Common analgesics used in the intensive care unit

Drug nameCharacteristicsHalf-lifeAdvantagesDisadvantages
MorphineThe reference drug, recommended as bolus regimes because of the long half-life and active metabolites3–7 h
  • Reduces acute/chronic pain

  • Histamine release can cause hypotension

  • Reduces respiratory drive

  • Continuous titration of effective dose

  • Hydrophilic agents (ideal for obsess patients)

  • Risk of accumulation (especially in acute/chronic renal failure)

  • Synergic effect with α2-agonist

Abolishes REM sleep stage
RemifentanilUltra-short-acting drug, can only be administered by infusion3–10 min
  • Fast elimination with no accumulation

  • Risk of muscle rigidity with rapid infusion

  • Reduces pain

  • High risk of withdrawal symptoms because of short half-life

  • Reduces respiratory rate (in a dose-dependent way)

  • Intravenous bolus not indicated

Synergic effect with α2-agonistExpensive
MidazolamActive metabolites especially with renal failure3–11 h
  • Rapid onset

Synergic effect with α1-agonist
PropofolRisk of propofol infusion syndrome at high doses/prolonged periods3–12 h
  • Rapid onset time (90 s)

  • Dose-dependent cardio-circulatory effects

Reduced cerebral metabolic rate of oxygen and anticonvulsant effectRespiratory depression and loss of upper airway patency
DexmedetomidineCannot be used for deep sedation2 h
  • Selective α2-agonist

  • Bradycardia

  • pioid and sedative sparing effect

  • Hypotension

  • Short distribution and elimination

Intravenous bolus not indicated
May help reduce delirium in critically ill

REM: rapid eye movement. Reproduced from [129] with permission from the publisher.