Anhydrous Polymorphic Forms A, B, D and E and polymorphic form C of 1-[(4-methyl-quinazolin-2-yl)methyl]-3-methyl-7-(2-butyn-1-yl)-8-(3-(R)-amino-piperidin-1-yl)-xanthine (I), are new. Form A has a melting point of 206+-[deg]C； Form D melts at 150+-3[deg]C； and Form E melts at 175+-3[deg]C. Form B transforms reversibly into the polymorph A at 10-40[deg]C. Form C loses water at 30-100[deg]C. An independent claim is included for a method (M1) of preparing polymorph form C involving refluxing (I) in methanol； cooling the methanolic solution to 40-60[deg]C； adding a solvent such as tert-butylmethylether； cooling the resulting suspension to 15-25[deg]C and then to 0-5[deg]C； filtering the crystals by suction and drying in vacuo at 70[deg]C. ACTIVITY : Antidiabetic； Anorectic； Antarthritic； Antirheumatoid； Osteopathic； Immunosuppressive. No biological data is given. MECHANISM OF ACTION : Dipeptidyl peptidase (DPP)-IV inhibitor.
