FIELD OF THE INVENTION:
The present invention relates to the Novel crystalline form of l-(4-aniino-6, 7-dimethoxy-2-quinazolinyl)-4-[(2,3-dihydro-l, 4"benzodioxin"2-yl) carbonyl] piperazine mono methane sulfonate (Doxazosin Mesylate) and process for preparation there of The crystalline form of present invention is conveniently designated as Form-Y and herein after it is referred as crystalline Form-Y of Doxazosin Mesylate. The Doxazosin Mesylate can be depicted as Formula (1).

BACK GROUND OF THE INVENTION:
Doxazosin Mesylate has been used as an anti hypertensive drug in all over the world.
USP 4,188,390 describes the process for the preparation of Doxazosin along with its
pharmaceutically acceptable salts and it also claims the composition comprising the Doxazosin
or its pharmaceutically acceptable salts.
US 6130218/EP 0849264 describes a method for synthesis of Crystalline Polymorph Form-I of
l-(4-amino-6, 7-dimethoxy-2-quinazolinyl)-4-[(2,3-dihydro-l, 4-benzodioxin-2-yI) carbonyl]
piperazine mono methane sulfonate (Doxazosin Mesylate) by suspending Doxazosin base in

alcohol-water mixture or in alkyl glycols followed by addition of weak acid and
methanesulfonic acid to result the title compound.
US 6133269/ EP 0849265 describes a method for synthesis Novel Polymorphic Form - 11 of
Doxazosin Mesylate by suspending Doxazosin in ketones such as acetone, methyl ethyl ketone,
diethyl ketone, and methyl isobutyl ketone.
US 6140334/EP 0849266 describes a method for synthesis of a Novel Polymorphic Form-Hi
of Doxazosin Mesylate by converting doxazosin to its acetate with acetic acid in an Organic
solvents preferably Ethyl Acetate, further adding methanesulfonic acid to result Doxazosin
Mesylate. The obtained product is refluxed with an alcohol preferably methyl alcohol to afford
the desired crystalline form.
WO 99/35143 describes a method for synthesis of novel crystalline form and referred as
Modification-D of Doxazosin Mesylate, by reacting Doxazosin base in a mixture of N-methyl-
2-pyrrolidine and methanol with methane sulfonic acid.
US 6,399,775 describes a method for synthesis of Form-D of Doxazosin mesylate which
comprises reacting Doxazosin base and methane sulfonic acid in an alcohol having 1 to 8
carbon atoms.
The crystalline Form-Y of Doxazosin mesylate was resulted during our laboratory
experimentation as a part of process development. The X-ray diffractogram of the present
crystalline form is compared with the prior art crystalline forms of Doxazosin mesylate and
found to be novel.
The crystalline Form-Y of Doxazosin mesylate obtained in the present invention is
characterized by its X-ray diffractogram, Differential Scanning Colorimetric thermogram and
Infra red spectrum.

In general, crystalline forms of an active ingredient may have some advantageous over
amorphous forms; hence, the novel crystalline Form-Y of Doxazosin Mesylate may be well
suited for pharmaceutical formulations as it is free flowing and non-solvated crystalline solid.
The present invention further embodies to provide a process for novel crystalline Form-Y of
Doxazosin mesylate, which is simple, eco-friendly and commercially viable process.
SUMMARY OF THE INVENTION:
The present invention is directed to novel crystalline Form-Y of Doxazosin Mesylate and to a
process for preparation thereof. The process for the present invention comprises heating the
Form-D of Doxazosin mesylate at 230-250^C with occasional stirring resulted the required
Form-Y of Doxazosin mesylate. The novel crystalline form obtained in the present invention
is differing in the X-ray diffractogram pattern of prior art crystalline forms.
The process of the present invention is simple and well suited for industrial scale up.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING:
Fig. 1 is X-ray powder diffractogram of crystalline Form-Y of Doxazosin mesylate obtained in
the present invention.
Fig. 2 is Differential scanning calorimetric thermogram of crystalline Form-Y of Doxazosin
mesylate obtained in the present invention.
Fig. 3 is Infra-red spectrum of crystalline Form-Y of Doxazosin mesylate obtained in the
present invention.

DETAILED DESCRIPTION OF THE INVENTION:
The present invention provides novel crystalline Form-Y of Doxazosin Mesylate and a process
for the preparation there of
The crystalline nature of Form-Y of Doxazosin mesylate is characterized by its Powder X-ray
diffractogram.
The X-ray diffractogram of novel crystalline Form-Y of Doxazosin mesylate is measured on a
Bruker Axs, D8 Advance Powder X-ray Diffractometer with Cu K alpha-1 Radiation source.
The X-ray diffractogram of crystalline Form-Y of Doxazosin mesylate is showing well
resolved peaks and the relevant diffractogram is depicted as Figure (1).



The present inventive substance of Doxazosin Mesylate is also characterized by Differential
Scanning Calorimetry thermogram, which is analyzed on Schimadzu differential scanning
colorimeter in a temperature range of 25-300*^C with a heating rate of 10*^C/minute under
Nitrogen with a flow rate of 30.0 ml/minute.
The crystalline Form-Y of Doxazosin mesylate has exhibited the significant endo pattern and
the identified characteristic endo peak is around 278^C. The characteristic DSC thermogram
obtained for the present inventive substance is substantially depicted as Figure (2).
The present invention further provides the Infi-a red spectral data for novel crystalline Form-Y
of Doxazosin mesylate, which is measured by KBr-transmission method on Perkin-Elmer FT-
IR instrument and is substantially depicted as Figure (3). The identified significant IR bands of
the crystalline Form-Y are mentioned in the following Table-2.
Table-2


The present invention further provides a process for the preparation of novel crystalline Form-Y of Doxazosin mesylate, which comprises;
a. placing the crystalline Form-D of Doxazosin mesylate into round bottom flask;
b. heating the compound at 230-250°C with occasional stirring for 1-2 hours, preferably
15-30 minutes;
c. cooling to ambient temperature and taking out the desired novel crystalline Form-Y of
Doxazosin mesylate.
The novel crystalline Form-Y resulted in the above process is free flowing and non-solvated
solid; hence it is suitable for pharmaceutical applications.
The process of the present invention is simple, non-hazardous and well suited for commercial
production.

Thus, the present invention hence offers novel crystalline Form-Y of Doxazosin Mesylate and process for its preparation.
The crystalline Form-D of Doxazosin mesylate, which is used as starting material for the present invention is prepared as per the process disclosed in US 6,399,775. EXAMPLES
The present invention is described in detail with example given below that are provided by the way of illustration only and therefore, should not be construed to limit the scope of invention. Reference Example:
Preparation of crystalline Form-D of Doxazosin mesylate:
Doxazosin freebase (10 grams) was suspended in Methanol (80 ml) at 25-35^C and stirred for 5-10 minutes. Methane sulfonic acid (2.24 grams) was added at once to the reaction mass and further stirred to get clear dissolution. The resulting clear solution was filtered off to get a particle free solution. The reaction solution was stirred at 25 - 35*^C for 4 hours. Filtration followed by subsequent drying produced the title compound (weight: 10.8 grams). The Form-D of Doxazosin mesylate was confirmed by PXRD, DSC and IR. Example 1:
Preparation of Crystalline Form-Y of Doxazosin Mesylate:
Crystalline Form-D of Doxazosin mesylate (20 grams) was taken in a Round bottom flask and heated the compound at 230 - 250^ C with occasional stirring for about 15-30 minutes and then cooled to 25 - 35^C to render the novel crystalline Form-Y of Doxazosin mesylate (Weight: 19.8 grams). The crystalline Form-Y of Doxazosin mesylate was confirmed by PXRD, DSC and IR.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWING
Fig-1 is characteristic X-ray powder diffraction pattern of novel crystalline Form-Y of
Doxazosin mesylate.
Vertical axis: Intensity (CPS); Horizontal axis: 2 Theta (degrees).
The significant d values obtained are 7.709, 8.357, 9.887, 10.138, 10.722, 10.989, 11.707,
13.725, 14.354, 15.496, 16.023, 16.407, 16.708, 17.069, 18.054, 18.516, 19.367, 19.805,
20.350, 20.749, 22.034, 22.290, 23.149, 23.591, 24.426, 24,912, 27.003, 28.050, 28.922 and
30.624 degree two theta.
Fig.2 is a characteristic of differential scanning Calorimetry thermogram of crystalline Form-Y
of Doxazosin mesylate.
Vertical axis: mW; Horizontal axis: Temperature (^C).
The differential scanning calorimetry thermogram exhibits a significant endo peak at
278.55^0.
Fig.3 is a characteristic infrared absorption spectrum of crystalline Form-Y of Doxazosin
mesylate.
[Vertical axis: Transmission (%); Horizontal axis: Wave nimiber (cm"^)].
The characteristic identified IR bands are around 3355, 3187, 1635, 1596, 1494, 1438, 1264,
1234, 1213, 1177, 1113, 1044, 987, 844, 553 and 523 cm"^

We claim:
1. Novel crystalline Form-Y of l-(4-amino-6, 7"dimethoxy-2-quinazolinyl)-4-[(2,3-dihydro-1, 4-ben2odioxin-2-yl) carbonyl] piperazine mono methane sulfonate (Doxazosin mesylate).
2. The novel crystalline Forai-Y of Doxazosin mesylate of claim 1 is characterized by X-ray powder diffraction pattern and the identified significant peaks are at 7.709, 8.357, 9.887, 10.138, 10.722, 10.989, 11.707, 13.725, 14.354, 15.496, 16.023, 16.407, 16.708, 17.069, 18.054, 18.516, 19.367, 19.805, 20.350, 20.749, 22.034, 22.290, 23.149, 23.591, 24.426, 24.912, 27.003, 28.050, 28.922 and 30.624 degrees two theta.
3. The crystalline Form-Y of Doxazosin mesylate of claims 1 and 2 is having X-ray powder diffraction pattern substantially as depicted in Figure (1).
4. The crystalline Form-Y of Doxazosin mesylate of claim 1 has Differential Scanning Colorimetry thermogram, which exhibits a significant endo peak around 278°C.
5. The crystalline Form-Y of Doxazosin mesylate of claims 1 and 4 has Differential Scanning Colorimetry thermogram substantially as depicted in Figure (2).
6. The crystalline Form-Y of Doxazosin mesylate of claim 1 having an identified characteristic bands around 3355, 3187, 1635, 1596, 1494, 1438, 1264, 1234, 1213, 1177, 1113,1044, 987, 844, 553 and 523 cm'Un Infra red spectrum.
7. The crystalUne Form-Y of Doxazosin mesylate of claims 1 and 6 having an Infra red spectrum substantially as depicted in Figure (3).

8. A process for the preparation of novel crystalline Form-Y of Doxazosin mesylate,
which comprises:
a) placing the crystalline Form-D of Doxazosin mesylate into round bottom flask;
b) heating the compound at 230-250^C with occasional stirring for 1-2 hours, preferably for 15-30 minutes;
c) cooling to ambient temperature and taking out the desired novel crystalline Form-Y of Doxazosin mesylate.
9. The process for the preparation of novel crystalline Form-Y of Doxazosin mesylate is
substantially as herein described and exemplified.