FORM-2
THE PATENTS ACT, 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION Sec 10-Rule 13
"A Novel Pharmaceutical Composition of Linezoiid."
INDOCO REMEDIES LIMITED
Indian
R-92-93, T.T.C Industrial Area, Thane Belapur Road, Rabale MIDC
Navi Mumbai-400701
The following specification describes the invention.

Technical Field:
The present invention relates to a novel pharmaceutical composition of Linezolid. More particularly, the present invention relates to a novel pharmaceutical composition of Linezolid form III, Soy Polysaccharide as a disintegrant along with pharmaceutically acceptable excipients.
Background & Prior Art:
Linezolid is a synthetic antibiotic used for the treatment of serious infections caused by Gram-positive bacteria that are resistant to several other antibiotics. The empirical formula is C16H20FN3O4. Its molecular weight is 337.35, and its chemical structure is represented below:

The main indication of linezolid is the treatment of severe infections caused by Gram-positive bacteria that are resistant to other antibiotics; it should not be used against bacteria that are sensitive to drugs with a narrower spectrum of activity, such as penicillins and cephalosporins. In both, the popular press and the scientific literature, linezolid has been called a "reserve antibiotic"one that should be used sparingly so that it will remain effective as a drug of last resort against potentially intractable infections.
Linezolid Form III, was discovered and described in U.S. patent no. 7,714,128. The crystalline form III was characterized by an x-ray powder diffraction spectrum having peaks expressed as 29 at about 7.6, 9.6, 13.6, 14.9, 18.2, 18.9, 21.2, 22.3, 25.6, 26.9, 27.9 and 29.9 degrees.

WO2012029074 discloses pharmaceutical composition of Linezolid Form III, polacrilin potassium as disintegrant and hydroxypropylmethyl cellulose as binder along with pharmaceutically acceptable ingredients, prepared by dry granulation, wherein the composition retains linezolid in its original crystalline form.
US20070104785 discloses pharmaceutical dosage of Linezolid Form III, water-insoluble polymer or colloidal silicon dioxide or clay or carbon dioxide source as means to reduce the gelling tendency of linezolid along with pharmaceutically acceptable excipeints. However, there still persists the problem of erratic dissolution of the linezolid from the dosage form.
WO2010026597 discloses a multiparticulate composition comprising a core in the form of beadlet or pellet, manufacture by extrusion and spheronization method, the core comprises Linezolid form III, one or more binders, and one or more disintegrants. Both processes require either special material or equipment which are not desirable for commercial production.
WO2007102082 assigned to Glenmark Pharmaceuticals Ltd discloses compositions of Linezolid crystalline Form II containing lactose-based water soluble excipient.
Linezolid Form III exhibits a gelling tendency when it comes into contact with water, which eventually leads to erratic dissolution of the Linezolid from the dosage form. Hence, there is a need to develop solid dosage forms of Linezolid Form III, which provides consistent dissolution profile.
The inventors of the present invention have used Soy Polysaccharides which exhibits excellent disintegration and improved dissolution characteristics of Linezolid Form III i.e. significantly reduces gelling tendency of Linezolid Form III. Its use in soluble systems has evidenced fast and efficient disintegration of oral dosage forms prepared with a varying range of hardness values.

Soy Polysaccharides is an all-natural, soft white to light-tan powder, which does not contain starch or sugar. It is derived from dehulled and defatted soybean flakes by a special process.
Object of the Invention:
An object of the present invention is to provide a novel pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients.
Another object of the present invention is to provide a novel pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients, wherein gelling tendency of Linezolid Form III is reduced and it retains its polymorphic form over the period of stability.
Another object of the present invention is to provide a novel pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients, which exhibits a complete and consistent dissolution profile.
Yet another object of the present invention is to provide a process for preparing a novel pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients.
Further object of the present invention is to provide a stable pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients.

Further object of the present invention is to provide a stable solid dosage form comprising Linezolid Form III, Soy Polysaccharide as a disintegrant to reduce gelling tendency of Linezolid Form III and one or more pharmaceutically acceptable excipients.
Still further object of the present invention is to provide a novel pharmaceutical composition for oral administration of Linezolid Form III for treating severe infections caused by Gram-positive bacteria.
Summary of the Invention:
The present invention provides a stable pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients and method of preparing the same, wherein the composition retains Linezolid in its crystalline Form III.
The present invention provides a method of preparing stable pharmaceutical composition comprising Line2olid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients.
Description of the Invention:
The present invention provides a novel stable pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients.
In particular, the present invention provides a stable, immediate release solid oral pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant along with pharmaceutically acceptable excipients and a method of preparing the same.

In accordance with the present invention, methods of preparing pharmaceutical composition employed are wet granulation, dry granulation and direct compression, preferably dry granulation.
In one embodiment, method of preparing pharmaceutical composition is by dry granulation. Method of manufacturing by dry granulation includes mixing of Linezolid with one or more pharmaceutically acceptable excipients, further compaction followed by milling, sieving and addition of pharmaceutically acceptable excipients, lubrication, compression and coating.
In one embodiment, dry granulation can be performed by roller compaction.
In one embodiment, dry granulation can be performed by slugging.
In one embodiment, the present invention involves dry granulating Linezolid Form III with Soy Polysaccharides as disintegrant, hydroxypropyl cellulose as a binder with one or more pharmaceutically acceptable excipients to develop a novel formulation without polymorphic form conversion.
In preferred embodiment, the present invention involves dry granulation of Linezolid Form III with Soy Polysaccharides as disintegrant with one or more pharmaceutically acceptable excipients to develop a stable formulation without polymorphic form conversion.
In one embodiment, the present invention is to provide a novel pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant, . Hydroxypropyl cellulose as binder and optionally one or more additional excipients.

According to another embodiment, method of preparing pharmaceutical composition is by wet granulation. Method of manufacturing by wet granulation includes dry mixing of Linezolid Form III in a therapeutically effective amount with other pharmaceutically acceptable excipients, then granulation, drying, milling, addition of extra-granular excipients, lubrication, compression of the lubricated blend into tablets and coating of the compressed tablets.
In one embodiment, the present invention involves wet granulating Linezolid Form III using non aqueous solvents, Soy Polysaccharides as disintegrant, hydroxypropyl cellulose as binder and one or more pharmaceutically acceptable excipients to develop a novel formulation without polymorphic form conversion.
According to another embodiment, method of preparing pharmaceutical composition is by direct compression. Method of manufacturing by direct compression includes mixing of Linezolid Form III with pharmaceutically acceptable excipients, lubrication, compression and then coating.
In accordance with the present invention pharmaceutical composition comprises linezolid and one or more diluents, binders, lubricants, glidants, disintegrants and coating agents.
The one or more diluents may be selected from mannitol, sorbitol, xylitol, lactose monohydrate, microcrystalline cellulose, light magnesium carbonate, dicalcium phosphate, tribasic calcium phosphate, calcium sulphate or mixtures thereof.
The one or more binders may be selected from hydroxypropyl methylcellulose, povidone (polyvinylpyrrolidone K-30), hydroxypropyl cellulose, maize starch or mixtures thereof.
The one or more lubricants may be selected from magnesium stearate, zinc stearate, calcium stearate, sodium stearyl fumarate, stearic acid or mixtures thereof.

Optionally colloidal anhydrous silica is used as glidant.
The one or more disintegrants may be selected from sodium starch glycolate, croscarmellose sodium, soy polysaccharide and cross-linked polyvinyl pyrrolidone, calcium carboxymethylcellulose or mixtures thereof. Preferred disintegrant used in the present invention is Soy Polysaccharide.
Opadry White is used as coating agent.
In accordance to the present invention, the pharmaceutical composition contains in parts by weight from about 60% to 90% Linezolid Form III, from about 1% to 20% diluent, from about 0.5 % to 15% binder, from about 0.1% to 10% disintegrant, from about 1% to 3% lubricant.
In accordance with the present invention, Linezolid Form III is up to 90% by weight of solid dosage form.
In one embodiment, the pharmaceutical composition is in the form of solid oral dosage form.
In one embodiment, the pharmaceutical composition is in the form of tablet. The tablet is coated with coating agent. The coating is for aesthetic purpose and provides good appearance to the final dosage form.
In accordance with the present invention, the solid dosage form releases more than 90% of Linezolid in 45 minutes.
In accordance with the present invention, pharmaceutical composition manufactured with dry granulation process with compaction approach showed less gelling tendency in dissolution medium.

Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to person skilled in the art upon reference to the description. It is therefore contemplated that such modifications can be made without departing from spirit or scope of the present invention as defined. The invention is further exemplified with following examples and is not intended to limit the scope of the invention.
Examples: Example 1.

Example mg

A B C D
Intragranular
Linezolid 600 600 600 600
Maize starch 40 40 20 20
Microcrystalline cellulose 44 44 113 113
Soy Polysaccharide 18.8 - - _
Sodium starch glycolate . 12 12 -
Croscarmellose sodium - - - 12
Hydroxypropyl cellulose 12 12 12 12
Magnesium stearate 4.2 4.2 4.2 4.2
Extragranular
Microcrystalline cellulose 76.8 93.6 44.60 44.60
Soy Polysaccharide 40 - - -
Sodium starch glycolate - 30 30 -
Croscarmellose sodium - - - 30
Lubrication
Magnesium stearate 4.2 4.2 4.2 4.2
Theoretical weight of core tablets 840 840 840 840
Opadry white 25.20 25.20 25.20 25.20
Purified water qs qs qs qs
Theoretical weight of Coated tablets. 865.20 865.20 865.20 865.20

Manufacturing process:
1. Linezolid was sifted through ASTM # 24 mesh.
2. Maize starch, Microcrystalline cellulose and disintegrant were sifted through
ASTM # 40 mesh and dry mixed with step 1 and blended for sufficient time.
3. Magnesium stearate was sifted through ASTM # 40 mesh and added into step 2
and was mixed for sufficient time.
4. The blend of step 3 was used to form compacts of sufficient hardness using
Roller compactor.
5. The compacts of step 4 were milled using multi mill screen of 2mm and were
passed through ASTM #16 mesh.
6. Microcrystalline cellulose and disintegrant were sifted through ASTM # 40 mesh and loaded into blender of suitable size and were mixed with sized granules of step 5.
7. Magnesium stearate was sifted through ASTM # 40 mesh and added to step 6 and mixed for sufficient time.

8. Lubricated blend of step 7 was compressed into tablets.
9. Compressed tablets of step 7 were coated with Opadry white till weight gain of 3% was achieved.

Dissolution Data:

Time in minutes Example 1A (40°C/75%RH Condition.)

Initial 1 Month 3 Months 6 Months
0 0 0 0 0
5 78 79 77 78
10 84 84 88 85
15 87 88 89 89
20 88 90 90 89
30 90 91 91 91
45 94 93 93 91
The dissolution was more than 90% in 45 minutes for the tablets of example 1A containing Soy Polysaccharide as disintegrant with reduced gelling tendency.
The crystallinity of polymorph is determined by using X-ray powder diffraction (XRD) at initial as well as stability stages.
Brief Description of Drawings:
Figure 1: Overlay XRD diffractograms of the Linezolid Form III pharmaceutical
composition at 40° C / 75 RH.
Figure 2: XRD diffractogram of the Linezolid Form III.
Figure 3: XRD diffractogram of the Linezolid Form II.
Figure 4: Dissolution Profile.

Description of Drawings:
Figure 1 depicts polymorphic content of pharmaceutical composition 1A which was determined by X-ray powder diffraction for Initial, 1,2,3 and 6 months respectively.
- The symbol denotes XRD diffractogram for Initial period.
- The symbol denotes XRD diffractogram for 1 month.
- The symbol denotes XRD diffractogram for 2 months.
- The symbol denotes XRD diffractogram for 3 months.
- The symbol denotes XRD diffractogram for 6 months.
Characteristic peaks at reflection angle 28 (theta) values of Linezolid Form III viz. 7.038. 9.292, 13.439, 18.39, 18.657. 22.112 did not change for Initial, 1, 2, 3 and 6 months respectively.
Figure 2 depicts Standard XRD diffractogram of Linezolid Form III. Figure 3 depicts Standard XRD diffractogram of the Linezolid Form II.

We Claim:
1. A stable pharmaceutical composition comprising Linezolid Form III, Soy Polysaccharide as disintegrant and pharmaceutically acceptable excipients.
2. The pharmaceutical composition of claim 1, wherein the gelling tendency of Linezolid Form III is reduced and it retains its polymorphic form.
3. The pharmaceutical composition of claim 1, prepared by dry granulation.
4. The pharmaceutical composition of claim 1, wherein the pharmaceutical composition is in the form of a solid dosage form.
5. The pharmaceutical composition of claim 1, wherein the solid dosage form is coated.
6. The pharmaceutical composition of claim 5, wherein the Linezolid Form III is up to 90% by weight of solid dosage form.
7. The pharmaceutical composition of claim 1, wherein the solid dosage form releases more than 90% of Linezolid in 45 minutes.
8. The pharmaceutical composition as claimed in claim 1, wherein the pharmaceutical ly acceptable excipients comprises one or more of diluents, binders, lubricants, glidants, disintegrants and coating agents.