Patent ID: 6992194

Claim:
A process for preparing the crystalline atorvastatin hemi-calcium and solvates thereof characterized by a physical or spectroscopic analysis result selected from the group consisting of: a) a powder X-ray diffraction pattern generated using CuK α radiation with peaks at 4.8, 5.2, 8.0, 9.2, 9.6, 19.0, 20.0, 24.0 and 29.0±0.2 degrees two-theta; b) a powder X-ray diffraction pattern generated using CuK α radiation with peaks at 9.3, 9.6, 19.2, 20.0, 21.6, 22.4 and 23.9±0.2 degrees two-theta; c) d-spacings of about 30.81, 18.46, 16.96, 15.39, 14.90, 12.78, 11.05, 9.58, 9.22, 7.42, 6.15, 5.43, 4.62, 4.44, and 3.98 Å; d) a monoclinic unit cell with cell parameters: a=18.55-18.7 Å, b=5.52-5.53 Å, c=31.0-31.2 Å and β=97.5-99.5 e) a solid state cross-polarization/magic angle spinning 13 C nuclear magnetic resonance spectrum with resonances at 24.8, 25.2, 26.1, 119.5, 120.1, 121.8, 122.8, 126.6, 128.8, 129.2, 134.2, 135.1, 137.0, 138.3 and 139.8±0.1 parts per million; and f) a solid state cross-polarization/magic angle spinning 13 C nuclear magnetic resonance spectrum wherein the chemical shift differences between the lowest resonance and other resonances are: 2.2, 7.0, 7.4, 8.3, 22.5, 23.0, 23.7, 25.6, 26.3, 28.3, 53.0, 55.5, 96.3, 98.2, 101.7, 102.3, 104.0, 105.0, 108.8, 111.0, 111.4, 116.4, 117.3, 119.2, 120.5, 122.0, 142.0, 148.6, 161.0 and 168.7 parts per million; the process comprising the steps of: (i) suspending any other crystalline or amorphous form of atorvastatin hemi-calcium in a diluent selected from the group consisting of lower alcohols and mixtures of lower alcohols and water for a period of time sufficient to cause substantial conversion to the crystalline atorvastatin hemi-calcium characterized by a physical or spectroscopic analysis result selected from the group consisting of a), b), c), d), e) and f), or a solvate thereof, and (ii) separating the diluent.