HALOBETASOL FOAM COMPOSITION AND METHOD OF MANUFACTURE THEREOF

1 . A storage stable, foamable composition comprising 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; and

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

wherein the composition has a pH of between about 4.0 to 6.3, and

wherein the composition is produced by:

forming a homogenous solution including (b)-(h), wherein the solution is formed in a single batch vessel at a temperature of between about 55° to 75° C. while minimizing the evaporative losses;

cooling the homogenous solution to a temperature of between about 40° to 55° C.;

adding halobetasol, or a pharmaceutically acceptable salt, ester, or solvate thereof, to the cooled solution and forming a homogenous solution while maintaining a temperature of between about 40° to 55° C.;

filling an aerosol canister with the homogenous solution while the solution is maintained at a temperature of between about 40° to 50° C.; and

charging the canister with the propellant thereby forming the foamable composition.

2 . The composition of claim 1 , wherein the ethyl alcohol and benzoic acid are combined before adding the propylene glycol, polyoxyl 20 cetostearyl ether, cetostearyl alcohol and water.

3 . The composition of claim 2 , wherein the benzoic acid is added to the ethyl alcohol which is heated to at least about 55° C. before addition of the benzoic acid.

4 . The composition of claim 1 , wherein the homogenous solution including (b)-(h) is maintained at a temperature of between about 65° to 70° C.

5 . The composition of claim 1 , wherein the homogenous solution including (b)-(h) is cooled to a temperature of between about 45° to 50° C.

6 . The composition of claim 1 , wherein filling is performed while maintaining the solution at a temperature of between about 42° to 48° C.

7 . The composition of claim 1 , wherein the homogenous solution including (b)-(h) is prepared in a suitable vessel to keep evaporative losses below 0.25% w/w during compounding.

8 . The composition of claim 1 , wherein the halobetasol remains stable for at least three months at 40° C.

9 . The composition of claim 1 , wherein the propellant is propane, n-butane, isobutane, or combinations thereof, at 3.25 to 5.75% w/w.