Polymorphic forms of cipamfylline

A process for producing a crystalline polymorph of 1,3-di-cyclopropylmethyl-8-amino xanthine, Form I, which process comprises

• a) dissolving 1,3-di-cyclopropylmethyl-8-amino xanthine in 1-propanol or in a 1-propanol:water admixture;
• and
• b) cooling the solution to crystallize out of solution the desired polymorphic Form I, as characterized in any one of FIGS. 1, 4, 20, or wherein Form I exhibits a single crystal X-ray crystallographic analysis with (a) crystal parameters that are approximately equal to the following:
• Crystal shape (mm) Flat needles Crystal dimensions 1.0 × 0.12 × 0.08 mm Crystal color Colorless Space Group P1 triclinic #2 Temperature 295 K Cell Constants a = 10.829(2)Å b = 12.636(2)Å c = 5.105(3)Å alpha (α) = 99.48(4) beta (β) = 91.53(4) gamma (γ) = 83.84(3) Volume 685.0(8)Å3 Molecules/unit cell (Z) 4 Density, (ρ) g/cm=3 1.354 μ 7.362 cm−1 F(000) 292
• the atomic positions of all atoms relative to the origin of the unit cell as represented in the tables of FIGS. 12 to 15.