The combination of levodopa and carbidopa, called
Sinemet, is an important medication used in treating
Parkinson’s disease. However, there are some barriers to
absorption of Sinemet by the body.
1) If you take your Sinemet with a meal, or just
after a meal, it may take a very long time for the
Sinemet to be absorbed. This is because the
stomach takes about one to three hours to empty
food. The Sinemet is mixed with the food, so it
takes the same amount of time to clear the
stomach as the food does.
2) A high-fat meal takes even longer to clear the
stomach. Fat is digested very slowly compared
to carbohydrate and protein. If Sinemet is mixed
with the fat, it will clear the stomach at the same
time as the fat.
3) Protein in the meal is broken down in the
intestine into amino acids. These aminos must
travel across the intestinal wall to get into the
blood. Once in the blood, they must cross the
blood-brain barrier to get into the brain. Sinemet
also must cross the intestine and the blood-brain
barrier. And the aminos and Sinemet use exactly the
same carrier system to get across.
Most meals contain a large amount of protein,
and so the aminos use up all the “carriers.” The
Sinemet must wait until the carriers are free
again, in order to cross over into the
bloodstream. The same thing happens when
Sinemet tries to get to the brain, where it does its
work. Once more, aminos clog up all the
“carriers” and Sinemet can’t get through to the