Some important constraints of anesthesia must be taken into consideration when the pharmacological properties of modern anesthetics are discussed. The most imp- tant of these could be that the target effect be achieved preferably within seconds, at most within a few minutes. Similarly, offset of drug action should be achieved within minutes rather hours. The target effects, such as unconsciousness, are pot- tially life-threatening, as are the side effects of modern anesthetics, such as respi- tory and cardiovascular depression. Finally, the patient's purposeful responses are not available to...