Topical compositions and methods for treating psoriasis

1. A topical pharmaceutical composition for treating psoriasis, the composition comprising:

(a) halobetasol propionate at a concentration of about 0.01% by weight of the composition;

(b) tazarotene at a concentration of about 0.045% by weight of the composition; and

(c) a dermatologically acceptable carrier comprising:

diethyl sebacate at a concentration of about 2.5% to 3.5% by weight of the composition, a mineral oil at a concentration of about 7.5% to 8.5% by weight of the composition, carbomer copolymer type B at a concentration of about 0.3% to 0.5% by weight of the composition,

carbomer homopolymer type A at a concentration of about 0.5% to about 0.7% by weight of the composition, and

purified water.

2. The topical pharmaceutical composition of claim 1 , further comprising one or more components selected from the group consisting of a surfactant, a humectant, one or more antimicrobial preservatives, a chelating agent, and a pH-adjusting agent.

3. The topical pharmaceutical composition of claim 2 , wherein the surfactant is sorbitan monooleate, which is present at a concentration of about 0.05% to 0.2% by weight of the composition.

4. The topical pharmaceutical composition of claim 2 , wherein the humectant is sorbitol solution (70%), which is present at a concentration of about 10% to about 11% by weight of the composition.

5. The topical pharmaceutical composition of claim 2 , wherein the antimicrobial preservatives consist of methyl paraben, which is present at a concentration of about 0.1% to about 0.2% by weight of the composition, and propyl paraben, which is present at a concentration of about 0.02% to about 0.04% by weight of the composition.

6. The topical pharmaceutical composition of claim 2 , wherein the chelating agent is edetate disodium dihydrate, which is present at a concentration of about 0.03% to about 0.06% by weight of the composition.

7. The topical pharmaceutical composition of claim 2 , wherein the pH adjusting agent is sodium hydroxide, which is present in an amount to provide a pH of 5.5±0.5.

8. The topical pharmaceutical composition of claim 1 , further comprising a surfactant, a humectant, one or more antimicrobial preservatives, a chelating agent, and a pH-adjusting agent.

9. The topical pharmaceutical composition of claim 8 , wherein the surfactant is sorbitan monooleate, which is present at a concentration of about 0.05% to 0.2% by weight of the composition.

10. The topical pharmaceutical composition of claim 9 , wherein the humectant is sorbitol solution (70%), which is present at a concentration of about 10% to about 11% by weight of the composition.

11. The topical pharmaceutical composition of claim 10 , wherein the antimicrobial preservatives consist of methyl paraben, which is present at a concentration of about 0.1% to about 0.2% by weight of the composition, and propyl paraben, which is present at a concentration of about 0.02% to about 0.04% by weight of the composition.

12. The topical pharmaceutical composition of claim 11 , wherein the chelating agent is edetate disodium dihydrate, which is present at a concentration of about 0.03% to about 0.06% by weight of the composition.

13. The topical pharmaceutical composition of claim 12 , wherein the pH adjusting agent is sodium hydroxide, which is present in an amount to provide a pH of 5.5±0.5.

14. The topical pharmaceutical composition of claim 8 , wherein:

the diethyl sebacate is present at a concentration of about 2.97% by weight of the composition,

the mineral oil is light mineral oil, which is present at a concentration of about 8.03% by weight of the composition,

the carbomer copolymer type B is present at a concentration of about 0.4% by weight of the composition,

the carbomer homopolymer type A is present at a concentration of about 0.6% by weight of the composition,

the surfactant is sorbitan monooleate, which is present at a concentration of about 0.1% by weight of the composition,

the humectant is sorbitol solution (70%), which is present at a concentration of about 10.7% by weight of the composition,

the antimicrobial preservatives consist of methyl paraben, which is present at a concentration of about 0.17% by weight of the composition, and propyl paraben, which is present at a concentration of about 0.03% by weight of the composition,

the chelating agent is edetate disodium dihydrate, which is present at a concentration of about 0.05% by weight of the composition, and

the pH adjusting agent is sodium hydroxide, which is present in an amount to provide a pH of 5.5±0.5.

15. A method of treating psoriasis, the method comprising topically applying a pharmaceutical composition according to claim 1 to an affected area of a body of a subject suffering from psoriasis, wherein the applying is carried out one or more times per day for a period of time sufficient to treat the psoriasis.

16. The method of claim 15 , wherein the applying is carried out once per day for eight weeks.

17. The method of claim 15 , wherein:

the diethyl sebacate is present at a concentration of about 2.97% by weight of the composition,

the mineral oil is light mineral oil, which is present at a concentration of about 8.03% by weight of the composition,

the carbomer copolymer type B is present at a concentration of about 0.4% by weight of the composition,

the carbomer homopolymer type A is present at a concentration of about 0.6% by weight of the composition,

and wherein the composition further comprises:

sorbitan monooleate at a concentration of about 0.1% by weight of the composition,

sorbitol solution (70%), at a concentration of about 10.7% by weight of the composition,

methyl paraben at a concentration of about 0.17% by weight of the composition,

propyl paraben at a concentration of about 0.03% by weight of the composition,

edetate disodium dihydrate at a concentration of about 0.05% by weight of the composition, and

sodium hydroxide in an amount to provide a pH of 5.5±0.5.