Propofol, the newest induction agent of anesthesia.

Propofol is a rapidly acting intravenous anesthetic agent which has many advantageous kinetic properties explaining its usefulness by bolus dose for induction of anesthesia or for administration by continuous intravenous infusion. It is rapidly distributed in the body with a half-life of only around 2 min and has an efficient hepatic and extrahepatic clearance (total body clearance may exceed liver blood flow). Premedication has little effect on the already good induction characteristics of propofol. The incidence of cardiorespiratory depression appears to be higher than that of other induction agents, but, on the other hand, the absence of tachycardiac response prevents the increase in cardiac oxygen demands. In patients with cardiac disease, especially after high or repeated doses, propofol may be more depressant to the cardiovascular system than thiopentone resulting in imbalance of regional myocardial oxygen demand and supply. Recovery from propofol is rapid and clear-headed with almost no hangover effect. This makes it very suitable for out-patient anesthesia and for cardioversion. However, even with the new emulsion formulation of the drug, pain on injection is still a problem. With regard to a longer lasting combination anesthesia propofol remains an alternative to older induction agents. When given as a continuous intravenous infusion for total intravenous anesthesia or for sedation in intensive care unit propofol has shown little accumulation. Its clinical effects are predictable, consistent and recovery is rapid, independent of the dose given. Propofol has proved to be a useful induction agent regardless of the age of patients, but in the elderly there appears to exist a marked sensitivity to it. Up to now there is no evidence that propofol in emulsion drug form can produce allergic or anaphylactoid reaction more often than other induction agents in use and no severe hematological nor visceral toxicity have been reported. In the present situation, when althesin is not marketed any more due to a high frequency of anaphylactoid reactions and etomidate will have a limited use in clinical practice because of its blocking effect on adrenocortical function, propofol offers an important alternative anesthetic agent to thiopentone.