Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
  • C07D401/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings
  • C07D401/04—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings directly linked by a ring-member-to-ring-member bond

Definitions

• the present invention relates to an improved process, which is simple, convenient, economical and industrially viable, for the preparation of stable, free flowing, non- hygroscopic crystalline alpha form of Imatinib mesylate, free from the beta form.
• Imatinib is the international non-proprietary name of 4-(4- methylpiperazin- 1 -yl methyl)-N-[4-methyl-3-(4-pyridin-3-yl) pyrimidin-2-ylamino) phenyl]-benzamide. Imatinib was disclosed in Eurpean Patent Application EP 0 564 409.
• Imatinib is indicated for the treatment of patients with Philadelphia chromosome positive (PH+) chronic myeloid leukemia (CML) and with Kit-positive gastrointestinal stromal tumours (GIST) including unresectable and/or metastatic malignant disease and resected disease post-surgery, for use in adult patients with newly diagnosed PH+ acute lymphoblastic leukemia (ALL) in combination with chemotherapy, and as single agent for patients with relapsed or refractory Ph+ALL.
• PH+ Philadelphia chromosome positive
• CML chronic myeloid leukemia
• GIST Kit-positive gastrointestinal stromal tumours
• ALL PH+ acute lymphoblastic leukemia
• the structural formula of imatinib mesylate is given below:
• Imatinib is sold by Novartis using the trademark GLEEVEC, in the form of Tablets containing imatinib mesylate equivalent to 100 mg or 400 mg of imatinib free base. It is well known that imatinib mesylate may crystallize in some polymorphic forms.
• U.S. Patent No. 6,894,051 (“the ⁇ 51 patent"), disclosed two polymorphic forms of mesylate salt of imatinib viz: alpha-crystal form and beta-crystal form and the processes for their preparation.
• the ⁇ 51 patent also discloses that the crystalline alpha-form is characterized by needle-shaped crystals having a hygroscopic nature, which make them "not particularly well suited to pharmaceutical formulation as solid dosage forms, because their physical properties, for example their flow characteristics, are unfavorable".
• the process disclosed in the ⁇ 51 patent for the preparation of the alpha-crystalline form comprises suspending imatinib base in ethanol, adding methane sulfonic acid dropwise to the said solution, heating the solution to reflux and filtering; evaporating the filtrate to 50%, filtering off the residue; evaporating the mother liquor to dryness; suspending the residue and filtered material in ethanol; dissolving under reflux conditions by simultaneously adding water; cooling overnight, filtering and drying to obtain alpha-crystalline form.
• This process disclosed for preparing alpha crystalline form not only involves several steps, such as isolation of crude methanesulfonate crystals from the reaction mixture, evaporating ethanol from the reaction mixture and re-suspending the methanesulfonate salt in the same solvent, but also is cumbersome and does not give reproducible results.
• U.S. Patent Application No. 2006/0223816 Al (“the 816 publication”), describe a stable, free-flowing imatinib mesylate alpha-form, which is substantially free of the beta- form.
• This publication describes a process, which comprises: a. mixing imatinib base with an organic solvent selected from ketones, nitriles and cycloalkanes (more particularly methyl ethyl ketone, methyl isobutyl ketone, 4-methylcyclohexanone, cyclohexane, acetonitrile and mixtures thereof); b. heating to dissolve at least a portion of the imatinib base in the organic solvent; c.
• an organic solvent selected from ketones, nitriles and cycloalkanes (more particularly methyl ethyl ketone, methyl isobutyl ketone, 4-methylcyclohexanone, cyclohexane, acetonitrile and mixtures thereof
• U.S. Patent No. US 7,732,601 describe a process for the preparation of alpha-crystal form of imatinib mesylate which involves the use of not more than 0.99 equivalents of methanesulfonic acid, per equivalent of imatinib, in a solvent selected from the group consisting of C 2 -e aliphatic alcohols and mixtures thereof, optionally with the addition of a solvent selected from the group consisting of esters formed from a d- C 4 aliphatic alcohols and lower carboxylic acids and inoculating the reaction mixture with the alpha crystal form.
• U.S. Patent No. US 8,048,883 describe a non-needle alpha 2 form and a process for its preparation comprising Imatinib base in a solvent, the solvent comprising acetone, acetonitrile, a mixture of methanol and isopropanol, or a mixture of isoproponal and water; adding methanesulfonic acid to the resulting suspension at room temperature, refluxing the solution and cooling to room temperature to obtain the alpha 2 form.
• the present invention discloses a reproducible process for preparation of a stable, free flowing, non-hygroscopic crystalline alpha form of imatinib mesylate, which is free of the beta form, and also amenable to scale-up.
• a process for the preparation of stable, free flowing, non-hygroscopic crystalline alpha form of imatinib mesylate, free of the beta form comprising:
• step c) on heating
• step e) Cooling of the reaction mixture obtained in step d) followed by seeding of the clear solution with pure alpha crystalline form of Imatinib mesylate on heating;
• FIG. 1 illustrates a powder X-ray diffraction pattern (XRPD) of imatinib mesylate alpha form prepared according to Example- 1 .
• XRPD powder X-ray diffraction pattern
• FIG. 2 illustrates a characteristic differential scanning calorimeter (DSC)
• thermogram of imatinib mesylate alpha form prepared according to Example-1 .
• FIG. 3 illustrates a characteristic differential scanning calorimeter (DSC)
• thermogram of imatinib mesylate alpha form of the present invention obtained at ambient temperature .
• the present invention discloses a reproducible process for preparation of a stable, free flowing, non-hygroscopic crystalline alpha form of imatinib mesylate, free of the beta form and also amenable to scale-up.
• a stable, free flowing, non-hygroscopic crystalline alpha form of imatinib mesylate can be characterized by its X- ray powder diffraction pattern (XRPD), and Differential Scanning Calorimeter (DSC), as well as by other analytical techniques.
• XRPD X- ray powder diffraction pattern
• DSC Differential Scanning Calorimeter
• the present invention provides a process for the preparation of stable crystalline alpha form of Imatinib mesylate, free of the beta crystalline form of Imatinib mesylate and amenable to scale-up, comprising:
• step c) adding solution of methane sulfonic acid in second organic solvent slowly to the above solution of step c) on heating;
• step d) Cooling of the reaction mixture obtained in step d) followed by seeding of the clear solution with pure alpha crystalline form of Imatinib mesylate on heating; f) Slowly cooling of the reaction mixture;
• imatinib base used in the process of the present invention is known in the art and can be prepared by any known method, for example, imatinib base can be synthesized by the process mentioned in US 7,550,591 .
• the process of providing a clear solution of imatinib base in organic solvent comprises combining the imatinib base with the organic solvent and heating it to the temperature till imatinib base is completely dissolved in the organic solvent as the Imatinib free base is insoluble in most of the organic solvents.
• the solubility of imatinib free base is as follows:
• the temperature suitable for dissolving imatinib base depends on the solvent used and the amount of imatinib base in the solution.
• the reaction is heated at a temperature of at least about 60 °C to about reflux; preferably, the reaction is heated at about 70 °C to about 90 °C, more preferably about 70 °C to about 80 °C.
• the imatinib free base will be soluble on heating and organic solvent chosen should have high boiling point.
• the organic solvent include, but are not limited to dimethyl sulphoxide (DMSO), CrC 4 alcohols such as isopropanol, methanol etc. and mixtures thereof.
• DMSO dimethyl sulphoxide
• CrC 4 alcohols such as isopropanol, methanol etc.
• the organic solvent is mixture of DMSO and isopropanol
• Imatinib base present in an amount of about 1 to about 10 volumes of the solvent, preferably about 2 to about 8 volumes, more preferably about 2 to about 6 volumes, most preferably about 3 to about 5 volumes.
• the methane sulfonic acid in the abovementioned step d) may be used in the range of about 0.9 to about 1 .1 mole per mole of imatinib base, preferably about 1 mole per mole of imatinib base.
• Methane sulfonic acid is added in the form of solution (dissolved in IPA) used for the reaction.
• the quantity of the solvent used to prepare a solution of methane sulfonic acid may range between about 1 and about 10 ml, per gram of imatinib base, preferably about 5 to about 8ml, per gram of imatinib base.
• the rate of addition of methane sulfonic acid solution is critical and it should be such that the reaction mixture always remain a clear solution, otherwise contamination with beta form is possible.
• the temperatures at which methane sulfonic acid can be added to the mass of step c) may range from about 10°C to about reflux temperature of the solvent.
• the addition of methane sulfonic acid can be added at a temperature of about 85 °C to about 105°C, more preferably at about 90 °C to about 95 °C.
• the temperature at which seeding with pure alpha crystalline form of Imatinib mesylate is done is critical as the solution should be clear even after seeding.
• the temperature of seeding may range from about 60 °C to about reflux temperature of the solvent.
• the seeding with alpha form can be added at a temperature of about 75 °C to about 95 °C, more preferably at about 75 °C to about 85 °C.
• step e) cooling the resultant reaction mass can be done at a temperature from about 60 °C or less, more preferably at temperature below 50° or less but in any case temperature should not go below 35 °C otherwise beta crystalline form will also precipitate with alpha crystalline form.
• the resultant imatinib mesylate alpha form formed from the present invention is isolated by filtration.
• substantially pure imatinib mesylate can be obtained with a degree of purity as determined by HPLC greater than or equal to about 99%, preferably greater than or equal to about 99.5% and more preferably greater than or equal to about 99.8%.
• the formation of the beta-form crystals is not observed even after incubating the crystallization mixture, containing the alpha-form crystals, for prolonged periods in the reaction vessel overnight, as determined by using the XRPD and DSC technique.
• Example-1 Preparation of crystalline alpha form of Imatinib mesylate (from a mixture of DMSO +IPA)
• Imatinib free base 80. Og
• DMSO 320ml_
• IPA 720ml_
• Solution of methane sulfonic acid in IPA (15.6g in 80ml_) was added slowly to the clear solution at 90-95 °C.
• the clear solution was cooled to 78-82 ⁇ C followed by seeding with pure alpha crystalline form of Imatinib mesylate (0.8g) at 78- 82 ⁇ C.the mass was slowly cooled to 35-45 °C in 1 .5-2.0 hours. The mass was stirred at 35-45 ⁇ for 1 -1 .5hours. The solid obtained was filtered and washed with IPA under nitrogen atmosphere. The wet product was dried at 45-55 °C under reduced pressure for 10-12 hours to get crystalline alpha form of Imatinib mesylate.
• Hygroscopicity Material is non-hygroscopic at 80% RH
• the XRD is set forth in FIG-1.
• the DSC is set forth in FIG-2.
• Example-2 Preparation of crystalline alpha form of Imatinib mesylate (from a mixture of DMSO +IPA)
• the clear solution was cooled to 78-82 ⁇ C followed by seeding with pure alpha crystalline form of Imatinib mesylate (0.4g) at 78- 82 ⁇ C.the mass was slowly cooled to 35-45 °C in 1 .5-2.0 hours. The mass was stirred at 35-45 ⁇ for 1 -1 .5hours. The solid obtained was filtered and washed with IPA under nitrogen atmosphere. The wet product was dried at 45-55 °C under reduced pressure for 10-12 hours to get crystalline alpha form of Imatinib mesylate.
• Example-3 Preparation of crystalline alpha form of Imatinib mesylate (from a mixture of DMSO +IPA)
• the clear solution was cooled to 78-82 °C followed by seeding with pure alpha crystalline form of Imatinib mesylate (0.4g) at 78- 82 q C.the mass was slowly cooled to 35-45 °C in 1 .5-2.0 hours. The mass was stirred at 35-45 ⁇ ⁇ for 1 -1 .5hours. The solid obtained was filtered and washed with IPA under nitrogen atmosphere. The wet product was dried at 45-55 °C under reduced pressure for 10-12 hours to get crystalline alpha form of Imatinib mesylate.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
• Plural Heterocyclic Compounds (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Oxygen Or Sulfur (AREA)

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Citations (17)

• 2012
  • 2012-08-22 WO PCT/IB2012/054240 patent/WO2013136141A1/en not_active Ceased
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