In a client with Parkinson's disease taking carbidopa-levodopa (Sinemet), which observation indicates the medication's effectiveness?

The effectiveness of carbidopa-levodopa in a client with Parkinson's disease is indicated by a lessening of tremors. Carbidopa-levodopa is a combination medication used to manage the symptoms of Parkinson’s disease by replenishing the levels of dopamine in the brain, which is deficient due to the disease's progression. One of the hallmark symptoms of Parkinson's disease is tremors, and a reduction in this symptom signifies that the medication is working effectively to improve motor function and control.

Other potential observations, such as decreased blood pressure or increased salivation, are not direct indicators of the medication's effectiveness in addressing the primary symptoms of Parkinson's disease. Increased attention span could be noted but is not a primary measure of the immediate effects of the medication focused on tremor control.