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Propofol is a highly lipid soluble, short-acting intravenous general anaesthetic. Onset of general anaesthesia occurs in most patients within 30-60 seconds. Most patients return to consciousness rapidly and recover without confusion or nausea. They are usually completely orientated within only a few minutes from recovery, and fit for discharge after only a few hours. Contrary to many other anaesthetic agents, propofol is not clinically significantly accumulated during maintenance dosage. It is therefore most suitable for sedation during intensive care.
Its distribution can best be described by a three compartment open model: rapid distribution from blood to tissues (half-life 2-3 minutes), rapid metabolic elimination from blood (half-life 30-60 minutes), and a slower final phase, during which propofol is eliminated from poorly perfused tissue. The rapid onset of action is based on the fact that propofol, as a lipid-soluble substance, easily passes the blood-brain barrier and is distributed to the central nervous system. The dosage, blood concentrations and duration of anaesthesia are directly interrelated on recommended dosages. Propofol is metabolized in the liver to inactive glucuronide and sulphate conjugates, which are excreted in urine.
Pharmacology
Propofol is a sedative-hypnotic agent for use in the induction and maintenance of anesthesia or sedation. Intravenous injection of a therapeutic dose of propofol produces hypnosis rapidly with minimal excitation, usually within 40 seconds from the start of an injection (the time for one arm-brain circulation). The action of propofol involves a positive modulation of the inhibitory function of the neurotransmitter gama-aminobutyric acid (GABA) through GABA-A receptors.