Naloxone is ineffective (and therefore contraindicated) for patients in which condition?

• A. Cardiac arrest
• B. Respiratory depression due to overdose
• C. Hypoglycemia
• D. Anaphylaxis

Answer: (A)

Naloxone works by blocking opioid receptors and reversing the respiratory depression caused by opioid overdoses. In a patient who is in cardiac arrest, the primary problem is the heart not beating effectively, not opioids suppressing respiration. Reversing opioid effects won’t restart circulation or restore a pulse, and there’s no benefit to giving naloxone in this situation during resuscitation. That’s why it’s not indicated in cardiac arrest, even if an opioid overdose could be suspected.

In contrast, if a patient has respiratory depression due to an opioid overdose and still has a pulse, naloxone can help restore breathing. The other conditions listed require different treatments: hypoglycemia is treated with glucose, and anaphylaxis with epinephrine and airway support.