Doxapram


  • Doxapram is a monohydrated pyrrolidinone derivative
  • As a respiratory stimulant
    • Post-operative respiratory depression
    • Acute-on-chronic respiratory failure

  • Treatment of laryngospasm
  • Facilitate blind nasal intubation
  • Treatment of post-operative shivering

Presentation

  • A clear, colourless solution of 20mg/ml - dose 1mg/kg
  • As 2mg/ml doxapram hydrochloride in 5% dextrose solution for infusion (dose 1.5 - 4mg/min)

  • Acts primarily on the carotid body chemoreceptors to stimulate respiration
  • Secondary action via stimulation of the medullary respiratory centre
  • Acts in 20-40s with duration of approximately 10mins

Distribution

  • VD 1.5L/kg

Metabolism

  • Unknown metabolic pathway

Excretion

  • 5% excreted unchanged
  • Very high clearance: 370ml/min
  • Half life 2-4hrs

Respiratory

  • Increases minute ventilation primarily through increasing tidal volume
  • At higher doses RR may increase
  • Increases work of breathing

Cardiovascular

  • Increases cardiac output, primarily by increasing SV
  • Can cause tachyarrhythmia and HTN

Neurological

  • Increased CBF

Renal

  • Increased UO
  • Increased GU motility

Gastrointestinal

  • Increased salivation
  • Increased gastrointestinal tone and motility

Metabolic

  • Increased catecholamine and steroid secretion
  • 30% increase in metabolic rate (there may be hypoxia due to increased oxygen consumption)