Which statement about carbidopa-levodopa is true?

Which statement about carbidopa-levodopa is true?

• A. It improves motor symptoms in Parkinson disease.
• B. It should be taken with pyridoxine to maximize effectiveness.
• C. It cures Parkinson disease.
• D. It is a cholinesterase inhibitor.

Answer: (A)

The key idea is that this medication replenishes dopamine in the brain to improve motor symptoms of Parkinson disease. Levodopa is a dopamine precursor that crosses into the CNS and is converted to dopamine, helping reduce bradykinesia, rigidity, and tremor. Carbidopa blocks the peripheral enzyme that would convert levodopa to dopamine outside the brain, which both lowers peripheral side effects (like nausea) and increases the amount of levodopa that reaches the brain. Together, they provide meaningful improvement in motor function for many patients, though they do not cure the disease and benefits can fluctuate over time. Taking it with pyridoxine (vitamin B6) is not advisable because B6 can enhance peripheral breakdown of levodopa, reducing its brain availability and effectiveness (a concern especially when the peripheral decarboxylase is not inhibited). The statement about curing the disease is incorrect—this treatment eases symptoms but does not cure Parkinson disease. It is not a cholinesterase inhibitor, so that description doesn’t apply.

The key idea is that this medication replenishes dopamine in the brain to improve motor symptoms of Parkinson disease. Levodopa is a dopamine precursor that crosses into the CNS and is converted to dopamine, helping reduce bradykinesia, rigidity, and tremor. Carbidopa blocks the peripheral enzyme that would convert levodopa to dopamine outside the brain, which both lowers peripheral side effects (like nausea) and increases the amount of levodopa that reaches the brain. Together, they provide meaningful improvement in motor function for many patients, though they do not cure the disease and benefits can fluctuate over time.

Taking it with pyridoxine (vitamin B6) is not advisable because B6 can enhance peripheral breakdown of levodopa, reducing its brain availability and effectiveness (a concern especially when the peripheral decarboxylase is not inhibited). The statement about curing the disease is incorrect—this treatment eases symptoms but does not cure Parkinson disease. It is not a cholinesterase inhibitor, so that description doesn’t apply.