Fastest acting agent

Blood-gas paition coefficient, also known as Ostwald coefficient for blood-gas, is a term used in pharmacology to describe the solubility of inhaled general anesthetics in blood. The coefficient is defined as the ratio of the concentration in blood to the concentration in gas that is in contact with that blood when the paial pressure in both compaments is equal. Newer anesthetics (such as desflurane) typically have smaller blood-gas paition coefficients than older ones (such as ether); these are preferred because they lead to faster onset of anesthesia and faster emergence from anesthesia once application of the anesthetic is stopped. If an anesthetic has a high coefficient, then a large amount of it will have to be taken up in the body's blood before being passed on to the fatty (lipid) tissues of the brain where it can exe its effect. Ref: Miller's anesthesia 8th edition Ref: Morgan & Mikhail's clinical anesthesiology 6e