Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
  • C07D487/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains two hetero rings
  • C07D487/04—Ortho-condensed systems
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
  • C07F5/00—Compounds containing elements of Groups 3 or 13 of the Periodic Table
  • C07F5/003—Compounds containing elements of Groups 3 or 13 of the Periodic Table without C-Metal linkages
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D471/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00
  • C07D471/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, at least one ring being a six-membered ring with one nitrogen atom, not provided for by groups C07D451/00 - C07D463/00 in which the condensed system contains two hetero rings
  • C07D471/08—Bridged systems
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K49/00—Preparations for testing in vivo
  • A61K49/06—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
  • A61K49/08—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by the carrier
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K49/00—Preparations for testing in vivo
  • A61K49/06—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
  • A61K49/08—Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations characterised by the carrier
  • A61K49/10—Organic compounds
  • A61K49/101—Organic compounds the carrier being a complex-forming compound able to form MRI-active complexes with paramagnetic metals
  • A61K49/106—Organic compounds the carrier being a complex-forming compound able to form MRI-active complexes with paramagnetic metals the complex-forming compound being cyclic, e.g. DOTA

Definitions

• the present invention relates to a new process for the preparation and purification of a complex of gadolinium and a chelating ligand derived from PCTA, which makes it possible to obtain, in a preferential manner, the stereoisomers of said complex which exhibit physical properties. particularly interesting chemicals for applications as a contrast agent in the field of medical imaging, in particular for Magnetic Resonance Imaging.
• the present invention also relates to the diastereoisomerically enriched complex as such, a composition comprising said complex, as well as a process for preparing the corresponding chelating ligand by decomplexing said complex, and the ligand as such.
• contrast agents are known based on lanthanide chelates (paramagnetic metal), in particular gadolinium (Gd), described for example in US Pat. No. 4,647,447. These products are often grouped together under the term GBCA (Gadolinium-based Contrast Agent, gadolinium-based contrast products).
• Gd gadolinium
• macrocyclic chelates such as meglumine gadoterate based on DOTA (1, 4,7, 10-tetraazacyclododecane- N, N ', N ", N"' - tetraacetic acid), gadobutrol based on D03A-butrol, gadoteridol based on HPD03A, as well as linear chelates, in particular based on DTPA (diethylenetriaminepentaacetic acid) or DTPA-BMA (gadodiamide ligand).
• DOTA diethylenetriaminepentaacetic acid
• DTPA-BMA gadodiamide ligand
• the complexes of chelating ligands derived from PCTA described in document EP 1 931 673 have in particular the advantage of being relatively easy to chemically synthesize and, moreover, of having a relaxivity greater than other GBCA (relaxivity which can range up to 11- 12 mM Ls 1 in water) currently on the market,
• thermodynamics Ktherm thermodynamics Ktherm
• NSF Neurogenic Systemic Fibrosis
• a first strategy for limiting the risk of lanthanide release in the body thus consists in opting for complexes which are distinguished by the highest possible thermodynamic and / or kinetic stabilities. In fact, the more stable the complex, the more the quantity of lanthanide released over time will be limited.
• lanthanide chelates in particular gadolinium
• Document US Pat. No. 5,876,695 dating back more than thirty years, reports, for example, formulations comprising, in addition to the chelate of lanthanide, an additional complexing agent, intended to prevent an unwanted in-vivo release of the lanthanide, by complexing the lanthanide (metal ion Gd 3+ ) released.
• the additional chelating agent can be introduced into the formulation either in its free form or in the form of a weak complex, typically of calcium, sodium, zinc or magnesium.
• the complex which it forms with the released lanthanide is less stable than the active complex, so as to prevent a transligation reaction between the active complex. and the additional chelate, which would in particular have the effect of completely consuming said additional ligand, which could therefore no longer trap the lanthanide released.
• This risk of consuming the additional chelating agent by transligation is more pronounced when it is added in free form than in the form of a calcium complex, for example.
• the complexes of chelating ligands derived from PCTA comprising a structure of pyclene type described in document EP 1 931 673, while having good kinetic stability, generally have a lower thermodynamic constant than that of the complexes of other macrocycles. cyclene derivatives.
• the complex of formula (II) corresponds to several stereoisomers, in particular due to the presence of the three asymmetric carbon atoms located in position a on the side chains of the complex, relative to the nitrogen atoms of the macrocycle onto which said side chains are grafted. These three asymmetric carbons are marked with an asterisk (*) in formula (II) shown above.
• the aminopropanediol groups of the side chains of the complex of formula (II) also contain an asymmetric carbon.
• the complex of formula (II) comprises a total of 6 asymmetric carbons, and therefore exists in the form of 64 stereoisomers of configuration.
• the only source of stereoisomerism considered for a given side chain will be, for the sake of simplicity, that corresponding to the asymmetric carbon carrying the carboxylate group, marked with an asterisk (*) in formula (II ) shown above.
• the complex of formula (II) exists in the form of 8 families of stereoisomers, hereinafter referred to as II-RRR, II-SSS, II- RRS, II-SSR, II-RSS, II-SRR, II-RSR and II-SRS. More precisely, according to the usual stereochemical nomenclature, the complex of formula (II) exists in the form of 8 families of diastereoisomers.
• iso4 which comprises a mixture of the ll-RRR and ll-SSS isomers of formulas (ll-RRR ) and (II-SSS) shown below, proves to be the most interesting as a contrast agent for medical imaging.
• Table 1 decomplexation kinetics of the groups of iso1 to iso4 isomers
• gadobutrol or gadoterate, macrocyclic complexes of gadolinium respectively exhibit a kinetic inertia of 18 hours and 4 days under the same conditions, while the Linear gadolinium complexes like gadodiamide or gadopentetate dissociate instantly.
• iso4 is more stable from a chemical point of view than iso3 in particular.
• the amide functions of the complex of formula (II) are in fact capable of being hydrolyzed.
• the hydrolysis reaction of an amide function (equation 3) results in the formation of a dicoupled impurity, which is accompanied by the release of 3-amino-1, 2-propanediol.
• the inventors studied the kinetics of the hydrolysis reaction of the complex of formula (II) in aqueous solution at pH 13, and observed that the amide functions of iso4 are more stable with respect to hydrolysis than those of iso3.
• the inventors have succeeded in developing a new process for the preparation and purification of the complex of formula (II) making it possible to preferentially obtain the II-RRR and II-SSS diastereomers of said complex, which exhibit particularly advantageous physicochemical properties.
• the method according to the invention comprises an isomeric enrichment step, by conversion of the less stable stereoisomers to the most stable stereoisomers, which, surprisingly, while being carried out on the hexaacid intermediate complex and not on the final complex , makes it possible to obtain overwhelmingly the most stable isomers of the complex of formula (II).
• the process for preparing the complex of formula (II) developed by the inventors is based on a step of isomeric enrichment of the gadolinium complex of intermediate hexaacid of formula (I) shown below:
• the complex of formula (I) corresponds to several stereoisomers, due to the presence of the three asymmetric carbon atoms located in position a on the side chains of the complex, relative to the nitrogen atoms of the macrocycle onto which said side chains are grafted. . These three asymmetric carbons are marked with an asterisk (*) in formula (I) shown above.
• each of the 3 asymmetric carbons bearing a carboxylate function can be of absolute configuration R or S
• the complex of formula (I) exists in the form of 8 stereoisomers, hereinafter referred to as l-RRR, l-SSS, l -RRS, l-SSR, l-RSS, l-SRR, I-RSR and l-SRS. More precisely, according to the usual stereochemical nomenclature, the complex of formula (I) exists in the form of 4 pairs of enantiomers, diastereomers between them.
• HPLC high performance liquid chromatography
• UHPLC ultra high performance liquid chromatography
• IsoD crystallizes in water.
• X-ray diffraction analyzes enabled the inventors to determine the crystal structure of this group of isomers, and thus to discover that it comprises the l-RRR and l-SSS diastereomers of the complex of formula (I), of formulas (l-RRR) and (l-SSS) shown below.
• the isomeric enrichment step of the process of the invention aims to enrich the intermediate hexaacid gadolinium complex of formula (I) in isoD.
• the synthesis of the complex of formula (II) involves in particular a conversion of the carboxylic acid functions of the intermediate hexaacid complex of formula (I) into an amide function.
• This amidification reaction does not modify the absolute configuration of the three asymmetric carbon atoms of the complex of formula (I).
• the amidification reaction is carried out on the hexaacid complex of formula (I) enriched in isoD previously obtained, it makes it possible to obtain the complex of formula (II) enriched in iso4.
• the purification process developed by the inventors makes it possible, when it is carried out following the process for preparing the complex of formula (II) mentioned above, to obtain the complex of formula (II) with a profile isomeric optimized, but also a significantly improved impurity profile.
• This diastereomerically enriched and purified complex exhibiting improved stability can therefore be formulated with a free macrocyclic ligand, such as free DOTA, in place of a DOTA calcium complex, the use of which was recommended in document WO 2014. / 174120.
• a free macrocyclic ligand such as free DOTA
• the use of free DOTA presents in particular an advantage from an industrial point of view, in that it makes it possible to eliminate a step of the process for synthesizing the formulation as described in document WO 2014/174120, namely addition of CaCL.
• the present invention therefore relates firstly to a complex of formula (II):
• diastereoisomeric excess is understood to denote, in the context of the present invention, and as regards the complex of formula (II), the fact that said complex is predominantly present in the form of an isomer or a group of isomers selected from II-RRR, II-SSS, II-RRS, II-SSR, II-RSS, II-SRR, II-RSR and II-SRS diastereoisomers.
• Said diastereoisomeric excess is expressed as a percentage and corresponds to the amount represented by the isomer or the majority group of isomers relative to the total amount of the complex of formula (II). It is understood that this percentage can be both molar and mass, insofar as isomers have, by definition, the same molar mass.
• the complex of formula (II) according to the invention has at least 85%, in particular at least 90%, in particular at least 92%, preferably at least 94%, advantageously at least 97%, more advantageously at minus 99% of the diastereomeric excess comprising the mixture of 11-RRR and 11-SSS isomers.
• said diastereoisomeric excess consists of at least 70%, in particular at least 80%, advantageously at least 90%, preferably at least 95% of the mixture of isomers II-RRR and II- SSS.
• said diastereoisomeric excess consists of the mixture of II-RRR and II-SSS isomers.
• mixture of II-RRR and II-SSS isomers also covers, by extension, the case where only one of the isomers, whether it is II-RRR or II-SSS, is present.
• mixture of II-RRR and 11-SSS isomers preferentially denotes all of the cases where each of the II-RRR and II-SSS isomers is present in a variable but not zero amount.
• the II-RRR and II-SSS isomers are present in said mixture in a ratio of between 65/35 and 35/65, in particular between 60/40 and 40/60, in particular between 55 / 45 and 45/55.
• the II-RRR and II-SSS isomers are present in the mixture in a 50/50 ratio.
• the diastereoisomeric excess as defined above corresponds to peak 4 of the UHPLC trace (that is to say the fourth mass of isomers in the order of elution and corresponding to iso4), characterized by a retention time of between 6.0 and 6.6 minutes, typically about 6.3 minutes, said trace being obtained by implementing the UHPLC method described below.
• UHPLC trace is meant, within the meaning of the present invention, the profile of the concentrations measured by the detector after passage and separation of a mixture of compounds (in the case of isomers of a compound) on a phase. stationary as a function of time for a given composition and eluent flow rate.
• the UHPLC trace consists of different peaks or clumps characteristic of the compound or of the mixture of compounds analyzed.
• UHPLC method CORTECS® UPLC T3 150 x 2.1 mm - 1.6 ⁇ m column from Waters.
• This is a reversed phase UPLC column with spherical particles consisting of a core, preferably very hard, of silica surrounded by a porous silica with a trifunctional C18 (octadecyl) grafting, and the silanols of which have been treated with styling agents (end-capped). It is further characterized by a length of 150 mm, an internal diameter of 2.1 mm, a particle size of 1.6 ⁇ m, a porosity of 120 ⁇ and a carbon content of 4.7%.
• the stationary phase used must be compatible with the aqueous mobile phases. analysis conditions:
• composition comprising the complex of formula (II)
• the present invention relates secondly to a composition
• a composition comprising:
• macrocyclic ligand or “macrocyclic chelate” can be used interchangeably.
• the term “macrocycle” denotes a ring typically comprising at least 9 atoms, whether they are carbon atoms or heteroatoms, and the "macrocyclic ligand” or “macrocyclic chelate” is a polydentate, at least bidentate, ligand.
• the term “free macrocyclic ligand” means the macrocyclic ligand in free form, that is to say not complexed, in particular with metals - including lanthanides and actinides - or with cations. alkaline earth metals such as calcium or magnesium.
• the free macrocyclic ligand is not in the form of a complex with gadolinium, and is not introduced into the composition in the form of a weak complex, typically of calcium, sodium, zinc or magnesium, as described in document US Pat. No. 5,876,695, the presence of said cations in the trace state in the composition, and therefore of the corresponding complexes not however being excluded.
• the complex of formula (II) present in the composition of the invention has at least 85%, in particular at least 90%, in particular at least 92%, more particularly at least 94%, preferably at least 97%, preferably at least 99%, of the diastereomeric excess comprising the mixture of isomers II-RRR and II-SSS.
• said diastereoisomeric excess consists of at least 70%, in particular at least 80%, advantageously at least 90%, preferably at least 95% of the mixture of isomers II-RRR and II- SSS.
• said diastereoisomeric excess consists of the mixture of II-RRR and II-SSS isomers.
• mixture of II-RRR and II-SSS isomers also covers, by extension, the case where only one of the isomers, whether it is II-RRR or II-SSS, is present.
• mixture of II-RRR and 11-SSS isomers preferentially denotes all of the cases where each of the II-RRR and II-SSS isomers is present in a variable but not zero amount.
• the II-RRR and II-SSS isomers are present in said mixture in a ratio of between 65/35 and 35/65, in particular between 60/40 and 40/60, especially between 55/45 and 45/55.
• the II-RRR and II-SSS isomers are present in the mixture in a 50/50 ratio.
• the composition according to the invention has a free gadolinium concentration of less than 1 ppm (m / v), preferably less than 0.5 ppm (m / v).
• Gd gadolinium
• Gd 3+ gadolinium oxide
• free Gd denotes the uncomplexed forms of gadolinium, and preferably available for complexation. This is typically the Gd 3+ ion dissolved in water. By extension, it can also be a source of free gadolinium, such as gadolinium chloride (GdCL) or gadolinium oxide (Gd 2 0 3 ).
• GdCL gadolinium chloride
• Gd 2 0 3 gadolinium oxide
• Gadolinium in free form is typically measured by colorimetric assay, generally xylenol orange or Arsenazo (III). In the absence of a metal ion (such as gadolinium), these indicators have a specific color: at acidic pH, xylenol orange has a yellow color, while Arsenazo has a pink color. In the presence of gadolinium, their color turns purple.
• the free gadolinium in the solution via a back-assay, for example using EDTA as the "weak" chelate of Gadolinium.
• the colored indicator is added until a purple color is obtained.
• EDTA a gadolinium ligand is added to the mixture dropwise. Since EDTA is a stronger complexing agent than the colored indicator, gadolinium will change ligand and will leave the colored indicator to preferentially complex to EDTA. The colored indicator will therefore gradually return to its uncomplexed form.
• the colored indicator When the amount of EDTA added equals the initial amount of free Gd, the colored indicator is completely in its free form and the solution "turns" yellow.
• the amount of EDTA added being known, this makes it possible to know the initial quantity of free Gd in the solution to be determined.
• the pH of the sample to be assayed is adjusted to be between 4 and 8.
• the pH of the sample is acidic, and in particular less than 4, the pH is advantageously adjusted by adding d a base, then the measurement of the free Gd is carried out on the sample at the adjusted pH.
• the composition according to the invention thus exhibits stability over time, that is to say that its composition remains in conformity with the specifications in terms of concentration of free gadolinium (in particular its concentration of free Gd remains less than 1 ppm (m / v)), over a period of at least 3 years, preferably at least 4 years or more preferably at least 5 years, in particular in terms of free paramagnetic metal content. According to ICH guidelines, an observation of this stability for 6 months at 40 ° C is considered a good indication of a stability of 3 years at 25 ° C.
• the composition according to the invention has a concentration of between 0.01 and 1.5 mol.L 1 , preferably between 0.2 and 0.7 mol.L 1 , more preferably between 0, 3 and 0.6 mol.L 1 in complex of formula (II) described above.
• the complex of formula (II) is assayed by methods known to those skilled in the art. It can in particular be assayed after mineralization and assay of the total gadolinium present in the composition, by optical emission spectrometry (also called ICP-AES or ICP Atomic Emission Spectrometry).
• optical emission spectrometry also called ICP-AES or ICP Atomic Emission Spectrometry
• complex of formula (II) allows this composition to have optimum contrasting power while having a satisfactory viscosity. Indeed, below 0.01 mol.L 1 of complex of formula (II) described above, the performance as a contrast product is less satisfactory, and at a concentration greater than 1.5 mol.L 1 , the viscosity of this composition becomes too high for easy handling.
• the composition according to the invention comprises between 0.002 and 0.4% mol / mol, in particular between 0.01 and 0.3% mol / mol, preferably between 0.02 and 0.2% mol / mol, more preferably between 0.05 and 0.15 mol / mol% of free macrocyclic ligand relative to the complex of formula (II).
• the macrocyclic ligand is selected from the group consisting of DOTA, NOTA, D03A, BT-D03A, HP-D03A, PCTA, DOTA-GA and their derivatives.
• DOTA (1,4,7,10-tetraazacyclododecane-1, 4,7,10-tetraacetic acid).
• the concentration of free DOTA in the composition is typically measured by a copper return assay, for example using copper sulfate as the source of copper ion.
• a solution is preferably used containing a known initial concentration Qo of copper sulfate, this concentration being greater than the amount of free ligand in the solution.
• Qo initial concentration of copper sulfate
• To this solution of copper sulphate is added the solution to be assayed, containing free DOTA in quantity Qi to be determined.
• DOTA is a very good complexing agent for copper: we therefore observe the formation of a DOTA-copper complex.
• a return assay of the copper remaining free in the solution is then advantageously carried out by potentiometry.
• EDTA is added to the mixture dropwise.
• EDTA will complex free copper in solution without decomplexing DOTA-copper, since DOTA is a stronger complexing agent than EDTA.
• the amount of EDTA added Q2 is equal to the amount of free copper in solution, a sharp drop in the potential of the solution is observed.
• HPLC methods can be used, in particular the HILIC LC-UV method.
• These measurement methods are implemented on solutions whose pH is advantageously between 4 and 8.
• the pH of the sample to be determined is adjusted to be between 4 and 8. 8.
• the pH of the sample is acidic, and in particular less than 4, the pH is advantageously adjusted by adding a base such as meglumine, then the measurement of the free DOTA is carried out on the sample at pH adjusted.
• the proportions specified in the present invention and in particular above are proportions before sterilization of the composition.
• the pH of the composition is between 4.5 and 8.5, preferably between 5 and 8, advantageously between 6 and 8, especially between 6.5 and 8. These pH ranges make it possible in particular to limit the appearance of certain impurities and promote complexation of the paramagnetic metal ion M.
• the composition according to the invention can be buffered, that is to say that it can also comprise a buffer chosen from the customary buffers established for the pH range 5 to 8 and preferably from the buffers.
• a buffer chosen from the customary buffers established for the pH range 5 to 8 and preferably from the buffers.
• the composition according to the invention comprises the Tris buffer.
• composition that is the subject of the invention is preferably sterile.
• the present invention further relates to a process for preparing the complex of formula (II) comprising the following successive steps: a) Complexation of the hexacid of following formula (III):
• step b) Isomerization by heating of the gadolinium hexaacid complex of formula (I) in an aqueous solution at pH between 2 and 4 , to obtain a diastereoisomerically enriched complex consisting of at least 80% of a diastereomeric excess comprising a mixture of the l-RRR and l-SSS isomers of said gadolinium hexaacid complex of formula (I), and c) Formation, at starting from the diastereoisomerically enriched complex obtained in step b), from the complex of formula (II), by reaction with 3-amino-1, 2-propanediol.
• Gd gadolinium
• Gd 3+ gadolinium oxide
• free Gd denotes the uncomplexed forms of gadolinium, and preferably available for complexation. This is typically the Gd 3+ ion dissolved in water. By extension, it can also be a source of free gadolinium, such as gadolinium chloride (GdCh) or gadolinium oxide.
• GdCh gadolinium chloride
• step a) comprises the reaction between the hexacid of formula (III) and a source of free Gd in water.
• the free Gd source is GDCH or Gd2Ü3, preferably Gd 2 u 3.
• the reagents used in step a) that is to say the source of gadolinium (typically gadolinium oxide), the hexacid of formula (III) and water, are the purest. possible, in particular as regards metallic impurities.
• the source of gadolinium will advantageously be gadolinium oxide, preferably with a purity greater than 99.99%, and more preferably greater than 99.999%.
• the water used in the process preferably comprises less than 50 ppm calcium, more preferably less than 20 ppm, and most preferably less than 15 ppm calcium.
• the water used in the process is deionized water, water for injection (ppi water) or purified water.
• the amounts of the reagents (the hexacid of formula (III) and the gadolinium) used during this step a) correspond to, or are close to, the stoichiometric proportions, as dictated by the balance equation of the reaction of complexation taking place during this step.
• stoichiometric proportions By “close to stoichiometric proportions” is meant that the difference between the molar proportions in which the reactants are introduced and the stoichiometric proportions is less than 15%, in particular less than 10%, preferably less than 8%.
• the gadolinium can in particular be introduced in slight excess relative to the stoichiometric proportions.
• the ratio of the quantity of material introduced in gadolinium to the quantity of material introduced in hexaacid of formula (III) is then greater than 1, but typically less than 1.15, in particular less than 1.10, advantageously less than 1.08 .
• the quantity of gadolinium introduced is greater than 1 equivalent (eq.), But typically less than 1.15 eq. , in particular less than 1, 10 eq. , advantageously less than 1.08 eq., relative to the quantity of hexacid of formula (III) introduced, which corresponds in turn to 1 equivalent.
• the amount of Gd203 introduced is then typically greater than 0.5 eq., But less than 0.575 eq., In particular less than 0.55 eq., advantageously less than 0.54 eq., relative to the amount of hexacid of formula (III) introduced (1 eq.).
• step a) comprises the following successive steps:
• step a2) Addition, to the aqueous solution obtained in step a1), of a source of free gadolinium.
• the hexaacid content of formula (III) in the aqueous solution prepared during step a1) is typically between 10% and 60%, in particular between 15% and 45%, preferably between 20% and 35%, advantageously between 25% and 35%, even more advantageously between 25% and 30% by weight relative to the total weight of the aqueous solution.
• steps a) and b) are carried out according to a one-pot (or “one-pot”) embodiment, that is to say in the same reactor and without an intermediate isolation or isolation step. purification.
• the gadolinium hexaacid complex of formula (I) formed during step a) is directly subjected to step b) of isomerization, without being isolated or purified, and in the same reactor as that used for step a).
• the hexaacid gadolinium complex of formula (I) formed by the complexation reaction between the hexaacid of formula (III) and gadolinium during step a) is initially obtained in the form of a mixture of diastereomers .
• Step b) aims to enrich the mixture of diastereoisomers in the l-RRR and l-SSS isomers, to obtain the gadolinium hexaacid complex of formula (I) diastereoisomerically enriched consisting of at least 85%, in particular of ' at least 90%, in particular at least 95%, preferably at least 97%, preferably at least 98%, more preferably at least 99% of a diastereomeric excess comprising the mixture of the I-isomers -RRR and l-SSS.
• formula (I) diastereoisomerically enriched consisting of at least 85%, in particular of ' at least 90%, in particular at least 95%, preferably at least 97%, preferably at least 98%, more preferably at least 99% of a diastereomeric excess comprising the mixture of the I-isomers -RRR and l-SSS.
• diastereoisomeric excess is intended to denote, in the context of the present invention, and as regards the hexaacid gadolinium complex of formula (I), the fact that said complex is predominantly present in the form of an isomer. or group of isomers chosen from the diastereoisomers l-RRR, l-SSS, l-RRS, l-SSR, l-RSS, I- SRR, l-RSR and l-SRS. Said diastereoisomeric excess is expressed as a percentage, and corresponds to the amount represented by the isomer or the majority group of isomers relative to the total amount of the hexaacid gadolinium complex of formula (I). It is understood that this percentage can be both molar and mass, insofar as isomers have, by definition, the same molar mass.
• said diastereoisomeric excess consists of at least 70%, in particular at least 80%, advantageously at least 90%, preferably at least 95% of the mixture of I-RRR and 1- isomers. SSS.
• said diastereoisomeric excess consists of the mixture of 1-RRR and 1-SSS isomers.
• the inventors have in fact discovered that factors such as the pH and the temperature of the solution of the hexaacid gadolinium complex of formula (I) obtained at the end of step a) have an influence on the ratio in which the various isomers of the complex of formula (I) are present in the mixture of diastereoisomers. Over time, the mixture tends to enrich itself in a group of isomers comprising the isomers which are surprisingly the most stable thermodynamically but also chemically, in this case the isomers 1-RRR and 1-SSS.
• mixture of l-RRR and l-SSS isomers also covers, by extension, the case where only one of the isomers, whether l-RRR or l-SSS, is present.
• the 1-RRR and 1-SSS isomers are present within said mixture in a ratio of between 65/35 and 35/65, in particular between 60/40 and 40/60, in particular between 55/45 and 45/55.
• the mixture of 1-RRR / 1-SSS isomers is a racemic mixture (50/50).
• Step b) of isomerization of the gadolinium hexaacid complex of formula (I) in an aqueous solution is typically carried out at a pH of between 2 and 4, in particular between 2 and 3, advantageously between 2.2 and 2, 8.
• the pH is preferably adjusted with an acid, preferably an inorganic acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid or phosphoric acid, for example with hydrochloric acid .
• an acid preferably an inorganic acid, such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid or phosphoric acid, for example with hydrochloric acid .
• an enrichment of the mixture for particular isomers in this case the l-RRR and l-SSS isomers, occurs, as it is known in the art.
• gadolinium chelates are characterized by low kinetic inertia in acidic medium. In fact, the higher the concentration of H + ions in the medium, the greater the probability that a proton is transferred to one of the donor atoms of the ligand, thus leading to the dissociation of the complex.
• gadolinium hexaacid complex of formula (I) in an aqueous solution at a pH between 2 and 4 would cause the dissociation of said complex, and not not its isomerization to 1-RRR and 1-SSS.
• Step b) is typically carried out at a temperature between 80 ° C and 130 ° C, in particular between 90 ° C and 125 ° C, preferably between 98 ° C and 122 ° C, advantageously between 100 ° C and 120 ° C, typically for a period of between 10h and 72h, in particular between 10h and 60h, advantageously between 12h and 48h.
• the aqueous solution of step b) comprises acetic acid.
• Step b) is then advantageously carried out at a temperature between 100 ° C and 120 ° C, in particular between 110 ° C and 1 18 ° C, typically for a period of between 12h and 48h, in particular between 20h and 30h, in particular between 24h and 26h.
• the acetic acid is preferably added before heating the solution of the gadolinium hexaacid complex of formula (I) obtained during step a) in an amount such that the acetic acid content is between 25% and 75%, in particular between 40% and 50% by mass relative to the mass of hexacid of formula (III) used during step a).
• aqueous solution is heated to a temperature advantageously between 100 ° C and 120 ° C, typically between 110 ° C and 118 ° C, acetic acid is added as the water evaporates. , so as to maintain a constant volume of solution.
• the diastereomerically enriched complex is isolated by crystallization, preferably by seeding crystallization.
• step b) comprises the following successive steps: b1) Isomerization by heating the hexaacid gadolinium complex of formula (I) in an aqueous solution at pH between 2 and 4, to obtain a complex diastereoisomerically enriched consisting of at least 80% of the diastereomeric excess comprising the mixture of the l-RRR and l-SSS isomers of said gadolinium hexaacid complex of formula (I), and b2) Isolation by crystallization of said diastereomerically enriched complex, preferably by seed crystallization.
• the crystallization step b2) aims on the one hand to remove any impurities present in the aqueous solution, which may result from previous steps, so as to obtain a product of greater purity, discolored, in the form of crystals, and on the other hand to continue the diastereoisomeric enrichment of the hexaacid gadolinium complex of formula (I), so as to obtain a diastereoisomeric excess comprising the mixture of the l-RRR and l-SSS isomers of said complex greater than that obtained in l 'from step b1).
• the 1-RRR and 1-SSS isomers of the hexaacid complex of formula (I) crystallize in water.
• the gadolinium hexaacid complex of formula (I) not enriched in said isomers does not crystallize.
• the crystallization in water of the isomers of interest of the gadolinium hexaacid complex of formula (I) makes it possible to avoid adding a solvent such as as described in Example 7 of document EP 1 931 673, which involves a step of precipitation in ethanol of the trisodium salt of said complex.
• Step b2) is advantageously carried out at a temperature between 10 ° C and 70 ° C, in particular between 30 ° C and 65 ° C, in particular between 35 ° C and 60 ° C.
• seeding involves the introduction into the reactor in which the crystallization is carried out (also called crystallizer) of a known quantity of crystals, called “seed” or “primer”. This makes it possible to reduce the crystallization time. Crystallization by seeding is well known to those skilled in the art.
• the inoculation by use of a primer in this case crystals of the gadolinium complex of hexaacid of formula (I) diastereoisomerically enriched added in the aqueous solution of the diastereomerically enriched complex, the temperature of which has been lowered beforehand, makes it possible to obtain nucleation, and thus to initiate crystallization.
• the duration of crystallization by seeding is advantageously between 2 h and 20 h, preferably between 6 h and 18 h, typically, it is 16 h.
• the crystals of the gadolinium hexaacid complex of formula (I) diastereomerically enriched are then typically isolated by filtration and drying, using any technique well known to those skilled in the art.
• the degree of purity of the gadolinium hexaacid complex of formula (I) diastereomerically enriched isolated at the end of step b2) is greater than 95%, in particular greater than 98%, advantageously greater than 99%, said degree of purity being expressed as a percentage by mass of the complex of formula (I) relative to the total mass obtained at the end of step b2).
• step b) comprises, in addition to the successive steps b1) and b2) described above, a step b3) of purification by recrystallization of the gadolinium hexacid complex of formula (I) isolated diastereoisomerically enriched.
• the recrystallization step b3) aims, like the crystallization step b2), on the one hand, to obtain a product of greater purity, and, on the other hand, to continue the diastereoisomeric enrichment of the gadolinium hexaacid complex of formula (I), so as to obtain a diastereoisomeric excess comprising the mixture of the I-RRR and I-SSS isomers of said complex greater than that obtained at the end of step b2).
• Step b3) typically comprises the following successive sub-steps:
• solubilization of said complex by heating to a temperature advantageously between 80 ° C and 120 ° C, for example at 100 ° C,
• the degree of purity of the gadolinium hexaacid complex of formula (I) diastereomerically enriched purified isolated at the end of step b3) is typically greater than 98%, in particular greater than 99%, advantageously greater than 99.5% , said degree of purity being expressed as a percentage by mass of the complex of formula (I) relative to the total mass obtained at the end of step b2).
• the diastereoisomerically enriched complex of step b) is further enriched by selective decomplexation of the diastereomers of the complex of formula (I) other than the l-RRR and l-SSS diastereomers, ie by selective decomplexation of the diastereomers l-RSS, l-SRR, l-RSR, l-SRS, l-RRS and I-SSR.
• step b) comprises, in addition to the successive steps b1) and b2) described above, a step b4) of selective decomplexing of the diastereoisomers of the complex of formula (I) other than the 1-RRR and 1-SSS diastereomers.
• step b) can further comprise step b3) described above, said step b3) being implemented between steps b2) and b4), or after step b4).
• Step b4) of selective decomplexation aims to continue the diastereoisomeric enrichment of the hexaacid gadolinium complex of formula (I), so as to obtain a diastereomeric excess comprising the mixture of the I-RRR and I-SSS isomers of said higher complex to that obtained at the end of step b2) or at the end of step b3), when the latter is implemented prior to step b4).
• Step b4) typically comprises the following successive sub-steps:
• Step b4) is made possible by the fact that the l-RRR and l-SSS isomers are the most stable in basic medium. Such basic conditions favor the formation of gadolinium hydroxide, and therefore the decomplexation of the less stable isomers.
• the l-RRR and I-SSS isomers are more stable both in an acidic medium, which allows step b1) of isomerization, and in a basic medium, which allows step b4) of selective decomplexing.
• the diastereomerically enriched complex obtained at the end of step b) according to any one of the variants described above has at least 85%, in particular at least 90%, in particular at least 95 %, preferably at least 97%, preferably at least 98%, more preferably at least 99% of the diastereomeric excess comprising the mixture of the 1-RRR and 1-SSS isomers.
• said diastereoisomeric excess consists of at least 70%, in particular at least 80%, advantageously at least 90%, preferably at least 95% of the mixture of I-RRR and 1- isomers. SSS.
• said diastereomeric excess consists of the mixture of I-RRR and 1-SSS isomers.
• mixture of l-RRR and l-SSS isomers also covers, by extension, the case where only one of the isomers, whether l-RRR or l-SSS, is present.
• mixture of 1-RRR and 1-SSS isomers preferably designates all cases where each of the l-RRR and 1-SSS isomers is present in a variable but not zero amount.
• the l-RRR and l-SSS isomers are present within said mixture in a ratio of between 65/35 and 35/65, in particular between 60/40 and 40/60, in particular between 55 / 45 and 45/55.
• the mixture of I-RRR / I-SSS isomers is a racemic mixture (50/50).
• Step c) aims to form the complex of formula (II) from its precursor, the gadolinium hexaacid complex of formula (I) diastereomerically enriched obtained in step b).
• the three carboxylic acid functions of the hexaacid complex of formula (I) carried by the carbon atoms located in position g on the side chains of the complex, relative to the nitrogen atoms of the macrocycle onto which said said side chains, are converted into amide functions by amidification reaction with 3-amino-1, 2-propanediol, in racemic or enantiomerically pure form, preferably in racemic form.
• step c) makes it possible to obtain the complex of formula (II) with a diastereoisomeric excess comprising a mixture of the II-RRR and II-SSS isomers identical to the diastereomeric excess comprising a mixture of the I-RRR isomers and l-SSS with which is obtained the gadolinium hexaacid complex of formula (I) diastereomerically enriched obtained at the end of step b), which is at least 80%.
• the complex of formula (II) obtained at the end of step c) has at least 85%, in particular at least 90%, in particular at least 92%, preferably at least 94% , preferably at least 97%, more preferably at least 99% of the diastereomeric excess comprising the mixture of isomers II-RRR and II-SSS.
• said diastereoisomeric excess consists of at least 70%, in particular at least 80%, advantageously at least 90%, preferably at least 95% of the mixture of isomers II-RRR and II- SSS.
• said diastereoisomeric excess consists of the mixture of II-RRR and II-SSS isomers.
• mixture of II-RRR and II-SSS isomers also covers, by extension, the case where only one of the isomers, whether it is II-RRR or II-SSS, is present.
• mixture of II-RRR and 11-SSS isomers preferentially denotes all of the cases where each of the II-RRR and II-SSS isomers is present in a variable but not zero amount.
• the II-RRR and II-SSS isomers are present in said mixture in a ratio of between 65/35 and 35/65, in particular between 60/40 and 40/60, in particular between 55 / 45 and 45/55.
• the II-RRR and II-SSS isomers are present in the mixture in a 50/50 ratio.
• amidification reaction can be carried out according to all the methods well known to those skilled in the art, in particular in the presence of an agent which activates carboxylic acid functions and / or in acid catalysis.
• said carboxylic acid functions can in particular be activated in the form of ester functions, acyl chlorides, acid anhydrides, or in any activated form capable of leading to an amide bond.
• the activated forms capable of leading to an amide bond are well known to those skilled in the art and can for example be obtained by all the methods known in peptide chemistry for creating a peptide bond. Examples of such methods are given in the publication Synthesis of peptides and peptidomimetics vol.
• step c) comprises the activation of the aforementioned carboxylic acid functions (- COOH) in the form of ester functions, acyl chlorides or acid anhydrides.
• This embodiment is preferred to peptide coupling by activation of the carboxylic acid function using a coupling agent such as EDCI / HOBT as described in document EP 1 931 673.
• a coupling agent such as EDCI / HOBT as described in document EP 1 931 673.
• such a coupling leads to the formation. of an equivalent of 1-ethyl-3- [3- (dimethylamino) propyl] urea, which must be removed, in particular by chromatography on silica or by liquid / liquid extraction by adding a solvent.
• the implementation of such purification methods is not desirable, as discussed previously.
• the use of HOBT is in itself problematic, in that it is an explosive product.
• ester function is intended to denote a -C (0) 0- group. It may in particular be a -C (0) 0-R 1 group, in which R 1 corresponds to a (C 1 -C 6) alkyl group.
• (C 1 -C 6) alkyl means a saturated, linear or branched hydrocarbon chain comprising 1 to 6, preferably 1 to 4, carbon atoms.
• acyl chloride function also called “acid chloride function” is meant within the meaning of the present invention a -CO-Cl group.
• acid anhydride function is meant within the meaning of the present invention a -CO-O-CO- group. It may in particular be a -CO-O-CO-R2 group, in which R2 corresponds to a (Ci-Ce) alkyl group.
• the complex of formula (II) is then obtained by aminolysis of the activated carboxylic acid functions in the form of ester, acyl chloride or acid anhydride functions, in particular acid esters or anhydrides, preferably esters, by reaction with 3-amino-1, 2-propanediol, in racemic or enantiomerically pure form, preferably in racemic form.
• the stages of activation of the carboxylic acid functions and of aminolysis are carried out according to a one-pot embodiment (or “one-pot” in English), that is to say in the same reactor and without a stage.
• step c) comprises the following successive steps: c1) formation of an activated complex of formula (VII),
• Y represents a chlorine atom, a group -OR1 or -0-C (0) -R 2 , preferably Y represents a group -OR1 or -0-C (0) -R 2 , with Ri and R2 corresponding independently of one another to a (C1-C6) alkyl group, and c2) aminolysis of the activated complex of formula (VII) with 3-amino-1, 2-propanediol.
• reaction for forming the activated complex of formula (VII) does not modify the absolute configuration of the three asymmetric carbon atoms located in position a on the side chains, relative to the atoms of nitrogen of the macrocycle onto which said side chains are grafted.
• step c1) makes it possible to obtain the activated complex of formula (VII) with a diastereoisomeric excess comprising a mixture of isomers VII-RRR and VII-SSS, of formulas (VII-RRR) and (VII-SSS) shown below, identical to the diastereoisomeric excess comprising a mixture of the l-RRR and l-SSS isomers with which is obtained the gadolinium hexaacid complex of formula (I) diastereomerically enriched obtained at the end of step b), which is at least 80%.
• step c1) is typically carried out by reaction between the gadolinium complex of hexacid of formula (I) diastereomerically enriched obtained during step b) and thionyl chloride ( SOCI 2 ).
• step c1) is typically carried out by reaction between the gadolinium hexaacid complex of formula (I) diastereomerically enriched obtained during step b) and acetyl chloride.
• step c) comprises the activation of the aforementioned carboxylic acid functions (-COOH) in the form of ester functions.
• step c) can more particularly comprise the following successive steps: c1) formation of a triester of formula (VIII),
• Step d) is typically carried out in the alcohol of formula RiOH, which acts both as a solvent and as a reagent, in the presence of an acid such as hydrochloric acid.
• Step c2) is also typically performed in the alcohol of formula RiOH, in the presence of an acid such as hydrochloric acid.
• the gadolinium hexaacid complex of formula (I) and the alcohol RiOH are charged to the reactor.
• the reaction medium is then cooled to a temperature below 10 ° C, in particular below 5 ° C, typically at 0 ° C, and an acidic solution of the alcohol RiOH, typically hydrochloric acid in RiOH is then gradually added.
• the reaction medium is kept under stirring at room temperature (that is to say at a temperature between 20 and 25 ° C) for a period typically greater than 5 h, preferably between 10 h and 20 h.
• the reaction medium is cooled to a temperature below 10 ° C, in particular between 0 ° C and 5 ° C, prior to step c2).
• steps c1) and c2) can easily be implemented according to a one-pot (or “one-pot”) embodiment.
• the triester of formula (VII) is not isolated between steps c1) and c2).
• the alcohol of formula RiOH is preferably removed by vacuum distillation.
• vacuum distillation means the distillation of a mixture carried out at a pressure of between 10 and 500 mbar, in particular between 10 and 350 mbar, preferably between 10 and 150 mbar, in particularly between 50 and 100 mbar.
• 3-amino-1, 2-propanediol is introduced in large excess.
• the amount of 3-amino-1, 2-propanediol material introduced is greater than 4 eq., In particular greater than 7 eq., Advantageously greater than 10 eq., Relative to the amount of gadolinium complex material of diastereoisomerically enriched hexaacid of formula (I) initially introduced during step c), which in turn corresponds to 1 equivalent.
• step c) comprises the following successive steps: c1) formation of a methyl triester of formula (IV),
• the methyl triester of formula (IV) is not isolated between steps c1) and c2).
• step c2) the methanol is removed by vacuum distillation, until a temperature is typically greater than 55 ° C, in particular between 60 ° C and 65 ° C, and the reaction medium is maintained at this temperature under vacuum for a period typically greater than 5 h, in particular between 10 h and 20 h, before being cooled to room temperature and diluted with water.
• the hexaacid of formula (III), which occurs during step a) of the process for preparing the complex of formula (II) according to the invention, can be prepared according to all the methods already known and in particular according to the methods described in patent EP 1 931 673.
• the hexacid of formula (III) is obtained by alkylation of pyclene of formula (V):
• R3 and R4 represent, independently of one another, a (C3-Ce) alkyl group, in particular a (C4-Ce) alkyl group such as a butyl, isobutyl, sec-butyl, tert-butyl or pentyl group or hexyl, and
• G p represents a leaving group such as a tosylate or triflate group or a halogen atom, preferably a bromine atom,
• R3 and R4 are the same.
• the hexaacid of formula (III) is obtained by alkylation of pyclene of formula (V): with dibutyl 2-bromoglutarate, to obtain the butyl hexaester of formula (VI):
• the dibutyl 2-bromoglutarate used is in racemic or enantiomerically pure form, preferably in racemic form.
• dibutyl 2-bromoglutarate is particularly advantageous, compared to that of ethyl 2-bromoglutarate described in document EP 1 931 673.
• commercial diethyl 2-bromoglutarate is a relatively unstable compound, which degrades over time and under the effect of temperature. More specifically, this ester tends to hydrolyze or cyclize and therefore lose its bromine atom. Attempts to purify commercial diethyl 2-bromoglutarate, or to develop new synthetic routes to obtain it with improved purity, and thus prevent its degradation, have not been successful.
• the alkylation reaction is typically carried out in a polar solvent, preferably in water, in particular in deionized water, preferably in the presence of a base such as potassium or sodium carbonate.
• a polar solvent preferably in water, in particular in deionized water, preferably in the presence of a base such as potassium or sodium carbonate.
• the use of water is preferred in particular to that of acetonitrile, described in document EP 1 931 673, for obvious reasons.
• the reaction is advantageously carried out at a temperature between 40 ° C and 80 ° C, typically between 50 ° C and 70 ° C, in particular between 55 ° C and 60 ° C, for a period of between 5h and 20h, in particular between 8 a.m. and 3 p.m.
• the hydrolysis step is advantageously carried out in the presence of an acid or of a base, advantageously of a base such as sodium hydroxide.
• the hydrolysis solvent can be water, an alcohol such as ethanol, or a water / alcohol mixture. This step is advantageously carried out at a temperature between 40 ° C and 80 ° C, typically between 40 ° C and 70 ° C, in particular between 50 ° C and 60 ° C, typically for a period of between 10h and 30h, in particular between 3 p.m. and 25 p.m. Process for the purification of the complex of formula (II)
• the present invention also relates to a process for purifying the complex of formula (II) below:
• said complex of formula (II) having at least 80%, preferably at least 85%, in particular at least 90%, in particular at least 95%, more particularly at least 97%, preferably at least 98%, advantageously at least less 99%, of a diastereoisomeric excess comprising a mixture of II-RRR and II-SSS isomers was obtained beforehand according to the preparation process described above.
• the diastereoisomerically enriched complex on which the purification process is implemented has at least 85%, in particular at less 90%, in particular at least 92%, preferably at least 94%, preferably at least 97%, more preferably at least 99% of the diastereomeric excess comprising the mixture of isomers 11-RRR and 11-SSS.
• said diastereoisomeric excess consists of at least 70%, in particular at least 80%, advantageously at least 90%, preferably at least 95% of the mixture of isomers II-RRR and II- SSS.
• said diastereoisomeric excess consists of the mixture of II-RRR and II-SSS isomers.
• mixture of II-RRR and II-SSS isomers also covers, by extension, the case where only one of the isomers, whether it is II-RRR or II-SSS, is present.
• mixture of II-RRR and 11-SSS isomers preferentially denotes all of the cases where each of the II-RRR and II-SSS isomers is present in a variable but not zero amount.
• the II-RRR and II-SSS isomers are present in said mixture in a ratio of between 65/35 and 35/65, in particular between 60/40 and 40/60, in particular between 55 / 45 and 45/55.
• the II-RRR and II-SSS isomers are present in the mixture in a 50/50 ratio.
• Steps 1 b) and 1 c) aim to purify the complex of formula (I I) by removing any impurities that may be present due to its process for obtaining it.
• Said impurities can in particular comprise 3-amino-1, 2-propanediol and / or a dicoupled impurity.
• 3-amino-1, 2-propanediol can be present in the final product obtained during the implementation of a process for preparing the complex of formula (II), typically when the complex of formula (II) is obtained by amidization from the complex of formula (I) and 3-amino-1, 2-propanediol.
• the amidification reaction can comprise the activation of the three carboxylic acid functions carried by the carbon atoms located in position y on the side chains of the complex of formula (I), relative to the nitrogen atoms of the macrocycle.
• dicoupled impurity is intended to denote a complex of formula (II-dc-a), (II-dc-b), (II-dc-c) represented below or a mixture of these:
• the dicoupled impurity can in particular result from the hydrolysis reaction of an amide function of the complex of formula (II). It can also result from incomplete activation of the carboxylic acid functions of the complex of formula (I) (activation of two out of the three functions) or from incomplete aminolysis of the activated carboxylic acid functions (aminolysis of two out of the three functions), when the process for preparing the complex of formula (II) implements such steps. This is particularly the case with the process for preparing the complex of formula (II) according to the invention.
• Step 1 b) corresponds to the passage through ion exchange resin (s) of the complex of formula (II) diastereomerically enriched as described above.
• the term “ion exchange resin” is understood to mean a solid material generally in the form of beads composed of a polymer matrix onto which are grafted positively charged functional groups (anionic resin) or negatively. (cationic resin), which will allow trapping respectively anions or cations by adsorption. The adsorption of anions or cations on the resin occurs by ion exchange between the counterions of the functional groups initially present in order to ensure the electroneutrality of the resin, and the anions or cations intended to be trapped.
• Step 1 b) comprises contacting an aqueous solution of the complex of formula (II) diastereomerically enriched with a strong anionic resin.
• the water used is preferably purified water.
• Said strong anionic resin typically comprises as functional exchange groups ammonium groups (N (RR'R ”) + , where R, R 'and R” are identical or different (Ci-Ce) alkyl groups).
• Resin Amberlite ® FPA900 include commercially available from Dow Chemical, advantageously in the form HO. The passage through a strong anionic resin makes it possible to eliminate, at least in part, the dicoupled impurities.
• Step 1 b) may further comprise contacting an aqueous solution of the complex of formula (II) diastereomerically enriched with a weak cationic resin.
• the water used is preferably purified water.
• Said weak cationic resin typically comprises as functional exchange groups carboxylate (CO 2) groups.
• IMAC resin may be cited ® HP336 sold by Dow Chemical, preferably H + form.
• the passage through a weak cationic resin makes it possible to eliminate, at least in part, the 3-amino-1, 2-propanediol, and the possible residues of Gd 3+ .
• step 1 b) of passage through ion exchange resin (s) is made possible by the improved stability of the complex of formula (II) diastereomerically enriched according to the invention, whose integrity is therefore preserved during this step.
• Step 1c) corresponds to the ultrafiltration of the complex of formula (II) diastereomerically enriched as described above.
• ultrafiltration is understood to denote, in the present invention, a method of filtration through a semi-permeable, mesoporous membrane, the pores of which generally have a diameter of between 1 and 100 nm, in particular between 2 and 50 nm. nm, in particular between 10 and 50 nm (mesopores), under the effect of forces such as pressure gradients, typically between 1 and 10 bars, and possibly concentration. It is therefore a membrane separation process by which particles in solution or in suspension whose size is greater than that of the pores are retained by the membrane, and separated from the liquid mixture which contained them.
• ultrafiltration is particularly advantageous for removing endotoxins.
• the ultrafiltration membrane used during step 1 c) has a cutoff threshold of less than 100 kD, in particular less than 50 kD, in particular less than 25 kD, typically a cutoff threshold of 10 kD.
• the transmembrane pressure is between 1 and 5 bars, in particular between 2.25 and 3.25 bars.
• steps 1 b) and 1 c) are also combined with a step 1 a) of nanofiltration.
• nanofiltration is understood to denote, in the present invention, a method of filtration through a semi-permeable, porous membrane, the pores of which generally have a diameter of between 0.1 and 100 nm, in particular between 0 , 1 and 20 nm in particular between 1 and 10 nm, under the effect of forces such as pressure gradients, typically between 1 and 50 bars, and optionally of concentration. It is therefore a membrane separation process by which particles in solution or in suspension whose size is greater than that of the pores are retained by the membrane, and separated from the liquid mixture which contained them.
• Nanofiltration step 1a makes it possible to remove most of the 3-amino-1, 2-propanediol (optionally in the form of a salt, in particular of the hydrochloride, or of derivatives, in particular the acetamide derivative) in excess and the salts minerals.
• the nanofiltration step can be carried out directly on the crude diastereoisomerically enriched complex of formula (II) as obtained according to the preparation process described above.
• the nanofiltration membrane used during step 1 a) has a cutoff threshold of less than 1 kD, in particular less than 500 Daltons, in particular less than 300 Daltons, typically a cutoff threshold of 200 Daltons.
• the transmembrane pressure is between 10 and 40 bars, in particular between 2 and 30 bars.
• the temperature of the solution of the complex of formula (II) subjected to ultrafiltration during step 1a) is between 20 and 40 ° C, in particular between 25 and 35 ° C.
• step 1 b) does not comprise bringing an aqueous solution of the complex of formula (II) diastereomerically enriched with a weak cationic resin into contact.
• steps 1a) when the latter is present, 1b and 1c are carried out in this order. This advantageous embodiment makes it possible in particular to minimize the quantities of resins used and therefore the industrial manufacturing cost.
• Step 2) aims to isolate in solid form the complex of formula (II) purified obtained at the end of the combination of steps 1 b) and 1 c), and optionally further combined in step 1 a).
• This isolation step in solid form can be carried out using any method well known to those skilled in the art, in particular by atomization, by precipitation, by lyophilization or by centrifugation, advantageously by atomization.
• step 2) comprises atomization.
• the temperature of the air entering the atomizer is then typically between 150 ° C and 180 ° C, in particular between 160 ° C and 175 ° C, advantageously between 165 ° C and 170 ° C.
• the outlet temperature is for its part typically between 90 ° C and 120 ° C, preferably between 105 ° C and 110 ° C.
• the degree of purity of the complex of formula (II) diastereomerically enriched with the mixture of II-RRR and II-SSS isomers purified and isolated at the end of step 2) is greater than 95%, in particular greater than 97%, preferably greater than 97.5%, more preferably greater than 98%, advantageously greater than 99%, said degree of purity being expressed as a percentage by mass of the complex of formula (II) relative to the total mass obtained in from step 2).
• the present invention also relates to the complex of formula (II) diastereomerically enriched and purified, which can be obtained according to the purification process of the invention.
• the complex of formula (II) included in the composition according to the invention described above is the complex of formula (II) diastereomerically enriched and purified, capable of being obtained according to the purification process of the invention.
• UHPLC Separation of the groups of iso1, iso2, iso3 and iso4 isomers of the complex of formula (II) by UHPLC
• a UHPLC device consisting of a pumping system, an injector, a chromatographic column, a UV detector and of a data station is used.
• the chromatographic column used is a UHPLC 150 x 2.1 mm ⁇ 1.6 ⁇ m column (CORTECS® UPLC T3 column from Waters).
• Route A 100% acetonitrile and Route B: aqueous solution of H2SC> 4 (96%) at 0.0005% v / v
• Peak 4 of the UHPLC trace namely iso4, corresponds to a retention time of 6.3 minutes.
• the butyl hexaester is reextracted in the toluene phase by dilution with 145 kg of toluene and 165 kg of water followed by basification with 30% (m / m) sodium hydroxide to achieve a pH of 5-5.5.
• the lower aqueous phase is removed.
• the butyl hexaester is obtained by concentration to dryness in vacuo at 60 ° C with a yield of about 85%.
• Gadolinium oxide (0.525 molar eq.) Is suspended in a hexacid solution of formula (III) at 28.1% by mass.
• the acetic acid 99-100% (50% by mass / hexaacid of formula (III) pure) is poured onto the medium at room temperature.
• the medium is heated to reflux and then distilled to 13 ° C by mass, recharging the medium with acetic acid as the water is removed. At 113 ° C, add a sufficient amount of acetic acid to achieve the starting volume.
• the medium is maintained at 113 ° C. overnight.
• the gadolinium hexaacid complex of formula (I) in solution is cooled to 40 ° C, the primer is added, left in contact for at least 2 hours. It is then isolated by filtration at 40 ° C and washed with reverse osmosis water.
• the gadolinium hexaacid complex of formula (I) obtained above dry extract at about 72%) are suspended in 390 kg of water.
• the medium is heated to 100 ° C to dissolve the product, then cooled to 80 ° C to be primed by adding a little primer. After cooling to room temperature, the gadolinium hexaacid complex of formula (I) is isolated by filtration and drying.
• the dry product is charged to the reactor with reverse osmosis water / at 20 ° C.
• the mass of water added is equal to twice the mass of the hexacid gadolinium complex of theoretical formula (I).
• 30.5% (m / m) (6.5 eq) sodium hydroxide is poured onto the medium at 20 ° C.
• the medium is left in contact at 50 ° C. at the end of the addition of NaOH for 16:00.
• the medium is cooled to 25 ° C. and the product filtered through a bed of Clarcel. Content of the mixture of l-RRR and l-SSS diastereomers
• the ratio in which the different isomers of the complex of formula (I) are present in the mixture of diastereomers depends on the conditions under which the complexation and isomerization steps are carried out, as shown in Table 3 below.
• the concentrate is maintained for 16 hours at this temperature under vacuum.
• the medium is diluted with 607 kg of water while cooling to ambient temperature.
• the solution of the crude complex of formula (II) is neutralized with acid hydrochloric acid 20% (m / m). 978.6 kg of solution are thus obtained, with a concentration of 10.3%, representing 101 kg of material.
• the yield obtained is 86.5%, the purity of the complex of formula (II) is 92.3% (HPLC s / s).
• the amount of dicoupled impurities is 6.4% (HPLC s / s).
• the nanofiltration membrane used has a cutoff of 200 Daltons (Koch Membran System SR3D). This treatment is carried out as follows:
• the crude solution of complex of formula (II) is heated to 30 ° C.
• the nanofilter is filled with said solution.
• the pump is started at a low flow rate first to purge the system, then the flow rate of the nanofilter pump is gradually increased to the desired recirculation flow rate (1.0 m 3 / h for a 2.5 X 40 inch membrane) .
• the system is then put into full recirculation at 30 ° C for at least 2 hours to establish a polarization layer.
• the medium is then passed through diafiltration at 30 ° C. under 25 bars while maintaining the volume constant by adding pure water until a conductivity of the retentate of less than 1000 pS is obtained. At the end of the diafiltration, the medium is concentrated until a concentration of approximately 40% (m / m) is obtained.
• the solution of the complex of formula (II) resulting from the nanofiltration is diluted with purified water with stirring to obtain a 15% (m / m) solution.
• This solution is eluted in series on 50 liters of strong anionic resins (FPA900) in OH form then on 50 liters of weak cationic resins (HP336) in H + form at an average elution rate of 2V / V / H (2 volumes solution per volume of resin per hour).
• the resins are then rinsed with about 450 liters of purified water until a refractive index of less than 1.3335 is reached.
• the complex solution of formula (II) is then concentrated by heating to 50-60 ° C under a vacuum of 20 mbar to reach a concentration of 35% (m / m).
• the ultrafiltration membrane is a UF 10KD Koch Spiral membrane.
• the ultrafilter is fed with the above solution of the complex of formula (II) at 35% heated to 40 ° C. Ultrafiltration is applied at a flow rate of 3m 3 / H with a transmembrane pressure of 2.5-3 bars.
• Several rinses of the system with 13 liters of pyrogen-free purified water are carried out until a final dilution of the complex of formula (II) of 25% (m / m) is reached.
• the complex of formula (II) is obtained in powder form by atomization of the preceding solution of complex of formula (II) concentrated at 25%.
• the atomization is carried out as follows:
• the atomizer is equilibrated with pure non-pyrogenic water by adjusting the inlet temperature to 165 ° C - 170 ° C and by adapting the feed rate so that the outlet temperature is between 105 and 110 ° C. .
• the method of manufacturing a composition according to the invention is carried out by following the following steps: a) 485.1 g (i.e. 0.5 M) of complex of formula (II) is dissolved in water (qs 1 liter) by heating the tank to a temperature between 39 and 48 ° C and carrying out a strong stirring of the solution until complete dissolution of this complex in water. The solution is then cooled to about 30 ° C. b) 0.404 g (i.e. 0.2% mole / mole relative to the proportion of complex added in step a)) of DOTA (Simafex, France) is added with stirring to the solution obtained in step a) via a 10% w / v DOTA solution.
• a) 485.1 g (i.e. 0.5 M) of complex of formula (II) is dissolved in water (qs 1 liter) by heating the tank to a temperature between 39 and 48 ° C and carrying out a strong stirring of the solution until complete dissolution of this complex in water. The solution is then
• composition according to the invention is then filtered through a polyethersulfone membrane and placed in its final container, which is finally subjected to sterilization at 121 ° C. for 15 minutes.
• Example of composition according to the invention is filtered through a polyethersulfone membrane and placed in its final container, which is finally subjected to sterilization at 121 ° C. for 15 minutes.
• non-optimized PA denotes the active principle, namely the complex of formula (II), obtained according to the process described in document EP 1 931 673.
• optical PA denotes the complex of formula ( II) diastereoisomerically enriched and purified obtained by the process according to the invention.
• the complex of formula (II) diastereomerically enriched and purified obtained by the process according to the invention can be formulated with free DOTA. Indeed, the absence of free Gd is observed in the composition at 6 months, 40 ° C, regardless of the pH of the formulation and whether or not buffering species are present. In addition, the consumption of the chelating excipient is very low, since it does not exceed 0.08% mol / mol.

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