ABSTRACT
RG 12525 is an active leukotriene antagonist which belongs to a series of (2quinolinylmethoxy)phenoxy tetrazoles.1,2 Conveniently prepared using a four step linear synthesis, final material is obtained during a tetrazole forming step.3 Initial studies showed that the target molecule would crystallize in two different polymorphic forms.4 After determining which polymorphic form was desired for further development, a process was defined to prepare that form (form II). After successfully manufacturing in one pilot plant, the process was transferred to a second pilot plant. Unfortunately on larger scale, form II was no longer obtained as a pure polymorph. This unexpected result was difficult to understand from the available data. Therefore, a more thorough and somewhat exhaustive study into solid state properties was required.
