Reduction of hair growth

1. A method of reducing hair growth in a human, comprising selecting an area of skin from which reduced hair growth is desired, and

applying to the area of skin, in an amount effective to reduce hair growth, a dermatologically acceptable composition including a compound or a pharmaceutically acceptable salt, the compound having the following structure:

wherein R 3 is XR 4 ; X is O, NH, or S; and each of R 1 , R 2 , and R 4 , independently, is H, C 1-30 alkyl or Cr 2-30 aryl, wherein R 1 and R 2 together may be part of a cyclic structure.

2. The method of claim 1 , wherein α-difluoromethylornithine dissociates from the compound after the compound penetrates the skin.

3. The method of claim 2 , where the dissociation is enzymatic or hydrolytic.

4. The method of claim 1 , wherein each of R 1 , R 2 , and R 4 is, independently, C 1-20 alkyl or C 5-20 aryl.

5. The method of claim 1 , wherein R 3 is OH.

6. The method of claim 3 , wherein the compound is selected from the group consisting of 2-amino-2-difluoromethyl-5-[(4-isopropenyl-cyclohex-1-enylmethylene)-amino]-pentanoic acid; 2-amino-2-difluoromethyl-5-[(furan-2-ylmethylene)-amino]-pentanoic acid; 2-amino-2-difluoromethyl-5-[(2,4-dimethyl-cyclohex-3-enylmethylene)-amino]-pentanoic acid; 2-amino-2-difluoromethyl-5-[(4-methoxy-benzylidene)-amino]-pentanoic acid; 2-amino-5-[(4-tert-butyl-benzylidene)-amino]-2-difluoromethyl-pentanoic acid; 2-amino-2-difluoromethyl-5-(2-pentyl-3-phenyl-allylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-[(3-hydroxy-2-methyl-5-phosphonooxymethyl-pyridin-4-ylmethylene)-amino]-pentanoic acid; 2-amino-5-[(benzo[1,3]dioxol-5-ylmethylene)-amino]-2-difluoromethyl-pentanoic acid; 2-amino-2-difluoromethyl-5-(3-phenyl-allylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(1-trifluoromethyl-heptadecylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(1-trifluoromethyl-heneicosa-6,9,12,15-tetraenylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(1,7,7-trimethyl-bicyclo[2.2.1]hept-2-ylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(5-isopropenyl-2-methyl-cyclohex-2-enylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(2-heptyl-cyclopentylideneamino)-pentanoic acid isopentylcyclohexanone; 2-amino-2-difluoromethyl-5-[1-(10,13-dimethyl-3-oxo-2,3,6,7,8,9,10,11,12,13,14,15,16,17-tetradeca-hydro-1H-cyclopenta[a]phenanthren-17-yl)-ethylideneamino]-pentanoic acid; 5-[1-(17-acetoxy-6-chloro-10,13-dimethyl-3-oxo-1,2,3,8,9,10,11,12,13,14,15,16,17,20-tetradecahydro-cyclopropa[1,2]cyclopenta[a]phenanthren-17-yl)-ethylideneamino]-2-amino-2-difluoromethyl-pentanoic acid; 2-amino-2-difluoromethyl-5-(1-p-tolyl-ethylideneamino)-pentanoic acid and 2-amino-2-difluoromethyl-5-[3-(4-hydroxy-phenyl)-1-methyl-propylideneamino]-pentanoic acid or 2-amino-2-difluoromethyl-5-[3-(6-methoxy-naphthalen-2-yl)-1-methyl-propylideneamino]-pentanoic acid.

7. The method of claim 1 , wherein the compound is 2-amino-5-amino-5-(benzylidene-amino)-2-difluoromethyl-pentanoic acid.

8. The method of claim 5 , wherein the compound is 2-amino-2-difluoromethyl-5-[(4-hydroxy-3-methoxy-benzylidene)-amino]-pentanoic acid.

9. The method of claim 5 , wherein the compound is 2-amino-2-difluoromethyl-5-(2-methyl-3-phenyl-alkylideneamino)-pentanoic acid.

10. The method of claim 5 , wherein the compound is 2-amino-2-difluoromethyl-5-[(napthalen-2-ylmethylene)-amino]-pentanoic acid.

11. The method of claim 5 , wherein the compound is 2-amino-2-difluoromethyl-5-[(4-isopropyl-benzylidene)-amino]-pentanoic acid.

12. The method of claim 5 , wherein the compound is 2-amino-2-difluoromethyl-5-[(2,4,6,-trimethyl-benyzlidene)-amino]-pentanoic acid.

13. The method of claim 5 , wherein the compound is selected from the group consisting of 2-amino-2-difluoromethyl-5-(1-trifluoromethyl-heptadecylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(1-trifluoromethyl-heneicosa-6,9,12,15-tetraenylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(1,7,7-trimethyl-bicyclo[2.2.1]hept-2-ylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(5-isopropenyl-2-methyl-cyclohex-2-enylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(2-heptyl-cyclopentylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-(1-p-tolyl-ethylideneamino)-pentanoic acid; 2-amino-2-difluoromethyl-5-[3-(4-hydroxy-phenyl)-1-methyl-propylideneamino]-pentanoic acid or 2-amino-2-difluoromethyl-5-[3-(6-methoxy-naphthalen-2-yl)-1-methyl-propylideneamino]-pentanoic acid.

14. The method of claim 1 , wherein the composition includes from about 0.1% to about 20% of the compound by weight.

15. The method of claim 14 , wherein the composition includes from about 2% to about 15% of the compound by weight.

16. The method of claim 1 , wherein the area of skin in on the face, legs or underarm.

17. The method of claim 1 , wherein the composition includes a second compound capable of reducing hair growth.