12/17/2023 0 Comments Deltagraph nonlinear regression![]() The affinity of fluorinated anesthetics for fluorophilic molecules prompted the investigation of the emulsification of volatile anesthetics using a semifluorinated surfactant. In addition, fluorinated surfactants have been shown to form highly stable perfluorocarbon–water emulsions with fluorinated compounds by significantly reducing the interfacial tension between the perfluorocarbon and water. For the same reason, highly fluorinated anesthetics such as isoflurane, sevoflurane, and desflurane prefer the environment provided by fluorophilic molecules such as perfluorooctyl bromide versus Intralipid. As an example, perfluorooctyl bromide presents only a limited solubility in either water or hydrocarbons, but it is completely miscible with perfluorosolvents. This phase does not mix with both polar and nonpolar hydrogenated phases. The physical–chemical properties of organic molecules are deeply affected by the introduction of fluorine substituents to the point that highly fluorinated organic molecules can generate a new phase of liquid matter, usually referred to as a fluorous phase. Highly fluorinated compounds such as perfluorooctyl bromide are characterized by both lipophobicity and extreme hydrophobicity, the hallmark of fluorophilicity. 13demonstrated that the presence of Oxygent greatly increases the blood:gas partition coefficient of isoflurane, sevoflurane, and desflurane compared with Intralipid. ![]() 12The second-generation emulsion Oxygent (Alliance Pharmaceutical Corp., San Diego, CA) incorporates 30% by volume of perfluorooctyl bromide (perflubron). Perfluorocarbon emulsions have been widely studied for use as blood substitutes. 11This property is evident in the limited concentrations of anesthetics that are soluble in Intralipid. However, fluorinated volatile anesthetics are partially fluorophilic, and they do not mix well with classic nonfluorinated lipids. 9All of these examples have either used Intralipid (a phospholipid-stabilized soybean oil emulsion sold commercially) or directly used phospholipids as the emulsifier. 8–10Studies on these emulsions also showed that intravenous delivery of fluorinated volatile anesthetics can be used to produce preconditioning and thereby reduce the extent of myocardial infarction. 1–4Later efforts successfully used fat emulsions as a means of delivery for halothane 5–7and, more recently, isoflurane and sevoflurane. Initial instances of direct intravenous delivery of neat halothane, whether intentional or not, caused significant pulmonary damage and death in both animals and humans. Direct injection into the bloodstream eliminates the time for the anesthetic to equilibrate with the lungs and leads to a more rapid onset of anesthesia. THE intravenous delivery of halogenated volatile anesthetics has been of interest for more than 40 yr because of the possibility of improving on traditional methods of delivery.
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