FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
Complete Specification
[See Sections 10 and rule 13]
Title: "Stable composition of Fesoterodine"
Applicant: (a) Astron Research Limited
(b) Company Registered under Indian Company ACT
(c) 10th Floor, Premier House Bodakdev. Opp. Gumdwara Sarkhej - Gandhinagar Highway Ahmedabad- 380054
Gujarat India
The following specification particularly describes the invention and the manner in which it is to be performed:

FILED OF THE INVENTION
The present invention relates to a stable pharmaceutical composition comprising Fesoterodine or pharmaceutically acceptable salt thereof; wherein the composition is devoid of sugar alcohols used as stabilizer. Further, the present invention discloses processes for the preparation of the said pharmaceutical composition prepared by direct compression.
BACKGROUND OF THE INVENTION
Fesoterodine is chemically 2-[(lR)-3-(diisopropylamino)-'l-phenylpropyl]-4-(hydroxymethyi)phenyl isobutyrate. Fesoterodine is a prodrug; which gets rapidly de-esterified to its active metabolite (R)-2-(3-diisopropylamino-l-phenylpropyl)-4-hydroxymethyl-phenoI or 5-hydroxymethyl tolterodine (5-HMT), which is a muscarinic receptor antagonist. Molecular formula of Fesoterodine is C26H37NO3 and has following chemical structure:

W099/58478 discloses novel derivatives of 3,3-diphenylpropylamines which cover Fesoterodine. Further WO01/35957 discloses stable salts of Fesoterodine including Fesoterodine hydrogen fumarate. Fesoterodine is marketed under trade name Toviaz®; which contains Fesoterodine fumarate as active ingredient and is approved as extended-release tablet for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency.

It is believed that Fesoterodine may undergo substantia! degradation under stress conditions, e.g., in a humid environment and at increased temperature. Probable reasons for degradation of Fesoterodine are hydrolysis and oxidation. To overcome the said problem several approaches are reported as follows:
Fesoterodine is currently marked as Toviaz which is extended-release tablet contains 4 or 8 mg of Fesoterodine fumarate as active ingredient and following inactive ingredients: glyceryl behenate, hypromellose, indigo carmine aluminum lake, lactose monohydrate. soya lecithin, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol, talc, titanium dioxide, and xylitol. The composition uses xylitol as stabilizer to control the degradation of Fesoterodine.
US78077I5 discloses a pharmaceutical composition comprising Fesoterodine or salt thereof and a pharmaceutically acceptable stabilizer, wherein stabilizer is selected from the group consisting of sorbitol, xylitol. polydextrose, isomalt, dextrose, and combinations thereof, preferably a sugar alcohol selected from xylitol and sorbitol.
US7807715 further discloses that wet granulation method for preparation of composition is preferable over dry granulation and direct compression.
WO2010/043408 discloses microencapsulated Fesoterodine; wherein Fesoterodine is present in core which is surrounded by shell; the shell contains excipients which modify the release of Fesoterodine. The microencapsulated Fesoterodine is further formulated in the form of tablets.
WO2011/050961 discloses a composition, comprising Fesoterodine and fiber, wherein fiber is selected from alginate, gelatin, agar, gum arabic, tragacanth. xanthan gum and carrageenan. Focus of WO2011/050961 is to prepare a

composition comprising Fesoterodine and fiber; wherein fiber act as stabilizer as well as sustained release adjuvant.
WO2011/117884 discloses a pharmaceutical composition comprising of Fesoterodine or its salts, wherein the said pharmaceutical composition is devoid of sugar stabilizer. According to the invention disclosed in WO2011/117884. Fesoterodine compositions are prepared using judicial combination of excipients, without using sugar alcohol.
The inventors of the present invention tried to develop a stable extended release pharmaceutical composition of Fesoterodine or its salt by judicial use of excipients as disclosed in WO2011/! 17884. however failed to obtain a stable extended release pharmaceutical composition of Fesoterodine or its salt.
Considering the prior efforts as disclosed in the background, a need exists which would address the issues relating to degradation of Fesoterodine in the pharmaceutical composition and provides a stable pharmaceutical composition of Fesoterodine or its salt.
OBJECT OF THE INVENTION
First object of the invention is to provide a stable pharmaceutical composition of Fesoterodine or its salt, wherein the said pharmaceutical composition is devoid of sugar alcohol.
Another object of the invention is to provide processes for the preparation of stable pharmaceutical composition of Fesoterodine or its salt, wherein the said pharmaceutical composition is devoid of sugar alcohol.
Another object of the invention is to provide a stable pharmaceutical composition of Fesoterodine or its salt, wherein the total impurity in the said pharmaceutical

composition is not more than 2% w/w after subjecting the said pharmaceutical composition to a storage condition of 40°C / 75% RH for a period of 3 month.
Another object of the invention is to provide a stable pharmaceutical composition of Fesoterodine or its salt, wherein the total impurity in the said composition is not more than 2% w/w, impurity A and impurity C are not present in an amount more than 0.625% w/w individually: after subjecting the said pharmaceutical composition to a storage condition of 40°C / 75% RH for a period of 3 month.
SUMMARY OF THE INVENTION
Present invention provides a stable pharmaceutical composition of Fesoterodine or its salt and process for the preparation of the same; wherein the said pharmaceutical composition is devoid of sugar alcohol. The incremental innovation of the present invention relates to use of amorphous hydrated silicon dioxide (eg. product marketed as SYLOID ' FP) and pre-dried excipients for the preparation of a stable pharmaceutical composition of Fesoterodine or its salt.
DETAILED DESCRIPTION OF THE INVENTION
Present invention provides a stable pharmaceutical composition of Fesoterodine or its salt, wherein the composition is devoid of sugar alcohol; and amorphous hydrated silicon dioxide and pre-dried excipients are used for the preparation of the said stable composition.
In one of the embodiments, the pharmaceutical composition of Fesoterodine or its salt according to the present invention are prepared by direct compression techniques. Direct compression techniques are well know to a person skilled in the art and are well-documented in reference literatures for pharmaceutical sciences.
Further, according to the present invention, the pharmaceutical composition of Fesoterodine or its salt is devoid of sugar alcohol. The term "sugar alcohol"' used

hereinafter in the present invention relates to hydrogenated form of carbohydrate, whose carbonyl group has been reduced to a primary or secondary hydroxyl group, Examples of sugar alcohols include inositol, erythritol, xylitol, mannitol. sorbitol, dulcitol, iditol, isomalt, maltitol, lactitol, ribitol, arabitol and the likes thereof.
According to the present invention, amorphous hydrated silicon dioxide (eg. product marketed as SYLOID FP) is used in the preparation of a stable pharmaceutical composition comprising Fesoterodine or its salt. Amount of amorphous hydrated silicon dioxide used in pharmaceutical composition is proportionate to the amount of Fesoterodine or its salt used in the said composition. Accordingly, the ratio of Fesoterodine or its salt to amorphous hydrated silicon dioxide used in the said pharmaceutical composition is 4:1 to 1:10. Preferably, ratio of Fesoterodine or its salt to amorphous hydrated silicon dioxide in the said pharmaceutical composition is 1:1 to 1:4. Exemplary product SYLOID® FP is available in different grades eg.. SYLOID® 63FP, SYLOID® 72FP, SYLOID® 244FP characterized by unique combination of adsorptive capacity, meso-porosity, particle size and surface morphology. According to the preferred embodiment, one or more than one grade of SYLOID® FP may be incorporated in the said composition to achieve the said objectives of the invention.
Further, according to the present invention, the pre-dried excipients are used for the preparation of a stable pharmaceutical composition of Fesoterodine or its salt. The term "pre-dried excipients" hereinafter refers to pharmaceutical excipients having a moisture content of not more than 2% w/w of the said excipient. To achieve the pre-dried excipients, all the excipients used in the pharmaceutical composition are dried to achieve LOD (loss on drying) below 2% \v/\v, preferably all the excipients having percentage weight of more than 2 % vv/w in the said composition are pre-dried.

According to the present invention, pharmaceutical composition of Fesoterodine or its pharmaceutically acceptable salt are solid oral dosage forms, eg. tablets. In one of the embodiment, the said solid oral dosage form can be for immediate release, extended release, sustained release, prolonged release etc, of Fesoterodine or its pharmaceutically acceptable salt from the said dosage form.
Pharmaceutical excipients selected for the said solid oral dosage form would depend on the type of solid oral dosage form. Pharmaceutical excipients used in the said pharmaceutical composition of Fesoterodine or its salt may be selected from conventional tablet excipients such as binder, diluent, lubricant, disintegrant, glidant, rate-controlling agents, and the likes thereof. Amount of pharmaceutical excipients to be used in the said pharmaceutical composition may vary according to the requirement of finished dosage form.
According to present invention, diluent may include but not limited to lactose anhydrous, lactose monohydrate, spray dried lactose, dicalcium phosphate, calcium phosphate tribasic, calcium carbonate, calcium sulfate, starch, corn starch, potato starch, wheat starch, pregelatinized starch, cellulose microcrystalline, silicified microcrystalline cellulose, cellulose microcrystalline powdered and mixtures thereof.
According to present invention, binder may include but not limited to acacia, carbomer, carboxymethylcellulose, cellulose microcrystalline, copovidone, gelatin, guar gum, hydroxypropyl cellulose, low-substituted hydroxypropyl cellulose, hypromellose, hypromellose acetate succinate, methyl cellulose, ethyl cellulose, polyethylene oxide, povidone, starch, pregelatinized starch, ammonio methacrylate copolymer and mixtures thereof,
According to present invention, rate controlling polymer may include but not limited to hydroxypropyl methyl cellulose, ethyl cellulose, hydroxypropyl

cellulose, hydroxyethyl cellulose, ethyl cellulose, methylcellulose. sodium carboxymethylcellulose and or a mixture thereof and like thereof.
According to present invention, disintegrant may include but not limited to cellulose microcrystalline, croscarmellose sodium, crospovidone. low-substituted hydroxypropyl cellulose, sodium starch glycolate. starch, pregelatinized starch and mixtures thereof.
According to present invention, lubricant may include but not limited to calcium stearate, glyceryl behenate, magnesium stearate. mineral oil light, polyethylene glycol, castor oil, sodium stearyl fumarate. starch, stearic acid, talc. hydrogenated vegetable oil, zinc stearate, sodium benzoate and mixtures thereof.
According to present invention, glidant may include but not limited to calcium silicate, magnesium silicate, colloidal silicon dioxide, talc and mixtures thereof.
According to the present invention, accelerated stability conditions are storage conditions for the pharmaceutical composition of Fesoterodine or its salt, wherein the said composition is stored at 40°C / 75% RH for a period of 3 month.
According to the present invention, a stable pharmaceutical composition of Fesoterodine or its salt is characterized as a pharmaceutical composition of Fesoterodine or its pharmaceutically acceptable salt wherein the total impurity in the said composition is not more than 2% w/w, impurity A and impurity C are not present in an amount more than 0.625% w/vv individually; after subjecting the said pharmaceutical composition to a storage condition of 40°C / 75% RH for a period of 3 month.

According to the present invention, impurity A is chemically R-(+)-2-(3-diisopropylamino-1-phenylpropyl)-4-hydroxymethyl phenol (5-HMT) and has a chemical structure as follows:

Further, impurity C of Fesoterodine is R-(-s-)-isobutyric acid 4-isobutyroxy
methyl-2-(3-diisoproplamino-l-phenylpropyl)-phenyl ester and has a chemical structure as follows:

According to present invention, packaging of the said composition can be done in blister packs or the said composition can be packed into HDPE bottle. The HDPE bottle may contain moisture absorbers including but not limited to activated carbon, silicas, zeolites, molecular sieves and like thereof. The moisture absorber may be present in the form of a sachet, cartridge or canister.
Further, process for the preparation of the said composition involves direct compression wherein the critical steps to obtain a stable pharmaceutical composition of Fesoterodine or its pharmaceutical!}' acceptable salt are:

1) Use of amorphous hydrated silicone dioxide as an excipient in the said
composition and
2) Pre-drying of all the excipients to achieve LOD below 2% vv/w.
The said composition of the present invention can be optionally film coated with aqueous or non-aqueous coating material.
As per the preferred embodiment for preparation of the said composition by direct compression technique involves the following steps:
1. Sifting of Fesoterodine or its salt
2. Sifting of amorphous hydrated silicon dioxide.
3. Sifting of other pharmaceutical excipients selected from a group comprising of rate controlling polymer, diluent, binder, disintegrant through appropriate mesh.
4. Drying the all excipients of step no. 2 and step no. 3 to achieve LOD below 2% w/vv.
5. Blending the material obtained in step 1 and step 4.
6. Adding suitable lubricant and / or glidant (optionally pre-dried) to the blend obtained in step 5.
7. Compressing the blend obtained in step 6 to obtain tablet dosage form.
The above process further optionally involves process of film coating. The film coating composition may be an aqueous or non-aqueous coating composition comprising of film forming agent and optionally plasticizer, anti-tacking agent, coloring agent and opacifier.
EXAMPLES
The present invention has been described by way of example only, and it is to be recognized that modifications thereto falling within the scope and spirit of appended claims, and which would be obvious to a person skilled in the art based

upon the disclosure herein, are also considered to be within the scope of this invention.
Following examples describes the invention and its advantages with regards to pharmaceutical composition of Fesoterodine or its pharmaceutical!}' acceptable salt. A comparison of accelerated stability data are provided hereinafter for the pharmaceutical composition of Fesoterodine or its salt prepared by judicial use of excipients as per known - art (Example 1 and Example 2) and the pharmaceutical composition disclosed according to the present invention (Example 3-8) and pharmaceutical composition prepared without pre-drying of pharmaceutical excipients (Example 9).
Example 1:
Example 1 was formulated with composition according to below table.

Sr. No Ingredients Qty/Tablet (mg)
Dry Mixing
1. Fesoterodine Fumarate 8.00
2. HPMCK100M 70.00
HPMCK4M 55.00
4. Lactose Anhydrous 57.00
5. Microcrystalline cellulose 105.00
6. Colloidal Anhydrous silica 2.00
Lubrication
7. Magnesium Stearate 3.00
Theoretical weight of core tablet 300.00
Coating
8. Opadry Blue 15.00
9. P. water Q.S.
Theoretical weight of coted tablet 315.00

There was no pre-drying of pharmaceutical excipients carried out while formulating example 1.
Manufacturing procedure:
1. Sifting: sift the Fesoterodine fumarate. HPMC K100M, HPMC K4M, Lactose Anhydrous, Microcrystalline cellulose, Colloidal Anhydrous silica through appropriate mesh.
2. Blending: blend the contents obtained in step no 1.
3. Lubrication: lubricate the blend obtained in step no 2 with sifted magnesium stearate.
4. Compression: compress the blend obtained in step no 3 to obtain tablet dosage form.
5. Coating: disperse the Opadry Blue in purified water and coat the tablets obtained in step 4.
Example 2:
Example 2 was formulated with same composition as for example 1; with an exception that pre-dried excipients were used in the composition.
Manufacturing process:
1. Sifting: sift the Fesoterodine fumarate through appropriate mesh.
2. Sift HPMC K100M, HPMC K4M, Lactose Anhydrous, Microcrystalline cellulose. Colloidal Anhydrous silica through appropriate mesh and pre-dry all the pharmaceutical excipients till the LOD is below 2% w/w.
3. Blending: blend The contents obtained in step no I and step 2.
4. Lubrication: lubricate the blend obtained in step no 3 with sifted magnesium stearate.
5. Compression: compress the blend obtained in step no 4 to obtain tablet dosage form.
6. Coating: disperse the Opadry Blue in purified water and coat the tablets obtained in step 5.

Example 3-5:
Examples 3-5 were formulated with composition according to the below table:

Example 3 Example 4 Example 5 j
Sr
.N
0. Objective With single SYLOID^FP instead of colloidal anhydrous silica With 2 grades of SYLOID®FP; LOD of Blend < 2.0% & Non Aqueous coating With 2grades of SYLOlD® FP; LOD of Blend < 2.0% & Aqueous coating

Ingredients (mg/tab)

Dry Mixing
1 Fesoterodine Fumarate 8.00 8.00 8.00
2 Syloid® FP - 4.50 4.50
3 HPMCK100M 50.00 40.00 40.00
4 HPMC K4M 80.00 80.00 80.00
5 Lactose anhydrous 57.00 57,00 57.00
6 Microcrystalline Cellulose 100.00 103.00 103.00
7 Syloid®FP 4.50 4.50 4.50
Lubrication
8 Magnesium stearate 3.00 3.00 3.00
Theoretical weight of core tablet 302.50 300.00 300.00
Coating
9 Opadry Blue 9.00 - 15.00
10 P.Water Q.S. - Q.S.
11 Instamoistshield Blue - 15.00 -
12 Isoprpopyl alcohol - Q.S. -
13 Dichoromethane - Q.S. -
Theoretical weight of coated tablet 3)1.50 315.00 315.00

Manufacturing procedure:
1. Sifting: sift Fesoterodine fumarate using appropriate mesh.
2. Sift the excipients through appropriate mesh and dry excipients till the LOD is below 2% w/w.
3. Blending: blend the contents obtained in step no 1 and step no 2.
4. Lubrication: lubricate the blend obtained in step no 3 with sifted magnesium stearate.
5. Compression: compress the blend obtained in step no 4 to obtain tablet dosage form.
6. Film-coaling: Prepare the film-coating composition and coat the tablets obtained in step no 5.
Stability results: The accelerated stability study of the above examples 1 - 5 were carried out at 40°C / 75%RH for 3 months. The stability results obtained are as below:

Time
period Impurity A Impurity C Total impurity Assay of Fesoterodine fumarate Inference
Example 1 * Initial 0.087% ND 0.179% NP Pails

3 months 1.388% 1.338% 3.337% NP

Example 2* Initial 0.073% ND 0.171% NP Fails

3 months 0.759% 0.761% 1.927% NP

Example 3* Initial 0.234% 0.063% 0.391% 98.90% Passes

3 months 0.572% 0.410% 1.127% 99.70%

Example 4* Initial 0.100% 0.027% 0.239% 100.90% Passes

3 months 0.522% 0.335% 1.111% 100.10%

Example 5* Initial 0. i 00% 0.021% 0.218% 99.20% Passes

3 months 0.416% 0.307% 0.902% 100.00%

* Packaging: II DPI7, bottle with molecular sieve
NP- No! performed as sample fails in other parameters
Limit of Impurity A: 0.625% w/w

Limit of impurity C: 0.625% vv/w Limit of total impurity: 2%w/w
Examples 6-8:
Examples 6-8 were formulated with composition according to the below table:

Example 6 Example 7 Example 8

Ingredients (mg/tab)
Dry Mixing
1 Fesoterodine Fumarate 8.00 8.00 8.00
2 Syloid® 63 FP 4.50 4.50 4.50
Hypromellose 2208 (100000 mpa.s) 100.0 32.5 32.5
4 Hypromellose 2208 (4000 mpa.s) - 65.0 65.0
5 Lactose anhydrous 70.0 67.0 67.0
6 Microcrystalline Cellulose 110.0 115.5 115.5
7 Syloid* 244 FP 4.50 4.50 4.50
Lubrication
8 Magnesium stearate 3.00 3.00 3.00
Theoretical weight of core tablet 300.00 300.00 300.00
Coating
9 Opadry Blue 15.0 - 15.00
10 P.Water Q.S. - Q.S.
11 Instamoistshield Blue - 15.00 -
12 Isoprpopyl alcohol - Q.S. -
13 Dichoromethane - Q.S. -
Theor tablet etical weight of coated 315.00 315.00 315.00

Manufacturing procedure:
1. Sifting: sift Fesoterodine fumarate using appropriate mesh.
2. Sift the excipients through appropriate mesh and dry excipients till the LOD is below 2% w/w.
3. Blending; blend the contents obtained in step no 1 and step no 2.
4. Lubrication: lubricate the blend obtained in step no 3 with sifted magnesium stearate.
5. Compression: compress the blend obtained in step no 4 to obtain tablet dosage form,
6. Film-coating: Prepare the film-coating composition and coat the tablets obtained in step no 5.
Stability results: The accelerated stability study of the above examples 6 - 8
were carried out at 40°C / 75%RH for 3 months. The stability results obtained are as below:

Time period Impurity A Impurity C Total impurity Assay of
Fesoterodine
funiarate inference
Example 6* Initial 0.132% 0.032% 0.213% 101.4% Passes

3 months 0.479% 0.32% 1.098% 96.3%

Example
7* Initial 0.164% 0.074% 0.349% 99.7% Passes

3 months 0.415% 0.346% 0.944% 99.5%

Example 8* Initial 0.174% 0.081% 0.363% 100.8% Passes

3 months 0.553% 0.415% 1.146% 99.6%

* Packaging: HDPE bottle with molecular sieve Limit of Impurity A: 0.625% w/w Limit of Impurity C: 0.625% w/w Limit of total impurity: 2% w/w
Example 9: Composition of example 9 was qualitatively and quantitatively same as of example 7 except process for preparation of the composition. Process for

preparation of example 9 does not involve step of pre-drying of excipients. Composition of example 9 was prepared by process given below,
Manufacturing procedure for example 9:
1. Sifting: sift Fesoterodine fumarate using appropriate mesh.
2. Sift the excipients through appropriate mesh
3. Blending: blend the contents obtained in step no 1 and step no 2.
4. Lubrication: lubricate the blend obtained in step no 3 with sifted magnesium stearate.
5. Compression: compress the blend obtained in step no 4 to obtain tablet dosage form.
6. Film-coating: Prepare the film-coating composition and coat the tablets obtained in step no 5.
Stability results: The accelerated stability study of the above example 9 was carried out at 40°C / 75%RH for 3 months. The result obtained of the stability study was compared with results of stability study of example 7; the same is given below.

Time period Impurity A Impurity C Total
impurity Assay of
Fesoterodine
fumarate Inference
Example 7* Initial 0.164% 0.074% 0.349% 99.7% Passes

3 months 0.415% 0.346% 0.944% 99.5%

Example 9* Initial 0.159% 0.026% 0.262% 99.6% Fails

3 months 0.943% 0.41% 1.866% 98.7%

* Packaging: HDPE bottle with molecular sieve Limit of Impurity A: 0.625% wAv Limit of Impurity C: 0.625% wAv Limit of total impurity: 2% wAv

In example 1. the amount of impurity after 3 month accelerated stability study at 40°C / 75%RH indicates that the composition is not stable. In example 2, the amount of impurity after 3 month accelerated si ability study at 40°C / 75%RH indicates that the pre-drying of excipients control total impurity levels but fails to control individual impurity A and impurity C.
In examples 3-8, the amount of impurity after 3 month accelerated stability study at 40°C / 75%RH indicates that the pre-drying of excipients and use of amorphous hydrated silicon dioxide, control total impurity level and individual impurity levels of impurity A and impurity C; and render the pharmaceutical composition of Fesoterodine fumarate stable. Thus, stable pharmaceutical composition comprising Fesoterodine or a pharmaceutically acceptable salt thereof can be prepared by using pre-dried excipients and amorphous hydrated silicon dioxide (product marketed as SYL01D® FP) by the process described herein in the invention.
In example 9 wherein the process for preparation of composition does not comprise step of pre-drying, the amount of impurity after 3 month accelerated stability study at 40°C / 75%RH indicates that the amount of impurity A is much higher than the composition of example 7.

We claim.
1. A stable pharmaceutical composition comprising Fesoterodine or pharmaceutically acceptable salt thereof and other pharmaceutically suitable excipients; wherein the composition is devoid of sugar alcohol.
2. A stable pharmaceutical composition comprising Fesoterodine or pharmaceutically acceptable salt thereof, amorphous hydrated silicon dioxide. and other pharmaceutically suitable excipients; wherein the composition is devoid of sugar alcohol.

3. The stable pharmaceutical composition according to claim 1 or 2. wherein the composition comprises pre-dried excipients.
4. The stable pharmaceutical composition according to claim 1 or 2, wherein the process for preparation of a stable pharmaceutical composition comprising step of pre-drying of excipients.
5. The stable pharmaceutical composition according to claim 1 or 2, wherein the total impurity in the said pharmaceutical composition is not more than 2% w/w after subjecting the said pharmaceutical composition to a storage condition of 40°C / 75% RH for a period of 3 month.
6. The stable pharmaceutical composition according to claim 1 or 2, wherein the total impurity in the said composition is not more than 2% w/w, impurity A and impurity C are not present in an amount more than 0.625% w/w individually;

after subjecting the said pharmaceutical composition to a storage condition of 40°C / 75% RH for a period of 3 month.
7. A process for preparation of a stable pharmaceutical composition comprising
Fesoterodine or pharmaceutical!}' acceptable salt thereof comprising the steps of:
a) sifting of Fesoterodine or pharmaceutically acceptable salt thereof through
appropriate mess,
b) sifting of pharmaceutically suitable excipients through appropriate mesh and drying of the excipients till the LOD is below 2% w/w,
c) blending of materia! obtained in step a and step b.
d) compressing the blend obtained in step c to obtain the stable pharmaceutical composition and optionally,
e) coating the composition obtained in step d.
8. A stable pharmaceutical composition comprising Fesoterodine or
pharmaceutical!}' acceptable salt thereof, amorphous hydrated silicon dioxide and
other suitable pharmaceutically acceptable excipients. wherein the composition is
devoid of sugar alcohol; and process for preparation of the stable pharmaceutical
composition comprises of step of pre-drying of excipients.
9. The stable pharmaceutical composition according to claim 8, wherein the total
impurity in the said pharmaceutical composition is not more than 2% w/w after
subjecting the said pharmaceutical composition to a storage condition of 40oC /
75% RH for a period of 3 month.
10. The stable pharmaceutical composition according to claim 8. wherein the
total impurity in the said composition is not more than 2% w/w, impurity A and

impurity C are not present in an amount more than 0.625% w/w individually; after subjecting the said pharmaceutical composition to a storage condition of 40°C / 75% RH for a period of 3 month.