Solid-state phase transitions initiated by water vapor sorption of crystalline L-660,711, a leukotriene D4 receptor antagonist.

Significant water vapor sorption at room temperature by the crystalline and lyophilized forms of L-660,711, a potent, selective leukotriene D4 receptor antagonist, has been measured and shown to produce increasingly more nonflowing, semisolid masses with increasing relative humidity. Thermal analysis, SEM, powder X-ray diffraction, solid-state NMR, and thermomicroscopic measurements reveal that water vapor sorbed at room temperature converts the crystalline form to a noncrystalline form resembling the lyophilized sample. Evidence is presented to indicate that L-660,711 has surface active properties with a critical micellization concentration of approximately 1 x 10(-4) M and an ability to form thermotropic and lyotropic mesomorphic phases when the crystal is heated above 80 degrees C in the anhydrous state; it is lyophilized from aqueous solution, and it is exposed to relative humidities at and above 12%, at room temperature.