Maxolon tablets/syrup (metoclopramide)
How does it work?
Maxolon tablets and syrup contain the active ingredient metoclopramide hydrochloride, which is a type of medicine called a dopamine antagonist. (NB. Metoclopramide is also available without a brand name, ie as the generic medicine.) Metoclopramide is an antisickness medicine, though it also has other uses due to its action on the gut.
Metoclopramide works primarily by blocking dopamine receptors found in an area of the brain known as the chemoreceptor trigger zone (CTZ). The CTZ is activated by nerve messages from the stomach when an irritant is present. It is also activated directly by agents circulating in the blood, for example anti-cancer medicines. Once activated, it sends messages to another area of the brain, the vomiting centre, which in turn sends messages to the gut, causing the vomiting reflex.
Blocking the dopamine receptors in the CTZ prevents nausea messages from being sent to the vomiting centre. This reduces the sensation of sickness and prevents vomiting.
Metoclopramide also acts in the upper end of the digestive system, where it enhances the action of a natural chemical called acetylcholine. Increasing the action of acetylcholine results in the tightening of the muscles at the entry to the stomach, relaxation of the muscles at the exit of the stomach and increased contraction of the muscles in the stomach itself. These actions speed the passage of food through the stomach into the intestine, which physically helps to prevent vomiting.
Both actions make metoclopramide useful in treating nausea and vomiting due to many causes, including anti-cancer chemotherapy and radiotherapy, various digestive disorders, heart failure,...
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