Propofol
Propofol
Mechanism of action, clinical uses, dosing, pharmacology, adverse effects and high-yield examination points for anaesthesia trainees.
Propofol at a Glance
Propofol is a short-acting intravenous hypnotic agent widely used for induction and maintenance of general anaesthesia and for procedural sedation. Its rapid onset and short context-sensitive recovery make it particularly useful when rapid recovery is desired.
Key Facts
Mechanism of Action
Propofol produces central nervous system depression primarily through enhancement of inhibitory neurotransmission mediated by GABAA receptors. This increases inhibitory signalling within the CNS and produces sedation and hypnosis.
Propofol does not provide reliable analgesia. When painful stimulation is expected, an appropriate analgesic technique or agent is generally required.
Pharmacology
After intravenous administration, propofol rapidly reaches the brain, producing loss of consciousness. Recovery after a single induction dose is usually rapid because the drug redistributes away from the brain followed by metabolism and elimination.
Propofol undergoes extensive hepatic metabolism, with additional extrahepatic metabolism and clearance contributing to its disposition. Metabolites are subsequently eliminated predominantly through the kidneys.
Common Clinical Doses
| Clinical use | Typical dose | Important consideration |
|---|---|---|
| IV induction in adults | Approximately 1.5–2.5 mg/kg | Titrate to clinical response; lower doses may be appropriate in elderly or haemodynamically compromised patients. |
| Procedural sedation | Small titrated IV boluses or infusion | Dose depends on age, comorbidity, procedure and other sedative/analgesic drugs. |
| Maintenance of anaesthesia | Continuous IV infusion | Use an appropriately titrated infusion according to the anaesthetic technique and monitoring. |
Clinical Uses
- Induction of general anaesthesia
- Maintenance of general anaesthesia as part of total intravenous anaesthesia
- Procedural sedation
- Sedation in selected intensive-care settings under appropriate monitoring
- Short procedures where rapid recovery is desirable
Important Advantages
- Rapid onset of hypnosis
- Generally rapid recovery after short administration
- Useful for induction and TIVA
- Antiemetic properties
- Usually produces less postoperative nausea and vomiting than some alternative anaesthetic techniques
Adverse Effects
Cardiovascular
Hypotension is common, particularly after rapid administration or in patients with limited cardiovascular reserve.
Respiratory
Dose-dependent respiratory depression and apnoea may occur, especially with rapid bolus administration or when combined with other CNS depressants.
Injection pain
Pain on injection is a well-known adverse effect and can be reduced by appropriate techniques such as administration through a larger vein or use of lidocaine where appropriate.
Other effects
Myoclonus-like movements, involuntary movements and transient discomfort may occur. Rare but serious complications can occur with prolonged, high-dose infusion.
Contraindications & Precautions
Propofol should be used cautiously when significant cardiovascular instability or severe hypovolaemia is present because of its potential to reduce arterial blood pressure.
Dose reduction and careful titration are particularly important in elderly, frail or haemodynamically vulnerable patients.
Pregnancy
Propofol is used in obstetric anaesthesia when clinically indicated. Decisions regarding its use should consider the maternal indication, gestational age, fetal considerations and the overall anaesthetic plan.
Propofol Infusion Syndrome
Propofol infusion syndrome (PRIS) is a rare but potentially fatal complication associated particularly with prolonged high-dose propofol infusion and certain clinical risk factors.
Features may include severe metabolic acidosis, rhabdomyolysis, hyperkalaemia, cardiac dysfunction, arrhythmias and renal failure. Risk is influenced by dose, duration and patient factors.
High-Yield Anaesthesia Exam Points
- Propofol is an intravenous hypnotic agent.
- It primarily enhances GABAA-mediated inhibitory neurotransmission.
- It has a rapid onset of action.
- It does not provide reliable analgesia.
- Hypotension is an important cardiovascular adverse effect.
- Respiratory depression and apnoea may occur after induction doses.
- Injection pain is a classic adverse effect.
- Propofol has antiemetic properties.
- It is commonly used for TIVA.
- Prolonged high-dose infusion can be associated with propofol infusion syndrome.
Propofol Viva Questions
Frequently Asked Questions
Is propofol an analgesic?
No. Propofol is primarily a hypnotic agent. Analgesia should be provided separately when required.
Why does propofol cause hypotension?
Its cardiovascular effects include reduced systemic vascular resistance and myocardial depression, with the clinical effect influenced by dose and patient condition.
Why is propofol useful for TIVA?
Its rapid onset, predictable titratability and generally rapid recovery make it well suited to continuous intravenous anaesthesia.
Continue Learning
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Educational content for anaesthesia trainees and healthcare professionals. Drug doses should always be checked against current institutional protocols, prescribing information and the patient's clinical condition.