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Irene Rosenthal wrote: > > What is the carbodopa supposed to do? It's a bit complicated. What you want is for dopamine to get into the brain. But dopamine won't cross the "blood-brain barrier", one of the body's natural defenses. However, levodopa, a chemical precursor of dopamine, WILL cross the barrier, and then can convert to useful dopamine. Problem: The conversion occurs anywhere, and you don't want it to occur before the levodopa gets into the brain, because it will then go to waste. Also, it happens that excess dopamine outside the brain nearly always makes you nauseous. So, they mix the levodopa with carbidopa, which also cannot get into the brain, but inhibits the unwanted conversion of levodopa before IT gets into the brain. They call the combination Sinemet, from the Latin "sine emesis", or "no vomiting". If you saw the film "Awakenings" you may recall that Dr. Sacks had to give huge doses of dopamine in order to get enough into his catatonic patients' brains to help their PD symptoms. The trick of starting with levodopa was discovered much later, by Dr. Kotzias and others, and carbidopa came soon after that. Cheers, Joe J. R. Bruman (818) 789-3694 3527 Cody Road Sherman Oaks, CA 91403-5013