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(Levodopa is only one of the PD medications used to treat PD, but if I include data on all of them, we will be here all week!) Levodopa (L-dopa for short) has been used successfully in the treatment for Parkinson's Disease for over 30 years. It remains the most effective treatment for Parkinson's Disease. L-dopa is a natural chemical found in animals and plants. When L-dopa is formulated for drug use, the generic name levodopa is used. In patients with Parkinson's Disease the cells in the brain that produce dopamine die. Levodopa works by being taken up by the surviving dopamine-producing cells in the brain, and is converted by these cells into dopamine. People with Parkinson's Disease can't simply take dopamine tablets or vegetable products containing dopamine (e.g.fava beans) to replace the missing dopamine, because dopamine taken by mouth cannot get across the blood/brain barrier, and is used by parts of the body other than the brain, and can be "pirated". Levodopa on the other hand does get into the brain and, once there, it converts to dopamine. Levodopa combined with carbidopa (Sinemet CR, Sinemet) or benserazide (Madopar) is the main treatment for Parkinson's Disease. Combining carbidopa or benserazide with levodopa has several benefits: *Carbidopa or benzerazide prevent levodopa from being converted to dopamine outside the brain. *They allow more levodopa to enter the brain where it is needed. *They help to reduce or prevent the side effects of dizziness and nausea. Nausea and vomiting can be a problem, as they may result in the dose being ejected. Any bodily process that delays the passage of the medication to the small intestine may result in a reduced dose, or even a missed dose. Constipation is another bodily process that can affect passage of the medication, and prevent absorption within the "half-life" (approx. 30mins) of the drug. In PWP, constipation can have several causes, such as taking opiate-containing medication (eg Codein). "Wearing Off" - This happens when Parkinson's symptoms begin to recur before the next scheduled dose of the drug, due to progression of the disease. When this happens, it is easy to think that the drug is making your symptoms worse - for a while after you take the next dose, your symptoms can continue to worsen until the next dose "kicks in". This happens because the drug takes a while to be absorbed and reach your brain. "On-Off" - These are unpredictable fluctuations in response to drug therapy that may last up to several hours. They are thought to be due to a combination of levodopa dosage and progression of symptoms. The dopamine storage cells may lose their capacity to retain the dopamine delivered by the medication. Dopamine is one of the catecholamine group of neurotransmitters, which includes adrenaline (epinephrine) and noradrenaline (norepinephrine), the so-called "fight or flight" hormones. In times of stress, the brain can turn dopamine into these other hormones, thus depleting the store of dopamine. Sorry for the long-winded explanation, but it is as short as I can get it, and still make sense. Jim (Dr. James F Slattery, PhD Soc Sc) ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn