1,2,4-thiadiazolium derivatives as melanocortin receptor modulators

1. A method of treating a disorder mediated by a melanocortin receptor selected from the group consisting of obesity, impaired oral glucoase tolerance, elevated blood glucose levels, type II diabetes, Syndrome X, diabetic retinopathy, acute neurodegenerative disorders, chronic neurodegenerative disorders, plexopathies, male erectile dysfunction, dry eyes, acne, dry skin, aged skin, seborrheic dermatitis, rosacea, excessive ear wax, meibomian gland disorder, pseudofolliculitis, yeast infections, dandruff, hiradenitis suppurativa, ocular rosacea and eccrine gland disorder, comprising administering to a subject in need thereof a therapeutically effective amount of a compound of formula (I)

wherein

R 1 is selected from the group consisting of alkyl, aryl, aralkyl, heteroaryl, heteroaryl-alkyl, heterocycloalkyl, heterocycloalkyl-alkyl, cycloalkyl and cycloalkyl-alkyl; wherein the aryl, aralkyl, heteroaryl, heteroaryl-alkyl, heterocycloalkyl, heterocycloalkyl-alkyl, cycloalkyl or cycloalkyl-alkyl group is optionally substituted with one or more substituents independently selected from halogen, hydroxy, alkyl, alkoxy; halogenated alkyl, halogenated alkoxy, amino, alkylamino or di(alkyl)amino;

R 2 is selected from the group consisting of alkyl, aryl, aralkyl, heteroaryl, heterocycloalkyl and cycloalkyl-alkyl; wherein the aryl, aralkyl, heteroaryl, heterocycloalkyl or cycloalkyl-alkyl group is optionally substituted with one or more substituents independently selected from halogen, hydroxy, alkyl, alkoxy; halogenated alkyl, halogenated alkoxy, amino, alkylamino or di(alkyl)amino;

R 3 is selected from the group consisting of hydrogen, alkyl, alkenyl and alkynyl; wherein the double bond of the alkenyl or the triple bond of the alkynyl group is at least one carbon atom removed from the point of attachment;

R 4 is selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, heteroaryl, heterocycloalkyl, and cycloalkyl-alkyl; wherein the aryl, aralkyl, heteroaryl, heterocycloalkyl or cycloalkyl-alkyl group is optionally substituted with one or more substituents independently selected from halogen, hydroxy, alkyl, alkoxy; halogenated alkyl, halogenated alkoxy, amino, alkylamino or di(alkyl)amino;

X − is selected from the group consisting of bromide, chloride, iodide, acetate, benzoate, citrate, lactate, malate, nitrate, phosphate, diphosphate, succinate, sulfate, tartrate and tosylate;

and pharmaceutically acceptable salts thereof.

2. A method as in claim 1 wherein

R 1 is selected from the group consisting of aryl, aralkyl and heteroaryl; wherein the aryl, aralkyl or heteroaryl group is optionally substituted with one or more substituents independently selected from halogen, hydroxy, alkyl, alkoxy, trihalomethyl, trihalomethoxy, amino, alkylamino or di(alkyl)amino;

R 2 is selected from the group consisting of aryl, aralkyl and heteroaryl; wherein the aryl, aralkyl or heteroaryl group is optionally substituted with one or more substituents independently selected from halogen, hydroxy, alkyl, alkoxy, trihalomethyl, trihalomethoxy, amino, alkylamino or di(alkyl)amino;

R 3 is selected from the group consisting of hydrogen and alkyl;

R 4 is selected from the group consisting of aryl, aralkyl and heteroaryl; wherein the aryl, aralkyl or heteroaryl group is optionally substituted with one or more substituents independently selected from halogen, hydroxy, alkyl, alkoxy, trihalomethyl, trihaomethoxy, amino, alkylamino or di(alkyl)amino;

and pharmaceutically acceptable salts thereof.

3. A method as in claim 2 wherein

R 1 is aryl; wherein aryl group is optionally substituted with one to two substituents independently selected from halogen, alkyl and alkoxy;

R 2 is aryl; wherein the aryl group is optionally substituted with one to two substituents independently selected from alkyl and alkoxy;

R 3 is selected from the group consisting of hydrogen and alkyl;

R 4 is selected from the group consisting of aryl, aralkyl, and heteroaryl; wherein the aryl or aralkyl group is optionally substituted with one to two substituents independently selected from halogen, alkyl and alkoxy;

and pharmaceutically acceptable salts thereof.

4. A method as in claim 3 wherein the compound is selected from the group consisting of

2-(2-methoxyphenyl)-3-(2-methoxyphenyl)-5-phenylamino-[1,2,4]-thiadiazol-2-ium;

2-(2-methoxyphenyl)-3-(2-methoxyphenyl)-5-(2-methoxyphenylamino)-[1,2,4]-thiadiazol-2-ium;

2-(2-methoxyphenyl)-3-(2-methoxyphenyl)-5-(4-tolylamino)-[1,2,4]-thiadiazol-2-ium;

2-(2-methoxyphenyl)-3-phenyl-5-(4-methoxyphenylamino)-[1,2,4]-thiadiazol-2-ium;

2-(2-methoxyphenyl)-3-phenyl-5-(4-tolylamino)-[1,2,4]-thiadiazol-2-ium;

2-(2-methoxyphenyl)-3-phenyl-5-(2-tolylamino)-[1,2,4]-thiadiazol-2-ium;

and pharmaceutically acceptable salts thereof.

5. The method of claim 1 , wherein the disorder mediated by a melanocortin receptor is selected from the group consisting of obesity, impaired oral glucose tolerance, elevated blood glucose levels, type II diabetes and Syndrome X.

6. The method of claim 1 , wherein the disorder mediated by a melanocortin receptor is selected from the group consisting of acne, dry skin and seborrheic dermatitis.

7. The method of claim 1 , wherein the melanocortin receptor is a selected from the group consisting of the melanocortin-3 receptor, the melanocortin-4 receptor and the melanocortin-5 receptor.