Functional Category:
Aerosol propellant.
Applications in Pharmaceutical Formulation
Difluoroethane, a hydrofluorocarbon (HFC), is an aerosol propellant used in topical pharmaceutical formulations.(1) Difluoroethane may be used as a vehicle for dispersions and emulsions. Since difluoroethane does not contain chlorine, there are no environmental controls on the use of this material as a propellant, since it does not deplete the ozone layer and is not a greenhouse gas
Description
Difluoroethane is a liquefied gas and exists as a liquid at room temperature when contained under its own vapor pressure, or as a gas when exposed to room temperature and atmospheric pressure. The liquid is practically odorless and colorless. Difluoroethane is noncorrosive and nonirritating.
Stability and Storage Conditions
Difluoroethane 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
Incompatibilities
Compatible with the usual ingredients used in the formulation of pharmaceutical aerosols.
Safety
Difluoroethane may be used as an aerosol propellant in topical pharmaceutical formulations. It is generally regarded as an essentially nontoxic and nonirritant material. Deliberate inhalation of excessive quantities of this propellant may result in death, and the following ‘warning’ statements must appear on the label of all aerosols: WARNING: Avoid inhalation. Keep away from eyes or other mucous membranes. (Aerosols designed specifically for oral and nasal inhalation need not contain this statement.) WARNING: Do not inhale directly; deliberate inhalation of contents can cause death. or WARNING: Use only as directed; intentional misuse by deliberately concentrating and inhaling the contents can be harmful or fatal. Additionally, the label should contain the following information: WARNING: Contents under pressure. Do not puncture or incinerate container. Do not expose to heat or store at room temperature above 1208F (498C). Keep out of the reach of children. When propellants are used in topical aerosols they may cause a chilling effect on the skin, although this effect has been somewhat overcome by the use of vapor-tap valves. The propellants quickly vaporize from the skin, and are nonirritating when used as directed.