A small amount of atropine is added to diphenoxylate in order to:
**Core Concept**
Atropine is added to diphenoxylate in a combination medication to counteract its side effects, particularly the constipating effect, while still maintaining its analgesic and anti-diarrheal properties. This combination is used to treat diarrhea.
**Why the Correct Answer is Right**
The addition of atropine serves as an anticholinergic agent, which counteracts the muscarinic effects of diphenoxylate. Diphenoxylate works by activating the mu-opioid receptors in the gut, causing a decrease in gut motility. Atropine, on the other hand, blocks the action of acetylcholine on muscarinic receptors, leading to a decrease in gut secretions and further reducing gut motility, thereby enhancing the constipating effect of diphenoxylate.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because atropine is not added to enhance the analgesic effects of diphenoxylate. While atropine does have some analgesic properties, its primary function in this combination is to counteract the side effects of diphenoxylate.
**Option B:** This option is incorrect because atropine does not increase the absorption of diphenoxylate. Atropine's addition is not related to the absorption of diphenoxylate.
**Option C:** This option is incorrect because atropine does not reduce the risk of dependence on diphenoxylate. Atropine's addition is not related to the risk of dependence.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that atropine is added to combination medications like Lomotil (diphenoxylate and atropine) to counteract its side effects, making it a safer and more effective treatment for diarrhea.
**Correct Answer:** C.