Intravenous anaesthetics

In recent decades, increasing attention has been focused on the intravenous anaesthetic agents. This interest has been stimulated by the discovery and availability of agents with increasingly favourable pharmacokinetic and dynamic properties, coupled with advances in knowledge of pharmacology and advances in computer technology. For most patients and operative procedures, anaesthesia is induced with a bolus or fast infusion of a short-acting drug, most commonly propofol. Increasingly, anaesthesia is thereafter also maintained with an infusion of an agent with favourable kinetics, again usually of propofol, commonly supplemented with boluses or infusions of opioids. Propofol is also commonly used for procedural and intensive care sedation. It has highly favourable pharmacokinetics and pharmacodynamics for these applications as sedative or hypnotic agent—rapid, smooth onset, minimal accumulation, and rapid smooth offset of effect—but is by no means an ideal agent. In some specific situations, such as when its haemodynamic or respiratory effects are detrimental, use of alternative agents such as ketamine and etomidate are warranted. All the currently available agents have adverse effects, some of which are related to the active compound and some of which are related to the vehicle. Efforts are thus being made to develop new formulations, with fewer adverse effects, and to develop newer and better drugs. In the future we are also likely to see increasing use of older agents, but for newer indications (such as the use of ketamine as an antidepressant).