Which antidote would be used to treat loperamide overdose?

• A. Naloxone
• B. Flumazenil
• C. Atropine
• D. Activated charcoal

Answer: (A)

Loperamide, even though it’s used to treat diarrhea, can cause opioid-like toxicity at high doses because it acts on μ-opioid receptors. The antidote is naloxone, a competitive μ-opioid receptor antagonist, which reverses the CNS and respiratory depression by displacing loperamide from the receptors. Administer naloxone promptly and titrate to effect, since symptoms can recur due to loperamide’s longer duration of action. Flumazenil, atropine, and activated charcoal don’t counteract opioid toxicity—flumazenil targets benzodiazepines, atropine is for anticholinergic effects, and activated charcoal is an absorption-limiting measure rather than a true antidote.