EP1765767A1 - Process for the preparation of gabapentin - Google Patents

Process for the preparation of gabapentin

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Publication number
EP1765767A1
EP1765767A1 EP05766090A EP05766090A EP1765767A1 EP 1765767 A1 EP1765767 A1 EP 1765767A1 EP 05766090 A EP05766090 A EP 05766090A EP 05766090 A EP05766090 A EP 05766090A EP 1765767 A1 EP1765767 A1 EP 1765767A1
Authority
EP
European Patent Office
Prior art keywords
gabapentin
hydroxide
formula
mixture
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP05766090A
Other languages
German (de)
French (fr)
Inventor
Rafael Garcia
Johannes Ludescher
Jordi Rifa
José Diago
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sandoz AG
Original Assignee
Sandoz AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sandoz AG filed Critical Sandoz AG
Publication of EP1765767A1 publication Critical patent/EP1765767A1/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C227/00—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton
    • C07C227/14—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton from compounds containing already amino and carboxyl groups or derivatives thereof
    • C07C227/16—Preparation of compounds containing amino and carboxyl groups bound to the same carbon skeleton from compounds containing already amino and carboxyl groups or derivatives thereof by reactions not involving the amino or carboxyl groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/14—The ring being saturated

Definitions

  • the present invention relates to a new process for the preparation of gabapentin by the neutralization of the acid addition salt of gabapentin in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide. More particularly the invention relates to a process for the preparation of Gabapentin form II.
  • Gabapentin of formula (1) is the generic name of a well-known anticonvulsant agent, described for example in the Merck Index, 13 th Edition (2001), page 767 (4342).
  • gabapentin 1-(aminomethyl)-1-cyclohexane acetic acid
  • Gapentin has been used for the treatment of cerebral disorders such as epilepsy, hypokinesia, faintness attacks and brain trauma.
  • Commercially available gabapentin currently on the market is an anhydrous crystalline form that, hereinafter, will be referred to as form II.
  • form II anhydrous crystalline form that, hereinafter, will be referred to as form II.
  • Several other gabapentin polymorphic forms have been described in the literature, being the more important gabapentin monohydrate (form I 1 EP0340677) and gabapentin form III (W 098/28255).
  • WO99/18063 discloses a multi step synthesis wherein gabapentin of formula (1) is obtained as a final product after the catalytic hydrogenation of chemical intermediates comprising a cyano group.
  • the involvement of cumbersome multi-step synthesis, high pressure hydrogenation and use of cyanides or other toxic reagents make these processes difficult from the technical point of view.
  • solutions of acid addition salts of gabapentin in water or in short chain alcohols are eluted through ion exchange columns to get solutions of gabapentin of formula (1) in a free amino acid form.
  • the rather long elution time needed, the large volumes of water or alcohols that should be evaporated and the need to introduce a rinse of the column in order to maintain the exchange capacity make these processes difficult to scale up.
  • the neutralization can be carried out with the use of a base (WO98/28255, US5362883, and US53191385).
  • WO98/028255 discloses a process for preparing gabapentin of formula (1) consisting of dissolving gabapentin hydrochloride in a solvent and neutralizing it by addition of an amine in solution, said solvent being chosen in such a way that the amine hydrochloride formed during the neutralization is more soluble therein than the anhydrous gabapentin.
  • a new form of anhydrous gabapentin named form III, is prepared in the neutralization process. It is necessary to reprocess this form III by digestion or recrystallization in another solvent, to be able to prepare the pharmaceutical grade anhydrous gabapentin base, which is named form Il in WO98/028255.
  • This process does not require the use of ion exchange resins, but has the drawback that, unless closely adjusted amounts of neutralizing amine are used, the product obtained may be contaminated with appreciable amounts of the amine used in the neutralization and which have to be removed subsequently from the end product, by additional purification steps. Furthermore, this process also requires the preparation of an intermediate, the so-called form III, which has to be reprocessed, with the corresponding decrease in yield and productivity.
  • US5362883 and US5319135 disclose that gabapentin among other products, may be prepared from the acid addition salts thereof, e.g., from the hydrochloride, by their neutralization with a long list of bases, among which there are the free amines, sodium hydroxide, potassium hydroxide, calcium hydroxide and basic ion exchange resins.
  • bases among which there are the free amines, sodium hydroxide, potassium hydroxide, calcium hydroxide and basic ion exchange resins.
  • Method F the examples (Method F) of said patents only describe the use of the said resins for neutralizing aqueous solutions of gabapentin hydrochloride, i.e., a method corresponding with the one already described for example in the aforementioned patent EP0340677.
  • the obtained gabapentin is contaminated with mineral salts (by-products) insoluble in organic solvents.
  • mineral salts by-products
  • the only way of getting rid of these mineral salts is by adding water, but then the yield decreases due to the high solubility of gabapentin in water.
  • the polymorph of gabapentin which is obtained is the monohydrate (Form I).
  • WO00/001660 discloses a process for the preparation of gabapentin in anhydrous form (i.e. form II), without using monohydrate gabapentin (i.e. form I), by treating an aqueous suspension of gabapentin with 2-methoxyethanol or 2-ethoxyethanol and crystallizing with an alcoholic solvent.
  • this process the isolation of gabapentin monohydrate is avoided since water is eliminated by azeotropic distillation, however big volumes of water should be distilled in order to be removed.
  • the present invention provides a new and straightforward process for the preparation of gabapentin by the neutralization of an acid addition salt of gabapentin in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide.
  • This process avoids the several drawbacks associated with the aforementioned processes; multistep synthesis, isolation of intermediates (monohydrate or crude gabapentin), evaporation of larges volumes of solvents.
  • quaternary ammonium hydroxide as neutralizing agent according to the invention brings the advantage to form by-products (quaternary ammonium salt) that will remain soluble in the reaction organic solvent. Accordingly, the by products could be easily eliminated after filtration and will not contaminate the gabapentin.
  • the object of the present invention is related to a process for the preparation of gabapentin in anhydrous or hydrated form of formula (1),
  • XH represents a mineral acid or a strong organic acid, in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide and
  • a stoichiometric amount of a quaternary ammonium hydroxide is added during the neutralization step (a).
  • the neutralization of an acid addition salt of gabapentin according to the invention can be easily monitored e.g. by measuring the pH of the resulting solution. Accordingly, the exact stoichiometric amount of quaternary ammonium hydroxide can be added for the completion of the reaction.
  • the neutralization is completed when the pH of the solution is between 6.5 and 8.5, preferably between 7.0 and 8.0.
  • the neutralization step (a) comprises the following sub-step: (a1 ) Addition of a quaternary ammonium hydroxide to a solution of an acid addition salt of gabapentin of formula (2) in a first organic solvent, preferably a C1-C6 lower alkyl alcohol or a mixture thereof., preferably at room temperature, (a2) Heating the resulting solution at a temperature from 30 to 68°C, preferably from 55 to 65°C, (a3) Adding, preferably at the same temperature, a second organic solvent, preferably a
  • separation step (b) comprises the filtration followed by the washing of the resulting solid gabapentin of formula (1) with an organic solvent or a mixture thereof. More preferably, the organic solvent is a C1-C6 lower alkyl alcohol or a mixture thereof.
  • the gabapentin of formula (1) prepared according to the invention may be further purified by methods known in the art, such as recrystallization or slurrying the gabapentin in a suitable organic solvent or a mixture thereof.
  • the gabapentin is recrystallized in a C1-C6 lower alkyl alcohol or a mixture thereof.
  • Preferred mineral acid are selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid.
  • the commercially available gabapentin hydrochloride is preferred as starting material according to the invention.
  • Other acid addition salts of gabapentin of formula (2) can be prepared for example according to WO03/089403 or from gabapentin monoamide as described in WO 03/070683.
  • Preferred strong organic acids are selected from the group consisting of paratoluensulphonic acid and formic acid.
  • the quaternary ammonium hydroxide is of formula (3)
  • R-i, R 2 , R 3 and R 4 represents each independently a C1-C6 alkyl; a benzyl; an aryl, particularly a phenyl; a substituted C1-C6 alkyl or a substituted aryl.
  • Particularly preferred quaternary ammonium hydroxide are selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, benzyltrimethylammonium hydroxide and benzyltriethylammonium hydroxide.
  • tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide All those preferred quaternary ammonium hydroxide are commercially available.
  • the quaternary ammonium salt is used in solid form or dissolved in an organic solvent or mixture thereof, preferably in alcoholic solvents or mixture thereof.
  • Preferred alcoholic solvents used in the neutralization and in the isolation step are C1-C6 alkyl alcohols solvents or mixture thereof.
  • Preferred C1-C6 alkyl alcohols include, but are not limited to, methanol, ethanol, 2-propanol (isopropanol), butanol (such as n-butanol, isobutanol, and t-butanol) and isoamyl alcohol (isopentanol) or a mixture thereof.
  • Preferred C1-C6 alkyl alcohols include methanol, ethanol, isopropanol or a mixture thereof.
  • C1-C6 alkyl alcohol solvent of the neutralizing step (a) and the isolating step (b) is selected from the group consisting of methanol, ethanol and isopropanol or a mixture thereof.
  • methanol, isopropanol or a mixture thereof are particularly preferred in the separating step (b) according to the invention.
  • Any other polymorph or hydrate of gabapentin of formula (1) can also be isolated as end product by using specific ratio of organic solvents or mixture thereof as disclosed in the prior art.
  • gabapentin form III is isolated if the product is crystallized from isopropanol and gabapentin monohydrate could be obtained if water is used.
  • gabapentin of formula (1) isolated after filtration and washing without any further purification gives an assay by HPLC higher than 99% with a content of lactam lower than 0.1 %.
  • the isolation yield is between 70 and 80%.
  • a second crop can be isolated from the mother liquors giving an overall yield higher than 90%. Good results are obtained by isolating gabapentin hydrochloride from the mother liquors.
  • Example 1 Preparation of gabapentin form Il from gabapentin hydrochloride using tetramethylammonium hydroxide in solid form
  • Example 2 Preparation of gabapentin form Il from gabapentin hydrochloride using tetrabutylammonium hydroxide.
  • the yield of the first crop is 76%. Assay by HPLC: higher than 99%. Lactam content below

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

The present invention relates to a new process for the preparation of gabapentin by the neutralization of an acid addition salt of gabapentin in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide.

Description

Process for the preparation of Gabapentin
Field of the Invention
The present invention relates to a new process for the preparation of gabapentin by the neutralization of the acid addition salt of gabapentin in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide. More particularly the invention relates to a process for the preparation of Gabapentin form II.
Background of the Invention
Gabapentin of formula (1), is the generic name of a well-known anticonvulsant agent, described for example in the Merck Index, 13th Edition (2001), page 767 (4342).
1-(aminomethyl)-1-cyclohexane acetic acid (Gabapentin) has been used for the treatment of cerebral disorders such as epilepsy, hypokinesia, faintness attacks and brain trauma. Commercially available gabapentin currently on the market is an anhydrous crystalline form that, hereinafter, will be referred to as form II. Several other gabapentin polymorphic forms have been described in the literature, being the more important gabapentin monohydrate (form I1 EP0340677) and gabapentin form III (W 098/28255).
Many processes for the preparation of gabapentin have been hitherto described in the literature.
For example, WO99/18063 discloses a multi step synthesis wherein gabapentin of formula (1) is obtained as a final product after the catalytic hydrogenation of chemical intermediates comprising a cyano group. The involvement of cumbersome multi-step synthesis, high pressure hydrogenation and use of cyanides or other toxic reagents make these processes difficult from the technical point of view.
However, most of the reported synthesis proceed through the intermediate of an acid addition salt of gabapentin which is finally neutralized to gabapentin of formula (1). This neutralization can be carried out with the use of ion exchange columns (US03/009055, WO02/074727, US5319135, US5693845, US5362883, EP0432504, EPO414274, EP0414262, WO03/089403, WO02/034709, WO00/064857, US4024175, and EP0340677). In this neutralization process, solutions of acid addition salts of gabapentin in water or in short chain alcohols are eluted through ion exchange columns to get solutions of gabapentin of formula (1) in a free amino acid form. The rather long elution time needed, the large volumes of water or alcohols that should be evaporated and the need to introduce a rinse of the column in order to maintain the exchange capacity make these processes difficult to scale up.
In other cases, the neutralization can be carried out with the use of a base (WO98/28255, US5362883, and US53191385).
WO98/028255 discloses a process for preparing gabapentin of formula (1) consisting of dissolving gabapentin hydrochloride in a solvent and neutralizing it by addition of an amine in solution, said solvent being chosen in such a way that the amine hydrochloride formed during the neutralization is more soluble therein than the anhydrous gabapentin. In accordance with WO98/028255, a new form of anhydrous gabapentin, named form III, is prepared in the neutralization process. It is necessary to reprocess this form III by digestion or recrystallization in another solvent, to be able to prepare the pharmaceutical grade anhydrous gabapentin base, which is named form Il in WO98/028255. This process does not require the use of ion exchange resins, but has the drawback that, unless closely adjusted amounts of neutralizing amine are used, the product obtained may be contaminated with appreciable amounts of the amine used in the neutralization and which have to be removed subsequently from the end product, by additional purification steps. Furthermore, this process also requires the preparation of an intermediate, the so-called form III, which has to be reprocessed, with the corresponding decrease in yield and productivity.
US5362883 and US5319135 disclose that gabapentin among other products, may be prepared from the acid addition salts thereof, e.g., from the hydrochloride, by their neutralization with a long list of bases, among which there are the free amines, sodium hydroxide, potassium hydroxide, calcium hydroxide and basic ion exchange resins. However, the examples (Method F) of said patents only describe the use of the said resins for neutralizing aqueous solutions of gabapentin hydrochloride, i.e., a method corresponding with the one already described for example in the aforementioned patent EP0340677. If sodium hydroxide, potassium hydroxide or calcium hydroxide are used as neutralizing agent, the obtained gabapentin is contaminated with mineral salts (by-products) insoluble in organic solvents. The only way of getting rid of these mineral salts is by adding water, but then the yield decreases due to the high solubility of gabapentin in water. In addition, since water is used, the polymorph of gabapentin which is obtained is the monohydrate (Form I).
Finally, WO00/001660 discloses a process for the preparation of gabapentin in anhydrous form (i.e. form II), without using monohydrate gabapentin (i.e. form I), by treating an aqueous suspension of gabapentin with 2-methoxyethanol or 2-ethoxyethanol and crystallizing with an alcoholic solvent. In this process, the isolation of gabapentin monohydrate is avoided since water is eliminated by azeotropic distillation, however big volumes of water should be distilled in order to be removed.
It would be therefore desirable to develop alternative processes for a more straightforward preparation of gabapentin, allowing the industrial preparation of this product to be simplified and, therewith, the production costs to be reduced.
Summary of the invention
The present invention provides a new and straightforward process for the preparation of gabapentin by the neutralization of an acid addition salt of gabapentin in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide.
This process avoids the several drawbacks associated with the aforementioned processes; multistep synthesis, isolation of intermediates (monohydrate or crude gabapentin), evaporation of larges volumes of solvents.
The use of a quaternary ammonium hydroxide as neutralizing agent according to the invention brings the advantage to form by-products (quaternary ammonium salt) that will remain soluble in the reaction organic solvent. Accordingly, the by products could be easily eliminated after filtration and will not contaminate the gabapentin.
Description of the Invention
The object of the present invention is related to a process for the preparation of gabapentin in anhydrous or hydrated form of formula (1),
comprising the following steps:
(a) neutralizing an acid addition salt of gabapentin of formula (2)
wherein XH represents a mineral acid or a strong organic acid, in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide and,
(b) separating the gabapentin of formula (1 ) from the reaction mixture.
Preferably, a stoichiometric amount of a quaternary ammonium hydroxide is added during the neutralization step (a). The neutralization of an acid addition salt of gabapentin according to the invention can be easily monitored e.g. by measuring the pH of the resulting solution. Accordingly, the exact stoichiometric amount of quaternary ammonium hydroxide can be added for the completion of the reaction. Generally the neutralization is completed when the pH of the solution is between 6.5 and 8.5, preferably between 7.0 and 8.0.
Preferably the neutralization step (a) comprises the following sub-step: (a1 ) Addition of a quaternary ammonium hydroxide to a solution of an acid addition salt of gabapentin of formula (2) in a first organic solvent, preferably a C1-C6 lower alkyl alcohol or a mixture thereof., preferably at room temperature, (a2) Heating the resulting solution at a temperature from 30 to 68°C, preferably from 55 to 65°C, (a3) Adding, preferably at the same temperature, a second organic solvent, preferably a
C1-C6 lower alkyl alcohol or a mixture thereof, optionally distilling off a part of the solvent,
(a4) Cooling the mixture to room temperature, preferably in one hour and, (a5) Cooling the suspension, preferably to a temperature from -15 to O0C, more preferably from -10 to 00C and preferably maintained this temperature for 1 hour. Preferably, separation step (b) comprises the filtration followed by the washing of the resulting solid gabapentin of formula (1) with an organic solvent or a mixture thereof. More preferably, the organic solvent is a C1-C6 lower alkyl alcohol or a mixture thereof.
The gabapentin of formula (1) prepared according to the invention may be further purified by methods known in the art, such as recrystallization or slurrying the gabapentin in a suitable organic solvent or a mixture thereof. Preferably, the gabapentin is recrystallized in a C1-C6 lower alkyl alcohol or a mixture thereof.
Preferred mineral acid are selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrobromic acid. The commercially available gabapentin hydrochloride is preferred as starting material according to the invention. Other acid addition salts of gabapentin of formula (2) can be prepared for example according to WO03/089403 or from gabapentin monoamide as described in WO 03/070683.
Preferred strong organic acids are selected from the group consisting of paratoluensulphonic acid and formic acid.
Preferably, the quaternary ammonium hydroxide is of formula (3)
NR1R2R3R4 +OH" (3)
wherein R-i, R2, R3 and R4 represents each independently a C1-C6 alkyl; a benzyl; an aryl, particularly a phenyl; a substituted C1-C6 alkyl or a substituted aryl.
Particularly preferred quaternary ammonium hydroxide are selected from the group consisting of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, benzyltrimethylammonium hydroxide and benzyltriethylammonium hydroxide. Especially preferred are tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide. All those preferred quaternary ammonium hydroxide are commercially available. In one prefer embodiment of the invention the quaternary ammonium salt is used in solid form or dissolved in an organic solvent or mixture thereof, preferably in alcoholic solvents or mixture thereof.
Preferred alcoholic solvents used in the neutralization and in the isolation step are C1-C6 alkyl alcohols solvents or mixture thereof. Preferred C1-C6 alkyl alcohols include, but are not limited to, methanol, ethanol, 2-propanol (isopropanol), butanol (such as n-butanol, isobutanol, and t-butanol) and isoamyl alcohol (isopentanol) or a mixture thereof. Preferred C1-C6 alkyl alcohols include methanol, ethanol, isopropanol or a mixture thereof.
Preferably, C1-C6 alkyl alcohol solvent of the neutralizing step (a) and the isolating step (b) is selected from the group consisting of methanol, ethanol and isopropanol or a mixture thereof.
In order to isolate the gabapentin polymorphic form Il (commercially available form) methanol, isopropanol or a mixture thereof are particularly preferred in the separating step (b) according to the invention.
Any other polymorph or hydrate of gabapentin of formula (1) can also be isolated as end product by using specific ratio of organic solvents or mixture thereof as disclosed in the prior art. For example gabapentin form III is isolated if the product is crystallized from isopropanol and gabapentin monohydrate could be obtained if water is used.
As mentioned previously, the quaternary ammonium salt formed during the neutralization step remains soluble in the reaction organic solvent and is easily eliminated after filtration. Accordingly, gabapentin of formula (1) isolated after filtration and washing without any further purification gives an assay by HPLC higher than 99% with a content of lactam lower than 0.1 %. The isolation yield is between 70 and 80%. A second crop can be isolated from the mother liquors giving an overall yield higher than 90%. Good results are obtained by isolating gabapentin hydrochloride from the mother liquors.
This invention will be better understood from the Examples that follow. However, these examples illustrate but do not limit the invention. Those skilled in the art will readily appreciate that the specific process and results discussed are merely illustrative of the invention as described more fully in the claims that follow thereafter.
The following non-limiting examples illustrate further aspects of the invention. Example 1 : Preparation of gabapentin form Il from gabapentin hydrochloride using tetramethylammonium hydroxide in solid form
25.00 g of tetramethylammonium hydroxide pentahydrate are added to a solution of 28.55 g of gabapentin hydrochloride in 148 mL of methanol at room temperature. The resulting solution is heated at 55-65°C and isopropyl alcohol (148 mL) is slowly added while maintaining this temperature. Finally, the mixture is cooling to room temperature in one hour and afterwards the suspension is additionally cooled to -8/-100C and maintained at this temperature for 1 hour. The resulting crystals are collected by filtration, washed with 30 mL of methanol/isopropanol (1 :1) cooled at -100C and dried at 500C for two hours to obtain 16.50 g of gabapentin form Il (yield 71.6%). Assay by HPLC: higher than 99%. Lactam content below 0.1%. X-ray powder diffraction scan and FTIR spectrum are identical to those obtained for commercially available gabapentin form Il prepared according to prior art. From the mother liquors a second crop of gabapentin (for example, in form of gabapentin hydrochloride) is isolated giving an overall yield higher than 90%.
Example 2: Preparation of gabapentin form Il from gabapentin hydrochloride using tetrabutylammonium hydroxide.
Following example 1 but using 174 mL of a solution of tetrabutylammonium hydroxide in methanol (25% w/w) instead of 25.00 g of tetramethylammonium hydroxide pentahydrate.
The yield of the first crop is 76%. Assay by HPLC: higher than 99%. Lactam content below
0.1%.
' Example 3: Preparation of gabapentin form Il from gabapentin hydrochloride using tetraethylammonium hydroxide
Following example 1 but using 97 mL of a solution of tetraethylammonium hydroxide in methanol (25% w/w) instead of 25.00 g of tetramethylammonium hydroxide pentahydrate. The yield of the first crop is 71 %. Assay by HPLC: higher than 99%. Lactam content below 0.1 %.

Claims

1. A process for preparing gabapentin in an anhydrous or hydrated form of formula (1),
comprising the following steps:
(a) neutralizing an acid addition salt of gabapentin of formula (2)
wherein XH represents a mineral acid or a strong organic acid, in an organic solvent or a mixture of organic solvents with a quaternary ammonium hydroxide and, (b) separating the gabapentin of formula (1) from the reaction mixture.
2. A process according to claim 1 , wherein the acid addition salt of gabapentin of formula (2) is gabapentin hydrochloride.
3. A process according to claims 1 or 2, wherein the quaternary ammonium hydroxide is of formula (3)
NR1R2R3R4 +OH" (3)
wherein Ri, R2, R3 and R4 represents each independently a C1-C6 alkyl; a benzyl; an aryl; a substituted C1-C6 alkyl or a substituted aryl.
4. A process according to claims 1 to 3, wherein the quaternary ammonium hydroxide is selected from the group consisting of tetramethylammonium hydroxide, tetrabutylammonium hydroxide, tetrapropylammonium hydroxide, tetraethylammonium hydroxide, benzyltrimethylammonium hydroxide and benzyltriethylammonium hydroxide.
5. A process according to claims 1 to 4, wherein the organic solvents of the neutralizing step (a) and the isolating step (b) are C1-C6 alkyl alcohols solvents or mixture thereof.
6. A process according to claim 5, wherein the C1-C6 alkyl alcohol solvent of the neutralizing step (a) and the isolating step (b) is selected from the group consisting of methanol, ethanol and isopropanol or a mixture of thereof.
7. A process according to claim 6, wherein the C1-C6 alkyl alcohol of the separating step (b) is selected from the group consisting of methanol, isopropanol or a mixture of thereof.
8. A process according to claim 7, wherein the isolated gabapentin of formula (1) is the polymorphic form II.
EP05766090A 2004-07-05 2005-07-04 Process for the preparation of gabapentin Withdrawn EP1765767A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GBGB0415076.9A GB0415076D0 (en) 2004-07-05 2004-07-05 Process for the preparation of gabapentin
PCT/EP2005/007202 WO2006002972A1 (en) 2004-07-05 2005-07-04 Process for the preparation of gabapentin

Publications (1)

Publication Number Publication Date
EP1765767A1 true EP1765767A1 (en) 2007-03-28

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Country Status (3)

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Publication number Priority date Publication date Assignee Title
WO2008106217A1 (en) * 2007-02-28 2008-09-04 Teva Pharmaceutical Industries Ltd. Preparation of gabapentin by liquid-liquid extraction
JP2011509267A (en) * 2008-01-10 2011-03-24 ニコックス エス エイ Composition comprising a nitrooxy derivative of acetaminophen and an anticonvulsant for healing neuropathic pain

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GB707903A (en) * 1951-05-10 1954-04-28 British Drug Houses Ltd Improvements in or relating to the resolution of isomeric mixtures of 1-p-nitrophenyl-2-aminopropane-1,3-diol
IL119890A (en) * 1996-12-24 2002-03-10 Teva Pharma Gabapentin form iii and preparation of gabapentin form ii
US6255526B1 (en) * 1996-12-24 2001-07-03 Teva Pharmaceutical Industries Ltd. Preparation of gabapentin
ITMI20012750A1 (en) * 2001-12-21 2003-06-21 Procos Spa PROCESS FOR THE PRODUCTION OF 1- (AMINOMETHYL) -CYCLOHEXYL-ACETIC ACID IN PURE FORM
AU2002246303A1 (en) * 2002-02-22 2003-09-09 Shasun Chemicals And Drugs Limited Preparation of new mineral acid addition salts of gabapentin
EP1636163A4 (en) * 2003-05-19 2006-08-09 Shasun Chemicals And Drugs Ltd Process for the preparation of gabapentin
WO2004110981A1 (en) * 2003-06-12 2004-12-23 Matrix Laboratories Ltd A process for the preparation of gabapentin form-ii

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