Topical pharmaceutical foam composition

1. A method of treating a skin condition, comprising the steps of:

(i) providing, in a pressurized aerosol container, an aerosol formulation comprising:

(a) an oil-in-water emulsion, wherein the oil-in-water emulsion comprises an oil phase and an aqueous phase; and

(b) a propellant comprising a hydrofluoroalkane contacting the emulsion; and

(c) sulfur dissolved or dispersed in the oil-in-water emulsion,

(ii) expelling from the pressurized aerosol container the aerosol formulation, wherein the step of expelling the aerosol formulation produces an immediate foaming action, thereby forming a foam, and

(iii) administering topically to an area of skin of a human in need thereof an effective amount of the foam,

wherein

the aerosol formulation does not comprise urea, ethanol, or a hydrocarbon propellant;

the oil phase comprises emulsifying wax, polyoxyethylene stearyl ether, and cetyl alcohol;

the aqueous phase comprises water, propylene glycol, methylparaben, propylparaben, sodium sulfacetamide, and a pH modifying agent;

the propellant is about 5% to about 30% by weight of the aerosol formulation prior to expulsion from the pressurized container;

the foam has no odor and no color;

the foam is stable for at least 5 minutes at body temperature;

the foam has a yield stress between 250 and 60,000 dynes/cm 2 ;

the foam has an expansion factor between 1.5 and 15 cm 3 /g;

the foam has a zero shear viscosity between 15,000 and 700,000 cP;

the foam has a foam density from about 0.1 g/mL to about 0.6 g/mL; and

the skin condition is selected from the group consisting of a fungal infection, corns, warts, acne, rosacea, seborrheic dermatitis, eczema, xerosis, scabies, pediculosis, and psoriasis.

2. The method of claim 1 , wherein the concentration of sulfur in the aerosol formulation is about 1% to 60%.

3. The method of claim 1 , wherein the foam is stable for at least 20 minutes at body temperature.

4. The method of claim 1 , wherein the amounts of sulfur and sodium sulfacetamide are each about 0.01% to about 20% (w/w) of the aerosol formulation.

5. The method of claim 1 , wherein the amounts of sulfur and sodium sulfacetamide are each about 1% to about 15% (w/w) of the aerosol formulation.

6. The method of claim 1 , wherein the amounts of sulfur and sodium sulfacetamide are each about 6% to about 12% (w/w) of the aerosol formulation.

7. The method of claim 1 , wherein the hydrofluoroalkane is selected from the group consisting of 1,1,1,2-tetrafluoroethane ( 134 a ); 1,1,1,2,3,3,3-heptafluoropropane (227); and combinations thereof.

8. The method of claim 1 , wherein the pH modifying agent is about 0.1% to about 5% by weight of the oil-in-water emulsion.