Which of the following is an example of an antidiarrheal medication?

Loperamide is an effective antidiarrheal medication that works by slowing down gut motility and decreasing the frequency of bowel movements. It acts primarily on the mu-opioid receptors in the gastrointestinal tract, which helps reduce the number of stools and makes the stool less watery. This mechanism is crucial for managing conditions like acute nonspecific diarrhea and chronic diarrhea associated with inflammatory bowel disease. Its ability to improve symptoms makes it a first-line treatment in many cases of diarrhea.

In contrast, bisacodyl is a stimulant laxative used to treat constipation, metoclopramide is an antiemetic that helps with nausea and gastric emptying, and sodium bicarbonate is an antacid that neutralizes stomach acid. Each of these medications has a different primary use and mechanism of action unrelated to treating diarrhea.