Does levodopa/carbidopa, a common Parkinson's Disease drug, affect stomach emptying, blood pressure and heart rate?

Levodopa/carbidopa (Sinemet) is the most commonly used medication for Parkinson's disease, but the way it is absorbed into the body is complex and varies from person to person. One factor that affects this is how quickly the stomach empties its contents into the small intestine — a process called gastric emptying — which directly influences how fast the drug is absorbed and how effective it is. This study is looking at how a standard therapeutic dose of levodopa/carbidopa affects gastric emptying speed, blood pressure, and blood flow in the abdomen after drinking a glucose solution. Researchers also want to understand the relationship between gastric emptying rate and the rise of levodopa in the blood, and whether the medication helps protect against the post-meal drop in blood pressure that is common in people with Parkinson's disease. This is a carefully controlled study comparing the effects before and after taking the medication. You may be eligible if you are aged 50 to 80, have a confirmed diagnosis of mild to moderate Parkinson's disease, and are currently taking short-acting levodopa/carbidopa. People with diabetes, severe heart, liver, or kidney disease, stomach or GI conditions unrelated to Parkinson's, or who are taking medications that affect blood pressure or gut function are not eligible. The study is run by the University of Adelaide.