Researchers at Emory University and a group of international collaborators, using positron emission tomography (PET) brain imaging, have determined that a relatively new drug slows the loss of dopamine function in early stages of Parkinsons disease (PD) compared with an older, more commonly used drug.
Investigators say the drug ropinirole (brand name ReQuip ) slows the loss of dopamine, a neurotransmitter produced by neurons in the brain that is found in steadily decreasing amounts as the disease progresses, in a more effective manner than levodopa (brand name Sinemet ).
In this trial, the progression of the loss of dopamine function was slowed by over 30 percent in participants taking ropinirole as compared with participants in a comparable stage of the disease taking levodopa.
Three-dimensional PET scans were taken before and after the study to show the level of dopamine loss in the brain, which can be inferred from a radioactive marker whose uptake by neurons is measured in PET imaging.
This multi-site, international trial is called "Requip as EArly therapy versus L-dopa", or the REAL-PET study. Emory University, under the guidance of Ray Watts, M.D., professor of neurology, Emory University School of Medicine, led the American sites, recruiting the most patients worldwide in the study.
Dr. Watts and collaborators will present their findings at the American Academy of Neurology 54th Annual Meeting in Denver, Colo., on Tuesday, April 16.
"We are really pleased with the outcome of this trial because it is one of the first of its kind to demonstrate slowing of the rate of loss of dopamine function in PD patients," Dr. Watts says. "It is also one of the first studies designed to use PET imaging in PD patients to differentiate how two different therapies (ropinirole vs. levodopa) affect progression of the loss of dopamine function."