The top five biggest patent losses in 2016 are AstraZeneca, Daiichi Sankyo, Merck, Abbott and ViiV.

The top five biggest patent losses in 2016 per holder after AstraZeneca are Daiichi Sankyo, Merck, Abbott and ViiV.
read
 http://www.genengnews.com/insight-and-intelligence/the-major-pharmaceuticals-losing-patent-protection-in-2016/77900599/

NOTES, Data exclusivity, Tecfidera, Dimethyl fumarate

  Dimethyl fumarate

The CHMP has now completed its assessment and considers that dimethyl fumarate is different from Fumaderm
2. Therefore, the active substance of Tecfidera, dimethyl fumarate, is a new active substance. This conclusion is based on the review of the scientific evidence, and in line withclarification provided by the European Commission that:

i) a new active substance under Directive 2001/83/EC is a chemical substance not previouslyauthorised as a medicinal product in the European Union (Annex I to the Notice to applicants Volume 2A, Procedures for marketing authorisation, Chapter 1, Marketing authorisations, June 2013) and,ii) dimethyl fumarate is part of the medicinal product Fumaderm authorised in 1994 in Germany, but it has not been previously authorised as a medicinal product in the Euopean Union

.

The fact that tecfidera is new active substance under Directive 2001/83/EC it is eligible for 10 yrs exclusivity in EU

Tecfidera MA on 30 January 2014..........10 yrs from this date

Biogen Idec has won regulatory protection for its top-selling multiple sclerosis drug Tecfidera in Europe, paving the way for its launch in markets that could account for a large proportion of future sales.
The European Medicines Agency said on Friday it had granted the oral medicine a "new active substance" (NAS) designation, securing Biogen 10 years protection through data exclusivity that will stop generic firms from launching copycat versions.
In March, Tecfidera was approved in the United States and also recommended for approval in Europe - but its EU launch has been delayed, pending a resolution of uncertainty over data protection.
Without this protection, Biogen would have to rely on relatively weak patents relating the drug's use, which analysts believe might not prevent generic rivals launching cheaper copies in key markets like Germany.



Tecfidera was recommended on 25 March by Europe’s Committee for Medicinal Products for Human Use (CHMP) as a known active substance, rather than a new active substance. A Biogen spokesperson said it was entitled to 10 years’ exclusivity for Tecfidera in the EU under the “Independent Development” principle and its stand-alone data package. The EMA’s guidance on exclusivity will be announced when the final approval decision is given.
If Tecfidera is not granted exclusivity through new active substance status or the Independent Development principle, Biogen will only have patent protection in the EU rather than protection against competitors using its MS data for generic regulatory filings of Tecfidera. The company’s latest EU patent (EP 1131065) expires in 2019 and is directed to formulations of dimethyl fumarate and its uses for autoimmune diseases including MS, according to company documents.

Germany (Fumaderm)
Drug: BG00012

Other Names:

• dimethyl fumarate
• Tecfidera®

The proverbial thorn in Biogen Idec’s paw is a little used product called Fumaderm – which is approved in Germany for the treatment of psoriasis. A ‘chemical cousin’ of Tecfidera (Fumaderm is a compounded form of dimethyl fumarate – the active ingredient in Biogen Idec’s new MS treatment), Fumaderm generated sales of just $60 million in 2012 – a figure that Tecfidera is expected to surpass during its first three months of availability in the US market alone.
The similarities between Tecfidera and Fumaderm would appear to have guided Biogen Idec away from the pursuit of new active substance (NAS) status for Tecfidera – which ordinarily provides new product approvals a minimum of eight years data exclusivity and two years market exclusivity

Biogen Idec wins EU battle on Tecfidera exclusivity

Oral MS drug gains New Active Substance status

Biogen Idec has been buoyed by victory in its longstanding battle to secure market exclusivity for its oral multiple sclerosis (MS) drug Tecfidera in the EU.

Shares in the US biopharma company climbed around 10 per cent on Friday after the Committee for Medicinal Products for Human Use (CHMP) agreed that the active ingredient in Tecfidera - dimethyl fumarate - should be classed as a New Active Substance (NAS) in the EU.
Biogen Idec has delayed the introduction of Tecfidera in Europe while the matter was resolved, and can now move ahead with a launch, secure in the knowledge that it has gained 10 years of regulatory exclusivity for the fast-growing product.
Tecfidera was approved in the US in March, becoming the third orally-active MS treatment to reach the market after Novartis' Gilenya (fingolimod) and Sanofi's Aubagio (teriflunomide), and has romped away in its first few months on the market, racking up around $500m in sales in its first six months.
The drug was awarded a European patent on May 29 that protects it from generic competition until 2028, but has also been pushing for regulatory data protection and NAS status, which will confer an additional level of protection against patent challenges.
Biogen Idec said in a statement that Tecfidera's EU approval has been delayed while the regulatory status of the drug is resolved, but now - with a CHMP positive opinion already in the bag - it can now be referred to the European Commission for a final ruling on the marketing application.
"We are ready to introduce Tecfidera in EU countries shortly after anticipated approval," said the company's executive vice president of R&D Douglas Williams.
Analysts have predicted that the drug could lead the market for oral MS therapies as they become established in favour of injectable interferon-based treatments, with sales of $3bn-a-year or more in 2016.

The European Commission granted a marketing authorisation valid throughout the European Union for Tecfidera on 30 January 2014  ie dimethyl fumarate

read http://drugpatentsint.blogspot.in/2015/01/data-exclusivity-for-medicinal-products.html





FUMADERM An oral preparation containing dimethyl fumarate and monoethyl fumarate salts

New patent, Lomitapide mesylate , Zydus Cadila Healthcare Ltd, US 20160083345,

Lomitapide mesylate

Was developed and launched by Aegerion, under license from the University of Pennsylvania (which acquired rights from BMS).

US-20160083345

Sanjay Jagdish DESAI
Brij KHERA
Jagdish Maganlal PATEL
Harshita Bharatkumar SHAH
Arunkumar Shyam Narayan UPADHYAY
Sureshkumar Narbheram AGRAVAT

Polymorphic forms of lomitapide and its salts and processes for their preparation

Zydus Cadila Healthcare Ltd

The present invention relates to various polymorphic forms of lomitapide or its salts and processes for preparation thereof. The present invention provides Lomitapide mesylate in solid amorphous form and process for preparation thereof. The invention also provides an amorphous solid dispersion of lomitapide mesylate. Further, various crystalline forms of lomitapide mesylate like A, B and C and process for preparation thereof are provided. The invention also provides crystalline forms of lomitapide free base, in particular Form I and Form-II and their preparation. The invention further provides compositions comprising various forms of lomitapide and its salts.

A novel amorphous form of lomitapide mesylate (having >98% of purity and 0.5% of residual solvent and particles size D90 of >250 µm, D50 of >100 µm and D10 of >50 µm), a process for it preparation and a composition comprising it is claimed. Also claimed is an amorphous solid dispersion of lomitapide mesylate and a carrier (eg hydroxypropylmethyl cellulose acetate succinate). Further claimed are crystalline forms of lomitapide mesylate (designated ad Forms A, B, C, I, II and free base of lomitapide in amorphous form), processes for their preparation and compositions comprising them. Lomitapide is known to act as a microsomal triglyceride transfer protein inhibitor, useful for treating familial hypercholesterolemia.

Lomitapide is a synthetic lipid-lowering agent for oral administration. It is a microsomal triglyceride transfer protein inhibitor approved as Juxtapid® in US and as Lojuxta® in Europe as an adjunct to a low-fat diet and other lipid-lowering treatments, including LDL apheresis where available, to reduce low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), apolipoprotein B (apo B), and non-highdensity lipoprotein cholesterol (non-HDL-C) in patients with homozygous familial hypercholesterolemia (HoFH). The approved drug product is a mesylate salt of lomitapide, chemically known as N-(2,2,2-trifluoroethyl)-9-[4-[4-[[[4′(trifluoromethyl)[1,1′-biphenyl]-2-yl]carbonyl]amino]-1-piperidinyl]butyl]-9H-fluorene-9carboxamide methanesulfonate [“lomitapide mesylate” herein after] and has the structural formula

 (MOL) (CDX)

As per the approved label for Juxtapid® (US) “Lomitapide mesylate is a white to off-white powder that is slightly soluble in aqueous solutions of pH 2 to 5. Lomitapide mesylate is freely soluble in acetone, ethanol, and methanol; soluble in 2-butanol, methylene chloride, and acetonitrile; sparingly soluble in 1-octanol and 2-propanol; slightly soluble in ethyl acetate; and insoluble in heptane”.

As per Public Assessment Report for Lojuxta® (Europe) “Polymorphism has been observed for lomitapide mesylate. Of the different solid-state forms, hydrates, and solvates identified in the polymorph studies, only 2 desolvated solid-state forms, Form I and Form II, were identified in batches after drying to final drug substance.” The report further states, under the heading Manufacture, that “The final particle size distribution is controlled during the crystallisation step” (emphasis added) suggesting that the approved drug product lomitapide mesylate is a crystalline compound

U.S. Pat. No. 5,712,279 A discloses the lomitapide compound and a process for its preparation. It also discloses a process for preparation of lomitapide monohydrochloride.

U.S. Pat. No. 5,883,109 A discloses lomitapide mesylate specifically but no solid form was disclosed.

The reference article Synthesis and Applications of Isotopically Labelled Compounds, Vol. 8, Pg. 227-230 (2004) discloses the preparation of Deuterium labelled [d₄]BMS-201038, [³H]BMS-201038, [¹⁴C]BMS-201038 wherein BMS-201038 is lomitapide mesylate.

International (PCT) Publication No. WO 2015/121877 A2 discloses lomitapide crystalline Form I and Form II as well as amorphous form of Lomitapide mesylate and processes for their preparation.

There is still a need to provide a novel polymorph of lomitapide or its salts which is suitable for pharmaceutical preparations. Therefore, the present invention provides new crystalline forms of lomitapide free base and lomitapide mesylate. The present invention also provides amorphous form of lomitapide free base and lomitapide mesylate, which is stable and useful for pharmaceutical preparations.

EXAMPLES

Example-1

Preparation of Lomitapide Mesylate

In a 250 mL round bottom flask, equipped with a mechanical stirrer, thermometer and an addition funnel, 10 g lomitapide and 20 mL methanol were added and stirred to obtain a solution. 1.5 g methane sulfonic acid dissolved in 20 mL water was added slowly to the above solution under stirring. The reaction mixture was stirred till maximum salt formation was achieved. 50 mL water was added to the mixture, stirred for 15-20 min, filtered and washed with water. The product was dried further to obtain lomitapide mesylate.

EXAMPLE 2

Preparation of Amorphous Form of Lomitapide Mesylate

10 g lomitapide mesylate, 50 mL acetone and 150 mL ethyl acetate were heated in a 500 mL round bottom flask, equipped with a mechanical stirrer, thermometer and an addition funnel at 50-55° C. and stirred to obtain clear solution. The solution was subjected to spray drying in JISL Mini spray drier LSD-48 with feed pump running at 30-35 rpm, inlet temperature 50-55° C., out let temperature 45-50° C., aspiration rate 1200-1300 rpm, hot air supply 1.8-2.2 Kg/cm² and vacuum for conveying the dry product 80 mmHg. The product was collected from cyclone and characterized to an amorphous form by x-ray powder diffraction. The product was further dried to obtain the amorphous form of lomitapide mesylate

/////////////New patent, Lomitapide mesylate , Zydus Cadila Healthcare Ltd, US 20160083345, Amorphous

New patent, WO 2016042573, Acitretin, Emcure Pharmaceuticals Ltd

Acitretin

PDT PATENT US4105681

WO-2016042573

Process for preparation of acitretin

Emcure Pharmaceuticals Ltd

EMCURE PHARMACEUTICALS LIMITED [IN/IN]; an Indian company at EMCURE HOUSE, T-184, MIDC., Bhosari, Pune - 411 026 Maharashtra (IN)

GURJAR MUKUND KESHAV; (IN).
JOSHI SHASHIKANT GANGARAM; (IN).
BADHE SACHIN ARVIND; (IN).
KAMBLE MANGESH GORAKHANATH; (IN).
MEHTA SAMIT SATISH; (IN)

The present invention Provides a process for preparation of {(2E, 4E, 6E, 8E) -9- (4-methoxy-2,3,6-trimethyl) phenyl-3,7-dimethyl-nona-2,4,6 , 8} tetraenoate, acitretin year intermediate of formula (VI) with trans isomer ≥97%, comprenant of Reacting 3-formyl-Crotonic acid butyl ester of formula (V) Substantially free of impurities, with 5- (4-methoxy- 2,3,6-trimethylphenyl) -3-methyl-penta-2,4-diene-l-triphenyl phosphonium bromide of formula (IV) and isolating resulting compound of formula (VI) Treating the filtrate with iodine for isomerization of the Undesired cis intermediate and finally Obtaining acitretin (I), with trans isomer Desired ≥97%.

Samit Satish Mehta holds the position of the President - Research & Development

Acitretin of formula (I), chemically known as (2E,4E,6E,8E)-9-(4-methoxy-2,3,6- trimethyl)phenyl-3,7-dimethyl-nona-2,4,6,8-tetraenoic acid, is a second generation retinoid a roved by USFDA in 1996, for the treatment of psoriasis.

Acitretin (I)

The process for preparation of acitretin (I) was first disclosed in US 4,105,681 wherein the intermediate, 5-(4-methoxy-2,3,6-trimethylphenyl)-3-methyl-penta-2,4-diene-l-triphenyl phosphonium bromide was reacted with 3-formyl-crotonic acid butyl ester in presence of sodium hydride as base and dimethylformamide as solvent. The resultant ester derivative was obtained with a trans is (E/Z) ratio of around 55:45 which was subjected to hydrolysis in presence of potassium hydroxide and ethyl alcohol to obtain acitretin.

Use of hazardous, highly pyrophoric and moisture sensitive reagent like sodium hydride, along with cumbersome work-up and successive crystallizations to obtain the desired isomer rendered the process unviable for commercial scale.

Indian patent application 729/MUM/2012 discloses use of organic bases such as triethyl amine or pyridine for the reaction of 3-formyl-crotonic acid butyl ester and 5-(4-methoxy-2,3,6-trimethylphenyl)-3-methyl-penta-2,4-diene-l -triphenyl phosphonium bromide for the synthesis of acitretin. The process utilizes a large excess of the organic base (2.85:1.0) with respect to the reactant phosphonium bromide derivative. Further, there is no mention of the ratio of cis and trans geometric isomers of the product thus obtained either at the intermediate or final stage. The trans: cis (E/Z) ratio of the intermediate significantly impacts the final yield and purity of the product as several purifications and crystallizations are required to obtain the desired trans isomer.

The present inventors have experimentally observed that use of organic base in such large quantities severely hampers the removal of the undesired side product triphenyl phosphonium oxide formed in significant amounts. Also, the intermediate is obtained with a very modest trans: cis (E/Z) ratio.

WO2012/155796 discloses another method wherein alkali metal alkoxides are used as bases in the reaction of 5-(4-methoxy-2,3,6-trimethylphenyl)-3 -methyl -penta-2,4-diene-l -triphenyl phosphonium bromide with 3-formyl-crotonic acid. The obtained reaction mass, after adjusting pH to 7-8 with acid, is directly subjected to catalytic isomerization using catalysts such as Pd(OAc)₂ or Pd(NH₃)₂Cl_2. The reaction mixture so obtained is quenched with water, neutralized and filtered to get the desired product, which is further recrystallized from ethyl acetate. Although this procedure avoids the hydrolysis step and attempts in-situ isomerization, however the use of expensive, soluble palladium catalyst which cannot be recycled from the reaction mass coupled with lengthy reaction time of 25-30 hours and large solvent volumes make the process unviable.

It may be noted that in the synthesis of acitretin, the key reaction of 5-(4-methoxy-2,3,6-trimethylphenyl)-3 -methyl-penta-2 ,4-diene- 1 -triphenylphosphoniumbromide with 3 -formyl crotonic acid or its ester in presence of either strong inorganic bases such as sodium hydride, alkali metal alkoxides or organic bases like triethylamine is common to almost all synthetic routes disclosed in the prior art. Hence, all these routes suffer from the inherent problems of formation of undesired impurities including cis-isomeric compounds and their separation from the desired all-trans product which necessitates various purification methods ranging from column chromatography, multiple crystallizations etc.

Thus, there still exists a need for a convenient, easy-to-scale up process for synthesis of acitretin (I) which avoids use of pyrophoric strong bases and provides a robust method which affords acitretin having desired isomeric purity in high yield.

5-(4-methoxy,2,3,6 trimethylphenyl)- 3-formyl crotonic acid butyl glyoxalate L(+) tartaric acid

3-methyl-penta-2,4-dien-1-triphenyl butyl ester (V) dibutyl ester

phosphonium bromide (IV)

Acitretin (I)

Satish Mehta,CEO, Above and here Inspiring the participants

EXAMPLES

Example 1: Preparation of 4-(4-methoxy-2,3,6-trimethylphenyl)-but-3-en-2-one (II)

Acetone (6000 ml) was added to 4-methoxy-2,3,6 trimethyl benzaldehyde (500.3 g) and the mixture was stirred at 20-30°C. Aqueous solution of sodium hydroxide (134.8 g in 500 ml water) was gradually added to it and the resulting mixture was heated to 45-50°C with continued stirring. After completion of the reaction, as monitored by HPLC, the reaction mass was cooled and acetic acid was added till pH 4.5 to 5.5. Distillation of acetone, followed by addition of cyclohexane to the residue, followed by washing with water, separation and concentration of the organic layer gave 4-(4-methoxy-2,3,6 trimethylphenyl)-but-3-en-2-one of formula (II).

Yield: 80-84%

Example 2: Preparation of 5-(4-methoxy-2,3,6-trimethylphenyl)-3-methyl-penta-2,4-diene- 1-triphenyl phosphonium bromide (IV)

4-(4-Methoxy-2,3,6-trimethylphenyl)-but-3-en-2-one (II; 500 g) dissolved in toluene (2000 ml) was gradually added to a mixture of vinyl magnesium bromide (3500 ml; 1 molar solution in THF) and lithium chloride (4.8 g) and stirred at 20-30 C till completion of the reaction as monitored by HPLC. The reaction mixture was quenched with water and concentrated hydrochloric acid was added till the pH was between 3 and 4. The organic layer was separated and concentrated to give residue containing 5-(4-methoxy-2,3,6 trimethylphenyl)-3 -methyl -penta l,4-dien-3-ol (III). Methyl isobutyl ketone (3500 ml) was added to the residue, followed by gradual addition of triphenyl phosphine hydrobromide (745.3 g) at room temperature. The reaction mixture was heated to 50-60°C till completion of the reaction. The reaction mixture was cooled and filtered to give 5-(4-methoxy-2,3,6-trimethylphenyl)-3-methyl-penta-2,4-diene-l-triphenyl phosphonium bromide of formula (IV).

Yield: 1000 g (76%)

Example 3: Preparation of 3-formyl crotonic acid butyl ester (V)

Dibutyl-L- tartrate (500 g) was dissolved in isopropanol (3500 ml) at room temperature, and water (750 ml) was added to it. The reaction mixture was cooled to 15-25°C and sodium metaperiodate (448.5 g) was gradually added to it with stirring. The reaction was continued at 20-30°C till completion of the reaction based on GC analysis. The reaction mixture was filtered and the filtrate was concentrated. The resulting residue was dissolved in toluene (1000 ml), stirred and filtered to obtain the filtrate containing butyl glyoxylate. Propionaldehyde (221.0 g) was added to the filtrate and heated to around 60°C, followed by gradual addition of piperidine (26.4 g, dissolved in toluene). The reaction mixture was further heated and stirred at 110-120°C till completion of the reaction, as monitored by GC. After completion, the reaction mass was cooled, washed with aqueous sulfuric acid, water and finally with aqueous sodium bicarbonate solution. The organic layer was concentrated and the residue was distilled to give 3-formyl crotonic acid butyl ester (V)

Yield: 230-280 g (35-43%)

Example 4. Preparation of butyI{(2E,4E,6E,8E)-9-(4-methoxy-2,3,6-trimethyl) phenyl-3,7-dimethyl-nona-2,4,6,8}tetraenoate (VI)

Sodium carbonate (297. lg), was added to the mixture of 5-(4-Methoxy-2,3,6-trimethylphenyl)-3-methyl-penta-2,4-diene-l-triphenyl-phosphoniumbromide (IV; 1000 g) in toluene (5000 ml) followed by gradual addition of 3-formyl crotonic acid butyl ester (330 g) at room temperature. The stirred reaction mixture was heated to 60-70°C till completion of the reaction as monitored by HPLC. The reaction mass was cooled, quenched with water. The organic layer was separated, concentrated and n-heptane was added to the residue. The mass was stirred, filtered and 40% aqueous methanol (2000 ml) was added to it with stirring. Layer separation, concentration of the organic layer, and crystallization of the resulting residue from isopropyl alcohol, optionally with seeding followed by filtration gave crop I of butyl {{(2E,4E,6E,8E)— 9-(4-methoxy-2,3,6 trimethyl)phenyl-3,7 dimethyl -nona-2,4,6,8} tetraenoate (VI),.

Yield: 45-50%;

Cis: Trans isomer ratio (2.0:98.0)

The filtrate was concentrated, the residue was dissolved in toluene (2000 ml) and treated with iodine (4.5 g) at room temperature. After completion of the reaction, as monitored by HPLC, the reaction mixture was stirred with aqueous sodium thiosulfate solution. Separation and concentration of the organic layer and crystallization of the resulting residue from isopropyl alcohol, optionally with seeding, gave crop II of butyl {{(2E,4E,6E,8E)-9-(4-methoxy-2,3,6-trimethyl)phenyl-3,7-dimethyl-nona-2,4,6,8} tetraenoate (VI).

Yield (crop II): 15 to 20%.

Cis: Trans isomer ratio (2.0:98.0)

Total yield (crop I+II): 60-70%.

Example 5: Preparation of acitretin (I)

Aqueous solution of potassium hydroxide (155.2 g in 600 ml water) was added to a solution of butyl {(2E,4E,6E,8E)-9-(4-methoxy-2,3 ,6-trimethyl) phenyl-3 ,7-dimethyl-nona- 2,4,6,8}tetraenoate, VI (300.0 g) in ethanol (1800 ml) at 25-30°C and the reaction mixture was stirred at reflux temperature till completion of the reaction. After completion, as monitored by HPLC, the reaction mixture was quenched with water, and hydrochloric acid was added till pH was between 2.5 and 3.5. The mass was heated at 70°C, stirred, cooled to 40-50°C and filtered. Recrystallization of the resulting solid from tetrahydrofuran gave acitretin (I).

Yield: 154.0 g (60%)

Desired trans isomer: > 98%

India's hockey stars Sardara Singh and Sandeep Singh with Emcure Pharmaceuticals COO, Arun Khanna

HE Dr. Kenneth Kaunda, First President of Zambia interacting with Mr. A. K. Khanna, COO & ED, Emcure at Emcure booth at AIDS 2012 conference, Washington

Mr. Sunil Mehta is an Executive Director and Senior Director (Projects)

Arun Khanna is the Chief Operating Officer and Executive Director on the Board of Emcure Pharmaceuticals Limited.

//////New patent, WO 2016042573,  Acitretin,   Emcure Pharmaceuticals Ltd

WO 2016042441, Mankind Research Centre, Silodosin, New patent

WO 2016042441, Mankind Research Centre, Silodosin, New patent

WO-2016042441

Mankind Research Centre

MANKIND RESEARCH CENTRE [IN/IN]; 191-E, Sector 4-II, IMT-Manesar, Haryana 122050 (IN)

A novel process for the preparation of considerably pure silodosin

GANGWAR, Kuldeep Singh; (IN).
KUMAR, Anil; (IN).
BHASHKAR, Bhuwan; (IN)

The present invention relates to a novel, improved, commercially viable and industrially advantageous process for the preparation of Silodosin of Formula (I), its pharmaceutically acceptable salts or solvates thereof. The invention relates to the preparation of considerably pure Silodosin with high yield.

Silodosin, l-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl} amino)propyl]-2,3-dihydro-lH-indole-7-carboxamide of Formula (I) is an indoline antidysuric which has a selectively inhibitory effect against urethra smooth muscle constriction, and decreases urethra internal pressure without great influence on blood pressure. Silodosin is available under trade names RAPAFLO^® or UROREC^®. Silodosin was first disclosed in EP 0600675 as a therapeutic agent for the treatment of dysuria associated with benign prostatic hyperplasia, where a process for producing the compound is also disclosed.

Formula (I)

Since, Silodosin is an optically active compound having a complex chemical structure; its synthesis is relatively complex and requires a sequence of multiple steps.

US patent no. 6,310,086, discloses a process for preparing Silodosin analogue compound from reaction of (R)-3-{5-(2-aminopropyl)-7-cyano-2,3-dihydro-lH-indol-l-yl} propylbenzoate with 2-(2-ethoxyphenoxy)ethyl methanesulfonate and finally isolated as a crude compound which is purified by column chromatography. The said process has a major disadvantage of using column chromatography which is not feasible at plant scale production.

PCT application no. WO 2012147019, discloses the preparation of Silodosin as shown in scheme- 1, wherein the Ν,Ν-dialkyl impurity of Formula (Ila) formed during condensation of 3-{7-cyano-5-[(2R)-2-aminopropyl]-2,3-dihydro-lH-indol-l-yl}propyl benzoate of Formula (III) with 2-(2-(2,2,2-trifluoroethoxy)phenoxy)ethyl methanesulfonate of Formula (IV); is removed through preparation of monotartarate salt to give compound of Formula (VI). The compound of Formula (VI) is base hydrolyzed followed by cyano hydrolysis to give crude Silodosin of Formula (VIII) which is then further purified by crystallization to get desired pure Silodosin.

Scheme- 1:

Major drawback of above said reaction process is that multiple isolations and crystallizations are required to get pure Silodosin.

Similarly, US 7,834,193 discloses monooxalate salt represented by Formula Via having 0.9% of dialkyl impurity represented by Formula Ila. The oxalate salt so obtained is subjected to alkaline hydrolysis followed by transformation of the nitrile to an amide.

Formula (Ila)

Similarly, PCT application no. WO 2012147107, discloses the method wherein Silodosin is prepared by condensation of 3-{7-cyano-5-[(2R)-2-aminopropyl]-2,3-dihydro-lH-indol-l-yl} propyl benzoate with 2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl methanesulfonate in solvent using base and phase transfer catalyst wherein, dialkyl impurity is formed up to 11%, followed by hydroxyl deprotection in protic solvent using base and phase transfer catalyst which is then subjected to purification to remove N,N-dialkyl impurity represented by Formula (lib) up to 0.6% through the preparation of acetate salt. This process suffers from a serious drawback i.e., accountable formation of dialkyl impurity and even after purification the impurity is reduced to only up to 0.6%. Secondly, the process requires multiple isolations and purifications ensuing into time engulfing workups and purifications and hence incurring solvent wastage. This makes process lengthy, uneconomical and tedious to be performed at plant scale.

Another PCT application no. WO 2012131710, discloses the preparation of Silodosin in which the chiral compound (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) is reacted with 2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl methane sulfonate in isopropyl alcohol using sodium carbonate as base. The reaction is completed in 40-50h and about 9-11% of dimer is formed during condensation. After completion of reaction, it is subjected to hydroxyl deprotection and the crude compound so obtained is purified to remove the Ν,Ν-dialkyl impurity of Formula (lib). The pure compound is then reacted with hydrogen peroxide in dimethyl sulfoxide to give Silodosin. The major drawback of this process is that the process is a multistep process wherein the condensation reaction is long-drawn-out resulting into countable amount of dimer formation during the process.

Thus, the prior art methods of preparing Silodosin require multiple and repeated purifications to synthesize DMF (Drug Master File) grade Silodosin. None of the prior art produces compound of Formula (VI) or (VII) with Ν,Ν-dialkyl impurity of Formula (Ila) or (lib) in an amount less than 0.6% to 0.5% even after purification. Therefore to prepare highly pure Silodosin, there is a need to explore new synthetic schemes that could be more economical and scalable. The present invention provides a novel, improved, commercially viable and industrially advantageous process for the synthesis of Silodosin and its pharmaceutically acceptable salts or solvates thereof. The present invention focus on preparation of highly pure Silodosin in appreciable yields with minimal use of solvents wherein the Silodosin is isolated with purity >99.5% having Ν,Ν-dialkyl impurity less than 0.03% and other individual impurities below 0.1%.

Ramesh Juneja (seated), founder of Mankind Pharma, with brother Rajeev, who is senior director (marketing & sales)

Mankind Pharma Chairman and Founder RC Juneja

In accordance to one embodiment of the present invention, the process of the preparation of Silodosin represented by Formula (I)

comprises the steps of:

a) condensing chiral compound represented by Formula (III)

Formula (III)

wherein, Bz represents to Benzoyl group with compound represented by Formula (IV)

Formula (IV)

wherein, Ms represents to Methanesulfonyl group in presence of base and phase transfer catalyst in an organic solvent to give intermediate represented by Formula (V)

Formula (V)

wherein, n is an integer of 1 and 2 and Bz is as defined above, wherein the compound having n=2 is formed in an amount of less than 5%;

b) optionally isolating compound of Formula (V),

c) without purification converting it to de-protected compound represented by Formula (IX) in an organic solvent;

Formula (IX)

wherein, n is as defined above;

d) optionally isolating compound of Formula (IX), and

e) without purification converting it to compound represented by Formula (X)

Formula (X)

wherein n is as defined above;

f) subjecting compound of Formula (X) to purification by converting to acid salt for removal of Ν,Ν-dialkyl impurity represented by Formula (lie);

Formula (He)

g) hydrolysis of the said acid salt to get Silodosin of Formula (I) with purity >99.5%.

Examples

The invention is explained in detail in the following examples which are given solely for the purpose of illustration only and therefore should not be construed to limit the scope of the invention.

Example 1

Preparation of Crude Silodosin:

Method A:

To the solution of lOg (0.0275 mol) of (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) in 100ml of toluene was added 14.3g (0.0826 mol) of dipotassium hydrogen phosphate and 8.20g (0.0261 mol) of 2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl methane sulfonate followed by addition of 2.0g (0.0055 mol) of tetrabutyl ammonium iodide and stirred the reaction mass at 85-90°C for 10-12h. Cooled the reaction mass, added de-mineralized water and separated the toluene layer followed by distillation to get crude viscous mass. Added 110ml of dimethyl sulfoxide and a solution of 1.51g (0.0415 mol) of sodium hydroxide dissolved in 8.52ml of water followed by addition of 6.42g (0.0567 mol) of 30% w/w of hydrogen peroxide. Stirred the reaction mass at 20-25°C till completion and added sodium sulfite solution. Extracted the compound in ethylacetate, washed the organic layer with brine solution and concentrated to get 10.2g of crude Silodosin.

Ν,Ν-dialkyl impurity is 3.2% as per HPLC.

Method B:

To the solution of lOg (0.0275 mol) of (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) in 100ml of toluene was added 14.3g (0.0826 mol) of dipotassium hydrogen phosphate and 8.20g (0.0261 mol) of 2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl methane sulfonate followed by addition of 2.0g (0.0055 mol) of tetrabutyl ammonium iodide and stirred the reaction mass at 85-90°C for 10-12h. Added solution of 4.4g of sodium hydroxide dissolved in 10ml of water and stirred the reaction at ambient temperature till completion. Quenched the reaction mass with water and separated the layers. Washed the toluene layer with brine and concentrated under reduced pressure to get crude mass. Dissolved the crude mass so obtained in 110ml of dimethyl sulfoxide and added a solution of 1.95g (0.0488 mol) of sodium hydroxide dissolved in 7.95ml of water followed by addition of 7.5g (0.066 mol) of 30% w/w of hydrogen peroxide. Stirred the reaction mass at room temperature followed by addition of 210ml of aqueous solution of sodium sulfite and extracted the compound in ethyl acetate. Washed the organic layer with brine and concentrated under reduced pressure to get 10. lg of crude Silodosin.

Ν,Ν-dialkyl impurity is 3.0% as per HPLC

Method C:

To the solution of lOg (0.0275 mol) of (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) in 100ml of dimethyl sulfoxide was added 14.3g (0.0826 mol) of dipotassium hydrogen phosphate and 8.20g (0.0261 mol) of 2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl methane sulfonate followed by addition of 2.0g (0.0055 mol) of tetrabutyl ammonium iodide and stirred the reaction mass at 85-90°C for 2-3h. Added 100ml of water and 50ml of toluene and stirred the reaction mass at room temperature for half an hour. Separated the toluene layer and concentrated under reduced pressure. To the crude mass so obtained was added 110ml of dimethyl sulfoxide and a solution of 4.4g of sodium hydroxide dissolved in 10ml of water followed by addition of 7.5g (0.066 mol) of 30% w/w of hydrogen peroxide. Stirred the reaction mass at room temperature followed by addition of 210ml of aqueous solution of sodium sulfite and extracted the compound in ethyl acetate. Washed the organic layer with brine and concentrated under reduced pressure to get 9.8 g of crude Silodosin.

Ν,Ν-dialkyl impurity is 2.1% as per HPLC

Method D:

To the solution of 20g (0.055 mol) of (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) in 200ml of toluene was added 28.6g (0.165 mol) of dipotassium hydrogen phosphate and 16.4g (0.0522 mol) of 2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl methane sulfonate followed by addition of 4.0g (0.11 mol) of tetrabutyl ammonium iodide and stirred the reaction mass at 85-90°C for 10-12h. Added de-mineralized water and stirred at room temperature for half an hour. Separated the toluene layer to which was added a solution of 8.8g of sodium hydroxide dissolved in 20ml of water and stirred the reaction at ambient temperature till completion. Quenched the reaction mass with water and separated the layers. Washed the toluene layer with brine and concentrated under reduced pressure to get crude mass. Dissolved the crude mass so obtained in 200ml of dimethyl sulfoxide and added a solution of 3.9g (0.0976 mol) of sodium hydroxide dissolved in 16ml of water followed by addition of 15g (0.132 mol) of 30% w/w of hydrogen peroxide. Stirred the reaction mass at room temperature followed by addition of 400ml of aqueous solution of sodium sulfite and extracted the compound in ethyl acetate. Washed the organic layer with brine and concentrated under reduced pressure to get 21. Og of crude Silodosin.

Ν,Ν-dialkyl impurity is 2.8% as per HPLC

Method E:

To the solution of 2g (0.0055 mol) of (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) in 20ml of was dimethyl sulfoxide was added 2.87g (0.0165 mol) of dipotassium hydrogen phosphate and 1.64g (0.0052 mol) of 2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl methane sulfonate followed by addition of 0.29g (0.0011 mol) of 16-crown ether and stirred the reaction mass at 85-90°C for 10-12h. Added a solution of 0.88g of sodium hydroxide dissolved in 2ml of water and stirred the reaction at ambient temperature till completion. Added de-mineralized water and toluene and stirred at room temperature for half an hour. Separated the toluene layer and concentrated under reduced pressure and to the solid mass so obtained were added 20ml of dimethyl sulfoxide and a solution of 0.38g (0.0231 mol) of sodium hydroxide dissolved in 1.6ml of water followed by addition of 1.5g (0.0132 mol) of 30% w/w of hydrogen peroxide. Stirred the reaction mass at room temperature followed by addition of aqueous solution of sodium sulfite and extracted the compound in ethyl acetate. Washed the organic layer with brine and concentrated under reduced pressure to get 2.1g of crude Silodosin.

Ν,Ν-dialkyl impurity is 2.2% as per HPLC

Method F:

To the solution of lOg (0.0275 mol) of (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) in 100ml of was acetonitrile was added 14.3g (0.0826 mol) of dipotassium hydrogen phosphate and 8.20g (0.0261 mol) of 2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl methane sulfonate followed by addition of 2.0g (0.0055 mol) of tetra butyl ammonium iodide and stirred the reaction mass at 85-90°C for 10-12h. Added a solution of 4.4g of sodium hydroxide dissolved in 10ml of water and stirred the reaction at ambient temperature till completion. Added de-mineralized water and toluene and stirred at room temperature for half an hour. Separated the toluene layer and concentrated under reduced pressure and to the solid mass so obtained were added 110ml of dimethyl sulfoxide and a solution of 1.95g (0.0488 mol) of sodium hydroxide dissolved in 7.95ml of water followed by addition of 7.5g (0.066 mol) of 30% w/w of hydrogen peroxide. Stirred the reaction mass at room temperature followed by addition of 210ml of aqueous solution of sodium sulfite and extracted the compound in ethyl acetate. Washed the organic layer with brine and concentrated under reduced pressure to get 9.5g of crude Silodosin.

Ν,Ν-dialkyl impurity is 3.1% as per HPLC

Method G:

To the solution of lOg (0.0275 mol) of (3-(5-((R)-2-aminopropyl)-7-cyanoindolin-l-yl)propyl benzoate) in 100ml of was Dimethyl sulfoxide was added 14.3g (0.0826 mol) of dipotassium hydrogen phosphate and 8.20g (0.0261 mol) of 2-[2-(2,2,2-trifluoroethoxy)phenoxy] ethyl methane sulfonate followed by addition of 4.0g (0.0055 mol) of tetra butyl ammonium iodide and stirred the reaction mass at 85-90°C for 10-12h. Added a solution of 4.4g of sodium hydroxide dissolved in 10ml of water and stirred the reaction at ambient temperature till completion. Added de-mineralized water and toluene and stirred at room temperature for half an hour. Separated the toluene layer and concentrated under reduced pressure and to the solid mass so obtained were added 110ml of dimethyl sulfoxide and a solution of 1.95g (0.0488 mol) of sodium hydroxide dissolved in 7.95ml of water followed by addition of 7.5g (0.066 mol) of 30% w/w of hydrogen peroxide. Stirred the reaction mass at room temperature followed by addition of 210ml of aqueous solution of sodium sulfite and extracted the compound in ethyl acetate. Washed the organic layer with brine and concentrated under reduced pressure to get 10.4g of crude Silodosin.

Ν,Ν-dialkyl impurity is 1.83% as per HPLC

Example 2

Purification of Crude Silodosin:

To the lOg (0.0080 mol) of crude mass of Silodosin was added 110ml of isopropyl alcohol followed by addition of 1.75g of oxalic acid at ambient temperature. Stirred the solution 6-8h and filtered the precipitates. Added ethyl acetate and water in the ratio of 1: 1 to the above solid followed by addition of 5ml of liquor ammonia. Stirred the reaction mass at ambient temperature for 15 min and separated the layers. Concentrated the organic layer to ¼ of its volume and left undisturbed overnight. Filtered the precipitates and recrystallized with ethyl acetate followed by drying under reduced pressure to get 5.1g of pure Silodosin. The amount of impurities and the percent impurity of the Silodosin obtained was as follows:

Ν,Ν-dialkyl impurity: undetectable amount

Other impurities: 0.03 to 0.09%

Silodosin purity: 99.65% (HPLC)

////WO 2016042441, Mankind Research Centre, Silodosin, New patent