FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION:
"INJECTABLE COMPOSITION OF STABLE PACLITAXEL MICROEMULSION
2. APPLICANT:
(a) NAME: MAC CHEM PRODUCTS INDIA PVT. LTD.
(b) NATIONALITY: Indian Company incorporated under the Indian Companies ACT, 1956
(c) ADDRESS: 304, Town Centre, Andheri-Kurla Road, Andheri (East), Mumbai-400059, Maharashtra, India


3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.


Technical Field:
The present invention relates to the composition of a stable microemulsion injection comprising anti-cancer drug, paclitaxel. More particularly, the invention relates to an intravenous and intramuscular administrable composition having excellent anti-cancer effect comprising paclitaxel in association with suitable solubilizer, emulsifier, chelating agent and stabilizer to improve the solubility and, stability of paclitaxel at room temperature and therefore the bioavailability. Further, the invention relates to a stable formulation with simple and rapid manufacturing process.
The injectable composition of paclitaxel is not only showing a lower toxicity but also superior solubility of paclitaxel and stability at room temperature, thus enable venous and muscular injection by having fine nano particles. The composition has designed with a particle size of around 20nm, suitable for intravenous and intramuscular administration and the composition is very stable when stored at room temperature till 24 hours and does not cause any adverse effect of emulsifier.
Background and prior art:
Paclitaxel is a mitotic inhibitor used in cancer chemotherapy. Paclitaxel is now used as to treat patients with lung, ovarian, breast cancer, head and neck cancer, and advanced form of Kaposi's sarcome. Paclitaxel works by interfering with normal microtubule breakdown during cell division.
Whereas drugs like colchicines cause the depolimerization of microtubule, paclitaxel arrest their function by having the opposite effect to hyper stabilize their structure. This destroys the cell's ability to use its cycloskeleton in a flexible manner. Specifically, paclitaxel binds to the β sub unit of tubulin
Further, research induces programmed cell death (apoptosis) in cancer cells by binding to an apoptosis stopping protein called Bcl-2 (B-cell leukemia 2) and thus arrest its function. The paclitaxel injection composed in Chinese patent no. CH 1969818, which describes an anti cancer slow release injection containing Epothione derivatives which comprises slow release microspheres and dissolvent, the slow
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release microblloons includes paclitaxel, alkyl agent and plant alkaloids, epothilone derivatives and slow release auxiliary materials.
An injectable composition for the treatment of cancers, comprising a poorly water soluble anticancer drug paclitaxel and glucofurol and solutol HS 15 as Solubilizer of anti cancer drug has been described in WO2005/097105 Al.
A sub microemuision injection of polyene taxol with a certain target performance and low poison is prepared from polyne taxol, the oil for injection, emulsifier, stabilizer, isotonic regulator, pH regulator, and emulsifying aid and its preparing process are disclosed in Chinese patent no. CN 100998559 and water type injection containing paclitaxel and its preparation with C02 for improving the stability of taxol are described in Chinese patent no. CNI00998557-.
US 7115565 describes Chemotherapeutic microemuision compositions of paclitaxel with improved oral bioavailability Pharmaceutical compositions suitable for oral administration comprising paclitaxel, a solvent, a surfactant (solutol HS 15), a substituted cellulosic polymer, and optionally but preferably a P-glycoprotein inhibitor.
WO/2002/064132 describes chemotherapeutical microemuision compositions of paclitaxel with improved oral bioavailability.
The composition of intravenous injection emulsion of paclitaxel and Chinese medicinal volatile oil and its preparing process, wherein, the emulsion also comprises emulsifying agent, osmoregulation agent, tocopherol, pH regulator and water are described in Chinese patent no CN 1919190.
Patent no. KR 20050001903 describes the composition of paclitaxel injection which has high solubility of drugs and extended storage as well as improved cell membrane permeability and excellent anti cancer efficacy.
The paclitaxel injection consists of paclitaxel 0.01-2%,(w/v), stabilizer l-70%(w/v), and the remainder is solvent for injection, wherein the stabilizer is selected from
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soyabean phospholipid, yolk phospholipid, tween-80, cholesterol, sodium cholate, poloxamer 188, monoolein has been described in patent no WO2007009355.
Paciitaxel injection composition having ultra fine particle shape prepared by mixing paciitaxel, solid lipid and stabilizer at room temperature to improve Solubilizing property and stable paciitaxel are described in patent no. KR100446959B.
Patent no KR20050001903 describes the composition of paciitaxel injection comprising 0.0001-10 wt.% of paciitaxel, 30-49.999 wt.% of Solubilizing agent selected from (oxyethylene) sorbitol (olate)m or (oxyethylene)l and sorbitol sorbitan (oJate)m, wherein I is an integer of 15-60 and m is an integer of 1-4, 0.0001-30 wt.% of cell membrane permeability-improving agent selected from conjugated Iinoleic acid phosphatidyl choline and docosahexaenoic acid phosphatidyl choline, and 30-49.999 wt.% of anhydrous alcohol selected from anhydrous ethanol, anhydrous isopropylalcohol, anhydrous-n-propylalcohol and t-butylalcohol.
A Chinese patent CN 1754535 provides a category of Paclitaxel-containing slow release micro-balloons for local injection, which can be used for the local treatment of tumor tissues and focus positions. The micro-balloons comprise Paciitaxel 0.2-40wt% of the micro-balloon and biocompatible medicinal macromolecular adjuvant 50-99.8 wt% of micro-balloons having a molecular weight of 5000-70000 Daltons. The actuation duration of the medicament can be extended.
Chinese patent no. CN1634021 disclosed a novel paciitaxel emulsion for intravenous injection and its preparation method which consists of, dissolving new alcohol with oil for injection and preparing emulsion from medicinal adjuvant.
The paciitaxel composition for injection with improved stability has been described in KR 200000611112 and KR 20000061 111.
The pharmaceutical composition comprises an effective amount of paciitaxel, a polyoxymethylated ricinus oil, an alcohol and an aqueous solution for injection and is added with a sufficient amount of CO2in the composition are described in JP2006143699( Paciitaxel aqueous injection and method for preparing the same)
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A pharmaceutical composition of paclitaxel comprising polyethoxylated castor oil and an acid is disclosed to be relatively acidified to a pH of than 8.1 and preferably within a pH range of 5 to 7, inclusively. Ethanol is optionally included in the formulation which is adapted for use in a body for the treatment of cancer, a cancer formulation method is disclosed in US Patent Application US 2003/0065022 Al, US 6306894, US 6770670 and patent no 6306894, 5733888.
The injectable composition of paclitaxel comprising paclitaxel, solubilizer, stabilizer and anhydrous ethanol, wherein the solubilizer is polyoxyl hydrogenated castor oil or poloxamer and wherein the stabilizer is ethanamine, arginine, lysine or N- acetyl amino acid are disclosed in US Patent Application US 2005/0026995 Al, EP0674510B1, US 7186751, WO2003/022247A1 and AU2002/330328A1.
The long term storage stability of injectable pharmaceutical compositions comprising paclitaxel or taxoid is improved by incorporating an effective amount of an anti¬oxidant.
An injectable pharmaceutical composition for human administration comprising a homogenous solution of a taxoid, a solubihzing dispersing agent and anti oxidant is described in Patent no. 6071952.
A pharmaceutical composition in a form of a self microemulsifying drug delivery system comprising one or more taxoids (paclitaxel), vitamin-E, one or more co-solvents selected from propylene glycol and ethanol, bile salts, TPGS and tyloxapol is described in EP 1480636 Bl and the self nano-emulsifying oily formulation for the administration of poorly water soluble drugs is described in US 2006/0292186, AU 2003/214538 Al, WO2003/074027A2, WO2003/074027A3R4 and WO 2003/074027 A3R5.
A process for producing a sterile lyophilized powder consisting of nanoparticles of paclitaxel and human serum albumin having antitumor properties, wherein the lyophilized powder is obtained by adding paclitaxel in powder form to an aqueous solution of albumin with chloroform followed by subjecting to high pressure
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homogenization treatment is described in US Patent Application US2003/0185894 Al and US 2006/0121119 Al.
A paclitaxel composition and the preparation methods thereof for the treatment of bladder cancer wherein the paclitaxel composition comprising of at least one mono glycerides, one oil and one emulsifier with paclitaxel is described in WO 2004/009076 A1
A stable injection paclitaxel formulation having polyoxyethylene sorbitol oleic polyester as main solubilizer, and appears to have less toxicity and greater stability compared to polyethoxylated castor oil- containing formulation. The formulation includes paclitaxel, povidone, oxyethylene sorbitol oleate, (oxyethylene glycol) 15-20 fatty acid monoester, polyethylene glycol and anhydrous glycol and anhydrous alcohol is described in US 6046230.
Patent application no WO 2005/097105 Al disclosed injectable composition for the treatment of cancers comprising a poorly water- soluble paclitaxel drug, and glycofurol and solutol HS15 as solubilizer of the anti-cancer drug.
A formulation containing nanoparticles of polymeric micelles containing a drug selected from paclitaxel, a derivative or the analogs, an alcohol, a co-polymer, an anionic surfactant, a buffering agent and an intravenous aqueous diluting fluid are described in Patent no 6365191.
The present invention relates to the paclitaxel mixed composition and water in oil type emulsion formulation for chemoembolization and preparation method thereof. The combinatory formulation of anticancer drugs can be easily prepared since the emulsion formulation of the present invention can include other hydrophilic or hydrophobic drugs are disclosed in WO 2003/122264 Al and CN01823631 A.
Many such compositions containing paclitaxel are known but are not stable for long periods of time, US5504102 is directed to a stabilized formulation of paclitaxel that contains Cremophor EL, a condensation product of castor oil and ethylene oxide sold by BASF. US5733888 discloses another stabilized paclitaxel formulation that
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contains Cremophor EL. However, Cremophor EL has been implicated in causing anaphylactic reactions in some patients. Additionally, when such Cremophor EL containing formulations are admixed with aqueous parenteral infusion fluids such as 0.9% saline, the admixture is stable without precipitation for a short period of time.
However there is no formulation or composition for paclitaxel in particular, in microemulsion injection without any adverse effect of emulsifier. Moreover, paclitaxel is very poorly soluble in water and also physically unstable. In addition, conventional paclitaxel formulations have many problems in terms of poor stability of anticancer drugs and high toxicity of solubilizer used. Thus, a number of studies regarding these problems of paclitaxel are now being actively undertaken.
Stabilization of emulsion is also one of the most important criteria, as there are no chances of separation after mixing. To solve these problems, much research is being actively conducted.
Therefore, in view of the above problems, the present invention has been directed to provide an injectable microemulsion formulation useful for the treatment of cancer comprising poorly water soluble anti cancer drug which allows the anti cancer drug to exhibit improved solubility as well as greatly reduced toxicity.
Objectives of the Invention:
An objective of the present invention is to provide commercially stable, micro emulsion for intravenous and intramuscular administration of anti cancerous drug comprising paclitaxel along with pharmaceutically acceptable excipients which overcomes the difficulties that paclitaxel has such as very low solubility (about 30μg/ml) in water and physical instability.
It is another object of this invention to provide a microemulsion paclitaxel injection formulation for intravenous and intramuscular administration which has improved stability and also less toxicity compared to the presently known paclitaxel injection formulation containing polyethoxylated castor oil as a Solubilizer for the paclitaxel.
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Summary of the invention:
In accordance with the above objective, the present invention provides stable microemulsion injectable composition of anti cancer drug, paclitaxel for painless intravenous and intramuscular administration with suitable excipients like appropriate solubilizer, compatible pH stabilizer, and chelating agent which are very safe and improve the dissolution of poorly soluble drug paclitaxel using simple and rapid manufacturing process.
In one aspect, the present invention discloses novel composition, which is capable of
providing an efficient formulation of microemulsion injection of paclitaxel for
painless intramuscular and intravenous delivery.
As it is microemulsion particle is in nano size and easily filterable.
Due to nano particle size suitable for Intravenous and Intramuscular administration
and provides painless drug delivery.
It is an aspect of the invention to provide a microemulsion paclitaxel injection
formulation for intravenous and intramuscular administration devoid of
polyethoxylated castor oil (cremopho EL) as a solubilizer, which has improved
stability and also less toxicity compared to the presently known paclitaxel injection
formulation.
Detailed Description of invention:
The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.
Accordingly, the present invention describes an improved microemulsion formulation comprising paclitaxel, which has good stability and maintain solubility for an extended period of time in microemulsion form.
Extensive efforts have been taken by the inventors to develop an improved paclitaxel formulation by completely solubilizing poorly soluble paclitaxel thus forming
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microemulsion for painless delivery of administration as compared to presently known formulation by simple and rapid manufacturing process.
As the result of this efforts, it has been determined that the solutol HS 15 is advantageous in the view of toxicity and also the stability when compared to ethylene oxide adduct of castor oil; and also results in nano size particle formulation of microemulsion thereby facilitates the intramuscular and intravenous administration devoid of pain..
The injectable composition of the present invention advantageously utilizes selective solubilizer for improving the water solubility of the anti cancer drug. According to the present invention, the aqueous glucitol solution is used as a solution adjuvant, and the solutol HS 15 (polyethylene660 12-hydroxystearate) is used as a surfactant/solub il izer.
Aqueous glucitol is obsolete name for sorbitol, one of the fruit alcohols, has no toxicity and is highly suitable for the solubilization of poorly soluble paclitaxel, is commercially available.
The solutol HS 15 is a surfactant manufactured by BASF Corporation under the brand name of solutol HS 15, chemically known as polyethylene660 12-hydroxystearate which contains about 30% polyethylene glycol and about 70% polyethylene glycol ester.
The solutol HS 15 is non toxic and plays a roll in effectively solubilizing the poor water-soluble anti cancer drug when used in combination with the aqueous glucitol solution, citrate buffer and disodium EDTA.
Citrate buffer as pH stabilizer and EDTA as complexing agent are used in the present compositions.
The pH of the solution can be adjusted using sodium hydroxide to a pH of 4.5 to 5 Further the, the stable formulation showed less toxicity as compared to known paclitaxel formulation with castor oil.
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Particle size analysis is done on PCS submicron particle size analyzer (BECKMAN COULTER) and the particle size found to be in the range of 20 to 50nm.
The preferred embodiment of the present inventive composition useful in cancer therapy comprising:
a) Paclitaxel in the range of about 0.6%(w/v);
b) polyglycol ester of 12-hydroxystearic acid and Polyethylene glycol(solutolHS15) in the range of 2% (w/v) to 5%(w/v);

c) aquous glucitol solution in the range of about 60-80%(v/v);
d) anhydrous Citric acid in the range of about 0.2%(w/v) to 0.5%(w/v);
e) disodium EDTA in the range of 0.2% and;
f) sodium hydroxide to adjust pH in the range about 4.5 to 5.0±0.2 .
The inventive formulation according to the present invention is prepared by a process, which comprise the following steps:
a) weighing accurate amount of paclitaxel;
b) adding paclitaxel in glucitol with continuous stirring till clear solution obtained;
c) accurately weighing citric acid anhydrous, and disodium EDTA followed by dissolving in above solution obtained step (b);
d) adding and dissolving solutol HS15 to the above solution with continuous stirring;
e) adding NaOH to adjust the pH between 4.5 to 5.0;
f) Making up the volume with water for injection in quantity sufficient and mixing well;
g) checking the final pH of the solution; and
h) filtering the solution through 0.22μ membrane filter.
The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.
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Examples: Example 1:
Formulae with verifying concentration of solutol (I)

Formula EDT A Paclitaxe 1 Citric
acid
anhydrou
s (%) Soluto 1 HS 15
(%) Aqueous
glucitol
solution
(%v/v) Water for
injectio n Sodium
hydroxid
e Observatio n
1 0.2% 0.6% 0.3% 1.0% 50% q.s q.s Hazy
2 0.2% 0.6% 0.3% 2.0% 50% q.s q.s Hazy
3 0.2% 0.6% 0.3% 3.0%o 50% q.s q.s Little
solubility
improved
4 0.2% 0.6% 0.3%) 3.5% 50% q.s q.s Translucent
5 02% 0.6% 03% 4.0% 50% q.s q.s Translucent
6 0.2% 0.6% 0.3% 5.0% 50% q.s q.s Translucent
Example 2:
Formulae 3, 4, 5 further taken for optimization of glucitol concentration (II)

Formula EDT A Paclitaxel Citric
acid
anhydrou
s (%) Solutol HS15
(%) Aqueou s
glucitol solution
(%v/v) Water
for
injection Sodium hydroxide Observation
1 0.2% 0.6% 0.3% 3.0% 60% q.s q.s Translucent
2 0.2% 0.6% 0.3% 3.0% 70% q.s q.s Clear
microemulsion
3 0.2% 0.6% 0.3% 3.5% 60% q.s q.s Translucent
4 0.2% 0.6% 0.3% 3.5% 70% q.s q.s Clear
microemulsio n
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Microemulsion formula 2, and 4 found excellent with respect to description, less time to form microemulsion, and desired particle stability.
Stability Data:

Formula Assay 400C/Month Particlesize Total Impurity pH

0 3 6 0 3 6 0 6 0 3 6
2 100.11 99.76 97.11 10-20 40-20 20-30 0.26 0.32 0.6 4.56 4.62 4.7
4 101.03 98.0 99.10 10-20 40-20 20-30 0.27 0.31 0.5 4.57 4.66 4.68
The stability data of the present invention was found to be stable upto 6 months at 40°C temperature.
No significant change in any of the test specification obtained till accelerated study. Advantages of the present invention:
1. The microemulsion injection is in isotonic form and it is stable till 24 hours room temperature.
2. The formulation reduces or obviates the need for the use of disadvantageous excipients cremophor.
3. By administering to a patient paclitaxel in a vehicle containing a solubilizer other than cremophor, acute hypersensitivity caused by the cremophor can be avoided.
4. Since the particles obtained are in nano size, the painless administration is
achieved.
It will be readily apparent to one skilled in the art that varying substitution and modification may be made to the invention disclosed herein without departing from the scope and spirit of the invention. Thus, it should be understood that although the present invention has been specifically disclosed by preferred embodiments and optional features, modification and variation of the concepts herein disclosed may be restored to by those skilled in the art, and that such modification and variation are considered to be falling within the scope of the invention.
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We Claim,
1. A stable injectable microemulsion composition useful for treatment in cancer
therapy comprising:
a) paclitaxel in an amount of 0.6 to 0.9%w/v;
b) surfactant (solubilizer/stabilizer) in an amount of 2% (w/v) to 5% (w/v);
c) solution adjuvant in an amount of 60-80%(w/v);
d) Chelating agent in an amount of 0.2%
e) pH stabilizer in an amount of 0.2%(w/v) to 0.5%(w/v) and
f) pH adjusting agent

2. The composition as claimed in claim 1, wherein the solubilizer and stabilizer is polyglycol ester of 12-hydroxystearic acid and Polyethylene glycol (solutol HS 15).
3. The composition as claimed in claim 1, wherein the solution adjuvant is aqueous glucitol solution.
4. The composition as claimed in claim 1, wherein the pH stabilizer selected is Citric acid anhydrous buffer.
5. The composition as claimed in claim 1, wherein the complexing agent is disodium EDTA.
6. The composition as claimed in claim 1, wherein the pH adjusting agent is sodium hydroxide.
7. The stable injectable microemulsion composition comprising:
a) Paclitaxel in the range of about 0.6%(w/v);
b) polyglycol ester of 12-hydroxystearic acid and Polyethylene
glycol(solutolHS15) in the range of 2% (w/v) to 5% (w/v);
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c) aquous glucitol solution in the range of about 60-80%(v/v);
d) anhydrous Citric acid in the range of about 0.2%(w/v) to 0.5%(w/v);
e) disodium EDTA in the range of 0.2% and;
f) sodium hydroxide to adjust pH in the range about 4.5 to 5.0±0.2 .
8. A process for preparation of paclitaxel microemulsion injection formulation comprising the steps of:
a) weighing accurate amount of paclitaxel;
b) adding paclitaxel in glucitol with continuous stirring till clear solution
obtained;
c) accurately weighing citric acid anhydrous, and disodium EDTA followed by dissolving in above solution obtained step (b);
d) adding and dissolving solutol HS15 to the above solution with continuous stirring;

e) adding NaOH to adjust the pH between 4.5 to 5.0;
f) making up the volume with water for injection in quantity sufficient and mixing well;
g) checking the pH of the solution; and
h) filtering the solution through 0.22μ membrane filter.
Dated this 2nd day of September 2008

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