US20130338355A1 - Process for preparing amorphous rifaxmin and the amorphous rifaximin thus obtained - Google Patents

Process for preparing amorphous rifaxmin and the amorphous rifaximin thus obtained Download PDF

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Publication number
US20130338355A1
US20130338355A1 US13/970,576 US201313970576A US2013338355A1 US 20130338355 A1 US20130338355 A1 US 20130338355A1 US 201313970576 A US201313970576 A US 201313970576A US 2013338355 A1 US2013338355 A1 US 2013338355A1
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Prior art keywords
rifaximin
amorphous
absolute ethanol
dissolved
stirring
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US13/970,576
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Emilio Vecchio
Roberta Pizzocaro
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Priority to US13/970,576 priority Critical patent/US20130338355A1/en
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Priority to US14/261,138 priority patent/US9273063B2/en
Assigned to BARCLAYS BANK PLC, AS COLLATERAL AGENT reassignment BARCLAYS BANK PLC, AS COLLATERAL AGENT SECURITY AGREEMENT Assignors: GLYCYX PHARMACEUTICALS, LTD., SALIX PHARMACEUTICALS, INC., SALIX PHARMACEUTICALS, LTD., SANTARUS, INC.
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D491/00—Heterocyclic compounds containing in the condensed ring system both one or more rings having oxygen atoms as the only ring hetero atoms and one or more rings having nitrogen atoms as the only ring hetero atoms, not provided for by groups C07D451/00 - C07D459/00, C07D463/00, C07D477/00 or C07D489/00
    • C07D491/22—Heterocyclic compounds containing in the condensed ring system both one or more rings having oxygen atoms as the only ring hetero atoms and one or more rings having nitrogen atoms as the only ring hetero atoms, not provided for by groups C07D451/00 - C07D459/00, C07D463/00, C07D477/00 or C07D489/00 in which the condensed system contains four or more hetero rings
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D498/00—Heterocyclic compounds containing in the condensed system at least one hetero ring having nitrogen and oxygen atoms as the only ring hetero atoms
    • C07D498/22—Heterocyclic compounds containing in the condensed system at least one hetero ring having nitrogen and oxygen atoms as the only ring hetero atoms in which the condensed system contains four or more hetero rings

Definitions

  • the present invention relates to the preparation of Rifaximin in amorphous form.
  • Rifaximin is a non-systemic antibiotic belonging to the rifaximin-family, applied in the treatment of various pathologies including in particular diarrhoea caused by E. coli or irritable bowel syndrome.
  • the present invention instead relates to the preparation of Rifaximin in amorphous form, by a process that comprises precipitating the desired product in absolute ethanol starting from a solution of crude Rifaximin.
  • FIG. 1 ( a and b ) and FIG. 2 ( a and b ) show respectively the PXRD and IR spectra of rifaximin obtained according to the process of the present invention.
  • the process of the invention uses as starting product crude Rifaximin containing water.
  • the starting product is dissolved in absolute ethanol in the presence of ascorbic acid and the solution subjected to mild heating with stirring; the product precipitates by cooling the solution while stirring, and is then collected by filtration, washed with cold absolute ethanol and dried under vacuum.
  • the product on the filter was washed with 20 ml of cold absolute ethanol and the wet solid dried under vacuum at 70° C. for 18 hours until a KF value less than 4% was attained.
  • the PXRD and IR spectra of the obtained product are shown in FIGS. 1 a and 2 a respectively.
  • the product on the filter was washed with 20 ml of cold absolute ethanol and the wet solid dried under vacuum at 60° C. for 18 hours until a KF value less than 4% was attained.
  • the dissolution profile of the substance in amorphous form was also determined, and compared with that of the substance in crystalline form.
  • the substance in crystalline form After one hour of dissolution, the substance in crystalline form has a concentration of dissolved substance equal to about 7% of that of the substance in amorphous form.
  • the substance in amorphous form has a dissolved percentage which is one order of magnitude greater than that of the substance in crystalline form.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)
  • Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

Abstract

A process is described which enables Rifaximin in a completely amorphous form to be obtained. Said process comprises the steps of dissolving crude Rifaximin in absolute ethanol while hot and then collecting after precipitation by—cooling the title compound under amorphous form.

Description

    FIELD OF THE INVENTION
  • The present invention relates to the preparation of Rifaximin in amorphous form.
    • STATE OF THE ART
  • As is known Rifaximin is a non-systemic antibiotic belonging to the rifaximin-family, applied in the treatment of various pathologies including in particular diarrhoea caused by E. coli or irritable bowel syndrome.
  • Various polymorphic forms of the product are known, for which various synthesis and purification processes have been described.
  • The present invention instead relates to the preparation of Rifaximin in amorphous form, by a process that comprises precipitating the desired product in absolute ethanol starting from a solution of crude Rifaximin.
  • Pharmaceutical active principles in amorphous form are in general more soluble than the corresponding crystalline forms, and this can present advantages in terms-of improved absorption per os and consequently improved bioavailability.
    • BRIEF DESCRIPTION OF THE FIGURES
  • FIG. 1 (a and b) and FIG. 2 (a and b) show respectively the PXRD and IR spectra of rifaximin obtained according to the process of the present invention.
    •  DETAILED DESCRIPTION OF THE INVENTION
  • The process of the invention uses as starting product crude Rifaximin containing water.
  • The starting product is dissolved in absolute ethanol in the presence of ascorbic acid and the solution subjected to mild heating with stirring; the product precipitates by cooling the solution while stirring, and is then collected by filtration, washed with cold absolute ethanol and dried under vacuum.
  • The absence of significant peaks in the PXRD spectra carried out on the product obtained in this manner is evidence of the purity of the amorphous product obtained.
    • EXAMPLE 1
  • 20 g of crude rifaximin (containing an average water quantity of between 4 and 7%) were placed in a reaction flask in which 0.2 g of ascorbic acid and 200 ml of absolute ethanol were added. The suspension was heated to 60° C. with stirring until completely dissolved. The solution was allowed to cool to 25° C., maintaining stirring for a further three hours.
  • After precipitation, the suspension was left for a further 2 hours with stirring at a temperature of 12° C., then filtered.
  • The product on the filter was washed with 20 ml of cold absolute ethanol and the wet solid dried under vacuum at 70° C. for 18 hours until a KF value less than 4% was attained.
  • 15 g of pure amorphous rifaximin were obtained.
  • The PXRD and IR spectra of the obtained product are shown in FIGS. 1 a and 2 a respectively.
    • EXAMPLE 2
  • 20 g of crude rifaximin (containing an average quantity of water of between 4 and 7%) were placed in a reaction flask in which 0.2 g of ascorbic acid and 200 ml of absolute ethanol were added. The suspension was heated to 40° C. with stirring until completely dissolved. The solution was allowed to cool to 18° C., maintaining stirring for a further three hours.
  • After precipitation the suspension was left for a further 2 hours with stirring at a temperature of 8° C., then filtered.
  • The product on the filter was washed with 20 ml of cold absolute ethanol and the wet solid dried under vacuum at 60° C. for 18 hours until a KF value less than 4% was attained.
  • 14 g of pure amorphous rifaximin were obtained.
  • The PXRD and IR spectra of the obtained product are shown in FIGS. 1 b and 2 b respectively.
  • The dissolution profile of the substance in amorphous form was also determined, and compared with that of the substance in crystalline form.
  • It was found that the amorphous form easily dissolves in ethanol even without stirring, while the crystalline form is less wettable.
  • Moreover, with regard to water solubility, after conditioning a dissolution tester (Pharma Test Type PTW S III s/n 5390) using distilled water at a temperature of 37° C.±0.5° C. at a speed of 100 rpm, four dissolutions were carried out, in each of which the first three vessels of the dissolution tester were used for the substance in crystalline form and the last three for the substance in amorphous form.
  • 10 ml of the solute were withdrawn from each vessel after 15 minutes of stirring; the withdrawn samples were filtered with 0.45 μm filters and subjected to spectophotometric analysis, repeating the operation after 30 and 60 minutes.
  • After one hour of dissolution, the substance in crystalline form has a concentration of dissolved substance equal to about 7% of that of the substance in amorphous form.
  • Consequently, the substance in amorphous form has a dissolved percentage which is one order of magnitude greater than that of the substance in crystalline form.

Claims (7)

1. Process for preparing amorphous rifaximin in which crude rifaximin is dissolved in absolute ethanol while hot, then collected after precipitation by cooling of the solution.
2. Process as claimed in claim 1 wherein the crude rifaximin has a water content of between 4 and 7%.
3. Process as claimed in claims 1 and 2 wherein the crude rifaximin is dissolved in absolute ethanol in the presence of ascorbic acid.
4. Process as claimed in claims 1 to 3 wherein the crude rifaximin is dissolved with stirring at a temperature of 40-60° C. and then re-precipitated by cooling the solution to 8-12° C.
5. Process as claimed in claim 4 wherein the precipitated rifaximin is collected by filtration, washed with absolute ethanol and dried.
6. Process as claimed in claim 5 wherein said drying is conducted under vacuum at 60-70° C.
7. Amorphous rifaximin obtained according to the process of claims 1-6.
US13/970,576 2007-06-20 2013-08-19 Process for preparing amorphous rifaxmin and the amorphous rifaximin thus obtained Abandoned US20130338355A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US13/970,576 US20130338355A1 (en) 2007-06-20 2013-08-19 Process for preparing amorphous rifaxmin and the amorphous rifaximin thus obtained
US14/261,138 US9273063B2 (en) 2007-06-20 2014-04-24 Method for preparing a rifaximin product

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
ITMI2007A001241 2007-06-20
IT001241A ITMI20071241A1 (en) 2007-06-20 2007-06-20 PROCESS FOR THE PREPARATION OF RIFAXIMINA AMORFA AND RIFAXIMINA AMORPHAS SO OBTAINED
PCT/IB2008/052396 WO2008155728A1 (en) 2007-06-20 2008-06-18 Process for preparing amorphous rifaximin and the amorphous rifaximin thus obtained
US45215209A 2009-12-15 2009-12-15
US13/970,576 US20130338355A1 (en) 2007-06-20 2013-08-19 Process for preparing amorphous rifaxmin and the amorphous rifaximin thus obtained

Related Parent Applications (3)

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US12/452,152 Continuation US20100137580A1 (en) 2007-06-20 2008-06-18 Process for preparing amorphous rifaximin and the amorphous rifaximin thus obtained
PCT/IB2008/052396 Continuation WO2008155728A1 (en) 2007-06-20 2008-06-18 Process for preparing amorphous rifaximin and the amorphous rifaximin thus obtained
US45215209A Continuation 2007-06-20 2009-12-15

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US14/261,138 Continuation US9273063B2 (en) 2007-06-20 2014-04-24 Method for preparing a rifaximin product

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US12/452,152 Abandoned US20100137580A1 (en) 2007-06-20 2008-06-18 Process for preparing amorphous rifaximin and the amorphous rifaximin thus obtained
US13/970,576 Abandoned US20130338355A1 (en) 2007-06-20 2013-08-19 Process for preparing amorphous rifaxmin and the amorphous rifaximin thus obtained
US14/261,138 Active US9273063B2 (en) 2007-06-20 2014-04-24 Method for preparing a rifaximin product

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US (3) US20100137580A1 (en)
EP (1) EP2170904B1 (en)
KR (1) KR101719366B1 (en)
AR (1) AR067055A1 (en)
CA (1) CA2691394C (en)
CL (1) CL2008001823A1 (en)
IT (1) ITMI20071241A1 (en)
WO (1) WO2008155728A1 (en)

Families Citing this family (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ITMI20032144A1 (en) 2003-11-07 2005-05-08 Alfa Wassermann Spa REFLEXIMINE POLIMORPHIC FORMS, PROCESSES TO OBTAIN THEM AND
US7906542B2 (en) 2004-11-04 2011-03-15 Alfa Wassermann, S.P.A. Pharmaceutical compositions comprising polymorphic forms α, β, and γ of rifaximin
US7902206B2 (en) 2003-11-07 2011-03-08 Alfa Wassermann, S.P.A. Polymorphic forms α, β and γ of rifaximin
ES2522895T3 (en) 2005-03-03 2014-11-19 Alfa Wassermann S.P.A. New polymorphic forms of rifaximin, procedures for their production and use in medicinal preparations
NZ575550A (en) * 2006-09-22 2011-12-22 Cipla Ltd Rifaximin
US7709634B2 (en) 2007-09-20 2010-05-04 Apotex Pharmachem Inc. Amorphous form of rifaximin and processes for its preparation
US8486956B2 (en) 2008-02-25 2013-07-16 Salix Pharmaceuticals, Ltd Forms of rifaximin and uses thereof
MY158257A (en) 2008-02-25 2016-09-30 Salix Pharmaceuticals Ltd Forms of rifaximin and uses thereof
WO2011061748A1 (en) * 2009-11-19 2011-05-26 Strides Arcolab Limited Rifaximin premix
IT1399141B1 (en) * 2010-04-02 2013-04-05 Secci METHOD FOR THE PREPARATION OF RIFAXIMINA IN THE AMORPHOUS STATE.
EP2401282B2 (en) † 2009-12-28 2017-01-04 Silvio Massimo Lavagna Method for the production of amorphous rifaximin
IT1398550B1 (en) * 2010-03-05 2013-03-01 Alfa Wassermann Spa RIFAXIMINA COMPREHENSIVE FORMULATIONS USEFUL TO OBTAIN A PROLONGED EFFECT IN TIME
WO2012035544A2 (en) * 2010-09-13 2012-03-22 Sequent Scientific Ltd. A novel polymorphic form of rifaximin and process for its preparation
IT1403847B1 (en) 2010-09-22 2013-11-08 Alfa Wassermann Spa PHARMACEUTICAL COMPOSITIONS INCLUDING RIFAXIMINA AND THEIR USE.
WO2012060675A1 (en) * 2010-11-05 2012-05-10 Interquim, S.A. De C.V. Process for the preparation of amorphous rifaximin
AU2012214239B2 (en) 2011-02-11 2016-06-30 Salix Pharmaceuticals, Ltd. Forms of Rifaximin and uses thereof
WO2012155981A1 (en) 2011-05-19 2012-11-22 Friulchem Spa New process for the synthesis of rifaximin and a new pseudo-crystalline form of rifaximin obtained thereby
ITMI20110983A1 (en) * 2011-05-30 2012-12-01 A M S A Anonima Materie Sint & Affini S P A RIFAXIMINA AMORPHOUS AND PROCESS FOR ITS PREPARATION
ITBO20110461A1 (en) 2011-07-29 2013-01-30 Alfa Wassermann Spa PHARMACEUTICAL COMPOSITIONS INCLUDING RIFAXIMINA, PROCESSES FOR THEIR PREPARATION AND THEIR USE IN THE TREATMENT OF VAGINAL INFECTIONS.
WO2013185211A1 (en) 2012-06-13 2013-12-19 Apotex Pharmachem Inc. Polymorphic forms of rifaximin
ITBO20120368A1 (en) 2012-07-06 2014-01-07 Alfa Wassermann Spa COMPOSITIONS INCLUDING RIFAXIMINA AND AMINO ACIDS, RIFAXIMINE CRYSTALS DERIVING FROM SUCH COMPOSITIONS AND THEIR USE.
US20160038468A1 (en) 2013-03-15 2016-02-11 Alfa Wassermann S.P.A. Rifaximin for use in the treating of vaginal infections
WO2014140995A2 (en) 2013-03-15 2014-09-18 Alfa Wassermann S.P.A. Method for diagnosing vaginal infections
CN105324109A (en) 2013-04-12 2016-02-10 意大利阿尔法韦士曼制药公司 NSAID administration and related compositions, methods and systems
EP2927235B1 (en) 2014-03-31 2017-02-08 Euticals S.P.A. Polymorphic mixture of rifaximin and its use for the preparation of solid formulations
ES2810010T3 (en) 2014-05-12 2021-03-08 Alfasigma Spa Preparation and use of the tau crystalline form of rifaximin solvated with DEGME
EP2982764A1 (en) 2014-08-05 2016-02-10 ALFA WASSERMANN S.p.A. Identification of vaginal bacteria

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Publication number Priority date Publication date Assignee Title
IT1154655B (en) * 1980-05-22 1987-01-21 Alfa Farmaceutici Spa IMIDAZO-RIFAMYCIN DERIVATIVES METHODS FOR THEIR PREPARATION AND USE AS AN ANTIBACTERIAL ACTION SUBSTANCE
IT1199374B (en) * 1984-05-15 1988-12-30 Alfa Farmaceutici Spa PROCESS FOR THE PREPARATION OF PIRIDO-IMIDAZO-RIFAMICINE
ITMI20032144A1 (en) * 2003-11-07 2005-05-08 Alfa Wassermann Spa REFLEXIMINE POLIMORPHIC FORMS, PROCESSES TO OBTAIN THEM AND
ES2522895T3 (en) * 2005-03-03 2014-11-19 Alfa Wassermann S.P.A. New polymorphic forms of rifaximin, procedures for their production and use in medicinal preparations
NZ575550A (en) * 2006-09-22 2011-12-22 Cipla Ltd Rifaximin
US7709634B2 (en) * 2007-09-20 2010-05-04 Apotex Pharmachem Inc. Amorphous form of rifaximin and processes for its preparation

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EP2170904B1 (en) 2019-09-18
EP2170904A1 (en) 2010-04-07
CA2691394A1 (en) 2008-12-24
KR20100038081A (en) 2010-04-12
US20150011750A1 (en) 2015-01-08
AR067055A1 (en) 2009-09-30
CL2008001823A1 (en) 2009-05-22
KR101719366B1 (en) 2017-03-23
US9273063B2 (en) 2016-03-01
CA2691394C (en) 2016-10-11
ITMI20071241A1 (en) 2008-12-21
US20100137580A1 (en) 2010-06-03
WO2008155728A1 (en) 2008-12-24

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STCB Information on status: application discontinuation

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AS Assignment

Owner name: BARCLAYS BANK PLC, AS COLLATERAL AGENT, NEW YORK

Free format text: SECURITY AGREEMENT;ASSIGNORS:GLYCYX PHARMACEUTICALS, LTD.;SALIX PHARMACEUTICALS, INC.;SALIX PHARMACEUTICALS, LTD.;AND OTHERS;REEL/FRAME:035364/0396

Effective date: 20150401