16.03.1 Treatment for Diarrhea

In the treatment of diarrhea, the replacement of fluids and electrolytes is a common treatment. In severe, prolonged bacterial infections, anti-bacterial drugs may be used.

When people abuse the opioid heroin, they become constipated. When the opioid morphine is used to relieve pain, it also causes constipation. Heroin and morphine stimulates opioid m-receptors to decrease intestinal motility, which leads to increased absorption of water from the colon, and to constipation (Figure 16.5). This adverse effect in people with normal gut function has been used to develop an opioid agent suitable for use in diarrhea.

This agent is loperamide, which stimulates the gastrointestinal tract m-receptors to be anti-diarrheal in subjects with diarrhea. Loperamide does not have any potential to be abused, as it is a poor penetrant of the central nervous system. Also, there are no central nervous side effects with loperamide. Loperamide is used in most forms of diarrhoea and in the diarrhea part of irritable bowel syndrome.