CRYSTALLINE FORM OF ATORVASTATIN HEMI-CALCIUM
The present invention relates to a new crystalline form of Atorvastatin hemi-calcium and also relates to a process for preparation of the same by treating Atorvastatin hemi-calcium amorphous form or form-I or mixture of amorphous and crystalline forms with methanol.
1 . Crystalline form M of Atorvastatin hemi-calcium.
2 . Crystalline form M of Atorvastatin hemi-calcium which exhibits characteristic XRD pattern as depicted in FIG. 1 .
3 . Crystalline form M of Atorvastatin hemi-calcium which exhibits a characteristic XRD pattern with characteristic peaks at 16.3, 18.6, 4.7, 5.5, 5.9, 8.2, 9.6, 10.4, 11.0, 20.3, 21.9, 23.7±0.2 degrees 2θ.
4 . Crystalline form M of Atorvastatin hemi-calcium which exhibits one broad endotherm at below 100° C. and a second endotherm at 170-180° C. in DSC.
5 . A process for preparation Crystalline form M of Atorvastatin hemi-calcium comprising the steps of:
a) dissolving Atorvastatin hemi-calcium in methanol;
b) maintaining the solution for a period to crystallize form M; and
c) recovering the form M.
6 . The process as claimed in claim 5 , wherein the Atorvastatin hemi-calcium 25 used is step a) is in amorphous form.
7 . The process as claimed in claim 5 , wherein the Atorvastatin hemi-calcium used in step a) is crystalline form.
8 . The process as claimed in claim 5 , wherein the Atorvastatin hemi-calcium used in step a) is mixture of amorphous and crystalline forms.
9 . The process as claimed in claim 5 , wherein the solution of step b) is maintained for a period of about 2 to 30 hrs.
10 . The process as claimed in claim 5 , wherein the solution of step e is maintained for a period of about 4 to 18 hrs.
11 . The process as claimed in claim 5 , wherein the solution of step b) is maintained at a temperature of about 15° C. to 65° C.
12 . The process as claimed in claim 5 , wherein the solution of step b) is maintained at a temperature of about 15° C. to 35° C.
13 . The process as claimed in claim 5 , wherein the isolated form M is further dried at about 35 to 65° C.
14 . The process as claimed in claim 5 , wherein the isolated form M is further dried at about 35 to 50° C.
15 . The process of claim 5 , further comprising the step cc of seeding the dissolved Atorvastatin with Atorvastatin hemi-calcium form M.
16 . The process as claimed in claim 13 , wherein the drying is carried out for about 4 to 12 hrs.
17 . The process as claimed in claim 14 , wherein the drying is carried out for about 4 to 12 hrs.