DESC:FORM 2

THE PATENTS ACT 1970
(SECTION 39 OF 1970)

&

THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(Section 10 and Rule 13)

NOVEL CRYSTALLINE FORMS OF IRON MALTOL COMPLEX AND PROCESS FOR THE PREPARATION

We, Viruj Pharmaceuticals Private Limited.,
a company incorporated under the companies act, 1956 having address at B-4, IDA Gandhinagar, Hyderabad – 500037, Telangana, India.

The following specification particularly describes the invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
The present invention relates to novel crystalline forms of an iron complex.
The present invention specifically relates to novel crystalline forms of Ferric maltol of the formula (I).
Formula (I)

The present invention also provides a process for the preparation of novel crystalline forms of Ferric maltol of the formula (I).
The present invention provides an improved process for the preparation of Ferric maltol of the formula (I).

BACKGROUND OF THE INVENTION
Ferric maltol comprises a complex of one ferric iron and three maltol anions and has the following molecular formula: (C6H5O3)3Fe. Maltol is also known as 3-hydroxy-2-methyl-4- pyrone. Accordingly, Ferric Maltol is also known by Ferric hydroxypyrone.
The chemical name of ferric maltol is 3-hydroxy-2-methyl-4H-pyrane-4-one iron (III) complex (3:1) and has the following structure:

Ferric Maltol is a ferric, non-salt-based oral iron formulation demonstrating improved tolerance in patients with previous intolerance to other iron formulations. Ferric Maltol is the first of its kind Oral Iron Formulation for the Treatment of Iron Deficiency in Adults. All other prior-known iron deficiency treatments are injectable based. Being an oral formulation, Ferric maltol, provides patient compliance and convenience of administration.
Polymorphism has been observed for ferric maltol. Two different crystalline forms can be isolated under aqueous synthetic conditions used to manufacture ferric maltol: Form A and Form C. Consistent formation of Form C within the manufacturing process is ensured during the manufacturing process, and it is controlled by XRD analysis. However, the XRD data of either Form A and Form C is not reported.
WO 2016/066555 A1 claims / disclose four different crystalline forms Viz., Form I, Form II, Form III and Form IV, characterized by specific XRD data.
IN 201921043623 claims Ferric maltol alfa form with specific XRD pattern.
Ferric maltol is conventionally synthesized from iron salts and maltol in seven main steps: dissolution of ferric citrate in purified water, mixing of maltol with a sodium hydroxide solution, filtration of the sodium maltol solution, addition of the ferric citrate solution to the sodium maltol solution under controlled temperature to and crystallization, drying and milling using well defined starting materials with acceptable specifications.
US 7,459,569 discloses a process of forming an iron hydroxypyrone compound which is a ferric hydroxypyrone complex comprising hydroxypyrone and ferric iron in the stoichiometric ratio of 3:1 hydroxypyrone: ferric iron, which comprises the step of reacting one or more iron salt of a carboxylic acid and one or more hydroxypyrone in an aqueous solution at a pH greater than 7, wherein the aqueous solution comprises one or more base selected from the group consisting of alkali metal hydroxides, sodium or potassium carbonate and mixtures thereof, wherein the carboxylic acid is selected from the group consisting of citric acid, isocitric acid, succinic acid, fumaric acid, maleic acid, malonic acid, aconitic acid, glutaric acid, tartaric acid, gluconic acid, lactic acid, and mixtures thereof, wherein the hydroxypyrone is selected from the group consisting of maltol or ethyl maltol, and mixtures thereof; and wherein the concentration of the base is from 1 to 50% by weight of the aqueous solution.
GB 2 128 998 and EP 0 107 458 disclose a process of preparation of neutral (i.e., charge balanced) iron (III) maltol complexes which involves mixing a solution of maltol in chloroform with a 1M solution of ferric chloride in ethanol to provide a 3:1 molar ratio of maltol:iron in the mixture. After 5 minutes at 20°C a 10 molar excess of solid sodium carbonate is added to the solution and the mixture is stirred for 10 minutes. The mixture is then filtered and solvent evaporated to give the neutral complex containing maltol and the ferric cation in 3:1 proportion. Recrystallisation of the 3:1 complex from ethanol provides the pure neutral ferric complex.
US 9,096,629 B2 discloses a process of forming an iron hydroxypyrone compound comprising reacting a hydroxypyrone with a non-carboxylate iron salt in an aqueous solution and precipitating the iron hydroxypyrone compound from the aqueous solution having a pH of greater than 7.
In view of the importance of Ferric maltol in treating iron deficiency there exist a continuous need for identify stable forms and also a process for preparing Ferric maltol with simple, economical, cost effective and environmental friendly process at relatively high yields and high purity.

OBJECTIVE OF THE INVENTION
The main objective of the present invention is to provide novel crystalline forms of an iron complex.
Another objective of the present invention is to provide novel crystalline forms of Ferric maltol of the formula (I).
Yet another objective of the present invention is to provide a process for the preparation of novel crystalline forms of Ferric maltol of the formula (I).
Still another objective of the present invention is to provide an improved process for the preparation of Ferric maltol of the formula (I).

SUMMARY OF THE INVENTION
Accordingly, the present invention provides novel crystalline forms of an iron complex.
In another aspect, the present invention provides novel crystalline forms of Ferric maltol of the formula (I).
Formula (I)
In one aspect, the present invention provides novel crystalline Form V1 characterized by X-ray powder diffraction pattern having peak at 11.6 ± 0.2º 2? value.
In one aspect, the present invention provides novel crystalline Form V1 characterized by X-ray powder diffraction pattern having peaks at 5.49, 10.95, 11.6, 12.65, 14.58, 16.11, 16.48, 16.82, 17.02, 17.67, 18.83, 19.54, 20.25, 20.7, 21.45, 23.19, 23.53, 23.69, 24.34, 25.06, 25.64, 26.64, 27.64, 28.15, 28.40, 28.82, 29.38, 29.71, 30.82, 31.75 ± 0.2º 2? values.
In one aspect, the present invention provides novel crystalline Form V1 characterized by DSC having endothermic peaks at 149.73 ºC and 287.06ºC.
In yet another aspect the present invention provides novel crystalline Form V1 further characterized by a TGA curve corresponding to a weight loss of about 16.458 %.
In one aspect, the present invention provides novel crystalline Form V2 characterized by peak at 6.84 ± 0.2º 2? value.
In one aspect, the present invention provides novel crystalline Form V2 characterized by X-ray powder diffraction pattern having peaks at 6.84, 10.66, 13.87, 15.24, 16.09, 22.94, 24.23, ± 0.2º 2? values.
In one aspect, the present invention provides novel crystalline Form V2 characterized by DSC having endothermic peak at 289.43ºC.

In yet another aspect the present invention provides novel crystalline Form V2 further characterized by a TGA curve corresponding to a weight loss of about 0.618 %.
In one aspect, the present invention provides novel crystalline Form V3 characterized by peak at 11.81 ± 0.2º 2? value.
In one aspect, the present invention provides novel crystalline Form V3 characterized by X-ray powder diffraction pattern having peaks at 7.15, 11.81, 14.53, 18.98, 23.00, 24.30, 26.52 ± 0.2º 2? values.
In one aspect, the present invention provides novel crystalline Form V4 characterized by peak at 13.37 ± 0.2º 2? value.
In one aspect, the present invention provides novel crystalline Form V4 characterized by X-ray powder diffraction pattern having peaks at 6.67, 11.64, 13.37, 15.74, 16.45, 19.27, 21.64, 22.58, 23.99 ± 0.2º 2? values.
In one aspect, the present invention provides novel crystalline Form V4 characterized by DSC having endothermic peaks at 143.85 ºC and 285.22ºC.
In yet another aspect the present invention provides novel crystalline Form V4 further characterized by a TGA curve corresponding to a weight loss of about 4.728%.
In one aspect, the present invention provides novel crystalline Form V5 characterized by peak at 10.26 ± 0.2º 2? value.
In one aspect, the present invention provides novel crystalline Form V5 characterized by X-ray powder diffraction pattern having peaks at 5.09, 6.10, 10.26, 11.18, 11.99, 12.98, 13.39, 13.69, 14.99, 15.96, 18.08 19.74, 21.03, 23.88, 24.69, 25.96 ± 0.2º 2? values.
In one aspect, the present invention provides novel crystalline Form V5 characterized by DSC having endothermic peaks at 155.70 ºC and 285.50ºC.
In yet another aspect the present invention provides novel crystalline Form V5 further characterized by a TGA curve corresponding to a weight loss of about 7.226 %.
In one aspect, the present invention provides novel crystalline Form V6 characterized by peak at 13.8 ± 0.2º 2? value.

In one aspect, the present invention provides novel crystalline Form V6 characterized by X-ray powder diffraction pattern having peaks at 6.85, 10.62, 12.16, 13.05, 13.80, 15.13, 15,89, 16.33, 20.95, 22.23, 22.54, 22.87, 24.16, 24.58, ± 0.2º 2? values.
In one aspect, the present invention provides novel crystalline Form V6 characterized by DSC having endothermic peak at 291.32ºC.
In yet another aspect the present invention provides novel crystalline Form V6 further characterized by a TGA curve corresponding to a weight loss of about 0.104 %.
In one aspect, the present invention provides novel crystalline Form V7 characterized by peak at 5.36 ± 0.2º 2? value.
In one aspect, the present invention provides novel crystalline Form V7 characterized by X-ray powder diffraction pattern having peaks at 5.36, 8.70, 9.32, 11.57, 13.84, 14.27, 14.84, 15.86, 16.14, 17.48, 18.39, 21.59, 23.31, 23.85, 25.06 ± 0.2º 2? values.
In one aspect, the present invention provides novel crystalline Form V7 characterized by DSC exhibiting broad endotherm between 50 to 140 ºC and having endothermic peak at 275.58ºC.
In yet another aspect the present invention provides novel crystalline Form V7 further characterized by a TGA curve showing weight loss of about 1.621 %.
The present invention also relates to a process for the preparation of novel crystalline forms of Ferric maltol of the formula (I).
In another aspect, the present invention provides a process for the preparation of novel crystalline Form V1 of Ferric maltol of Formula I which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) slurrying the resulting solution obtained in step (i), and
iii) isolating crystalline Ferric maltol Form V1.
In another aspect, the present invention provides a process for the preparation of novel crystalline Form V2 of Ferric maltol of Formula I which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) keeping the resulting solution obtained in step (i) at room temperature, and
iii) isolating the resulting crystalline Ferric maltol Form V2 by filtration.

In another aspect, the present invention provides a process for the preparation of novel crystalline Form V3 of Ferric maltol of Formula I which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) adding an antisolvent to the solution obtained above,
iii) keeping the resulting solution obtained in step (ii) at room temperature, and
iv) isolating the resulting crystalline Ferric maltol Form V3 by filtration.
In another aspect, the present invention provides a process for the preparation of novel crystalline Form V4 of Ferric maltol of Formula I which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) keeping the solution obtained above in ice bath,
iii) keeping the resulting solution obtained in step (ii) at low temperature,
iv) adding an anti-solvent and
iv) isolating the resulting crystalline Ferric maltol Form V4 by filtration.
In another aspect, the present invention provides a process for the preparation of novel crystalline Form V5 of Ferric maltol of Formula I which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) keeping the solution obtained above in ice bath,
iii) keeping the resulting solution obtained in step (ii) at low temperature,
iv) adding an anti-solvent and
iv) isolating the resulting crystalline Ferric maltol Form V5 by filtration.
In another aspect, the present invention provides a process for the preparation of novel crystalline Form V6 of Ferric maltol of Formula I which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) slurrying the resulting solution obtained above at room temperature,
iii) isolating the resulting crystalline Ferric maltol Form V6 by filtration.
In another aspect, the present invention provides a process for the preparation of novel crystalline Form V7 of Ferric maltol of Formula I which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) slurrying the resulting solution obtained above at room temperature,
iii) isolating the resulting crystalline Ferric maltol Form V7 by filtration.

The present invention specifically relates to an improved process for the preparation of Ferric maltol of the formula (I).

BRIEF DESCRIPTION OF DRAWINGS
Fig.1: Represents X-ray powder diffraction pattern of Ferric Maltol Form V1.
Fig.2: Represents DSC thermogram of Ferric Maltol Form V1.
Fig.3: Represents Thermal Gravimetric Analysis of Ferric Maltol Form V1.
Fig.4: Represents X-ray powder diffraction pattern of Ferric Maltol Form V2.
Fig.5: Represents DSC thermogram of Ferric Maltol Form V2.
Fig.6: Represents Thermal Gravimetric Analysis of Ferric Maltol Form V2.
Fig.7: Represents X-ray powder diffraction pattern of Ferric Maltol Form V3
Fig.8: Represents X-ray powder diffraction pattern of Ferric Maltol Form V4.
Fig.9: Represents DSC thermogram of Ferric Maltol Form V4.
Fig.10: Represents Thermal Gravimetric Analysis of Ferric Maltol Form V4.
Fig.11 Represents X-ray powder diffraction pattern of Ferric Maltol Form V5.
Fig.12: Represents DSC thermogram of Ferric Maltol Form V5.
Fig.13: Represents Thermal Gravimetric Analysis of Ferric Maltol Form V5.
Fig.14 Represents X-ray powder diffraction pattern of Ferric Maltol Form V6.
Fig.15: Represents DSC thermogram of Ferric Maltol Form V6.
Fig.16: Represents Thermal Gravimetric Analysis of Ferric Maltol Form V6.
Fig.17 Represents X-ray powder diffraction pattern of Ferric Maltol Form V7.
Fig.18: Represents DSC thermogram of Ferric Maltol Form V7.
Fig.19: Represents Thermal Gravimetric Analysis of Ferric Maltol Form V7.

DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to novel crystalline forms of Ferric Maltol.
In another aspect, the present invention provides novel crystalline form V1 of Ferric Maltol characterized by X-ray powder diffraction pattern, DSC, TGA shown in Figures 1, 2 and 3 respectively.

In another aspect, the present invention provides novel crystalline form V2 of Ferric Maltol characterized by X-ray powder diffraction pattern, DSC, TGA shown in Figures 4, 5, and 6 respectively.
In another aspect, the present invention provides novel crystalline form V3 of Ferric Maltol characterized by X-ray powder diffraction pattern shown in Figure 7.
In another aspect, the present invention provides novel crystalline form V4 of Ferric Maltol characterized by X-ray powder diffraction pattern, DSC, TGA shown in Figures 8, 9, and 10 respectively.
In another aspect, the present invention provides novel crystalline form V5 of Ferric Maltol characterized by X-ray powder diffraction pattern, DSC, TGA shown in Figures 11, 12, and 13 respectively.
In another aspect, the present invention provides novel crystalline form V6 of Ferric Maltol characterized by X-ray powder diffraction pattern, DSC, TGA shown in Figures 14, 15, and 16 respectively.
In another aspect, the present invention provides novel crystalline form V6 of Ferric Maltol characterized by X-ray powder diffraction pattern, DSC, TGA shown in Figures 17, 18, and 19 respectively.
The DSC and TGA of V1 clearly shows that the product is solvate, in this case chloroform solvate, which is desolvated first by losing around 16.5 % of weight and melts upon continuous heating.
Similarly, the DSC and TGA of V4, V5, V7 clearly shows that the product is solvate, in this case chloroform solvate, which is desolvated first by losing weight and melts upon continuous heating.
On the contrary from the TGA of V2 and V6 it can be inferred that it is anhydrous as the weight loss is less than 1.0%.
In yet another embodiment, the starting material Ferric Maltol used in the present invention is prepared by any procedures disclosed in the prior-art.
Solvent as defined in the present invention are selected from water or "alcohol solvents" such as methanol, ethanol, n-propanol, isopropanol, n-butanol and t-butanol and the like or "hydrocarbon solvents" such as benzene, toluene, xylene, heptane, hexane and cyclohexane and the like or "ketone solvents" such as acetone, ethyl methyl ketone, diethyl ketone, methyl tert-butyl ketone, isopropyl ketone and the like or "esters solvents" such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, sec-butyl acetate, and the like or "nitrile solvents" such as acetonitrile, propionitrile, butyronitrile and isobutyronitrile and the like or "ether solvents" such as di-tert-butylether, dimethylether, diethylether, diisopropyl ether, 1,4-dioxane, methyltert-butylether, ethyl tertbutyl ether, tetrahydrofuran, 2-methyl tetrahydrofuran, 2-methoxyethanol and dimethoxyethane, or “Amide solvents” such as formamide, DMF, DMAC, N-methyl-2- pyrrolidone, N-methylformamide, 2-pyrrolidone, 1-ethenyl-2-pyrrolidone, haloalkanes such as dichloromethane, 1,2-dichloroethane and chloroform, “Amine solvents” selected from diethylenetriamine, ethylenediamine, morpholine, piperidine, pyridine, quinoline, tributylamine, diisopropyl amine, acids such as formic acid, acetic acid, propionic acid and/or mixtures thereof.
The novel crystalline forms of Ferric Maltol of the present invention are stable, consistently reproducible and have good flow properties, and which is particularly suitable for bulk preparation and handling. The novel crystalline forms of Ferric Maltol of the present invention are also suitable for formulating into different dosage forms.
In a preferred embodiment, the present invention provides a pharmaceutical composition of novel crystalline forms of Ferric Maltol along with the pharmaceutically acceptable excipients such as diluents, chelating agents, disintegrant, glidant, lubricants and or anti-adherents.
The term "pharmaceutical composition" is intended to encompass a drug product including the active ingredient(s), pharmaceutically acceptable excipients that make up the carrier, as well as any product which results, directly or indirectly, from combination, complexation or aggregation of any two or more of the ingredients. Accordingly, the pharmaceutical compositions encompass any composition made by admixing the active ingredient, active ingredient dispersion or composite, additional active ingredient(s), and pharmaceutically acceptable excipients.
The pharmaceutical compositions comprising novel crystalline forms of Ferric Maltol may be further formulated as: solid oral dosage forms such as, but not limited to, powders, granules, pellets, tablets, and capsules; liquid oral dosage forms such as but not limited to syrups, suspensions, dispersions, and emulsions; and injectable preparations such as but not limited to solutions, dispersions, and freeze dried compositions. Formulations may be in the form of immediate release, delayed release or modified release. Further, immediate release compositions may be conventional, dispersible, chewable, mouth dissolving, or flash melt preparations, and modified release compositions that may comprise hydrophilic or hydrophobic, or combinations of hydrophilic and hydrophobic, release rate controlling substances to form matrix or reservoir or combination of matrix and reservoir systems. The compositions may be prepared using procedures such as direct blending, dry granulation, wet granulation, or extrusion and spheronization. Compositions may be presented as uncoated, film coated, sugar coated, powder coated, enteric coated or modified release coated. Compositions of the present application may further comprise one or more pharmaceutically acceptable excipients.
The present invention is further illustrated by the following examples which are provided merely to be exemplary of the inventions and is not intended to limit the scope of the invention. Certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.

EXAMPLES

Example 1 - Process for the preparation of Form V1:
3 grams of Ferric Maltol was taken into a round bottom flask, then 10.5 ml of chloroform was added and slurry continued for 48 hours at room temperature. The material formed was filtered and suck dried for 3 hours to obtain Ferric maltol Form V1.

Example 2 - Process for the preparation of Form V2:
650 mg of Form V1 of Ferric Maltol was taken into a 100 ml beaker, then 33 ml of MTBE was added to it. The beaker was tightly closed and kept stationary for 5 hours at room temperature. The material formed was filtered and suck dried for 4 hours to obtain Ferric maltol Form V2.

Example 3 - Process for the preparation of Form V2:
30 mg of Form V1 of Ferric Maltol was taken into a round bottom flask, then 300 ml of MTBE was added to it and slurry continued for 1 hour at room temperature. The material formed was filtered and suck dried for 4 hours to obtain Ferric maltol Form V2.

Example 4- Process for the preparation of Form V3:
80 mg of Ferric Maltol was dissolved in 4 ml of 1,2-dichloroethane and 4 ml of hexane was added to it. Precipitation noticed after 2 minutes and the slurry continued for overnight at room temperature. Filtered the material to obtain Ferric maltol Form V3.

Example 5- Process for the preparation of Form V4:
100 mg of Ferric Maltol was dissolved in 2.5 ml of Acetic acid at 60°C. The clear solution was immediately kept in ice bath for 20 min, then the solution moved to cold room (0-3°C) and 25 ml of cool Isopropyl ether was added. Precipitation observed immediately and the slurry continued for overnight in the cold room (0-3°C). Filtered the material to obtain Ferric maltol Form V4.

Example 6- Process for the preparation of Form V5:
100mg of Ferric Maltol was dissolved in 7.5 ml of Propionic acid at 60°C. The clear solution was immediately kept in ice bath for 20min, then the solution moved to cold room (0-3°C) and 50 ml of cool Isopropyl ether was added. Precipitation observed immediately and the slurry continued for overnight in the cold room (0-3°C). Filtered the material to obtain Ferric maltol Form V5.

Example 7- Process for the preparation of Form V6:
1250 gm of ferric maltol V1 was taken into a round bottom flask, then CHCl3 (10L) was added to form solution which is filtered through 0.22 um and then solvent is evaporated under reduced pressure to get slurry. To the slurry 5-10 L of MTBE was added and suspension was stirred for 30-60 min. then it was filtered, and suck dried to constant weight. The wet solid was taken to another lot of MTBE containing reactor and stirred for 12 to 24 hours to get final form V6.

Example 8- Process for the preparation of Form V7:

1 gram of ferric maltol form I and form II mixture (9:1 ratio) was taken into a round bottom flask, then added 2 ml of Dichloromethane and the slurry continued for 48 hours at room temperature. Filtered the material and PXRD analyzed. ,CLAIMS:We claim,

1. Novel crystalline forms V1, V2, V3, V4, V5, V6 and V7 of Ferric maltol.

2. The novel crystalline forms as claimed in claim 1, wherein the crystalline Form V1 is characterized by X-ray powder diffraction pattern having peak at 11.6 ± 0.2º 2? value.

3. The novel crystalline form as claimed in claim 2, wherein the crystalline Form V1 is characterized by X-ray powder diffraction pattern having peaks at 5.49, 10.95, 11.6, 12.65, 14.58, 16.11, 16.48, 16.82, 17.02, 17.67, 18.83, 19.54, 20.25, 20.7, 21.45, 23.19, 23.53, 23.69, 24.34, 25.06, 25.64, 26.64, 27.64, 28.15, 28.40, 28.82, 29.38, 29.71, 30.82, 31.75 ± 0.2º 2? values.

4. The novel crystalline form as claimed in claim 2, wherein the crystalline Form V1 is characterized by DSC having endothermic peaks at 149.73 ºC and 287.06ºC and TGA curve corresponding to a weight loss of about 16.458 %.

5. A process for the preparation of novel crystalline Form V1 of Ferric maltol as claimed in claim 2 which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) slurrying the resulting solution obtained in step (i), and
iii) isolating crystalline Ferric maltol Form V1.

6. The novel crystalline forms as claimed in claim 1, wherein the crystalline Form V2 is characterized by X-ray powder diffraction pattern having peak at 6.84 ± 0.2º 2? value.

7. The novel crystalline form as claimed in claim 6, wherein the crystalline Form V2 is characterized by X-ray powder diffraction pattern having peaks at 6.84, 10.66, 13.87, 15.24, 16.09, 22.94, 24.23, ± 0.2º 2? values.

8. The novel crystalline form as claimed in claim 6, wherein the crystalline Form V2 is characterized by DSC having endothermic peak at 289.43ºC and TGA curve corresponding to a weight loss of about 0.618 %.

9. A process for the preparation of novel crystalline Form V2 of Ferric maltol as claimed in claim 6 which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) keeping the resulting solution obtained in step (i) at room temperature, and
iii) isolating the resulting crystalline Ferric maltol Form V2 by filtration.

10. The novel crystalline forms as claimed in claim 1, wherein the crystalline Form V3 is characterized by X-ray powder diffraction pattern having peak at 11.81 ± 0.2º 2? value.

11. The novel crystalline form as claimed in claim 10, wherein the crystalline Form V3 is characterized by X-ray powder diffraction pattern having peaks at 7.15, 11.81, 14.53, 18.98, 23.00, 24.30, 26.52 ± 0.2º 2? values.

12. A process for the preparation of novel crystalline Form V3 of Ferric maltol as claimed in claim 10 which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) adding an antisolvent to the solution obtained above,
iii) keeping the resulting solution obtained in step (ii) at room temperature, and
iv) isolating the resulting crystalline Ferric maltol Form V3 by filtration.

13. The novel crystalline forms as claimed in claim 1, wherein the crystalline Form V4 is characterized by X-ray powder diffraction pattern having peak at 13.37 ± 0.2º 2? value..

14. The novel crystalline form as claimed in claim 13, wherein the crystalline Form V4 is characterized by X-ray powder diffraction pattern having peaks at 6.67, 11.64, 13.37, 15.74, 16.45, 19.27, 21.64, 22.58, 23.99 ± 0.2º 2? values.

15. The novel crystalline form as claimed in claim 13, wherein the crystalline Form V4 is characterized by DSC having endothermic peaks at 143.85 ºC and 285.22ºC and TGA curve corresponding to a weight loss of about 4.728%.

16. A process for the preparation of novel crystalline Form V4 of Ferric maltol as claimed in claim 13 which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) keeping the solution obtained above in ice bath,
iii) keeping the resulting solution obtained in step (ii) at low temperature,
iv) adding an anti-solvent and
iv) isolating the resulting crystalline Ferric maltol Form V4 by filtration.

17. The novel crystalline forms as claimed in claim 1, wherein the crystalline Form V5 is characterized by X-ray powder diffraction pattern having peak at 10.26 ± 0.2º 2? value.

18. The novel crystalline form as claimed in claim 17, wherein the crystalline Form V5 is characterized by X-ray powder diffraction pattern having peaks at 5.09, 6.10, 10.26, 11.18, 11.99, 12.98, 13.39, 13.69, 14.99, 15.96, 18.08 19.74, 21.03, 23.88, 24.69, 25.96 ± 0.2º 2? values.

19. The novel crystalline form as claimed in claim 17, wherein the crystalline Form V5 is characterized by DSC having endothermic peaks at 155.70 ºC and 285.50ºC and TGA curve corresponding to a weight loss of about 7.226 %.

20. A process for the preparation of novel crystalline Form V5 of Ferric maltol of Formula I as claimed in claim 17 which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) keeping the solution obtained above in ice bath,
iii) keeping the resulting solution obtained in step (ii) at low temperature,
iv) adding an anti-solvent and
iv) isolating the resulting crystalline Ferric maltol Form V5 by filtration.

21. The novel crystalline forms as claimed in claim 1, wherein the crystalline Form V6 is characterized by X-ray powder diffraction pattern having peak at 13.8 ± 0.2º 2? value.

22. The novel crystalline form as claimed in claim 21, wherein the crystalline Form V6 is characterized by X-ray powder diffraction pattern having peaks at 6.85, 10.62, 12.16, 13.05, 13.80, 15.13, 15,89, 16.33, 20.95, 22.23, 22.54, 22.87, 24.16, 24.58, ± 0.2º 2? values.

23. The novel crystalline form as claimed in claim 21, wherein the crystalline Form V5 is characterized by DSC having endothermic peak at 291.32ºC and TGA curve corresponding to a weight loss of about 0.104 %.

24. A process for the preparation of novel crystalline Form V6 of Ferric maltol as claimed in claim 21 which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) slurrying the resulting solution obtained above at room temperature,
iii) isolating the resulting crystalline Ferric maltol Form V6 by filtration.

25. The novel crystalline forms as claimed in claim 1, wherein the crystalline Form V7 is characterized by X-ray powder diffraction pattern having peak at 5.36 ± 0.2º 2? value.

26. The novel crystalline form as claimed in claim 25, wherein the crystalline Form V7 is characterized by X-ray powder diffraction pattern having peaks at 5.36, 8.70, 9.32, 11.57, 13.84, 14.27, 14.84, 15.86, 16.14, 17.48, 18.39, 21.59, 23.31, 23.85, 25.06 ± 0.2º 2? values.

27. The novel crystalline form as claimed in claim 25, wherein the crystalline Form V5 is characterized by DSC exhibiting broad endotherm between 50 to 140 ºC and having endothermic peak at 275.58ºC and TGA curve showing weight loss of about 1.621%.

28. A process for the preparation of novel crystalline Form V7 of Ferric maltol as claimed in claim 25 which comprises the steps:
i) providing a solution of Ferric maltol in a suitable solvent,
ii) slurrying the resulting solution obtained above at room temperature,
iii) isolating the resulting crystalline Ferric maltol Form V7 by filtration.

Dated this Eleventh (11th) day of February, 2023

__________________________________
Dr. S. Padmaja
Agent for the Applicant
IN/PA/883