Description

Racecadotril is an oral drug that is classified as a pro-drug of the active compound thiorphan. It is a unique anti-diarrheal agent that works by targeting the intestinal fluid secretion process. Unlike other common anti-diarrheal medications, such as loperamide, racecadotril does not affect gut motility and therefore does not cause constipation.

Indications

Racecadotril is indicated for the symptomatic treatment of acute watery diarrhea in adults and children. It is always used as an adjunct to standard rehydration therapy (oral rehydration salts or solution). It is not a substitute for rehydration, which is the most critical component of diarrhea management.

Mechanism of Action

Racecadotril’s mechanism of action is based on its ability to inhibit an enzyme that breaks down natural substances in the body.

1. Inhibition of Enkephalinase: After oral administration, racecadotril is rapidly converted into its active metabolite, thiorphan. Thiorphan is a highly selective and potent inhibitor of the enzyme enkephalinase (or neprilysin).

2. Increased Enkephalin Levels: Enkephalinase is an enzyme that degrades naturally occurring substances called enkephalins. Enkephalins are endogenous opioids that have an antisecretory effect on the intestines, meaning they reduce the secretion of water and electrolytes into the gut. By inhibiting enkephalinase, racecadotril allows the levels of endogenous enkephalins to increase.

3. Antisecretory Effect: The increased levels of enkephalins bind to opioid receptors in the intestinal wall. This binding leads to a reduction in the secretion of water and electrolytes from the intestinal cells into the gut lumen.
4. No Effect on Motility: Unlike opiate-based anti-diarrheal drugs, racecadotril does not affect the speed of intestinal transit or peristalsis. This means that while it reduces the fluid content of the stool, it does not cause constipation or the other side effects associated with opioid receptor agonists in the central nervous system.

In summary, racecadotril works by protecting the body’s own anti-diarrheal substances (enkephalins) from being broken down, which allows them to reduce intestinal fluid secretion and alleviate the symptoms of watery diarrhea without affecting the natural movement of the gut.