Propofol is a short-acting intravenous anaesthetic and sedative agent that is one of the most widely used drugs in modern operating theatres and intensive care units worldwide. It produces rapid loss of consciousness within about 30 to 60 seconds of injection and has an equally rapid recovery - patients wake up within minutes of the infusion being stopped, usually feeling clear-headed. Propofol has an immediately recognisable appearance: it is a white, milky emulsion that looks like full-fat milk.

Drug Class: General Anaesthetic 

Propofol belongs to the class of drugs called general anaesthetic agents, drugs that produce a controlled, reversible loss of consciousness sufficient to allow surgery, painful procedures or mechanical ventilation without the patient experiencing pain, awareness or distress. Propofol is classified as an intravenous (IV) anaesthetic.

Propofol is also used at sub-anaesthetic doses as a sedative keeping the patient calm, comfortable and cooperative without full loss of consciousness. At higher doses, propofol produces general anaesthesia with complete loss of consciousness and protective reflexes. Propofol has no analgesic (pain-relieving) effect on its own; patients receiving propofol still require appropriate analgesia for painful procedures.

Medical Uses

Doctors prescribe propofol for:

• Induction of general anaesthesia: The most common use; propofol is given as an IV bolus (a single rapid injection) to render the patient unconscious at the start of an operation; the induction dose in healthy adults is typically 1.5 to 2.5 mg per kg of body weight

• Maintenance of anaesthesia: Propofol can be used to maintain anaesthesia throughout surgery by continuous IV infusion (total intravenous anaesthesia, TIVA) often in combination with opioids and other agents; TIVA with propofol is preferred in patients at high risk of postoperative nausea and vomiting

• Sedation in the intensive care unit (ICU): Propofol is widely used to sedate critically ill patients on mechanical ventilators; it allows rapid adjustments to the depth of sedation and enables quick wake-up for neurological assessment; its short duration of action makes it easier to conduct daily sedation interruption (planned wake-up trials)

• Procedural sedation: Propofol is used in sub-anaesthetic doses for short procedures including endoscopy (gastroscopy, colonoscopy), bronchoscopy, cardioversion, dental procedures and minor surgical procedures; it is increasingly used for sedation during diagnostic imaging in children.

Side Effects

Propofol has several important side effects that anaesthetists must anticipate and manage:

• Pain on injection 

• Hypotension (low blood pressure) 

• Apnoea (stopping breathing) 

• Bradycardia (slow heart rate) 

• Propofol infusion syndrome - a rare but potentially fatal complication.

FAQs

1. What is propofol injection used for?

   Propofol injection is used to make patients unconscious (general anaesthesia) for surgery, to sedate patients in the intensive care unit on mechanical ventilators and to provide sedation for short procedures such as endoscopy, colonoscopy and dental procedures. It is the most widely used intravenous anaesthetic in the world.

2. Why does propofol make you fall asleep so fast?

   Propofol acts extremely quickly because it is a highly lipophilic drug meaning it dissolves easily in fat so it crosses the blood-brain barrier rapidly after injection. Once propofol enters the brain, it amplifies the effect of GABA (the brain's main calming chemical) causing widespread suppression of brain activity within seconds. From the moment propofol is injected into a vein to the moment a patient loses consciousness is typically only 30 to 60 seconds.

3. Is propofol the same drug that caused Michael Jackson's death?

   Yes propofol was the drug central to the death of Michael Jackson in 2009. His personal physician administered propofol outside of a hospital setting to help the singer sleep, which is not a recognised or safe medical use of the drug. Propofol requires continuous monitoring of breathing, heart rate, blood pressure and oxygen saturation as well as immediate access to airway management equipment. 

4. Does propofol hurt when it is injected?

   Yes pain on injection is one of the most common side effects of propofol, occurring in the majority of patients when the drug is given into a small vein on the back of the hand. Patients describe it as a burning, stinging or aching sensation lasting 10 to 30 seconds. 

5. Can propofol be used outside of an operation theatre?

   Propofol can and is used outside the operating theatre but it must always be given in a setting where the patient's breathing, heart rate, blood pressure and oxygen levels are continuously monitored. Propofol must never be given at home or in any setting without anaesthetic monitoring and airway management equipment.

6. How long does it take to wake up after propofol?

   Recovery from propofol is much faster than from most other general anaesthetic agents. Patients typically begin to regain consciousness within 5 to 10 minutes of the propofol infusion being stopped after a short procedure. After longer procedures where propofol has been given by infusion over many hours, recovery may take 15 to 30 minutes. Most patients feel relatively clear-headed on waking without the prolonged grogginess seen with older inhaled anaesthetic agents such as halothane.

7. Why is propofol white and milky in appearance?

   Propofol itself is a clear, oily liquid that is insoluble in water. To be injected into a vein, it must be dissolved in a water-compatible carrier. The formulation used is an oil-in-water emulsion: propofol is dissolved in purified soybean oil, then broken into tiny droplets and stabilised in water using egg lecithin (a natural emulsifier derived from egg yolk) and glycerol. The result is a white, opaque emulsion (very similar in appearance to full-fat milk) that is stable enough to be stored and injected safely.

8. Can propofol cause breathing problems during sedation?

   Yes respiratory depression and apnoea (stopping breathing) are among the most important and expected effects of propofol. Propofol suppresses the brain's respiratory drive particularly after the induction dose. Many patients stop breathing for 30 to 90 seconds after an induction dose. This is managed by the anaesthetist, who provides manual ventilation (bag-mask ventilation) until the patient resumes breathing or is intubated. For this reason, propofol must only be given in settings where trained personnel can immediately support the patient's breathing and where appropriate equipment is immediately available.

9. Is propofol safe for patients with egg or soy allergy?

   Propofol's emulsion contains egg lecithin (from egg yolk) and soybean oil. Patients with an allergy to eggs or soy are not automatically contraindicated from receiving propofol but the risk must be individually assessed. Most egg allergies are to egg white proteins (ovalbumin), not egg yolk lecithin. Most soy food allergies are to soy proteins, not soy oil. The propofol emulsion contains lecithin (a fat, not a protein) and refined soy oil, both of which contain negligible amounts of the proteins that trigger most allergic reactions. 

10. Does propofol cause nausea or vomiting after a procedure?

    Propofol has a notable antiemetic (anti-nausea) effect - it actually reduces nausea and vomiting compared to inhaled anaesthetic agents. Postoperative nausea and vomiting (PONV) is a common and distressing complication of inhaled anaesthesia. Propofol-based anaesthesia (TIVA) significantly reduces the risk of PONV and is specifically chosen for patients at high risk including women, non-smokers, patients with a history of PONV or motion sickness, and patients undergoing laparoscopy and ear surgery. 

References

1. Sahinovic MM, Struys MMRF, Absalom AR. Clinical pharmacokinetics and pharmacodynamics of propofol. Clin Pharmacokinet. 2018;57(12):1539–58. https://doi.org/10.1007/s40262-018-0672-3

2. Fodale V, La Monaca E. Propofol infusion syndrome: an overview of a perplexing disease. Drug Saf. 2008;31(4):293–303. https://doi.org/10.2165/00002018-200831040-00003

3. Jalota L, Kalira V, George E, et al. Prevention of pain on injection of propofol: systematic review and meta-analysis. BMJ. 2011;342:d1110. https://doi.org/10.1136/bmj.d1110

4. Smith I, White PF, Nathanson M, Gouldson R. Propofol: an update on its clinical uses. Anesthesiology. 1994;81(4):1005–43. https://doi.org/10.1097/00000542-199410000-00028

5. Kam PC, Cardone D. Propofol infusion syndrome. Anaesthesia. 2007;62(7):690–701. https://doi.org/10.1111/j.1365-2044.2007.05055.x