General anesthesia anesthetic agents

The membrane enzyme luciferase, responsible for light emission in fireflies, is sensitive to anesthetics (20,21), and the concentrations of inhalational agents which inhibit luciferase are the same as those which cause general anesthesia. Studies of various classes of inhalational agents and luciferase demonstrated that above a certain chain length in a homologous series, a point is reached where higher members are not anesthetic. The same cut-off effect in efficacy is observed in anesthesia (22). This effect is not explainable by Hpid theory. 

The total U.S. market value for the anesthetic agents Hsted was 299.9 million ia 1990 (162). General inhalation agents, valued at 154.5 million, comprised over half (51.5%) of the 1990 market. General iv anesthetics were valued at 111.5 million (37.2%). Local iajectable agents, at 33.9 million, represented the smallest portion of the market (11.3%). U.S. sales for selected anesthesia pharmaceuticals are given ia Table 6. 

Volatile anesthetic agents - Close perioperative monitoring is recommended in patients undergoing general anesthesia who are on amiodarone therapy as they may be more sensitive to the myocardial depressant and conduction effects of halogenated inhalational anesthetics. 

General anesthesia - Remifentanil is not recommended as the sole agent in general anesthesia because loss of consciousness cannot be assured and because of a high incidence of apnea, muscle rigidity, and tachycardia. Remifentanil is synergistic with other anesthetics and doses of thiopental, propofol, isoflurane, and midazolam have been... 

Ensuring an adequate depth of anesthesia depends on achieving a therapeutic concentration of the anesthetic in the CNS. The rate at which an effective brain concentration is achieved (ie, time to induction of general anesthesia) depends on multiple pharmacokinetic factors that influence the brain uptake and tissue distribution of the anesthetic agent. The pharmacokinetic properties of the intravenous anesthetics (Table 25-1) and the physicochemical properties of the inhaled agents (Table 25-2) directly influence the pharmacodynamic effects of these drugs. These factors also influence the rate of recovery when the administration of anesthetic is discontinued. 

Pharmacological Profile. The profile of the ideal local anesthetic agent depends largely on the type and length of the surgical procedure for which it is applied. Procedures could include neuraxial (spinal and epidural) anesthesia, nerve and plexus blocks, or field blocks (local infiltration). In general, tine ideal agent should have a short onset of anesthesia and be useful for multiple indications such as infiltration, nerve blocks. 

Eger El, 2nd. Characteristics of anesthetic agents used for induction and maintenance of general anesthesia. Am J Health Syst Pharm. 2004 61(suppl 4) S3-S10. 

This involves considerable art, which must be learned in the clinic. It falls into two divisions (1) surface application to the mucous membranes, especially of the eye, nose, throat, and urethra and (2) injections about nerves, in different parts of their course and distribution, from their spinal roots to their ultimate fibrils. The advantages and disadvantages in comparison with general anesthesia and the selection of the local anesthetic agent also depend on clinical discrimination. Nervous, fearful, and excitable patients often suffer severely from apprehension, which also disposes toward accidents. They may be at least somewhat quieted by sedatives, morphine (0.015 g hypodermically) half an hour before the operation, or by barbiturates. The latter also tend to prevent convulsions. 

In 1958, phencyclidine (PCP) was introduced into clinical anesthesia as an injectable anesthetic agent. PCP had physiological properties that made it a useful anesthetic. The most significant of these was that it was quite effective but had no risk of cardiac or respiratory depression, as was typical of classical general anesthetic agents. 

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