Used in Anesthesia

1 Anesthetic MAC Value Blood-Gas Ratio CV Effects Specific Characteristics  

1 Nitrous oxide i i 1 104% 0.5 Minimal Rapid onset and recovery, no metabolism Diffusional hypoxia Spontaneous abortions j 

1 Halothane 1 i 1 0.8% 2.3 Sensitizes heart to catecholamines Malignant hyperthermia, j hepatitis, cardiac j arrhythmias  

Anesthesia protocols include several agents in combinations. 

Inhaled anesthetics have varying potency in proportion to their lipid solubility. 

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For use in anesthesia the USP (22) also recognizes slightly less pure grades ethyl oxide (solvent ether), ether abs, and reagent-grade ether. 

De Week AL Immunochemical particularities of anaphylactic reactions to compounds used in anesthesia. Ann Fr Anesth Reanim 1993 12 126-130. 

The answer is a. (Hardman, p 373. Katzung, pp 430-431.) Midazolam is useful for sedation because it produces a higher incidence of amnesia and has a more rapid onset of action and a shorter half-life than other benzodiazepines used in anesthesia... 

Suxamethonium sensitivity," prolonged paralysis of respiratory muscle function caused by failure to cleave the short-acting muscle relaxant succinylcholine widely used in anesthesia, was made testable with a simple bedside assay in 1968 (Motulsky and Morrow). However, that test was not incorporated widely into practice. Most anesthesiologists felt they could simply monitor all patients and "bag" those not resuming respiratory action, without testing for a trait that would be found in only one of 2000 patients. 

Antipsychotic agents are also used for a diversity of other indications like hiccups, Tourette s syndrome, aggressive behavior in children and the elderly and alcohol withdrawal syndrome. Some of them are also used in anesthesia as they can potentiate the sedative, analgesics or anesthetic effects of other agents. Antipsychotics which are mainly active by blocking dopamine activity have also an effect on chemoreceptor trigger zone and may therefore be used as anti-emetics. 

The ultra-short acting thiopental, exclusively used in anesthesia, rapidly reaches CNS depressant concentrations due to its high lipid solubility and high blood flow to brain. Redistribution to muscle and other sites is responsible for its short duration of... 

Midazolam (Versed), diazepam (Valium), and lo-razepam (Ativan) are benzodiazepine derivatives that are useful in anesthesia. Midazolam is the most popular of these agents for the induction of anesthesia. Its popularity is related to its aqueous solubility and to its short duration of action, which permits a prompt return of psychomotor competence. Unlike midazolam, lor-azepam and diazepam are not water soluble and must be formulated in propylene glycol the latter is irritating to the vasculature on parenteral administration. 

Benzodiazepines are usually given orally and are well absorbed by this route. Since the benzodiazepines are weak bases, they are less ionized in the relatively alkaline environment of the small intestine, and therefore, most of their absorption takes place at this site. For emergency treatment of seizures or when used in anesthesia, the benzodiazepines also can be given parenter-ally. Diazepam and lorazepam are available for intravenous administration. 

Four highly fluorinated ethers with low boiling points are currently used in anesthesia enflurane, isoflurane, sevoflumne, and desflurane (Figure 8.89). Des-flurane and sevoflurane are now the most used (sevoflurane is especially used in pediatrics). They exhibit the lowest blood-gas partition coefficients, the lowest ratio of toxic metabolites, and the lowest solubilities in lipids. These features limit the retention and, consequently, the metabolism is delayed (Table 8.2). 

Dexmedetomidine Prominent sedative effects and used in anesthesia... 

Parenteral powder to reconstitute 20, 25 mg/mL for IV injection See Chapter 31 for formulations of opioid agents used in anesthesia. 

Barbiturates are referred to as sedative-hypnotics. These drugs will induce sleep which can lead to even deeper sedation (hypnosis) and can cause a fatal depression of the RAS affecting the respiratory system. The sleep which is encountered does not have the normal cycles of slow wave and rapid eye movement activity, so it is not always restful. However, these agents prove to be useful in anesthesia for both short and longer durations of time. Many of you may have been given thiopental prior to wisdom tooth extraction. Thiopental "wears off quickly and so the actual anesthetic for the time of the extraction is usually nitrous oxide. 

Dosages and routes of administration Alfentanil is only used parenterally. Because of strong respiratory depression administration under spontaneous respiration has to be confined to a dose range up to 200 pg/h. Higher doses as used in anesthesia need assisted ventilation. 

Rosow, C.E. Sufentanil citrate a new opioid analgesic for use in anesthesia, Pharmacotherapy 1984, 4, 11-19. 

Fentanyl [FEN ta nil], which is chemically related to meperidine, has 80 times the analgesic potency of morphine, and is used in anesthesia. It has a rapid onset and short duration of action (15 to 30 minutes). When combined with droperidol (see p.117) it produces a neurolept anesthesia. Sufentanil [soo FEN ta nil], a related drug, is even more potent than fentanyl. 

Nevertheless, some interactions of benzodiazepines with muscle relaxants used in anesthesia have been described. Diazepam has been reported to potentiate the effects of tubocurare (163) and gallamine (164) and to reduce the effects of suxamethonium (164). However, in 113 patients undergoing general anesthesia, intravenous diazepam 20 mg, lorazepam 5 mg, and lormetaze-pam 2 mg did not potentiate the neuromuscular blocking effects of vecuronium or atracurium (162). 

When mixed with O2 in proportions of 40% or more, acetylene acts as a narcotic and has been used in anesthesia. Acetylene... 

Alfentanil is a potent short-acting opioid used in anesthesia. Beside its effects on opioid receptors, there is some evidence that it may affect acetylcholine, since intrathecal neostigmine produced a dose-dependent increase in the effect of alfentanil (SEDA-22, 3). Its rapid onset and short duration of action make alfentanil suitable for use in day care, although it is important to treat adverse effects before discharge. 

Depressant drugs formerly used as sleeping pills currently used in anesthesia and treatment for epilepsy. 

Sufentanil Gtrate. Sufentanil citrate. /V- 4-(methoxy-mcthyl)-l- 2-<2-thienyl)ethyl -4-piperidyllpropionanilide citrate (Sufenta). a. structural analogue of fentanyl. has similar properties and is also used in anesthesia. It is available as an injection (0.05 ing/mL). 

Information on the molar concentration is least often available since it requires immunoassays (G18) or other specialized procedures. As will be explained below, information on enzyme activity, also, is not needed when the problem is to find an explanation for a prolonged effect of suc-cinylcholine as used in anesthesia in this situation, the important test is for the presence of genetic enzyme variants. 

As stated in Section 3.1, biochemical considerations make it necessary to use tests that are capable of indicating the presence of unusual esterase types rather than merely the levels of enzyme activity. However, different methods of esterase typing for use in anesthesia may yield different depths of information. Most often the purpose of the test is to document for future reference the cause of a prolonged effect of succinylcholine after recovery of the patient. This is usually a fairly simple task. By con-... 

K8. Kalow, W., Pharmacogenetics of drugs used in anesthesia. In Human Genetics" (Proc. 4th Int. Congr. Hum. Genet., Paris, 6-11 September 1971), pp. 415-427. Ex-cerpta Medica, Amsterdam, 1972. 

A life-threatening syndrome characterized by muscle rigidity, hyperthermia, hypertension, acidosis, and hyperkalemia. Associated with the use of skeletal muscle relaxants, especially succinylcholine, used in anesthesia regimens. Genotypic susceptibility may be related to mutations in the genes encoding ryanodine receptors and/or a protein component of the L-type calcium channel in skeletal muscle. 

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