Crystal forms of an angiotensin II receptor antagonist BR-A657

The compound BR-A657 is an angiotensin II receptor antagonist. The objective of this work was to investigate the existence of polymorphs and pseudopolymorphs of BR-A657 and the transformation of crystal forms. Three crystal forms of BR-A657 have been isolated by recrystallization and characterized by powder X-ray diffractometry, differential scanning calorimetry, and thermogravimetric analysis. After storage of three days at 0% RH (silica gel, 20°C), 52% RH (saturated solution of Na₂Cr₂O₇·2H₂O/20°C) and 95% RH (saturated solution of Na₂HPO₄/20°C), Forms 2 and 3 were transformed to Form 1.