A client with Parkinson disease is prescribed levodopa. Which mechanism best explains how this medication works?

• A. Blocks the effects of acetylcholine
• B. Increases the production of dopamine
• C. Restores the dopamine levels in the brain
• D. Promotes the production of acetylcholine

Answer: (C)

Levodopa replenishes dopamine in the brain by acting as a precursor that crosses the blood-brain barrier and is then converted to dopamine within dopaminergic neurons. This conversion increases the amount of dopamine available in the basal ganglia, counteracting the dopamine deficiency seen in Parkinson disease and improving motor symptoms. The best description is that this medication restores dopamine levels in the brain. It does not work by blocking acetylcholine, nor by directly promoting acetylcholine production. It also isn’t simply “increasing production” of dopamine without the conversion step; it provides the material that becomes dopamine in the brain, yielding replenishment of dopamine levels.