WO2013124748A1

WO2013124748A1 - Novel polymorphs of azilsartan medoxomil potassium

Info

Publication number: WO2013124748A1
Application number: PCT/IB2013/050650
Authority: WO
Inventors: Venkat Raman JAYARAMAN; Sundara Kalyana BALAJI; Dhiraj Rathod; Natarajan B. S.; Pinal AMIN
Original assignee: Alembic Pharmaceuticals Limited
Priority date: 2012-02-20
Filing date: 2013-01-25
Publication date: 2013-08-29
Also published as: WO2013124748A4

Abstract

Novel forms of Azilsartan medoxomil potassium (Formula I), their preparation and pharmaceutical compositions are provided. New polymorphic forms of Azilsartan medoxomil potassium, their preparation and pharmaceutical compositions are also provided.

Description

Title: - NOVEL POLYMORPHS OF AZILSARTAN MEDOXOMIL POTASSIUM

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 II 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- 1 ,2,4-oxadiazol-3 -yl)biphenyl-4yl]methyl } - 1 H-benzimidazole-7-carboxylate monopotassium salt having structural formula mentioned below.

Azilsartan medoxomil potassium

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 et al.. Journal in Medicinal Chemistry, vol. 39, p. 625 (1996), 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-oxadiazol-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 1 : X-ray powder diffraction (XRD) pattern of form I of Azilsartan medoxomil potassium. Fig 2: X-ray powder diffraction (XRD) pattern of Sesquihydrate form II of Azilsartan medoxomil potassium.

Fig 3 : X-ray powder diffraction (XRD) pattern of Hemihydrate form IIII of Azilsartan medoxomil potassium.

Fig 4: X-ray powder diffraction (XRD) pattern of Monohydrate form IV of Azilsartan medoxomil potassium.

Fig 5 : X-ray powder diffraction (XRD) pattern of form V of Azilsartan medoxomil potassium. Fig 6: X-ray powder diffraction (XRD) pattern of amorphous form VI of Azilsartan medoxomil potassium.

Fig 7: Thermogravimetric scan (TG) of sesquihydrate form-II of Azilsartan medoxomil potassium.

Fig 8: Thermogravimetric scan (TG) of hemihydrate form-Ill of Azilsartan medoxomil potassium.

Fig 9: Thermogravimetric scan (TG) of monohydrate form-IV of Azilsartan medoxomil potassium.

Fig 10: IR spectrum of form I of Azilsartan medoxomil potassium.

Fig 11 : IR spectrum of sesquihydrate form II of Azilsartan medoxomil potassium. Fig 12: IR spectrum of hemihydrate form III of Azilsartan medoxomil potassium.

Fig 13: IR spectrum of monohydrate form IV of Azilsartan medoxomil potassium.

Fig 14: IR spectrum of form V of Azilsartan medoxomil potassium.

Fig 15: IR spectrum of amorphous form VI of Azilsartan medoxomil potassium.

DESCRIPTION OF INVENTION:

The present invention provides novel crystalline forms of Azilsartan medoxomil potassium which have different XRD patterns.

The present invention discloses processes for the preparation of the said novel forms of Azilsartan medoxomil 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 isobutyl 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 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, 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 Azilsartan 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 IV 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, 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) Distill out the solvent at 40-50°C and drying the separated solid to obtain Monohydrate Form- rV of Azilsartan 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 medoxomil 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 forms 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- I OF AZILSARTAN MEDOXOMIL POTASSIUM

Pure Azilsartan medoxomil potassium [about 0.50g] 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 1 2.67°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 IR 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 II 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 1 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 hemihydrate 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, 1728, 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 I crystalline by XRD using PANalytical X'pert pro, Si(Al) Xccelerator detector using Cu K alpha source at 45kVand 40 niA , 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 2Θ using Cu K alpha

Differential Scanning Calorimetry (DSC) The extrapolated melting temperature measure using Mettler instrument at 10°C/min under nitrogen atmosphere. The DSC was calibrated for temperature and heat flow with indium.

The extrapolated melting temperature onset of Form-I was 152.67°C at lOdeg/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 lOdeg/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 lOdeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 98.63 & 124.14°C

The extrapolated melting temperature onset of monohydrate Form-IV was 103.78°C at lOdeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 110.92°C

The extrapolated melting temperature onset of Form-V was 84.68°C at lOdeg/min under nitrogen in crimped aluminum pans. The peak melting temperature was 104.63°C

Table 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

Claims

1. 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.

6. 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 Thermo gravimety 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, 23.1 17, 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 DSC 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 Thermo gravimety 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

16. 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 Thermo gravimety 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 Ci-Cs alcohol or mixture thereof.

29. The organic solvent according to claim 28, wherein the preferred organic solvent is methanol.