There is described a new polymorphic form of 4-(7-Hydroxy-2-isopropyl-4-oxo-4H-quinazolin-3-yl)-benzonitrile having structural formula I(B) and to a method of preparing it.There is further a process or method for the manufacture of a pharmaceutically active quinazolinone compounds of the formula I wherein the symbols have the meanings given in the description, said process comprising reacting a compound of the formula II, wherein R4* is R1*—C(═O)— wherein R1* is independently selected from the group of meanings of R1 as defined for a compound of the formula I so that R1* and R1 are identical to or different from each other, or R4* is especially H, and R1 and R3, R5 and R6 are as defined for a compound of the formula I, or a salt thereof, under simultaneous or sequential condensation and cyclisation conditions with an aniline compound of the formula III, wherein R2 and m are as defined for a compound of the formula I. Further reactions and related embodiments are also claimed and disclosed.