Question 2 of 15

On your way to an examination, you experience the vulnerable feeling that an attack of diarrhea is imminent. If you stopped at a drugstore, which one of the following antidiarrheal drugs could you buy without a prescription even though it is related chemically to the strong opioid analgesic meperidine?

Aluminum hydroxide

Diphenoxylate

Loperamide

Magnesium hydroxide

Metoclopramide

Aluminum hydroxide is constipating but is not related chemically to meperidine; magnesium hydroxide is a strong laxative. The 2 antidiarrheal drugs that are structurally related to opioids are diphenoxylate and loperamide. Loperamide is available over-the-counter; diphenoxylate is mixed with atropine alkaloids, and the product (Lomotil, others) requires a prescription. The answer is C.

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