Which medication should be given to a patient taking levodopa-carbidopa who has tremors and twitching?

Amantadine is the appropriate choice for a patient taking levodopa-carbidopa who is experiencing tremors and twitching. This medication works as an antiviral agent, but it has also been found to have effects on the treatment of Parkinson’s disease symptoms, particularly in addressing dyskinesia, which includes involuntary movements such as tremors and twitching.

Amantadine is thought to enhance dopamine release and inhibit its reuptake, making it beneficial for managing motor symptoms in patients already on dopaminergic therapy like levodopa-carbidopa. It is commonly used as an adjunct therapy to help manage the side effects that may arise from prolonged levodopa use.

Other potential options for treatment, such as carbamazepine, primarily serve as an anticonvulsant and mood stabilizer and are not indicated for Parkinson’s disease tremors. Ropinirole and pramipexole are dopamine agonists that can be effective in treating Parkinson's disease but may not specifically target the symptoms of dyskinesia as effectively as amantadine does, particularly in the context of managing side effects from levodopa therapy.