A 35-year-old presents with pinpoint pupils, bradycardia, respiratory rate of 6/min, and Glasgow Coma Scale of 8. He responds rapidly and fully to IV naloxone. The most critical clinical consideration when managing this patient is:

• A Give naloxone once and observe for 30 minutes before discharge if response is sustained
• B Oral naltrexone can substitute for IV naloxone in sustaining the reversal
• C Naloxone has a shorter duration of action (30–90 minutes) than most opioids; repeat dosing or IV infusion may be necessary to prevent re-narcotisation ✓
• D Once consciousness is regained, further monitoring is unnecessary

Explanation

Naloxone is a competitive opioid antagonist with a relatively short half-life of 30–90 minutes, significantly shorter than most opioid agonists (e.g., heroin metabolites last 3–5 hours; methadone 24–36 hours; buprenorphine 24–72 hours). After the initial naloxone dose reverses acute poisoning, the opioid's ongoing effect can outlast naloxone's antagonism, causing re-narcotisation and fatal respiratory depression. Management therefore requires repeated naloxone dosing (IV boluses every 20–30 minutes) or a continuous IV infusion (typically starting at two-thirds of the effective reversal dose per hour). Oral naltrexone has a delayed onset and is not an emergency intervention.

Reference: Kaplan & Sadock's Synopsis of Psychiatry, 11th ed.

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Written and medically reviewed by the StethoPrep medical team.