Propellants tetrafluoroethane

Quinn EA, Forbes RT, Williams AC, Oliver MJ, McKenzie L, and Purewas TS. Protein Conformational Stability in the Hydroxyfluoroalkane Propellants Tetrafluoroethane and Heptafluoropropane Analyzed by Fourier Transform Raman Spectroscopy. IntJPharm 1999 186 31-41. 

Dichloro-l,l,2,2-tetrafluoroethane (Propellant 114), physical properties of, 2 776t... 

J. C.Ravensberg, D.J.Alexander, D.Borkhataria, G.M.Rusch, and B.Schmit. 2000. Human safely and pharmacokinetics of the CFC alternative propellants HFC 134a (1,1,1,2-tetrafluoroethane) and HFC 227 (1,1,1,2,3,3,3-heptafluoropropane) following whole-body exposure. Regul. Toxicol. Pharmacol. 32 22-35. 

The active component of inhalation aerosol is beclomethasone dipropionate, an anti-inflammatory corticosteroid having the chemical name 9-chloro-ll(beta),17,21-trihy-droxy-16(beta)-methylpregna-l,4-diene-3,20-dione 17,21-dipropionate. It is a pressurized, metered-dose aerosol intended for oral inhalation only. Each unit contains a solution of beclomethasone dipropionate in propellant HFA-134a (1,1,1,2 tetrafluoroethane) and ethanol. The 40-mcg strength delivers 40 meg of beclomethasone dipropionate from the actuator and 50 meg from the valve. The... 

Tiwari D, Goldman D, Malick WA, Madan P. Formulation and evaluation of albuterol metered dose inhalers containing tetrafluoroethane (PI 34a), a non-CFC propellant. Pharma Dev Technol 1998 3 163-174. 

Clenil-Modulite contains HFA-134a, ethanol and glycerol. The propellant 1,1,1,2-tetrafluoroethane (HFA-134a) is a non-chlorofluorocarbon (CFC). Ethanol is commonly used in pharmaceutical formulations as a solvent and can act as a preservative and skin penetrant. Glycerol acts as a humectant, preservative and increases formulation viscosity. 

Tiwari, D., Goldman, D., Dixit, S., Malick, W. A., and Madan, P L. (1998), Compatibility evaluation of metered-dose inhaler valve elastomers with tetrafluoroethane (P134a), a non-CFC propellant, Drug Dev. Ind. Pharm., 24,345-352. 

Tetrafluoroethane is a hydrofluorocarbon (HFC) or hydro-fluoroalkane (HFA) aerosol propellant (contains hydrogen, fluorine, and carbon) as contrasted to a CFC (chlorine, fluorine, and carbon). The lack of chlorine in the molecule and the presence of hydrogen reduces the ozone depletion activity to practically zero. Hence tetrafluoroethane can be considered as an alternative to CFCs in the formulation of metered-dose inhalers (MDIs). It has replaced CFC-12 as a refrigerant since it has essentially the same vapor pressure. Its very low Kauri-butanol value and solubility parameter indicate that it is not a good solvent for the commonly used surfactants for MDIs. Sorbitan trioleate, sorbitan sesquioleate, oleic acid, and soya lecithin show limited solubility in tetrafluoroethane and the amount of surfactant that actually dissolves may not be sufficient to keep a drug readily dispersed. 

Tetrafluoroethane is a nonreactive and stable material. The liquified gas is stable when used as a propellant and should be stored in a metal cylinder in a cool dry place. 

Tetrafluoroethane is usually encountered as a liquefied gas and appropriate precautions for handling should be taken. Eye protection, gloves, and protective clothing are recommended. Tetrafluoroethane should be handled in a well-ventilated environment. The vapors are heavier than air and do not support life therefore, when cleaning large tanks that have contained the propellant, adequate provisions for oxygen supply in the tanks must be made in order to protect workers cleaning the tanks. 

Binary mixtures of hydrofluoroalkanes show behaviour which approaches ideality. Figure 2.3(a) shows the vapour pressure-composition plots for a mixture of the propellants HFA 134a (tetrafluoroethane) and HFA 227 (heptafluoropropane) the linearity of the plots indicates that Raoult s law is obeyed over the temperature range examined. It is frequently necessary to include a cosolvent such as alcohol in the aerosol formulation to... 

PROPELLANT 14 (76-14-2) see 1,2-dichloro-1,1,2,2-tetrafluoroethane. PROPELLENT 22 (75-45-6) see chloro-difluoromethane. 

Trichloroethane Trichlorofluoromethane Trichlorotrifluoroethane propellant, aerosols asthma inhalers Tetrafluoroethane propellant, aerosols industrial... 

Tetrafluoroethane propellant, aerosols oral sprays Tetrafluoroethane... 

Alternatives to CFCs are available. Currently, hydrochlorofluorocarbons (HCFCs), which are more benign in the stratosphere than CFCs, are being used, but because they still contain chlorine, the HCFCs are considered only a transitional solution. By 2020, it is anticipated that hydrofluorocarbons (MFCs) such as 1,1,1,2-tetrafluoroethane (CF3CH2F), which are less susceptible to photochemical decomposition in the stratosphere, will have replaced HCFCs as propellants, refrigerants, and so on. 

There are some exceptions and these include materials packaged into pressurized containers which contain flammable liquids included in Class 3 and propellant gases included in Class 2.1 (flammable gases). Some materials are solutions of inflammable solvents, and they also belong to Class 3 of flammable liquids. Seldom do materials involve toxic substances included in Class 6.1 (e.g., trichloroethylene) or CFCs (e.g., dichlorofluoroethane of tetrafluoroethane) present in some mold release sprays. 

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