moderate headaches. However, the appropriateness of acetaminophen use in this scenario depends on the patient's overall health status and any contraindications specific to the individual.
D. Acetaminophen is often used to reduce fever. A fever of 101°F (38.3°C) alone does not necessarily contraindicate acetaminophen use, but caution should be exercised in patients with liver disease.
Correct Answer is C
Explanation
A. These are adverse effects that usually subside after a few weeks: While some adverse effects of phenobarbital may diminish over time, the symptoms described by the patient are more likely related to its impact on REM sleep.
B. The drug must be stopped immediately because of possible adverse effects: Stopping phenobarbital abruptly can lead to withdrawal symptoms and potential rebound seizures; discontinuation should be done gradually under medical supervision.
C. This drug causes deprivation of REM sleep and may cause the inability to deal with normal stress: Phenobarbital is known to disrupt REM sleep, leading to emotional lability, irritability, and difficulty coping with stress.
D. This drug causes the rapid eye movement (REM) sleep period to increase, resulting in nightmares and restlessness: Phenobarbital actually decreases REM sleep, which can lead to disturbances in sleep patterns and mood changes.
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