Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
  • C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
  • C07D207/18—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member
  • C07D207/22—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having one double bond between ring members or between a ring member and a non-ring member with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D207/24—Oxygen or sulfur atoms
  • C07D207/26—2-Pyrrolidones
  • C07D207/263—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms
  • C07D207/27—2-Pyrrolidones with only hydrogen atoms or radicals containing only hydrogen and carbon atoms directly attached to other ring carbon atoms with substituted hydrocarbon radicals directly attached to the ring nitrogen atom
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K31/00—Medicinal preparations containing organic active ingredients
  • A61K31/33—Heterocyclic compounds
  • A61K31/395—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins
  • A61K31/40—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with one nitrogen as the only ring hetero atom, e.g. sulpiride, succinimide, tolmetin, buflomedil
  • A61K31/4015—Heterocyclic compounds having nitrogen as a ring hetero atom, e.g. guanethidine or rifamycins having five-membered rings with one nitrogen as the only ring hetero atom, e.g. sulpiride, succinimide, tolmetin, buflomedil having oxo groups directly attached to the heterocyclic ring, e.g. piracetam, ethosuximide
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P25/00—Drugs for disorders of the nervous system
  • A61P25/08—Antiepileptics; Anticonvulsants

Definitions

• levetiracetam is (S)-alpha-ethyl-2-oxo-l-pyrrolidineacetamide and is known from U.S. Patent No. 4,943,639.
• Levetiracetam is used as a protective agent for the treatment and prevention of hypoxic and ischemic type aggressions of the central nervous system. It is also effective in the treatment of epilepsy.
• 4,943,639 discloses the preparation of levetiracetam by reacting (S)-alpha-ethyl-2-oxo-l-pyrrolidineacetic acid successively with alkylhaloformate and with ammonia.
• (S)-alpha-ethyl-2-oxo-l-pyrroiidineacetic acid in turn was obtained by the chemical resolution of racemic ( ⁇ )-alpha-ethyl-2-oxo- 1 - pyrrolidineacetic acid.
• 6,107,492 and 6,124,473 describe the preparation of levetiracetam by optical resolution of the racemic mixture of alpha- ethyl-2-oxo-l-pyrrolidineacetamide through simulated mobile bed chromatography or preparative high performance liquid chromatography.
• WO 01/64637 discloses the preparation of levetiracetam by asymmetric hydrogenation of (Z) or (E)-2-(2- oxotetrahydro-lH-l-pyrrolyl)-2-butenamide, using a chiral catalyst. Summary of the Invention In one aspect there is provided a process for preparing pure levetiracetam having optical purity more than 99.5%.
• the process includes obtaining a solution of crude levetiracetam in one or more solvents; removing undissolved material; and recovering the pure levetiracetam having optical purity more than 99.5% from the solution thereof by the removal of the solvent.
• the solvent may be one or more of ketone, nitrile, hydrocarbon, chlorinated hydrocarbon, ether, cyclic ether or mixtures thereof.
• the ketone may include one or more of acetone, methyl ethyl ketone and methyl isobutyl ketone.
• the nitrile may include acetonitrile.
• the hydrocarbon may include toluene.
• the chlorinated hydrocarbon may include one or more of methylene chloride and ethylene dichloride.
• the ether may include one or more of diethyl ether and diisopropyl ether.
• the cyclic ether may include dioxane and tetrahydrofuran.
• Removing the solvent may include one or more of distillation, distillation under vacuum, filtration, filtration under vacuum, evaporation, decantation and centrifugation. The process may include further drying of the product obtained.
• additional/second solvent may be added to residue obtained after removal of the solvent and it may be cooled before filtration to obtain better yields of the pure levetiracetam.
• additional/second solvent examples include esters such as ethyl acetate, isobutyl acetate and isopropyl acetate; hydrocarbons such as hexane, cyclohexane, toluene and heptane; lower alkyl ethers such as diethyl ether, diisopropyl ether and mixtures thereof.
• the process may produce the pure levetiracetam having optical purity more than 99.5%. In particular, it may produce the pure levetiracetam having optical purity more than 99.8%.
• a pharmaceutical composition that includes a therapeutically effective amount of pure levetiracetam having optical purity more than 99.5%; and one or more pharmaceutically acceptable carriers, excipients or diluents.
• the inventors also have developed pharmaceutical compositions that contain the pure levetiracetam having optical purity more than 99.5% for example, more than 99.8%, in admixture with one or more solid or liquid pharmaceutical diluents, carriers, and/or excipients.
• the levetiracetam may be prepared by the methods known in the literature. In particular, it may be prepared using the reactions and techniques described in U.S. Patent No. 4,943,639; PCT patent application WO 01/64637; and British patent GB 2225322.
• the term "crude levetiracetam” includes levetiracetam having optical purity of not less than 90%. In general, the solution of crude levetiracetam may be obtained by dissolving crude levetiracetam in a suitable solvent.
• such a solution may be obtained directly from a reaction in which levetiracetam is formed.
• the solvent containing crude levetiracetam may be heated to obtain a solution. It can be heated from about 30°C to about reflux temperature of the solvent used, for example from about 30°C to about 100°C.
• the term "obtaining” includes dissolving, slurrying, stirring or a combination thereof.
• the pure levetiracetam may be recovered from the solution by a technique which includes, for example, distillation, distillation under vacuum, filtration, filtration under vacuum, evaporation, decantation, and centrifugation.
• suitable solvent includes any solvent or solvent mixture in which crude levetiracetam is soluble, including, for example, ketone, nitrile, hydrocarbon, chlorinated hydrocarbon and mixtures thereof.
• a suitable ketone includes one or more of acetone, methyl ethyl ketone and methyl isobutyl ketone.
• nitrile include acetonitrile.
• hydrocarbon include toluene and examples of chlorinated hydrocarbons include one or more of methylene chloride and ethylene dichloride.
• ethers include solvents such as diethyl ether and diisopropyl ether and cyclic ethers such as dioxane, tetrahydrofuran.
• the undissolved material may be removed by a technique which includes filtration, filtration under vacuum, centrifugation, and decantation. In general, after removing the undissolved material, the resulting solution may be cooled before recovering the pure levetiracetam. The solution may also be concentrated before cooling. Additional or second solvent may be added to residue obtained after concentration and it may be cooled before filtration to obtain better yields of the pure levetiracetam.
• additional/second solvent examples include esters such as ethyl acetate, isobutyl acetate and isopropyl acetate; hydrocarbons such as hexane, cyclohexane, toluene and heptane; lower alkyl ethers such as diethyl ether, diisopropyl ether and mixtures thereof.
• Example 1 Preparation of pure levetiracetam Crude levetiracetam (123g, optical purity ⁇ 96.00%) was mixed with acetone (2800ml) and stirred at ambient temperature for 60 minutes. The undissolved material was then filtered through hyflo bed and washed with acetone (200ml). The filtrate and washings were combined and concentrated under vacuum at 35 to 40°C to about 240ml of the volume. To the resulting slurry, ethyl acetate (480ml) was charged and stirred for 20 minutes at ambient temperature. The solid so obtained was filtered and washed with ethyl acetate (100ml). It was dried under vacuum at 40 to 45°C till loss on drying was less than 0.5% to give the pure product. Yield: 108g
• Example 2 Preparation of pure levetiracetam Crude levetiracetam (lOOg, optical purity ⁇ 98.48%) was mixed with acetone (2300ml) and stirred at ambient temperature for 60 minutes. The undissolved material was then filtered through hyflo bed and washed with acetone (160ml). The filtrate and washings were combined and concentrated under vacuum at 35 to 40°C to about 200ml. Ethyl acetate (200ml) was then charged into the resulting slurry and stirred for 20 minutes at ambient temperature. The solid so obtained was filtered and washed with ethyl acetate (400ml). The wet solid product was dried under vacuum at 40 to 45°C till loss on drying was less than 0.5% to give the pure product. Yield: 87g
• Example 3 Preparation of pure levetiracetam Crude levetiracetam (36g, optical purity ⁇ 96.00%) was mixed with acetone

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• Engineering & Computer Science (AREA)
• Pain & Pain Management (AREA)
• Epidemiology (AREA)
• Bioinformatics & Cheminformatics (AREA)
• Biomedical Technology (AREA)
• Neurology (AREA)
• Neurosurgery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)

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• 2004
  • 2004-09-02 EP EP04769257A patent/EP1663968A1/de not_active Withdrawn
  • 2004-09-02 WO PCT/IB2004/002850 patent/WO2005023763A1/en not_active Application Discontinuation

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