DA-6886 is a new 5-HT4 receptor agonist under development for the treatment of constipation-predominant irritable bowel syndrome.The objective of this work was to investigate the existence of polymorphs and pseudopolymorphs of DA-6886.Five crystal forms of DA-6886 have been isolated by recrystallization and characterized by differential scanning calorimetry (DSC), thermogravimetric (TG) anal., and powder X-ray diffractometry (PXRD).From the DSC and TG data, it was confirmed that Form 2 is 1/3 methanol solvate, Form 3 is 1 methanol solvate, Form 4 is 11/3 ethanol solvate, and Form 5 is 32/3 hydrate.The PXRD patterns of five crystal forms were different, resp.In the dissolution studies in pH 6.8 ± 0.05 buffer at 37 ± 0.5 °C, the solubility of Form 2 was the highest.And the dissolution rate at 5 min in water decreased in rank order: Form 2 > Form 4 > Form 1 > Form 3 > Form 5.After storage of 3 mo at 2 °C, 24 % relative humidity, Form 1, Form 2, Form 3, and Form 4 were not transformed, but Form 5 (32/3 hydrate) was transformed to dihydrate.