Water Anesthetics

Difluoroethanol is prepared by the mercuric oxide cataly2ed hydrolysis of 2-bromo-l,l-difluoroethane with carboxyHc acid esters and alkaH metal hydroxides ia water (27). Its chemical reactions are similar to those of most alcohols. It can be oxidi2ed to difluoroacetic acid [381-73-7] (28) it forms alkoxides with alkaH and alkaline-earth metals (29) with alkoxides of other alcohols it forms mixed ethers such as 2,2-difluoroethyl methyl ether [461-57-4], bp 47°C, or 2,2-difluoroethyl ethyl ether [82907-09-3], bp 66°C (29). 2,2-Difluoroethyl difluoromethyl ether [32778-16-8], made from the alcohol and chlorodifluoromethane ia aqueous base, has been iavestigated as an inhalation anesthetic (30,31) as have several ethers made by addition of the alcohol to various fluoroalkenes (32,33). Methacrylate esters of the alcohol are useful as a sheathing material for polymers ia optical appHcations (34). The alcohol has also been reported to be useful as a working fluid ia heat pumps (35). The alcohol is available ia research quantities for ca 6/g (1992). 

Medical Usage. Isopropyl alcohol is also used as an antiseptic and disinfectant for home, hospital, and industry (see Disinfectants and antiseptics). It is about twice as effective as ethyl alcohol in these appHcations (153,154). Rubbing alcohol, a popular 70 vol % isopropyl alcohol-in-water mixture, exemplifies the medicinal use of isopropyl alcohol. Other examples include 30 vol % isopropyl alcohol solutions for medicinal liniments, tinctures of green soap, scalp tonics, and tincture of mercurophen. It is contained in pharmaceuticals, eg, local anesthetics, tincture of iodine, and bathing solutions for surgical sutures and dressings. Over 200 uses of isopropyl alcohol have been tabulated (2). 

Propylene is a colorless gas under normal conditions, has anesthetic properties at high concentrations, and can cause asphyxiation. It does not irritate the eyes and its odor is characteristic of olefins. Propjiene is a flammable gas under normal atmospheric conditions. Vapor-cloud formation from Hquid or vapor leaks is the main ha2ard that can lead to explosion. The autoignition temperature is 731 K in air and 696 K in oxygen (80). Evaporation of Hquid propylene can cause skin bums. Propylene also reacts vigorously with oxidising materials. Under unusual conditions, eg, 96.8 MPa (995 atm) and 600 K, it explodes. It reacts violentiy with NO2, N2O4, and N2O (81). Explosions have been reported when Hquid propylene contacts water at 315—348 K (82). Table 8 shows the ratio TJTp where is the initial water temperature, and T is the superheat limit temperature of the hydrocarbon. 

In other applications of CT, orally administered barium sulfate or a water-soluble iodinated CM is used to opacify the GI tract. Xenon, atomic number 54, exhibits similar x-ray absorption properties to those of iodine. It rapidly diffuses across the blood brain barrier after inhalation to saturate different tissues of brain as a function of its lipid solubility. In preliminary investigations (99), xenon gas inhalation prior to brain CT has provided useful information for evaluations of local cerebral blood flow and cerebral tissue abnormalities. Xenon exhibits an anesthetic effect at high concentrations but otherwise is free of physiological effects because of its nonreactive nature. 

The technical concentrated ether contains very smaH amounts of alcohol, water, aldehydes, peroxides, and other impurities (Table 5). The more refined grades, such as anesthetic ether, are obtained from technical ether by redistiHation and dehydration foHowed by alkaH or charcoal treatment. 

Fire Hazards - Flash Point (deg. F) -213 (approx.) CC Flammable Limits in Air (%) 2.75 - 28.6 Fire Extinguishing Agents Stop flow of gas if possible. Use carbon dioxide, dry chemical, water fog Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Vapors are anesthetic Behavior in Fire Container may explode Ignition Temperature (deg. F) 842 Electrical Hazard Class I, Group D Burning Rate 7.4 mm/min. 

Single-substituent polymers, such as the procaine derivative shown as compound 24, are insoluble in water. In principle, the bioerosion characteristics can be modified by the presence of amino acid ester, glyceryl, or glucosyl (see later) cosubstituents, and this offers the possibility of a long-term release of a local anesthetic at a targeted site in the body. 

Reproductive Effects. Operating room nurses exposed to trichloroethylene have been reported to have an increased incidence of miscarriages, but they were exposed to many other anesthetics as well (Corbett et al. 1974). Survey results of 1,926 women who had spontaneous abortions revealed a greater risk of abortion associated with trichloroethylene exposure (Windham et al. 1991). This study is limited by multiple chemical exposure. Humans exposed to trichloroethylene in the drinking water in certain areas of the country have not shown adverse reproductive effects (Byers et al. 1988 Freni and Bloomer 1988 Lagakos et al. 1986a). 

In this chapter, the voltammetric study of local anesthetics (procaine and related compounds) [14—16], antihistamines (doxylamine and related compounds) [17,22], and uncouplers (2,4-dinitrophenol and related compounds) [18] at nitrobenzene (NB]Uwater (W) and 1,2-dichloroethane (DCE)-water (W) interfaces is discussed. Potential step voltammetry (chronoamperometry) or normal pulse voltammetry (NPV) and potential sweep voltammetry or cyclic voltammetry (CV) have been employed. Theoretical equations of the half-wave potential vs. pH diagram are derived and applied to interpret the midpoint potential or half-wave potential vs. pH plots to evaluate physicochemical properties, including the partition coefficients and dissociation constants of the drugs. Voltammetric study of the kinetics of protonation of base (procaine) in aqueous solution is also discussed. Finally, application to structure-activity relationship and mode of action study will be discussed briefly. 

Local anesthetics are positively charged amphiphiles in solution. We have selected hydrochlorides of dibucaine (DBC H ), procaine (PRC H ), tetracaine (TTC H ), and lido-caine (LDC H ). All of these drugs are structurally similar they consist of the substituted benzene ring and tertiary amine moieties, as shown by (VI)-(IX) in Fig. 1. The presence of the positive charge increases the solubility in water and in consequence, the anesthetic efficiency. 

Most recently, we have applied and H NMR to the delivery of local anesthetics from water to phospholipid bilayer membranes [48]. Preferential locations of the four drugs DBC-H+, PRC-H+, TTC-H+, and LDC-H+ in EPC SUV have been specified and compared. To specify the delivery sites of drugs on the atomic-site level from their... 

It should be emphasized that the ester carbonyl group in the interfacial zone II is most crucial and susceptible to the anesthetic action of the drugs. In our NMR study, we have found that the ester carbonyl site in zone II is particularly susceptible to the extent of hydration [51]. Above the G/LC transition temperature, the carbonyl is the innermost site where the water can penetrate. The strong perturbation of the NMR signal of the... 

It is expected that the neutral species of the anesthetics can penetrate more deeply into the hydrophobic bilayer interior than the cationic ones. From the H and C NMR, we have demonstrated that the neutral species, DEC and PRC, are trapped deeply in the bilayer DEC can penetrate into the hydrophobic core of the bilayer, zone III, and PRC can penetrate into the inside of the bilayer preferentially trapping from zone II to the middle of zone III [48]. This information is valuable in the sense that it is difficult to observe the NMR signal of the neutral species in water because of the extremely low solubility. The preferential location is in accordance with the solubility in water the neutral species of DEC and PRC, sparingly soluble in water, are expected to favor the hydrophobic bilayer interior. 

However, local anesthetics may be helpful when abrasion accompanies the injury.39 Application of an over-the-counter antibiotic ointment containing an anesthetic may provide soothing relief, promote healing of abrasions, and prevent soft-tissue infection. Minor abrasions should be cleansed thoroughly with mild soap and water before application. More severe abrasions may require removal of debris or foreign bodies by a clinician followed by irrigation with normal saline. 

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