Polymorph Forms M, H, P, X, and ZA of Compound (1) represented by the following structural formula:
are described. A method of preparing polymorph Form M of Compound (1) includes stirring a mixture of Compound (1) and a solvent system that includes isopropanol, ethyl acetate, n-butyl acetate, methyl acetate, acetone, 2-butanone (methylethylketone (MEK)), or heptane, or a combination thereof at a temperature in a range of 10° C. to 47° C. to form From M of Compound (1). A method of preparing polymorph Form H of Compound (1) includes stirring a solution of Compound (1) at a temperature in a range of 48° C. to 70° C. to form Form H of Compound (1). A method of preparing polymorph Form P of Compound (1) includes stirring a mixture of Compound (1) and a solvent system that includes a solvent selected from the group consisting of dichloromethane and tetrahydrofuran (THF), and a mixture thereof at room temperature to form Form P of Compound (1). A method of preparing polymorph Form X of Compound (1) includes removing ethyl acetate from ethylacetate solvate G of Compound (1). A method of preparing polymorph Form ZA of Compound (1) includes removing n-butyl acetate from n-butyl acetate solvate A of Compound (1).