Provided are various embodiments relating to fumarate salt of (R)-3-(1-(2,3-dichloro-4-(pyrazin-2-yl)phenyl)-2,2,2-trifluoroethyl)-1-methyl-1-(1-methylpiperidin-4-yl) urea, and methods of producing and using the same to treat conditions and disorders associated with an increase of ghrelin level, such as food abuse, alcohol addiction, and other disorders (e.g., Prader-Willi syndrome). Also provided are various embodiments relating to crystalline HM04 free base, different crystalline forms of HM04 fumarate salt, and methods of producing the same.