Which medication should a nurse anticipate administering to a patient taking levodopa/carbidopa who is experiencing tremors and twitching?

Levodopa/carbidopa is primarily used in the management of Parkinson's disease to help alleviate motor symptoms such as tremors, rigidity, and bradykinesia. However, as treatment progresses, some patients may experience exacerbation of symptoms such as tremors and twitching, often referred to as dyskinesias.

Amantadine is an antiviral medication that is also used in Parkinson's disease as an adjunct to levodopa/carbidopa treatment. It has been shown to help reduce dyskinesias and improve motor control in patients experiencing these symptoms. The mechanism by which amantadine works includes enhancing dopamine release and inhibiting the reuptake of dopamine, which can provide a stabilizing effect on movement-related symptoms.

This makes amantadine the most appropriate choice for a patient experiencing tremors and twitching while on levodopa/carbidopa, as it directly targets the dyskinetic movements often associated with this type of therapy.