Propellants heptafluoropropane

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. 

So far, two alternative propellants, tetrafluoro-ethane (HFA-134a, CF3CH2F) and heptafluoropropane (HFA-227, CF3CHFCF3), have been successfully tested and developed as propellants in pMDIs. The physical properties of these two propellants are compared with those of CFCs in Table 9. 

Heptafluoropropane (P-227) is classified as a hydrofluorocarbon (HFC) aerosol propellant since the molecule consists only of carbon, fluorine, and hydrogen atoms. It does not contain any chlorine and consequently does not affect the ozone layer, nor does it have an effect upon global warming. It is therefore considered as an alternative propellant to CFCs for metered-dose inhalers (MDIs). While some of its physical and chemical properties are known, little has been published in regard to its use as a replacement for CFCs in MDIs. 

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

The use of heptafluoropropane as a propellant for MDIs has been the subject of many patents throughout the world. These patents cover the formulation of MDIs, the use of specific surfactants and cosolvents, etc., and the formulator is referred... 

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... 

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. 

---