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Propellants liquefied

There are two general types of formulations. First, the micronized active ingredient may be suspended in liquefied propellants (CFCs or HFAs). This group makes up the most common type of MDI. Second, the drug may be dissolved in a mixture of CFCs or HFAs and ethanol, forming a solution. Less than 25% of MDI products are formulated as solutions developed over 50 years ago. [Pg.366]

The basic design and operation of the MDI has changed little over its lifetime. Aerosols are generated from a formulation of drug (0.1-1% w/w) either suspended or in solution in the liquefied propellant. The formulation is held under pressure in a canister. [Pg.690]

An emulsion system in which the propellant is in the external or continuous phase is shown in Figure 2b. As the liquefied propellant vaporizes, it escapes directly into the atmosphere, leaving behind droplets of the formulation which are emitted as a wet spray. Tliis system is typical of many water-based aerosols or w/o emulsions. [Pg.346]

Metered dose inhaler has been the most popular aerosol delivery device for the treatment of respiratory diseases, which is attributable to its portability and simple operation. Although seemingly easy to use, the MDI is a sophisticated device in design. The drug(s) are suspended or dissolved in a liquefied propellant system, which may also contain excipients such as cosolvents or surfactants. The formulation is kept pressurized in a small canister, sealed with a metering valve. Upon actuation through an actuator, the valve opens and the metered dose is dispensed as an aerosol spray from the expansion and vaporization of the propellant under ambient pressure. The inhalers may be used alone or with spacer devices, the electrostatic issues of which are considered in a later section. The present discussion focuses on the inherent charging of particles produced from MDIs. [Pg.1541]

The modern pressurized metered dose inhaler (pMDI) was developed between 1955 and 1956. However, the pMDI had its roots in research carried out many years before.During the 1930s and 1940s, the discovery of liquefied propellants (chlorinated-fluorocarbons or freon propellants) such as CFC12, CFC114, CFCll, and CFC22 was a major step in the realization of a portable inhaler. However, the first pMDI was not invented until 1956, when the metering valve used in the device was developed and patented. ... [Pg.2093]

Metered dose inhalers (MDIs) are pharmaceutical delivery systems designed for oral or nasal use, which deliver discrete doses of aerosolized medicament to the respiratory tract. The MDI contains the active substance, dissolved or suspended in a liquefied propellant system held in a pressurized container that is sealed with a metering valve. Actuation of the valve discharges a metered dose of medicament as an aerosol spray through an actuator during oral or nasal inhalation. [Pg.2269]

However, unlike non-liquefied compressed gases, the vapor pressure of liquefied propellants decreases significantly with decreases in temperature, such that below a certain temperature, the flash evaporation process is sufficiently retarded to give poor aerosol formation. For the propellants commonly used in MDIs, unacceptable aerosol formation is likely to occur below 0°C. [Pg.2269]

Chromatography at lower temperature is of practical interest because it has been found that jR/-values fall with decreasing temperature (Fig. 49). Since, however, not all compounds behave similarly, i. e., some show a more marked dependence on temperature, many separations are successful only at lower temperatures. Moreover, the spots are often more compact, i. e., smaller, than at ordinary temperature. Low temperature TLC is also called for in the separation of more volatile compounds like terpene hydrocarbons for example. A certain stabilisation of labile compounds has been observed also. It has been possible to employ low boiling solvents or liquefied gases as solvents in the Cryobox for the first time. Stahl and coworkers [675, 686] have achieved successful separations at —10 to —15 C with, for example, liquid butane and various liquefied propellent gases of the Freon type. The possibilities are by no means exhausted in particular there have been no detailed studies of partition chromatography in this connection. [Pg.95]

The word propellant is also used for the liquefied gas in a pressurized aerosol container. [Pg.329]

In 1987 nonmotor fuel uses of butanes represented ca 16% of the total consumption. Liquid petroleum gas (LPG) is a mixture of butane and propane, typically in a ratio of 60 40 butane—propane however, the butane content can vary from 100 to 50% and less (see Liquefied petroleum gas). LPG is consumed as fuel in engines and in home, commercial, and industrial appHcations. Increasing amounts of LPG and butanes are used as feedstocks for substitute natural gas (SNG) plants (see Fuels, synthetic). / -Butane, propane, and isobutane are used alone or in mixture as hydrocarbon propellents in aerosols (qv). [Pg.403]

There arc two major types of liquid propellants a storable propellant (that does not boil under a normal temperature) and a ciyogenic propellant (a liquefied... [Pg.1070]

Isobutane is used in cigarette lighters and camp stoves as a fuel. It is easily liquefied under pressure, and the liquid becomes a gas immediately when the pressure is released. It is also used as a propellant in hairsprays and spray breath fresheners. [Pg.224]

See Dichlorine oxide Dicyanogen Fluorine Halogens Oxygen (Liquid) Liquefied gases Ozone Dicyanogen ROCKET PROPELLANTS... [Pg.369]

The chlorofluorocarbon compounds of methane and ethane are collectively known as freons. They are extremely stable, unreactlve, non-toxic, non-corrosive and easily liquefiable gases. Freon 12 (CCI2F2) Is one of the most common freons In Industrial use. It Is manufactured from tetrachloromethane by Swarts reaction. These are usually produced for aerosol propellants, refrigeration and air conditioning purposes. By 1974, total freon production In the world was about 2 billion pounds annually. Most freon, even that used In refrigeration, eventually makes Its way Into the atmosphere where It diffuses unchanged Into the stratosphere. In stratosphere, freon Is able to Initiate radical chain reactions that can upset the natural ozone balance (Unit 14, Class XI). [Pg.40]

Aerosol fogs as used in entomological work are of three general types an oil solution of the insecticide dispersed as microscopic droplets by a liquefied gas propellant, usually Freon a mist or fog produced by mechanical means a fog produced by means of a thermal aerosol fog generator. [Pg.61]

Blondino FE, Byron PR. Surfactant dissolution and water solubilization in chlorine-free liquefied gas propellants. Drug Dev Ind Pharm 1998 24(10) 935-945. [Pg.246]

The crystalline inorganic monopropellants decompose directly from the solid to the vapor phase and are approximately described by the above mentioned theoretical work, in spite of the fact that the gas phase processes are simplified. However, the double-base propellants and other organic materials liquefy before vaporizing. In their combustion, so-called foam and fizz zones occur before the vapor phase processes. Much work has been done attempting to apply the conservation equations to the series of processes. This work forms the basis for the summary by Geckler (G3). It is the viewpoint of this author that too many parameters are determined empirically in this application of the theory, so that useful extrapolations are not possible. One must admire the manipulative skill of the early workers in this field and also their determination to formulate a complete theory. When and if the rate parameters become available, a useful theory will be developed with the aid of this early work. [Pg.26]

LPG (liquefied petroleum gas)— propane or (less commonly) butane, obtained by extraction from natural gas or from refinery processes. LPG has a vapor pressure sufficiently low to permit compression and storage in a liquid state at moderate pressures and normal ambient temperatures. Pressurized in metal bottles or tanks. LPG is easily handled and readily lends itself to a variety of applications as a fuel, refrigerant, and propellant in packaged aerosols. LPG is also called LP gas and bottled gas. See natural gas liquids. [Pg.182]

Inhalation aerosols have been used for the delivery of drugs to the respiratory system since the mid-1950s. The most common dosage form for inhalation is the metered-dose inhaler (MDI), by which the drug is delivered from a pressurized container using a liquefied gas propellant. Medication delivered via this dosage form has allowed for a quick therapeutic response to the symptoms of asthma, emphysema, and chronic obstructive pulmonary disease (COPD), and has resulted in an improvement in the quality of life for millions of asthma sufferers. [Pg.365]

MW 27.69 CAS [19287-45-7] used as a rocket propellant, a polymerization catalyst, a reducing agent, and in the vulcanization of rubber colorless gas with a sweet, repulsive odor liquefies at -92.5°C freezes at -165°C gas density 1.15 g/L decomposes in water soluble in CS2 highly toxic and flammable ignites in moist air. [Pg.311]

Butane is found in exhausts of gasoline engines and in waste disposal sites. Butane as a gas is highly inflammable and explosive pure butane has several applications in industries and processing associated with aerosol propellants, fuel source, solvents, rubber, plastics, food additive, and refrigeration. Occupational exposure to liquefied butane by direct contact results in severe adverse effects (e.g., bums or frostbite to skin, eyes, and mucous membrane, as well as CNS depression). [Pg.209]


See other pages where Propellants liquefied is mentioned: [Pg.66]    [Pg.690]    [Pg.693]    [Pg.958]    [Pg.997]    [Pg.2101]    [Pg.2269]    [Pg.2274]    [Pg.38]    [Pg.382]    [Pg.174]    [Pg.460]    [Pg.302]    [Pg.66]    [Pg.690]    [Pg.693]    [Pg.958]    [Pg.997]    [Pg.2101]    [Pg.2269]    [Pg.2274]    [Pg.38]    [Pg.382]    [Pg.174]    [Pg.460]    [Pg.302]    [Pg.504]    [Pg.504]    [Pg.235]    [Pg.195]    [Pg.46]    [Pg.319]    [Pg.39]    [Pg.453]    [Pg.247]    [Pg.368]    [Pg.307]    [Pg.13]   
See also in sourсe #XX -- [ Pg.2093 ]




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