Hydroxyzine

Formula : C21-H27-Cl-N2-O2
CAS : 68-88-2 

A histamine H1 receptor antagonist that is effective in the treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus. Unlike its major metabolite CETIRIZINE, it does cause drowsiness. It is also effective as an antiemetic, for relief of anxiety and tension, and as a sedative.

Hydroxyzine monohydrochloride

Formula : C21-H27-Cl-N2-O2.Cl-H
CAS : 1244-76-4 

A histamine H1 receptor antagonist that is effective in the treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus. Unlike its major metabolite CETIRIZINE, it does cause drowsiness. It is also effective as an antiemetic, for relief of anxiety and tension, and as a sedative.

Hydroxyzine pamoate

Formula : C21-H27-Cl-N2-O2.C23-H16-O6
CAS : 10246-75-0 

A histamine H1 receptor antagonist that is effective in the treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus. Unlike its major metabolite CETIRIZINE, it does cause drowsiness. It is also effective as an antiemetic, for relief of anxiety and tension, and as a sedative.