| abstract |
A stable topical aerosol foam is provided. The foam-forming formulation includes a HFA propellant and an active agent in an emulsion. The emulsion has an oil phase and an aqueous, i.e. water-containing, phase. The active agent may be present in either phase or dispersed in the emulsion. The oil phase may consist at least in part of the HFA propellant. Either or both of the oil phase and the aqueous phase may contain one or more surfactants, emulsifiers, emulsion stabilizers, buffers, and other excipients. In an alternative embodiment, the aqueous phase contains a water-soluble active agent, for example, a local anesthetic, and the oil phase contains a water-insoluble second active agent. The foam is stable on the skin, for example for at least 10 minutes at body temperature, and will disappear into the skin upon rubbing or after prolonged standing. The formulation has the advantage of an inert non-flammable hydrofluorocarbon propellant without requiring the use of additional co-solvents or co-propellants. The composition is administered to the skin or mucous membranes. |