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Naloxone (Narcan)

Category: Pharmacology Sources: raw/protocols/nm-sop-guidelines-treatment-2022.pdf; UCLA EMT Ultimate Study Guide (2026) Last updated: 2026-05-06

Overview

Naloxone (trade name Narcan) is an opioid receptor antagonist — it competitively displaces opioids from mu-opioid receptors in the brain, reversing respiratory depression, sedation, and miosis within 2–5 minutes. It is the only medication that reverses opioid toxicity. In NM and most states, naloxone is authorized under standing order for EMT-B. It is a life-saving intervention in opioid overdose and is specifically tested on the NREMT cognitive exam.

Key Points

  • Class: Opioid antagonist (reversal agent)
  • Trade name: Narcan
  • Indications: Suspected opioid overdose with respiratory depression (rate <8/min or inadequate depth) or unresponsive patient with opioid history or paraphernalia on scene
  • Dose (adult): 0.4–2 mg IM or intranasal (IN); repeat every 2–3 minutes as needed; titrate to adequate respirations, NOT full consciousness
  • Dose (pediatric): 0.1 mg/kg IM/IN; max 2 mg per dose
  • Route: IM (deltoid or lateral thigh) or intranasal (atomizer device); IV/IO at ALS level
  • Onset: 2–5 minutes IM/IN; <2 minutes IV/IO
  • Duration: 30–90 minutes — shorter than most opioids; patient may re-sedate after naloxone wears off
  • Authorization: Standing order in most NM EMS systems (check local protocol)
  • No contraindications in suspected opioid overdose — if you are wrong about opioids, naloxone causes no harm

The Naloxone Duration Problem — Redosing and Transport

The most critical clinical concept with naloxone: the drug wears off before the opioid does.

Fentanyl, heroin, oxycodone, and methadone all have longer durations than naloxone. A patient who responds to naloxone and appears awake and breathing adequately is not out of danger. As naloxone clears, opioid effect resumes — the patient can re-sedate and stop breathing again.

EMT-B implications: - Transport all naloxone patients — even if they appear fully awake and demand to refuse; re-sedation is a life threat - Reassess repeatedly — any deterioration in respiratory rate, LOC, or SpO₂ may indicate re-sedation - Titrate to respirations, not wakefulness — the goal is adequate breathing, not a fully alert, combative patient; over-reversal can precipitate acute opioid withdrawal (agitation, vomiting, combativeness, hypertension) - Repeat dosing: if respiratory rate remains <8/min or patient is not responding, repeat 0.4–2 mg every 2–3 minutes; document each dose and time

KEY DIFFERENTIATOR — Titrate to Breathing, Not Consciousness: Naloxone should restore adequate respirations, not necessarily full wakefulness. Over-reversing an opioid-dependent patient causes acute withdrawal — painful, dangerous, and results in a combative patient. Give enough to breathe; transport for the rest. NREMT tests this distinction.

Assessment Findings That Indicate Opioid Overdose

The opioid toxidrome — look for the triad:

Finding Opioid Overdose
Pupils PINPOINT (miosis) — bilateral, even in bright light
Respirations Slow (<8/min), shallow, or absent; snoring/gurgling (airway relaxation)
LOC Unresponsive or responds only to painful stimuli
Skin Pale, cyanotic, cool; may have diaphoresis
Scene clues Needles/syringes, pill bottles, drug paraphernalia, track marks

KEY DIFFERENTIATOR — Opioid vs. Sedative-Hypnotic Overdose: Both cause respiratory depression and decreased LOC. The distinction: opioids = pinpoint pupils + responds to Narcan. Sedative-hypnotics (benzos, barbiturates) = normal or slightly constricted pupils + NO EMT-level reversal agent. Pupil size is the single most useful differentiator.

Procedures

  1. BSI / scene safety — opioid overdose scenes may have other hazards (fentanyl powder, sharps)
  2. Primary assessment — airway, breathing first; begin BVM if respiratory rate <8/min or absent; SpO₂
  3. Confirm opioid overdose picture: pinpoint pupils + respiratory depression + scene clues
  4. Obtain authorization if not standing order
  5. Administer naloxone:
  6. Intranasal: draw up 1 mL (0.4 mg or per agency formulation); attach atomizer; administer 0.5 mL per nostril
  7. IM: draw up 0.4–2 mg; inject into deltoid or lateral thigh
  8. Continue BVM during the 2–5 minute onset period — do not stop ventilating while waiting for effect
  9. Reassess at 2–3 minutes — if no response, repeat dose
  10. Once respirations adequate, place in recovery position (lateral) — aspiration risk
  11. Document: time, dose, route, response, repeat doses
  12. Transport all naloxone patients regardless of apparent recovery
  13. Inform receiving facility: "Patient received [dose] mg naloxone at [time]; responded to [X] doses; last respiratory rate [X]; SpO₂ [X]%"

Post-Naloxone Patient Management

The awake, combative patient: a fully reversed opioid-dependent patient in acute withdrawal may be agitated, threatening, and demand to refuse transport. Key points: - Withdrawal is not immediately life-threatening, but re-sedation is - Explain calmly: the medication that woke them up wears off faster than the opioid - Contact medical control — physician may authorize additional doses or advise on refusal management - If they refuse and have capacity, follow refusal protocol; document thoroughly - Over-reversed patient: do NOT give more naloxone; supportive care; transport

Ongoing monitoring during transport: - Respiratory rate, depth, SpO₂ every 5 minutes - LOC (AVPU) - Be prepared to re-administer naloxone or begin BVM at any point

NM Protocol Notes (Naloxone — Suspected Opioid Overdose)

EMT-B scope (standing order): - NALOXONE (Narcan): Adult 0.4–2 mg IM or IN; may repeat every 2–3 minutes as needed; titrate to adequate respirations - Pediatric: 0.1 mg/kg IM/IN; max 2 mg per dose - Administer oxygen; place on cardiac monitor; establish IV/IO access if available - Transport all patients who receive naloxone — re-sedation risk

Caution note in NM protocol: Naloxone may precipitate acute opioid withdrawal in dependent patients. Symptoms include agitation, hypertension, nausea, vomiting, diaphoresis, abdominal cramping. Titrate to adequate respirations; avoid full reversal in dependent patients.

NREMT Relevance

  • Indication: opioid overdose with respiratory depression — do NOT give to patients breathing adequately
  • Dose: 0.4–2 mg IM or IN; repeat every 2–3 min if no response
  • Titrate to adequate respirations, NOT full wakefulness — over-reversal causes withdrawal
  • Duration: 30–90 min; opioids last longer; re-sedation is the primary transport reason
  • Pinpoint pupils + respiratory depression + responds to Narcan = opioid toxidrome
  • No contraindications in confirmed/suspected opioid overdose
  • Transport ALL naloxone patients even if they appear fully awake
  • overdose-poisoning — full opioid toxidrome, other toxidromes, poison control
  • six-rights — medication check before every naloxone administration
  • primary-assessment — respiratory depression detected here; BVM before naloxone if apneic
  • medication-orders — standing order authorization; on-line medical control for repeat/high doses
  • refusal-of-care — combative post-naloxone patients who refuse transport
  • reassessment — serial respiratory rate and SpO₂ monitoring for re-sedation

Sources

  • raw/protocols/nm-sop-guidelines-treatment-2022.pdf — Suspected Opioid Overdose protocol
  • UCLA EMT Ultimate Study Guide (2026) — Pharmacology / Opioid Antagonists