FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention-: NOVF.L POLYMORPHS OF AZILSART AN MEDOXOMIL
POTASSIUM
2. Applicant(s)
(a) NAME: ALEMBIC PHARMACEUTICALS LIMITED
(b) NATIONALITY: An Indian Company.
(c) ADDRESS: Alembic Campus, Alembic Road,
Vadodara-390, 003, Gujarat, India
3. PREAMBLE TO THE DESCRIPTION
The following specification describes the invention :

Field of the invention:
The present invention describes novel forms of Azilsartan medoxomil potassium, process for their preparation and pharmaceutical compositions containing them. More particularly, the present invention revels new polymorph of Azilsartan medoxomil potassium process of preparing them and various pharmaceutical composition containing them. The present invention relates to the use of novel polymorphs of Azilsartan medoxomil potassium disclosed herein and pharmaceutical composition containing them for the treatment of circulatory diseases such as hypertension, cardiac diseases (cardiac hypertrophy, cardiac failure, cardiac infarction and the like), nephritis, stroke and the like and metabolic diseases such as diabetes and the like, and use thereof.
Background of the invention:
The present invention relates to a novel benzimidazole derivative having superior properties of a pharmaceutical agent. More particularly, the present invention relates to a prodrug of a benzimidazole derivative having a particular structure, which has a strong and long lasting angiotensin 11 antagonistic activity and hypotensive action, and an insulin sensitizing activity, and which is useful as an agent for the prophylaxis or treatment of circulatory diseases such as hypertension, cardiac diseases (cardiac hypertrophy, cardiac failure, cardiac infarction and the like), nephritis, stroke and the like and metabolic diseases such as diabetes and the like, and use thereof.
Azilsartan medoxomil potassium is (5Methyl-2-oxo-l, 3-dioxol-4-yl) methyl 2-ethoxy-l-{[2'-(5-oxo-4,5-dihydro-l,2,4-oxadiazol-3-yi)biphenyl-4yl]methyl}-IH-benzimidazoie-7-carboxylate monopotassium salt having structural formula mentioned below.


Azilsartan medoxomil potassium is Angiotensin II causes vasoconstriction via an angiotensin II receptor on the cell membrane and elevates blood pressure. Therefore, an angiotensin II receptor antagonist can be an effective therapeutic drug for circulatory diseases such as hypertension and the like.
As a preferable chemical structure to express strong angiotensin II antagonistic activity, a structure having an acidic group such as a tetrazolyl group, a carboxyl group and the like on a biphenyl side chain is known, and, as a pharmaceutical compound having such structural characteristics, losartan, candesartan cilexetil, olmesartan medoxomil and the like have been clinically used (Ruth R. Wexler etat. Journal in Medicinal Chemistry, vol. 39, p. 625 (3 996), JP-A-4-364171, rp-A-5-78328 and the like). JP-A-5-271228 describes that a ompourid wherein an acidic group on a biphenyl side chain is 5-oxo-4,5-dihydro-l,2,4-oxadiazoI-3-yl group exhibits a long lasting and strong angiotensin II antagonistic activity and hypotensive action by oral administration.
A process of preparation of this compound is disclosed in EP2119715A1 which is hereby incorporated by reference in its entirety.
Our endeavor of developing new forms of Azilsartan medoxomil potassium has led to the development of six new forms of Azilsartan medoxomil potassium.
The present invention discloses six forms of Azilsartan medoxomil potassium i.e, Form-I, Sesquihydrate Form-II, Hemihydrate Form-Ill, Monohydrate Form-IV, Form-V and Amorphous Form-VI,
Object of the invention:
Accordingly, the present invention provides new crystalline forms.
Another object of the present invention is to provide a process for the preparation of novel forms
of Azilsartan medoxomil potassium and mixture thereof.
Yet another object is to provide novel crystalline forms or there mixture of Azilsartan medoxomil
potassium which are stable.
Yet another object to provide process for the preparation pharmaceutical composition comprising
the said novel forms of Azilsartan medoxomil potassium.

A further object of the present invention is to provide uses of the novel forms of Azilsartan medoxomil potassium for the treatment of circulatory diseases such as hypertension, cardiac diseases (cardiac hypertrophy, cardiac failure, cardiac infarction and the like), nephritis, stroke and the like and metabolic diseases such as diabetes and the like, and use thereof.
Brief description of Drawings:
Fig I: X-ray powder diffraction (XRD) pattern of form I of Azilsartan medoxomii potassium.
Fig 2: X-ray powder diffraction (XRD) pattern of Sesquihydrate form II of Azilsartan
medoxomil potassium.l
Fig 3: X-ray powder diffraction (XRD) pattern of Hemihydrate form 1111 of Azilsartan
medoxomii potassium.
Fig 4: X-ray powder diffraction (XRD) pattern of Monohydrate form IV of Azilsartan
medoxomii potassium.
Fig 5: X-ray powder diffraction (XRD) pattern of form V of Azilsartan medoxomii potassium.
Fig 6: X-ray powder diffraction (XRD) pattern of amorphous form VI of Azilsartan medoxomii
potassium.
Fig 7: Thermogravimetric scan (TG) of sesquihydrate form-11 of Azilsartan medoxomii
potassium.
Fig 8: Thermogravimetric scan (TG) of hemihydrate form-Ill of Azilsartan medoxomii
potassium.
Fig 9: Thermogravimetric scan (TG) of monohydrate form-lV of Azilsartan medoxomii
potassium.
Fig 10: IR spectrum of form ( of Azilsartan medoxomii potassium.
Fig 11: IR spectrum of sesquihydrate form II of Azilsartan medoxomii potassium.
Fig 12: IR spectrum of hemihydrate form III of Azilsartan medoxomii potassium.
Fig 13: IR spectrum of monohydrate form IV of Azilsartan medoxomii potassium.
Fig 14: IR spectrum of form V of Azilsartan medoxomii potassium.
Fig 15: IR spectrum of amorphous form VI of Azilsartan medoxomii potassium.
Description of invention:
The present invention provides novel crystalline forms of Azilsartan medoxomii potassium which have different XRD patterns.
The present invention discloses processes for the preparation of the said novel forms of Azilsartan medoxomii potassium and pharmaceutical compositions containing them and their use in the

treatment of circulatory diseases such as hypertension, cardiac diseases (cardiac hypertrophy, cardiac failure, cardiac infarction and the like), nephritis, stroke and the like and metabolic diseases such as diabetes and the like, and use thereof.
Preparation of Form I:
The novel monohydrate form I of Azilsartan medoxomil potassium may be prepared by a process comprising the following steps.
a) Preparing a solution of Azilsartan medoxomil potassium in mixture of solvent like water, and ketone solvent like acetone, methyl ethyl ketone, methyl tsobutyl ketone, methyl isopropyl ketone and the like or mixture there of at a suitable temperature selected in the range of 15-30°C, preferably at 20-25°C, more preferably at 21-23°C.
b) Heat the solution for about 1 hour at 30-50°C, preferably at 35-45°C and more preferably at 40-45°C.
c) Evaporate and drying the separated solid to obtain Form-I of Azilsartan medoxomil potassium. Form I is characterized by its XRD pattern as given in Fig 1.
Preparation of Sesquihydrate Form II:
The novel Sesquihydrate form II of Azilsartan medoxomil potassium may be prepared by a process comprising the following steps.
a) Preparing a solution of Azilsartan medoxomil potassium in mixture of solvent like water, methanol, isopropanol and ketone solvent like acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl isopropyl ketone at a suitable temperature selected in the range of 15-30°C, preferably at 20-25°C, more preferably at 21-23°C.
b) Stirring the solution for about 1 hour at 30-50°C. preferably at 35-45°C, more preferably at 40-
45°C.
c) Evaporate, distill and drying the separated solid to obtain Sesquihydrate Form-II of Azilsartan
medoxomil potassium.

Sesquihydrate Form II is characterized by its XRD pattern as given in Fig 2. Sesquihydrate Form II is characterized by its TG pattern as given in Fig 7.
Preparation of Hemihydrate Form III:
The novel Hemihydrate form III of Aziisartan medoxomil potassium may be prepared by a process comprising the following steps.
a) Preparing a solution of Aziisartan medoxomil potassium in mixture of solvent like water, methanol, and isopropanol at a suitable temperature selected in the range of 15-30°C, preferably at 20-25°C, more preferably at 21-23°C.
b) Stirring the solution for about 1 hour 30 minutes at 55-80°C, preferably at 60-75°C, more preferably at 65-70°C.
c) Evaporate and drying the separated solid to obtain Hemihydrate Form-Ill of Aziisartan medoxomil potassium.
Hemihydrate Form III is characterized by its XRD pattern as given in Fig 3. Hemihydrate Form III is characterized by its TG pattern as given in Fig 8.
Preparation of Monohydrate Form IV:
The novel Monohydrate form TV of Aziisartan medoxomil potassium may be prepared by a process comprising the following steps.
a) Preparing a solution of Aziisartan medoxomil potassium in mixture of solvent like water, methanol, and isopropanol at a suitable temperature selected in the range of 15-30°C, preferably at 20-25°C, more preferably at 21-23°C.
b) Heat the solution for about 1 hour 30 minutes at 45-70°C, preferably at 50-60°C, more preferably at 55-60°C
c) Distil! out the solvent at 40-50°C and drying the separated solid to obtain Monohydrate Form-
IV of Aziisartan medoxomil potassium.

Monohydrate Form IV is characterized by its XRD pattern as given in Fig 4. Monohydrate Form IV is characterized by its TG pattern as given in Fig 9.
Preparation of Form V:
The novel form V of Azilsartan medoxomil potassium may be prepared by a process comprising the following steps.
a) Preparing a solution of Azilsartan medoxomi1 potassium in a solvent like water, methanol, and isopropanol at a suitable temperature selected in the range of 15-30°C, preferably at 20-25°C, more preferably at 21 -23°C.
b) Heat the solution for about 1 hour at 40-60°C, preferably at 45-60°C, more preferably at 45-55°C.
c) Evaporate and drying the separated solid to obtain Form-V of Azilsartan medoxomil
potassium.
Form V is characterized by its XRD pattern as given in Fig 5.
Preparation of Amorphous Form VI:
The novel amorphous form VI of Azilsartan medoxomil potassium may be prepared by a process comprising the following steps.
a) Preparing a solution of Azilsartan medoxomil potassium in a solvent like methanol, and isopropanol at a suitable temperature selected in the range of 15-30°C, preferably at 20-25°C, more preferably at 21 -23°C.
b) Heat the solution for about 7 hour at 55-75°C, preferably at 60-75°C, more preferably at 65-68°C.
c) Evaporate and drying the separated solid to obtain amorphous Form-VI of Azilsartan medoxomil potassium.
Amorphous Form VI is characterized by its unique XRD pattern as given in Fig 6.

The various pharmaceutical composition and formulations of the novel forms of Azilsartan medoxomil potassium of the present invention can be prepared by known processes.
The dosage of novel forms of Azilsartan medoxomil potassium of the present invention is selected according to the usage and may vary as per the requirement of patents.
The novel fonns of Azilsartan medoxomil potassium are characterized by unique XRD pattern.
The process described in the present invention is illustrated in the following examples which should not be construed to limit the scope of the invention in any way.
EXAMPLE 1
PREPARATION OF FORM-1 OF AZILSARTAN MEDOXOMIL POTASSIUM*
Pure Azilsartan medoxomil potassium [about 0.50$] was dissolved in mixture of solvent like water and methyl isobutyl ketone at suitable temperature between the range of 15-30°C. Then it was heated at 30-50°C for 1 hour and the product was evaporated and dried in an oven at constant weight to obtain form I of Azilsartan medoxomil potassium. (yield 90 %, 98.5 % purity).
An embodiment of the invention is the Form I polymorph of Azilsartan medoxomil potassium characterized as having DSC extrapolated onset melting temperature of about 152.67°C.
An embodiment of the invention is the Form I polymorph of Azilsartan medoxomil potassium characterized as having DSC peak melting temperature of about 166.93°C.
Also Form I of Azilsartan medoxomil potassium characterized by 1R spectrum ( in KBr) having bands at 3401, 2981, 2869, 1815, 1771,1714, 1663, 1547, 1488, 1473, 1429, 1388, 1303, 1283, 1253, 1212, 1194, 1151, 1121, 1036, 1016, and 932 cm-1

EXAMPLE 2
PREPARATION OF SESQUIHYDRATE FORM-II OF AZILSARTAN MEDOXOMIL
POTASSIUM
Pure Azilsartan medoxomil potassium [about 0.50g] was dissolved in mixture of solvent like water, methanol and methyl isobutyl ketone at suitable temperature between the range of 15-30°C. Then the solution was stirred at 30-50°C for 1 hour and the product was evaporated and dried in an oven at constant weight to obtain Sesquihydrate form II of Azilsartan medoxomil potassium, (yield 80 %, 96,0 % purity).
The Thermogravimetry confirmed that the presence of sesquihydrate exhibiting a sharp weight loss of 4.48 % on heating which corresponds to mole ratio of water to drug of
1.5%
An embodiment of the invention is the sesquihydrate Form IT polymorph of Azilsartan medoxomil potassium characterized as having DSC extrapolated onset melting temperature of about 136.62°C.
An embodiment of the invention is the sesquihydrate Form II polymorph of Azilsartan medoxomil potassium characterized as having DSC peak melting temperature of about 150.78°C.
Also sesquihydrate Form II of Azilsartan medoxomil potassium characterized by IR spectrum ( in KBr) having bands at 3417, 2980, 2868, 1815, 1771, 1714, 1663, 1547, 1488, 1471, 1428, 1387, 1303, 1280, 1252, 1212, 1193, 1150, 1120, 1036, 1016, and 931 cm-1
EXAMPLE 3
PREPARATION OF HEMIHYDRATE FORM- III OF AZILSARTAN MEDOXOMIL
POTASSIUM
Pure Azilsartan medoxomil potassium [about l.Og] was dissolved in mixture of solvent like water, methanol and methyl isobutyl ketone at suitable temperature between the range of 15-30°C. Then the solution was stirred at 55-80°C for I hour 30minutes, and the product was evaporated and dried in an oven at constant weight to obtain form III of Azilsartan medoxomil potassium. (Yield 88 %, 94.0 % purity).

The Thermogravimetry confirmed that the presence of hemi hydrate exhibiting a sharp weight loss of 1.60 % on heating which corresponds to mole ratio of water to drug of 0.5 %.
An embodiment of the invention is the hemi hydrate Form III polymorph of Azilsartan medoxomil potassium characterized as having DSC extrapolated onset melting temperature of about 88.42°C and 112.60°C.
An embodiment of the invention is the hemihydrate Form III polymorph of Azilsartan medoxomil potassium characterized as having DSC peak melting temperature of about 98.63°C and 124.14°C.
Also hemihydrate Form III of Azilsartan medoxomil potassium characterized by IR spectrum (in KBr) having bands at 3454, 2984, 1818, 1775, 1724, 1551, 1489, 1468, 1430, 1388, 1321,1281, 1244, 1213, 1149, 1125, 1038, 1007, and 941 cm-1
EXAMPLE 4
PREPARATION OF MONO HYDRATE FORM- IV OF AZILSARTAN MEDOXOMIL
POTASSIUM
Pure Azilsartan medoxomil potassium [about 1.5g] was dissolved in mixture of solvent like water, methanol and methyl isobutyl ketone at suitable temperature between the range of 15-30°C. Then the solution was heated at 45-70°C for 1 hour and 30 minutes and distills out solvent the product was obtained dried in an oven at constant weight to obtain form IV of Azilsartan medoxomil potassium. (Yield 86 %, 90.0 % purity).
The Thermogravimetry confirmed that the presence of mono hydrate exhibiting a sharp weight loss of 2.65 % on heating which corresponds to mole ratio of water to drug of 1.0 %
An embodiment of the invention is the monohydrate Form IV polymorph of Azilsartan medoxomil potassium characterized as having DSC extrapolated onset melting temperature of about 103.78°C.

An embodiment of the invention is the monohydrate Form IV polymorph of Azilsartan medoxomil potassium characterized as having DSC peak melting temperature of about 110.92°C.
Also monohydrate Form IV of Azilsartan medoxomil potassium characterized by IR spectrum ( in KBr) having bands at 3648, 2981, 1828, 1772, 1723, 1618, 1556, 1489, 1463, 1432, 1388, 1322, 1281, 1225, 1212, 1148, 1124, 1040, 1006, and 940 cm-1
EXAMPLE 5
PREPARATION OF FORM- V OF AZILSARTAN MEDOXOMIL POTASSIUM
Pure Azilsartan medoxomil potassium [about l.Og] was dissolved in mixture of solvent like methanol and at suitable temperature between the range of 15-30°C. Then the solution was heated at 40-60°C for 1 hour. The product was evaporated and dried in an oven at constant weight to obtain form V of Azilsartan medoxomil potassium. (Yield 82 %, >96.0 % purity).
An embodiment of the invention of is the Form V polymorph of Azilsartan medoxomil potassium characterized as having DSC extrapolated onset melting temperature of about 84.68°C.
An embodiment of the invention of is the Form V polymorph of Azilsartan medoxomil potassium characterized as having DSC peak melting temperature of about 104.63°C.
Also Form V of Azilsartan medoxomil potassium characterized by IR spectrum (in KBr) having bands at 3400, 2981, 1820, 1772, 1723, 1615, 1548, 1487, 1463, 1427, 1387, 1321, 1279, 1228, 1213, 1149, 1122, 1039, 1006, and 937 cm-1
EXAMPLE 6
PREPARATION OF AMORPHOUS FORM- VI OF AZILSARTAN MEDOXOMIL
POTASSIUM
Pure Azilsartan medoxomil potassium [about 0.5g| was dissolved in mixture of solvent like methanol and at suitable temperature between the range of 15-30°C. Then the solution was heated at 55-75°C for 7 hour. The solvent was evaporated and the product dried in an oven at constant weight to obtain amorphous form VI of Azilsartan medoxomil potassium. (Yield 89 %, >92.0 % purity).

Also amorphous Form VI of Azilsartan medoxomil potassium characterized by IR spectrum (in KBr) having bands at 3401, 2982, 1772, 17.28, 1547, 1614, 1487, 1464, 1426, 1386, 1278, 1244, 1150, 1124, 1039, 1006, and 936 cm-1
CHARACTERIZATION OF POLYMORPHS
The polymorphic forms of Azilsartan medoxomil potassium are characterized using the following
procedures.
X-Ray Powder Diffraction Pattern Analysis:
Polymorph 1 crystalline by XRD using PAMalytical X'pert pro. Si(Al) Xccelerator detector using
Cu K alpha source at 45kVand 40 mA , and divergent beam (Automatic) and receiving beam slits
(0.5mm and 0.2mm). Peak positions were calibrated using a standard silicon disk (97.5 %) pure.
Table 1 below lists the XRD peak locations for Form-I, Sesquihydrate Form-II, Hemihydrate
Form-Ill, Monohydrate Form-IV and Form-V.
TABLE 1. X-Ray crystalline Reflections in 20 using Cu K alpha

Sesquihydralc Hemihydrate Monohydrate
Form-I Form-H Form-Ill Form-lV Fornn-V
6.081 5.927 6.885 7.08 7.108
7.237 7.1 7.033 7.981
9.237 9.23 11.237 10.955
10-036 10.04 12.071 11.679
11.273 11.576 12.353 12.881
11.625 11.922 12.964 13.391
11.958 13.28 13.347 14.288
12.211 14.399 13.849 14,725
13.333 14.704 14.758 15.24
13.724 16.088 16.035 15.96
13.975 17.483 16.281 16.329
14.397 19.134 16.515 16.801
14.673 20.476 17.039 17.16
15.144 21.132 19.204 17.604
16.047 22.477 20.507 18.672
17.134 23.493 21.273 18.962
17.502 24.217 22.552 19.214
17.886 24.999 23.117 20.131
18.383 26.476 24.162 20.474
] 8.806 27.301 24.936 20.982
19.132 27.692 26.154 21.431

19.49 28.996 22.293
20.306 23.019
20.553 23.248
20.881 23.691
21.147 24.004
22.34 24.79
22.634 26.006
23.368 26.546
23.736 27.29
24.172 28.183
25.051 28.97
25.437 30.481
26.55
27.689
28.397
28.959
29.763
30.3
Differential Scanning Calorimetry (DSC)
The extrapolated melting temperature measure using Mettler instrument at 10°C/rr]in under nitrogen atmosphere. The DSC was calibrated for temperature and heat flow with indium. The extrapolated melting temperature onset of Form-1 was 152.67°C at 1 Odeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 166.93°C
The extrapolated melting temperature onset of sesquihydrate Form-II was 136.62°C at 1 Odeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 150.78°C
The extrapolated melting temperature onset of hemi hydrate Form-Ill was 88.42 &112.60°C at 1 Odeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 98.63 & 124.I4°C
The extrapolated melting temperature onset of monohydrate Form-IV was 103.78°C at 1 Odeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 110.92oC
The extrapolaled melting temperature onset of Form-V was 84.68°C at 1 Odeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 104.63°C

Tabic 2 provides a comparison of the extrapolated melting temperature onset peak melting temperature for Form I, Sesquihydrate Form II, Hemihydrate Form III, Monohydrate Form IV, and Form V.
Table 2

Extrapolated onset temperature and peak temperature and AH fusion,kJ/mol by DSC at lG°C/min in crimped pans under nitrogen
Polymorphic form On set temperature(°C) Peak
tempera ture(°C)
Form I
Sesquihydrete Form II Hemihydrate Form III Monohydrate Form IV Form V 152.67 136.62 88.42 &112.60 103.78 84.68 166.93 150.78 98.63 &124.14 110.92 104.63

Claims
I. A polymorphic form I of Azilsartan medoxomil potassium having the below structural formula.

2. The polymorphic form I of Azilsartan medoxomil potassium according to claiml is characterized by X-ray powder diffraction pattern having peaks at about 6.081, 7.237, 9.237, 10.036, 11.273, 11.625, 11.958, 13.333, 16.047, 20.306, 22.340, 22.634, 23.368, and 24.172, ± 0.2 degrees two-theta.
3. The polymorph of Azilsartan medoxomil potassium according to claim 1, wherein the polymorph has a DSC extrapolated melting temperature on set of 152.67°C.
4. The polymorph of Azilsartan medoxomil potassium according to claim 1, wherein the polymorph has a DSC peak melting temperature of about 166.93°C.
5. A polymorphic form II of Azilsartan medoxomil potassium having the below structural formula.

The polymorphic form II of Azilsartan medoxomil potassium according to claim 5 is Sesquihydrate, characterized by X-ray diffraction pattern with peak at about 9.230, 10.040, 11.576, 13.280, 16.088, 20.476, 21.132, 23.493,and 24.217 ± 0.2 degrees two-theta.
7. The polymorphic form II of of Azilsartan medoxomil potassium according to claim 5, wherein the polymorph has a DSC extrapolated melting temperature on set of 136.62°C.
8. The polymorphic form II of Azilsartan medoxomil potassium according to claim 5, wherein the polymorph has a DSC peak melting temperature of about 150.78°C.
9. The polymorphic form II of Azilsartan medoxomil potassium according to claim 7, wherein the polymorph has a Thennogravimety confirmed that the presence of sesquihydrate by exhibiting a weight loss of 4.48 % which is corresponds to mole ratio of water to drug of 1.5%.
10. A polymorphic form III of Azilsartan medoxomil potassium having the below structural formula

11. The polymorphic form III of Azilsartan medoxomil potassium according to claim 10 is Hemihydrate characterized by X-ray diffraction pattern with peaks at about 6.885, 7.033, 12.353, 16,035, 16.515, 17.039, 22.552, 23.117, and 24.936 ± 0.2 degrees two-theta.

12. The polymorph in accordance with claim 10, wherein the polymorph has a DSC extrapolated melting temperature on set of 88.42 & 112.60°C.
13. The polymorph in accordance with claim 10, wherein the polymorph has a D SC peak melting temperature of about 98.63 & 124.14°C.
14. The polymorphic form III of Azilsartan medoxomil potassium according to claim 10, wherein the polymorph has a Thermogravimety confirmed that the presence of hemihydrate by exhibiting a weight loss of 1.6 % which is corresponds to mole ratio of water to drug of 0.5%.
15. A polymorphic form IV of Azilsartan medoxomil potassium having the below structural formula

1 6. the polymorphic form IV of Azilsartan medoxomil potassium according to claim 15 is monohydrate characterized by X-ray diffraction pattern with peak at about 7.080, 7.981, 12.881, 13.391, 15.960, 16.329, 16.801, 17.160, 23.019, 24.790, 26.006, and 26.546 ± 0.2 degrees two-theta.
17. The polymorph in accordance with claim 15. wherein the polymorph has a DSC extrapolated melting temperature on set of 103.78°C.
18. The polymorph in accordance with claim 15. wherein the polymorph has a DSC peak melting temperature of about 110.92°C.

19. The polymorphic form IV of Azilsartan medoxomil potassium according to claim 15, wherein the polymorph has a Thermogravimety confirmed that the presence of monohydrate by exhibiting a weight loss of 2.65 % which is corresponds to mole ratio of water to drug of 1.0%.
20. A polymorphic form V of Azilsartan medoxomil potassium having the below structural formula

21. The polymorphic form V of Azilsartan medoxomil potassium according to claim 20 is characterized by X-ray diffraction pattern with peak at about 7.108 ± 0.2 degrees two-theta.
22. Azilsartan medoxomil potassium Form V which is further characterized by X-ray diffraction pattern showing the presence of semi crystalline nature.
23. The polymorph in accordance with claim 28, wherein the polymorph has a DSC extrapolated melting temperature on set of 84.68 °C.
24. The polymorph in accordance with claim 20, wherein the polymorph has a DSC peak melting temperature of about 104.63 °C.
25. Amorphous Form of Azilsartan medoxomil potassium.

26. Amorphous for of Azilsartan medoxomil potassium according to claim 25 is designated as Form VI which is further characterized by X-ray diffraction pattern.
27. A process for the preparation of amorphous Form VI of Azilsartan medoxomil potassium comprising:

a) dissolving Azilsartan medoxomil potassium in organic solvent
b) Heating the solution
c) Evaporating off the organic solvent partially or completely.
d) Isolating the amorphous Form VI Azilsartan medoxomil potassium.
e) Drying the amorphous Form VI Azilsartan medoxomil potassium.

28. The process according to claim 27, wherein the said organic solvent is C1-C8 alcohol or mixture thereof.
29. The organic solvent according to claim 28, wherein the preferred organic solvent is methanol.