Abstract: A method of preparing cabergoline Form I, comprising forming a solvate including cabergoline and a p-disubstituted benzene of formula (A) or 1,3,5-trimethylbenzene and obtaining cabergoline Form I from the solvate. Another aspect of the present invention provides a method for preparing cabergoline Form I comprising dissolving cabergoline in p-disubstituted benzene or 1,3,5-trimethylbenzene and recovering the cabergoline Form I polymorph, suitably by direct crystallization of Form I or by recovery of a solvate which can be converted to Form I. Another aspect of the present invention provides a novel cabergoline polymorph designated cabergoline Form FB and a method of preparing said polymorph by dissolving or forming a solvate of cabergoline in fluorobenzene and recovering cabergoline Form FB.

Abstract: The present invention discloses a method for preparing cabergoline form I by combining cabergoline and a solvent comprising ethylbenzene to form a solvate and obtaining form I from the solvate. Also disclosed in a method for preparing cabergoline form I by combining cabergoline and a first solvent to form a solution and additionally including a second solvent to the solution, followed by crystallization to form cabergoline form I. Further disclosed is a solvate form of cabergoline comprising cabergoline and ethylbenzene and, optionally, n-heptane.