What are the emergency anaesthesia drugs, including their intravenous doses, duration of clinical effect, and primary actions?

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Last updated: September 19, 2026 • View editorial policy

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Emergency Anaesthesia Drugs: Doses, Onset, and Duration

For emergency airway management and procedural sedation, the core drugs are succinylcholine (2 mg/kg IV, onset 30-45 seconds, duration 5-10 minutes), etomidate (0.2-0.3 mg/kg IV for induction), ketamine (2 mg/kg IV), propofol (2-6 mg/kg IV), midazolam (0.07 mg/kg IV), and rocuronium (0.1-0.2 mg/kg IV, onset 2 minutes, duration 45-90 minutes). 1

Neuromuscular Blocking Agents

Succinylcholine (Depolarizing Agent)

  • IV Dose: 2 mg/kg (4 mg/kg for infants <6 months)
  • IM Dose: 4 mg/kg (5 mg/kg for infants <6 months)
  • Onset: 30-45 seconds IV; 3-5 minutes IM
  • Duration: 5-10 minutes
  • Action: Rapid paralysis for emergency intubation

Critical caveats: Always pretreat with atropine 0.02 mg/kg (minimum 0.1 mg, maximum 1 mg) to prevent bradycardia or asystole. This drug causes life-threatening hyperkalemia in patients with burns, crush injuries, spinal cord injury, neuromuscular disease, or myopathy—use rocuronium instead in these cases. Immediate cardiac arrest after administration suggests hyperkalemia, particularly in boys <9 years old. 1

Rocuronium (Nondepolarizing Agent)

  • IV Dose: 0.1 mg/kg for routine paralysis; 0.2 mg/kg for intubation
  • Onset: 2 minutes (slower than succinylcholine)
  • Duration: 45-90 minutes (dose-dependent)
  • Action: Longer-acting paralysis

Rocuronium is preferred when succinylcholine is contraindicated but requires 2 minutes for adequate intubating conditions versus 30-45 seconds for succinylcholine. 1

Vecuronium (Nondepolarizing Agent)

  • IV Dose: 0.1 mg/kg for routine paralysis; 0.2 mg/kg for intubation
  • Onset: 2 minutes
  • Duration: 45-90 minutes
  • Action: Alternative nondepolarizing agent with minimal cardiovascular effects

Used when longer paralysis is needed; preferred over rocuronium in some settings due to simple storage and lack of adverse effects. 2

Induction Agents

Etomidate

  • IV Dose: 0.2-0.3 mg/kg
  • Onset: Rapid (seconds)
  • Duration: Short-acting
  • Action: Induction with cardiovascular stability

Etomidate is the preferred induction agent for patients with cardiovascular dysfunction or volume depletion due to hemodynamic stability. 1 It can be safely administered for procedural sedation in the ED (Level C recommendation). 3 Common side effects include pain on injection and myoclonus (0-21% of patients, usually <1 minute duration). 3 The main concern is potential adrenal insufficiency with repeated dosing. 4

Ketamine

  • IV Dose: 2 mg/kg (after 0.07 mg/kg midazolam pretreatment in adults)
  • Onset: Rapid
  • Duration: Variable
  • Action: Dissociative anesthesia with analgesia

Ketamine can be safely administered to children for procedural sedation (Level A recommendation). 3 It is indicated for analgesia and anesthesia in trauma patients, except those with isolated or dominant craniocerebral trauma. 2 When combined with midazolam (0.07 mg/kg IV followed by ketamine 2 mg/kg IV), it provides effective sedation with minimal emergence reactions in adults. 3

Propofol

  • IV Dose: 2-6 mg/kg
  • Onset: Rapid (seconds)
  • Duration: Short-acting (minutes)
  • Action: Rapid induction and sedation

Propofol can be safely administered for procedural sedation (Level B recommendation). 3 Use lower doses if other sedatives/narcotics have been administered. Causes vasodilation and decreased cardiac output; higher doses associated with hypotension and apnea. Avoid in patients with cardiovascular dysfunction or volume depletion—use etomidate instead. 1 IM administration causes tissue necrosis. 1

Sedatives and Analgesics

Midazolam

  • IV Dose: 0.07 mg/kg (for procedural sedation)
  • Onset: 1-3 minutes
  • Duration: 30-60 minutes
  • Action: Anxiolysis, amnesia, sedation

The combination of fentanyl and midazolam is effective for procedural sedation (Level B recommendation). 3 Midazolam is used for sedation alone or in combination with ketamine or fentanyl for total intravenous anesthesia. 2 Recent evidence shows both intramuscular and intravenous routes are effective for acute agitation, though IV may require more active airway management. 5

Fentanyl

  • IV Dose: Titrate to effect (average 180 mcg, range 25-1,400 mcg in ED studies)
  • Onset: 1-2 minutes
  • Duration: 30-60 minutes
  • Action: Potent opioid analgesia

Fentanyl is safe when carefully dosed and titrated; respiratory compromise occurs in 0.7% of patients. 3 Mainly used for total intravenous anesthesia with controlled ventilation. 2 Naloxone must be immediately available. 3

Morphine

  • IV Dose: Titrate to effect
  • Onset: 5-10 minutes
  • Duration: 3-4 hours
  • Action: Opioid analgesia for major pain

Indicated for treatment of major pain, especially in internal medicine patients. 2

Critical Safety Requirements

All neuromuscular blocking agents require:

  • Immediate availability of personnel skilled in airway management
  • Age-appropriate equipment for suctioning, oxygenation, intubation, and ventilation
  • Ventilatory support capability
  • These drugs provide NO sedation, analgesia, or amnesia 1

For procedural sedation:

  • Nondissociative sedation agents should be titrated to clinical effect to maximize safety (Level B recommendation). 3
  • Respiratory depression is the most concerning side effect, but careful preparation and administration prevent harmful sequelae. 3
  • Oxygen saturation monitoring is mandatory
  • Flush IV line with saline before administering rocuronium or vecuronium to avoid precipitation 1

References

2
Research

[Analgesia, sedation and anaesthesia in emergency service].

Anaesthesiologie und Reanimation, 2004

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