Process for the preparation of pure gabapentin "Form II"
AssigneeFarchemia S.R.L.
InventorsGabriele Breviglieri, Sergio Contrini, Cinzia Assanelli
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Abstract
Pure gabapentin form II can be directly obtained adding the solution of the corresponding hydrochloride in dry ethanol (from which the inorganic salts have been filtered off) with a tertiary amine and a small amount of water.
Claims10
A process for the preparation of pure gabapentin, in the crystalline form II, starting from gabapentin hydrochloride, characterized in that said hydrochloride is dissolved in dry ethanol, the insoluble inorganic salts are filtered or centrifuged off, the ethanol solution free from the inorganic salts is added with a tertiary amine and a small amount of water, then cooled to 10-20° C., seeded with gabapentin form II, further cooled at +5 to −5° C. and the precipitated gabapentin form II is finally recovered.
A process as claimed in one or more of the above claims, characterized in that the tertiary amine is added in amounts of 1-1.25 mols per mole of hydrochloride.
A process as claimed in any one of the above claims, characterized in that the tertiary amine is N-ethyl-diisopropylamine.
A process as claimed in any one of the above claims, characterized in that the amount of water added to the ethanol solution free from the inorganic salts ranges from 7% to 10% by volume on the solution volume.
A process as claimed in any one of the above claims, characterized in that the solution added with the tertiary amine and water is cooled to about 15° C., seeded with gabapentin form II and, after 4-8 hours at this temperature, is further cooled to about 0° C.
A process as claimed in any one of the above claims, characterized in that the resulting gabapentin form II is further purified by suspension in approx. 10 parts by volume of ethanol containing about 10% by volume of water, heating for about 10-15 minutes at 35-45° C. and standing at room temperature overnight.
Dependencies are inferred from the claim text.