If you read The Parkinson regularly, you will know about the “Get it on Time” campaign. When you come to clinic, if you are taking levodopa we always advise taking it at least 30 – 40 minutes before food. Why is there such a fixation with taking these tablets at particular times?
Well, the problem with levodopa (Sinemet, Madopar, Stalevo) is that it only has a very short life in the brain. If you go too long between doses your symptoms can return before the next dose is due. If you do not take your tablets on time your Parkinson’s control will suffer. Taking levodopa at the same time as food containing protein (e.g. meat, fish, eggs, cheese, milk, etc) can result in the dose being poorly absorbed. Levodopa passes in to the blood stream not in the stomach but lower down in the duodenum which is the name for the first part of the small intestine.
To pass into the blood stream, protein and levodopa are broken down into molecules. As protein and levodopa both break down into the same type of molecule (large neutral amino acids), the mechanism that transports large neutral amino acids around the body cannot differentiate between protein and levodopa molecules. As there are many more protein molecules present than levodopa ones they swamp the transport mechanism so that many of the levodopa molecules get left behind and so are not absorbed.
Therefore, the best way of avoiding this is to take levodopa before food so that it can get to the duodenum well before the protein molecules, and the maximum amount can be absorbed. The minimum time for the levodopa to be absorbed before eating is about 30 – 40 minutes but if you can take your levodopa and leave a longer gap so much the better. If you need to take levodopa after meals, you need to leave at least an hour and ideally an hour and a half to allow the meal to have passed through the duodenum.