You can find out more about NPF's National Medical Director, Dr. Michael S. Okun, by also visiting the NPF Center of Excellence, University of Florida Center for Movement Disorders & Neurorestoration.
Many Parkinson’s disease patients and families members have been unnecessarily alarmed by the continuing reports that Sinemet and/or Madopar (European Sinemet) may accelerate disease progression, and that doses and drug intervals should be limited. These reports have unfortunately been fueled by sparse human evidence. Patients need to be aware that dopamine replacement therapies such as Sinemet and Madopar remain the single most effective, and single most important treatment for Parkinson’s disease worldwide. This month’s “What’s Hot” column will focus on the evidence including the most recent paper on this important topic.
In this month’s issue of Neurology, important evidence is presented that dopamine replacement therapy is not toxic, and does not accelerate disease progression. Parkkinen and colleagues at Queen Square in London examined pathology in 96 post-mortem Parkinson’s disease brains, and paired the tissue with clinical information including levodopa use. The study concluded that in the human condition “chronic use of L-dopa does not enhance progression of Parkinson’s pathology.”
In an accompanying editorial, two prominent neurologists in the field pointed out that there “remains lingering concerns as to whether levodopa is toxic to dopamine neurons and accelerates the degenerative process.” The science quoted to support these claims has included levodopa undergoing auto-oxidation, and forming reactive oxygen species and toxic protofibrils. Additionally, the science includes a classical experiment that showed when levodopa was mixed with brain cells placed in a dish, there was toxicity. The research, however, has fallen short in demonstrating toxicity of the drug in the human form of Parkinson’s disease. In fact, there now exists broad levels evidence from many studies across many countries (including most recently the ELLDOPA study) that levodopa is extremely beneficial to the human patient, and that levodopa has had a positive effect on disease course. Sinemet was recently reported as the most commonly administered drug among 4000+ patients being followed longitudinally in the National Parkinson Foundation Quality Improvement Initiative study. Expert practitioners who reported in this database, utilized levodopa more than any other drug-- including dopamine agonists, and they used levodopa more (not less) as disease durations increased.
What all this adds up to for patients and for Parkinson’s sufferers is that Sinemet and Madopar should be considered safe and effective as treatments for Parkinson’s disease. The doses and intervals should be frequently adjusted by an experienced neurologist/practitioner in order to maximize benefits, and to tailor to individual symptoms. Patients and families should keep in perspective that the “talk” about levodopa being toxic and accelerating disease progression can prove a major distractor to good care practices. Precious minutes in the doctor-patient relationship should not be wasted on these claims, and prescribers should not avoid or under-dose this critical therapy, especially in patients with treatable symptoms. Critics of Sinemet and Madopar will need to bring forward much stronger human data if they wish to change clinical practice. In the mean time, we need to serve our patients by sharing with them the weight of the evidence which strongly supports that levodopa replacement therapy is not toxic, and does not accelerate Parkinson’s disease.
Parkkinen L, O'Sullivan SS, Kuoppamäki M, Collins C, Kallis C, Holton JL, Williams DR, Revesz T, Lees AJ. Does levodopa accelerate the pathologic process in Parkinson disease brain? Neurology. 2011 Oct 11;77(15):1420-6. Epub 2011 Sep 14.
Warren Olanow C, Obeso JA. Levodopa toxicity and Parkinson disease: Still a need for equipoise. Neurology. 2011 Oct 11;77(15):1416-7. Epub 2011 Sep 14.
Fahn S. Parkinson disease, the effect of levodopa, and the ELLDOPA trial. Earlier vs Later L-DOPA. Arch Neurol. 1999 May;56(5):529-35.