Sevoflurane, USP Volatile Liquid for Inhalation

DESCRIPTION Sevoflurane, USP, volatile liquid for inhalation, a nonflammable and nonexplosive liquid administered by vaporization, is a halogenated general inhalation anesthetic drug. Sevoflurane, USP is fluoromethyl 2,2,2,-trifluoro-1-(trifluoromethyl) ethyl ether and its structural formula is: Sevoflurane, USP, Physical Constants are: Molecular weight 200.05 Boiling point at 760 mm Hg 58.6°C Specific gravity at 20°C 1.520 1.525 Vapor pressure in mm Hg 157 mm Hg at 20°C 197 mm Hg at 25°C 317 mm Hg at 36°C Distribution Partition Coefficients at 37°C: Blood/Gas 0.63 0.69 Water/Gas 0.36 Olive Oil/Gas 47 54 Brain/Gas 1.15 Mean Component/Gas Partition Coefficients at 25°C for Polymers Used Commonly in Medical Applications: Conductive rubber 14.0 Butyl rubber 7.7 Polyvinylchloride 17.4 Polyethylene 1.3 Sevoflurane, USP is nonflammable and nonexplosive as defined by the requirements of International Electrotechnical Commission 601-2-13. Sevoflurane, USP is a clear, colorless, liquid containing no additives. Sevoflurane, USP is not corrosive to stainless steel, brass, aluminum, nickel-plated brass, chrome-plated brass or copper beryllium. Sevoflurane, USP is nonpungent. It is miscible with ethanol, ether, chloroform, and benzene, and it is slightly soluble in water. Sevoflurane, USP is stable when stored under normal room lighting conditions according to instructions. No discernible degradation of sevoflurane, USP occurs in the presence of strong acids or heat. When in contact with alkaline CO2 absorbents (e.g. Baralyme® and to a lesser extent soda lime) within the anesthesia machine, Sevoflurane, USP can undergo degradation under certain conditions. Degradation of sevoflurane, USP is minimal, and degradants are either undetectable or present in nontoxic amounts when used as directed with fresh absorbents. Sevoflurane, USP degradation and subsequent degradant formation are enhanced by increasing absorbent temperature increased sevoflurane, USP concentration, decreased fresh gas flow and desiccated CO2 absorbents (especially with potassium hydroxide containing absorbents e.g. Baralyme). Sevoflurane, USP alkaline degradation occurs by two pathways. The first results from the loss of hydrogen fluoride with the formation of pentafluoroisopropenyl fluoromethyl ether, (PIFE, C4H2F6O), also known as Compound A, and trace amounts of pentafluoromethoxy isopropyl fluoromethyl ether, (PMFE, C5H6F6O). The second pathway for degradation of sevoflurane, USP, which occurs primarily in the presence of desiccated CO2 absorbents, is discussed later. In the first pathway, the defluorination pathway, the production of degradants in the anesthesia circuit results from the extraction of the acidic proton in the presence of a strong base (KOH and/or NaOH) forming an alkene (Compound A) from sevoflurane, USP similar to formation of 2-bromo-2-chloro-1,1-difluoro ethylene (BCDFE) from halothane. Laboratory simulations have shown that the concentration of these degradants is inversely correlated with the fresh gas flow rate (See Figure 1).