Methods and compositions for treating or preventing pruritis

1. A method of treating pruritis in a subject in need thereof, the method comprising administering to the subject an effective amount of a compound of formula I, wherein formula I is represented as follows:

represents an optional double bond;

when is a single bond, X is selected from the group consisting of: —O—, —S— and —CH 2 S

when is a double bond, X is selected from the group consisting of: ═N— and ═CH—;

Y is selected from the group consisting of: H, —OH, ═0, ═S and halo;

Z is selected from the group consisting of: a bond, —O—, —S—, —NH— and —CH2-;

R 1 , R 2 and R 3 are independently selected from the group consisting of: H, C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, halo, cyano, nitro, trifluoromethyl, trimethylsilyl, —OR a , SR a , SOR a , Sθ2R a , —NR a R b , —NR a COR b , NR a CO 2 R b , —C0 2 R a and —CONR a R b , and any two of R 1 , R 2 or R 3 may be joined together with the phenyl atom to which they are attached to form naphthyl; and

R a and R b are independently selected from the group consisting of: H, C 1-6 alkyl, phenyl and trifluoromethyl.

2. The method of claim 1 , wherein the compound of formula I is administered in combination with an anti-histamine or a corticosteroid.

3. The method of claim 2 , wherein the subject has a condition selected from the group consisting of a dermatologic disorder, exposure to a surface irritant, chronic renal disease, liver disease, bacterial or viral infection, a parasitic infestation, opioid administration, multiple sclerosis, hyperparathyroidism; diabetes mellitus, iron deficiency anemia, allergic reactions to a drug, an adverse side effect associated with a vasoactive drug, CNS active agent or chloroquine, Hodgkin's disease, polycythemia rubra vera, leukemia, mycosis fungoides, Sézary syndrome, visceral neoplasia, carcinoid, multiple myeloma, and pregnancy.

4. The method of claim 1 , wherein the subject has chloroquine-induced itch.