Antidiarrheal drugs: what are they?

Diarrhea is a defecation disorder characterized by the rapid and urgent emission of feces, having a semi-liquid or watery consistency.

More than a real pathology, diarrhea generally constitutes the symptom of an underlying pathological situation.

Therefore, it is clear that in the event of the appearance of this disorder it is essential to promptly identify the primary cause, so as to be able to establish an "adequate therapy.

However, diarrhea is a rather debilitating disorder, which can be associated with symptoms such as abdominal cramps, pains and bloating. In addition, diarrhea can cause a significant loss of water and minerals, resulting in dehydration. Therefore, in these cases, the use of antidiarrheal drugs is essential.

Loperamide is an opioid active ingredient, derived from morphine and with a marked antidiarrheal activity.
Compared to morphine, loperamide is more lipophilic and struggles to overcome the blood brain barrier; moreover, it undergoes a strong first pass metabolism. For these reasons, at the therapeutic doses usually used, loperamide does not produce central effects of the opioid type; therefore it has a low potential for abuse and dependence (so much so that the medicines containing it are sold as non-prescription drugs).

Loperamide carries out its antidiarrheal activity by exerting an agonist effect against the μ and δ opioid receptors present in the intestine. The activation of these receptors inhibits the release of acetylcholine by the cholinergic neurons, with consequent inhibition of intestinal peristalsis.