Halobetasol foam composition and method of use thereof

1. A storage stable, foamable composition consisting of, on a weight basis:

a) 0.02 to 0.10% halobetasol or its pharmaceutically acceptable salts, esters, and solvates;

b) 40 to 60% ethyl alcohol;

c) 0.1 to 5.0% Emulsifying Wax, NF;

d) 0.05 to 1.0% cetostearyl alcohol;

e) 0.05 to 1.0% polyoxyl 20 cetostearyl ether;

f) 1 to 10% propylene glycol;

g) 30 to 40% water;

h) greater than 0.0% and less than 0.0005% benzoic acid; and

i) a propellant,

wherein the composition has a pH of between about 4.0 to 6.3, and wherein an amount of degradation product of halobetasol is less than 2% after storage for 24 months at 25° C.

2. The composition of claim 1 , wherein the composition is present in a canister, and wherein the propellant is propane, n-butane, isobutane, or combinations thereof, at 3.25 to 5.75% w/w.

3. The composition of claim 2 , wherein the propellant is present in an amount ranging from 3.5 to 4% w/w.

4. The composition of claim 1 , wherein the composition has a pH of about 5.0-5.5.