NARCAN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NARCAN (NARCAN).
Opioid receptor antagonist; binds competitively to mu, kappa, and delta opioid receptors, reversing opioid effects.
| Metabolism | Primarily hepatic glucuronidation via UGT1A8 and UGT2B7 to naloxone-3-glucuronide; minimal CYP450 involvement. |
| Excretion | Primarily hepatic metabolism (glucuronidation) followed by renal excretion of metabolites; <5% excreted unchanged in urine. |
| Half-life | Approximately 1 hour in adults; context: shorter than most opioids (e.g., morphine 2-4 h), necessitating repeated doses for prolonged opioid effects. |
| Protein binding | Approximately 45-55% bound to serum proteins, primarily albumin. |
| Volume of Distribution | Approximately 1.0-1.5 L/kg; clinical meaning: extensive distribution outside plasma, indicating rapid tissue uptake. |
| Bioavailability | Intranasal: approximately 50% relative to intravenous; intramuscular/subcutaneous: approximately 50-100% due to first-pass metabolism. |
| Onset of Action | Intravenous: 1-2 minutes; intramuscular/subcutaneous: 2-5 minutes; intranasal: approximately 2-3 minutes. |
| Duration of Action | Approximately 30-90 minutes; clinical note: duration may be shorter than that of many opioids, requiring repeat dosing or continuous infusion. |
| Molecular Weight | 327.38 |
Initial dose: 0.4 mg to 2 mg IV, IM, or SC, repeated every 2 to 3 minutes as needed. For opioid-induced respiratory depression, may use 0.1 to 0.2 mg IV increments in patients with opioid dependence to avoid withdrawal.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required; naloxone is primarily metabolized by the liver and not significantly renally excreted. |
| Liver impairment | No specific dose adjustment; use with caution in severe hepatic impairment due to potential altered metabolism. |
| Pediatric use | 0.01-0.1 mg/kg IV, IM, or SC every 2-3 minutes as needed; maximum single dose 2 mg. For neonates: 0.01-0.1 mg/kg IV or IM, repeat every 2-3 minutes if needed. |
| Geriatric use | No specific dose adjustment; initiate at lower end of dosing range (0.1-0.2 mg) and titrate due to potential increased sensitivity and risk of withdrawal. |
| 1st trimester | Naloxone is not associated with an increased risk of major congenital malformations; however, opioid withdrawal may have risks. Use if clearly needed. |
| 2nd trimester | No known fetal risks from naloxone; monitor for opioid withdrawal. |
| 3rd trimester | No known fetal risks; naloxone does not cause perinatal depression. Use for opioid overdose. |
Clinical note
Comprehensive clinical and safety monograph for NARCAN (NARCAN).
| Placental transfer | Naloxone crosses the placenta in minimal amounts; no known adverse fetal effects from placental transfer. |
| Breastfeeding | Naloxone is poorly absorbed orally and is not expected to cause adverse effects in breastfed infants; it is considered compatible with breastfeeding. |
| Lactation Rating |
■ FDA Black Box Warning
Risk of precipitating acute opioid withdrawal; monitor for recurrence of respiratory depression due to short duration of action.
| Serious Effects |
Hypersensitivity to naloxone or any component of the formulation
| Precautions | May precipitate acute withdrawal in opioid-dependent patients; repeated doses may be needed due to shorter half-life than many opioids; not effective for non-opioid overdoses. |
| Food/Dietary | No known food interactions. NARCAN is for intranasal or injectable use; no dietary restrictions. |
| Clinical Pearls |
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| L1 - Safest |
| Teratogenic Risk | Naloxone (NARCAN) is not teratogenic in animal studies. Human data are limited, but no increased risk of major malformations has been reported. First trimester: No known teratogenic risk. Second/third trimester: No known fetal risks; naloxone crosses the placenta but has minimal fetal effects due to short half-life and lack of opioid agonist activity. |
| Fetal Monitoring | Monitor for recurrence of respiratory depression, blood pressure, heart rate, and oxygen saturation in the mother. Fetal monitoring includes heart rate and uterine activity if indicated (e.g., in opioid-dependent labor). No specific long-term monitoring required after reversal. |
| Fertility Effects | No known effects on fertility. Naloxone does not alter reproductive hormones or gamete function in animal studies. |
| Naloxone (NARCAN) has a short half-life (30-81 min) relative to many opioids; repeat doses may be needed, especially for long-acting opioids like methadone or fentanyl. Use the lowest effective dose to avoid precipitation of severe withdrawal. Intranasal administration provides rapid absorption and is preferred in community settings. Always monitor for rebound respiratory depression. In pregnant patients, naloxone does not cause harm to fetus, but reversal of opioid effects may precipitate withdrawal; manage with supportive care. |
| Patient Advice | Administer NARCAN at the first sign of opioid overdose, such as unresponsiveness, slow or stopped breathing, or blue lips/fingernails. · Spray one dose into one nostril; repeat every 2-3 minutes if no response. · Call 911 immediately after giving NARCAN, even if the person wakes up. · Place the person in the recovery position on their side after administration to prevent aspiration. · NARCAN is not a substitute for emergency medical care; effects last 30-90 minutes, and overdose may return. · Keep NARCAN at room temperature, away from light, and check expiration date regularly. |