• Acetaminophen
  • Fentanyl
  • Ketamine
  • Lorazepam
  • Morphine Sulfate


  • Mechanism of Action: Antipyretic/Analgesic. Inhibits prostaglandin synthesis on CNS and has direct action on hypothalamic heat-regulating systems.
  • Indications: Mild-moderate pain; fever
  • Contraindications: Allergy to class/drug
  • Dosage: 1000 mg PO q4-6 hours
  • Onset: 15-30 minutes PO for analgesia. 30 minutes for antipyretic
  • Duration: 4-6 hours
  • Adverse Reactions: Nausea, rash, and headache are common. 
  • Special Considerations: Doses above 4 grams/day may cause liver toxicity
Video Credit: Ninja Nerd

*Deep Dive: Acetaminophen (


  • Mechanism of Action: Narcotic opiate analgesic; binds to opiate receptors and blocks ascending pain pathways.
  • Indications: Moderate-severe pain, adjunct to sedation
  • Contraindications: Allergy to class/drug, respiratory depression, paralytic ileus
  • Dosage: Generally 1-2 mcg/kg IV/IM q30-60 minutes prn
  • Onset: 1-2 minutes (IV)
  • Duration: 2-4 hours
  • Adverse Reactions: Apnea, confusion, constipation, nausea/vomiting
  • Special Considerations: None
Video Credit: Nurse Ryan

*Deep Dive: Association between fentanyl treatment for acute pain in the ED and opioid use two weeks after discharge (American Journal of Emergency Medicine)


  • Mechanism of Action: NMDA receptor antagonist; dissociative anesthetic; analgesic/sedative; 
  • Indications: Analgesia, sedation, RSI induction
  • Contraindications: Allergy to drug/class
  • Dosage
    • Analgesic dose: 0.1-0.5 mg/kg IV
    • Procedural sedation dose: 0.5-1 mg/kg IV 
    • RSI induction: 2 mg/kg IV
    • Combative patient: 4-6 mg/kg IM or 1 mg/kg IV
  • Onset: Less than 1 minute (IV); 4 minutes (IM)
  • Duration: 5-15 minutes (IV); 15-30 minutes (IM)
  • Adverse Reactions: Laryngospasm, apnea, hypersalivation
  • Special Considerations: Does not affect respiratory drive, making it useful for awake or fiberoptic intubations. Ketamine is first line as an induction agent for intubations in asthmatic patients due to it’s bronchodilatory effects.
Video Credit: MedSchool Medic

*Deep Dive: Update from the K-Hole: Ketamine in the ED (EM Ottawa)


  • Mechanism of Action: Benzodiazepine; enhances inhibitory effects at GABA receptors. 
  • Indications: Seizures, agitation, delirium tremens, serotonin syndrome.
  • Contraindications:
  • Dosage: 1-2 mg IV bolus; 1-10 mg/hr infusion
  • Onset: 5 minutes (IV); 15-30 minutes (IM)
  • Duration: 6-8 hours
  • Adverse Reactions: Respiratory depression, hypotension, ataxia
  • Special Considerations: None
Video Credit: Nurse Ryan

*Deep Dive: Parenteral Benzodiazepines (Core EM)


  • Mechanism of Action: Opiate analgesic; binds to opioid receptors in the CNS to inhibit ascending pain pathways. Alters patient’s perception and response to pain.
  • Indications: Acute moderate-severe pain
  • Contraindications: Allergy to drug/class, severe asthma, paralytic ileus
  • Dosage: 0.1 mg/kg bolus (IV)
  • Onset: 5 minutes, peak at 20 minutes
  • Duration: 4-5 hours
  • Adverse Reactions: Respiratory depression, hypotension, nausea/vomiting, urticaria, dependence
  • Special Considerations: None
Video Credit: Lights Sirens Action EMS

*Deep Dive: The Death of MONA in ACS – Morphine (REBEL EM)

Brandon Simpson, PA-C
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