Iron complexes and their salts as MRI contrast agents

Abstract

The present invention relates to an iron complex having the general formula (I) or a pharmaceutically acceptable salt thereof. The present invention also relates to a pharmaceutical composition formulated for oral and / or parenteral administration, preferably intravenous administration, which is preferably formulated as an aqueous solution containing the complex or salt. The present invention further relates to the complex or salt thereof or the pharmaceutical composition for use as a contrast agent for magnetic resonance imaging (MRI), as well as methods and kits for in situ preparation of the complex or salt and the pharmaceutical composition.

Description

[Technical Field]

[0001] The present invention belongs to the field of contrast agents for magnetic resonance imaging (MRI), and relates to an iron complex having the general formula (I) or a pharmaceutically acceptable salt thereof, and a pharmaceutical composition containing said complex or salt. The present invention further relates to a method and a kit for preparing said complex or salt and said pharmaceutical composition in situ. [Background technology]

[0002] prior art In recent decades, magnetic resonance imaging (MRI) has become an important diagnostic technique due to its ability to obtain images with extremely high spatial and temporal resolution. MRI images are measured as a unit volume (voxel) of signal intensity. 1 This is a topological representation of H-NMR (SI), where the main contribution of SI is due to water protons, the main component of biological tissue. The contrast of MRI images can be altered by the operating procedures of the device (e.g., excitation sequence and signal acquisition) and the use of contrast agents (CA). Typical MRI contrast agents are paramagnetic substances, which, when administered, can shorten the relaxation times T1 and T2 of water protons in the anatomical region where they are distributed. One of the most important characteristics of MRI contrast agents is their "relaxivity," which is quantified by the change in T1 or T2 relative to the concentration of the contrast agent. In the 1980s, paramagnetic metal complexes were found to be the most suitable MRI contrast agents. In particular, the metal ion Gd 3+ has been demonstrated to be particularly effective, as it is characterized by high paramagnetism (seven unpaired electrons) and a relatively long electron relaxation time. 3+Gd can form thermodynamically stable complexes with linear octadentate ligands such as DTPA (diethylenetriaminepentaacetic acid) and cyclic octadentate ligands such as DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). In these complexes, the eight coordination sites of the metal ion are occupied by donor atoms (N and O) of the ligand, and the ninth position can be occupied by a water molecule. When used as a contrast agent and distributed in the aqueous environment of the anatomical region of interest for diagnosis, Gd 3+ The complexes proved to be particularly advantageous because they could exchange their coordinated water molecules with those of the external solvent, and the paramagnetic effect was transmitted to all water protons in the surrounding microenvironment. Furthermore, in terms of relaxivity, the gadolinium complexes showed excellent values ​​(3-4 mM). -1 s -1 ), and when complexes such as Gd-BOPTA (gadobenic acid), Gd-EOB-DTPA (gadoxetic acid), and MS-325 (gadofosveset) are used in human serum, the hydrophobic substituents on their surfaces allow reversible interactions with albumin present in serum, resulting in a significant increase. Therefore, gadolinium complexes exhibit excellent properties as contrast agents and are currently chosen for MRI diagnosis. 3+ The ions themselves are toxic to the human body (mainly Ca 2+ ions) resulting in a more stable complex, i.e., free Gd 3+ Much effort has been (and continues to be) made to produce complexes that do not release ions and can be excreted in amounts as close as possible to 100% of the dose administered to the patient. 3+Despite the known toxicity of the ion, until a few years ago, the scientific community believed that contrast agents based on stable gadolinium complexes (commonly referred to as "gadolinium-based contrast agents") were nontoxic. However, approximately 10 years ago, this confidence weakened when the administration of gadolinium complexes was associated with a condition called nephrogenic systemic fibrosis (NSF), which appears to be limited to patients with a glomerular filtration rate of less than 30 mL / min. More recently, another concern regarding the potential toxicity of GBCAs was the finding that very small amounts of gadolinium remain in the bodies of patients receiving GBCAs, even in the absence of renal failure. The amount of gadolinium remaining appears to depend on the number of doses and the type of complex. Although no clinical correlation (toxicity, acute) has been reported related to Gd retention, the European Medicines Agency (EMA) has revoked the marketing authorization of several Gd complexes believed to be most responsible for the so-called "Gd retention." This prompted the scientific community to search for alternatives that could achieve similar efficacy to that achieved with gadolinium complexes while ensuring toxicological safety. Therefore, we investigated Mn, which is essential for the human body and is expected to be easier to "manage" by living tissues than non-essential elements such as gadolinium, which do not have a recycling process in the body. 2+ and Fe 3+ Attention has been focused on paramagnetic complexes of endogenous metal ions such as Mn 2+ (5 unpaired electrons) Mn 2+ So far, no ligands have been found that can guarantee thermodynamic stability so that some of the ions are not transferred to biomolecules (e.g., albumin). In parallel, Fe is being investigated as an alternative to GBCA as a contrast agent for MRI, as reported, for example, in the publication by Worah D. et al. ("Ferrioxamine as a magnetic resonance contrast agent: preclinical studies and phase I and II human clinical trials"; Invest Radiol 1988; 23 (Suppl): S281-S285). 3+ Various efforts are being made to search for complexes (which also have five unpaired electrons). 3+The relaxivity of the complex is approximately 2 mM -1 s -1 Gd is the basis for the most widely used contrast agent today. 3+ The main reason for this is that the thermodynamic stability of the complex requires the presence of six Fe atoms. 3+ This is because all ion coordination sites must be occupied by ligand donor atoms, but in this case the possibility of water coordination (as occurs in gadolinium-based complexes) is lost, and only the relaxivity contributions from water molecules or mobile protons belonging to water molecules in the second or outer sphere come into play. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention solves the above-mentioned problems of the prior art by providing an MRI contrast agent that exhibits good relaxivity, is characterized by good solubility in an aqueous environment, can be administered to a patient using a limited amount of solution, and is excreted intact from the patient's body. The applicant has, in fact, surprisingly discovered that the previously investigated Fe 2+ -contrast agent can be obtained by using iron complexes with deferasirox (DFX = 4-[(3,5-bis-(2-hydroxyphenyl)-1,2,4)triazol-1-yl]-benzoic acid, ICL670) and its derivatives, which are commonly used in chelation therapy for treating iron overdose and accumulation in the body (e.g., as described in EP 0914118). 3+ The applicant has found that it is possible to provide an iron-based contrast agent for MRI, which is characterized by significantly improved relaxivity compared to the complex, and at the same time is completely excreted from the human body. According to the present invention, the applicant further provides an MRI contrast agent with controllable solubility by forming the iron complex with deferasirox and its derivatives into a salt and / or a pharmaceutical formulation. [Means for solving the problem]

[0004] The present invention relates to a compound represented by general formula (I) [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, C1-C5 alkoxyl; R3 is selected from H, C1-C5 alkyl, C1-C5 hydroxyalkyl, C1-C5 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl), wherein the at least one group is preferably located at the 4-position of the aromatic ring of the aryl). or a pharmaceutically acceptable salt thereof. The present invention also relates to a pharmaceutical composition formulated for oral and / or parenteral administration, preferably intravenous administration, which is preferably formulated as an aqueous solution containing the complex or salt. The present invention further relates to the complex or salt thereof or the pharmaceutical composition for use as a contrast agent in magnetic resonance imaging (MRI), as well as methods and kits for the in situ preparation of the complex or salt and the pharmaceutical composition. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 shows the 1 / T1 1H-NMRD profile (recorded in water and human serum at 25° C. with Larmor frequencies ranging from 0.01 to 80 MHz) and the 1 / T2 1H-NMRD profile (recorded in water and human serum at 25° C. with Larmor frequencies ranging from 20 to 80 MHz) of an Fe(DFX)2 complex of the invention. [Figure 2] Figure 2 shows the trend of relaxivity (r1p) of the Fe(DFX)2 complex in H2O under a fixed magnetic field (B0 = 0.5 T) with varying pH. [Figure 3]FIG. 3 shows the trend of relaxivity (R1p) of the Fe(DFX)2 complex of the present invention in PBS and human serum under a fixed magnetic field (B0=0.5 T) at varying temperatures. [Figure 4] FIG. 4 shows the time course of relaxivity (r1p) of the Fe(DFX)2 complex of the present invention measured in PBS and human serum under a fixed magnetic field (B0=0.5 T) at 25°C and at two temperatures (37°C and 4°C) for up to 6 days. [Figure 5] Figure 5 shows the trend of water proton relaxation time (R1 = 1 / T1) for aqueous solutions containing Fe(DFX)2 at a concentration of 0.5 mM in PBS (with increasing concentrations of human serum albumin). [Figure 6] Figure 6 shows MRI images of a mouse inoculated with tumor cells (TSA) (recorded under a fixed magnetic field of 7 T before and 20 minutes after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 7] Figure 7 shows the time course of the contrast enhancement rate (En%) in the tumor area of ​​a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 7 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 7a] Figure 7a shows the time course of the contrast enhancement rate (En%) in the kidney of a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 7 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 7b] Figure 7b shows the time course of the contrast enhancement rate (En%) in the bladder of a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 7 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 7c]Figure 7c shows the time course of the contrast enhancement rate (En%) in the spleen of a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 7 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 8] Figure 8 shows the time course of the contrast enhancement rate (En%) in the tumor area of ​​a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 3 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 8a] Figure 8a shows the time course of the contrast enhancement rate (En%) in the kidney of a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 3 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 8b] Figure 8b shows the time course of the contrast enhancement rate (En%) in the bladder of a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 3 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 8c] Figure 8c shows the time course of the contrast enhancement rate (En%) in the spleen of a mouse inoculated with tumor cells (TSA) (recorded in vivo under a fixed magnetic field of 3 T after administration of 0.1 mmol / kg Fe(DFX)2 and Gd-DTPA (Magnevist)). [Figure 9] FIG. 9 shows the time course of plasma Fe 3+ and Gd 3+ concentrations in mice administered 0.1 mmol / kg Fe(DFX) 2 and Gd-DTPA (Magnevist). DETAILED DESCRIPTION OF THE INVENTION

[0006] Detailed Description of the Preferred Embodiments of the Invention In the present invention, the terms "human blood serum" and "human serum" are used as completely interchangeable synonyms.

[0007] In the present invention, the expression "optionally substituted" means that the indicated group may be unsubstituted or substituted at 1, 2 or 3 positions.

[0008] The term "halogen" means, in the present invention, an element of the halogen group selected from fluorine, chlorine, bromine or iodine.

[0009] In the present invention, "C1-C5 alkyl" refers to a straight or branched chain alkyl group containing a minimum of 1 and a maximum of 5 carbon atoms. Similarly, "C1-C3 alkyl" refers to a straight or branched chain alkyl group containing a minimum of 1 and a maximum of 3 carbon atoms. Similarly, "C1-C2 alkyl" refers to a straight or branched chain alkyl group containing a minimum of 1 and a maximum of 2 carbon atoms.

[0010] "C1-C5 alkoxyl" refers to a straight or branched chain alkoxyl group containing a minimum of 1 and a maximum of 5 carbon atoms. Similarly, "C1-C3 alkoxyl" refers to a straight or branched chain alkoxyl group containing a minimum of 1 and a maximum of 3 carbon atoms.

[0011] In the present invention, "C1-C5 hydroxyalkyl" refers to a C1-C5 alkyl group substituted with one or more hydroxyl groups. Similarly, "C1-C3 hydroxyalkyl" refers to a C1-C3 alkyl group substituted with one or more hydroxyl groups.

[0012] In the present invention, "C1-C5 carboxyalkyl" refers to a C1-C5 alkyl group substituted with one or more carboxyl groups. Similarly, "C1-C3 carboxyalkyl" refers to a C1-C3 alkyl group substituted with one or more carboxyl groups.

[0013] In the present invention, "aryl" refers to a carbocyclic ring system having 6 to 15 carbon atoms, which may be a monocyclic, bicyclic or tricyclic ring system.

[0014] As used herein, the term "pharmaceutically acceptable salt" refers to a salt that retains the efficacy and biological properties of the iron complexes having general formula (I) according to embodiments of the present invention and is typically not biologically or otherwise objectionable.

[0015] The present invention relates to a compound of general formula (I): [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, C1-C5 alkoxyl; R3 is selected from H, C1-C5 alkyl, C1-C5 hydroxyalkyl, C1-C5 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl), wherein the at least one group is preferably located at the 4-position of the aromatic ring of the aryl). or a pharmaceutically acceptable salt thereof.

[0016] According to a preferred embodiment of the present invention, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl. According to another preferred embodiment of the present invention, R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from: H, C1-C2 alkyl), said at least one group being present in the 4-position of the aromatic ring of said aryl.

[0017] According to a preferred embodiment, the present invention comprises: R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from: H, C1-C2 alkyl), said at least one group being present in the 4-position of the aromatic ring of said aryl; The present invention relates to an iron complex having the general formula (I) or a pharmaceutically acceptable salt thereof:

[0018] According to another preferred embodiment, the present invention relates to an iron complex having the general formula (I) or a pharmaceutically acceptable salt thereof, wherein R1 and R2 are both located at the 5-position of the aromatic ring. According to a particularly preferred embodiment of the present invention, R3 is an aryl optionally substituted with a group selected from COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H and C1-C5 alkyl), said group being located at the 4-position of the aromatic ring of the aryl. Preferably, R3 is an aryl optionally substituted with a group selected from COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2, where Z is simultaneously or independently selected from H and C1-C2 alkyl; said group being located at the 4-position of the aromatic ring of the aryl.

[0019] According to a particularly preferred embodiment, the present invention provides a compound of formula (Ia): [ka] wherein R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and both are H; and R3 is an aryl substituted with a COOH group at the 4-position of the aromatic ring, or a pharmaceutically acceptable salt thereof.

[0020] In the present invention, the iron complex having the aforementioned formula (Ia) or a pharmaceutically acceptable salt thereof can also be described as Fe(DFX), where DFX stands for 4-[(3,5-bis-(2-hydroxyphenyl)-1,2,4)triazol-1-yl]-benzoic acid, known under the trade names Deferasirox and Exjade. According to one embodiment, the iron complex having formula (I) or a pharmaceutically acceptable salt thereof of the present invention is in the form of a racemic or enantiomerically enriched mixture. According to a particularly preferred embodiment, the present invention relates to a pharmaceutically acceptable salt of the iron complex having formula (I), which is obtained by salifying the complex. That is, the pharmaceutically acceptable salt is an iron complex having general formula (I) salified with an inorganic or organic base, preferably selected from the group consisting of alkali metals or alkaline earth metals, amines, and amino alcohols. The amino alcohol is preferably selected from the group consisting of tris(hydroxymethyl)aminomethane, glucosamine, glucamine, and N-methylglucamine (meglumine), more preferably meglumine. Preferably, the pharmaceutically acceptable salt is a salt obtained by reacting an iron complex having formula (I) of the present invention with meglumine. According to a particularly preferred embodiment, the pharmaceutically acceptable salt is a salt obtained by reacting an iron complex having formula (Ia) of the present invention with meglumine. Preferably, the iron complex having general formula (I) of the present invention or a pharmaceutically acceptable salt thereof has a relaxivity in human serum of 2.5 mM or less, measured at 37°C and 1 T. -1 s -1 Greater than 3.4 mM, preferably 3.4 mM -1 s -1 (Gd-DTPA relaxivity) is characterized by a larger

[0021] According to a preferred embodiment of the present invention, wherein the iron complex of the present invention is a complex having formula (Ia) or a pharmaceutically acceptable salt thereof, preferably a salt with meglumine, the relaxivity in human serum measured at 37° C. and 1 T is 3.5 mM -1 s -1The applicant has found that the iron complex of the present invention having the general formula (I) or a pharmaceutically acceptable salt thereof, preferably the iron complex of the present invention having the formula (Ia) or a pharmaceutically acceptable salt thereof, preferably a salt with meglumine, stably binds to albumin present in human serum to form an adduct. Therefore, without wishing to be bound by a particular theory, the high relaxivity of the iron complex of the present invention or a salt thereof in human serum is due to: i) the increase in the applied magnetic field and the formation of an adduct with albumin; 3+ The electronic relaxation time of the ion (T 1e ) and ii) the particularly long molecular reorientation time (T R ) (i.e., 10 to 50 nanoseconds, preferably 15 to 45 nanoseconds). In other words, the relaxivity of the iron complex of the present invention or a pharmaceutically acceptable salt thereof is determined by the ratio of the applied magnetic field to the TR in accordance with the following formula: C It can be said that it increases as the number of variables increases until the number of variables is determined.

number

[0022] Preferably, the iron complex having general formula (I) or a pharmaceutically acceptable salt thereof of the present invention is further characterized by high thermodynamic stability, i.e., greater than 25 log β2, preferably greater than 30 log β2. According to a preferred embodiment of the present invention, when the iron complex of the present invention is a complex having formula (Ia) or a pharmaceutically acceptable salt thereof, preferably a salt with meglumine, the thermodynamic stability is 35-40 log β2. The present invention further relates to a pharmaceutical composition comprising the iron complex having general formula (I) or a pharmaceutically acceptable salt thereof and one or more additives, diluents, and / or pharmaceutically acceptable vehicles. The additives are preferably selected from the group consisting of NaCl, HCl, NaOH, sulfuric acid and its sodium salt, phosphoric acid and its sodium salt, citric acid and its sodium salt, ascorbic acid, sodium ascorbate, sodium carbonate, disodium carbonate, EDTA, and benzalkonium chloride. The diluents are preferably selected from the group consisting of water for injection, saline, dextrose solution, ethanol, and propylene glycol. The pharmaceutically acceptable vehicle is preferably selected from the group consisting of dextrose, mannitol, dextran, and cyclodextrins (α, γ, HP-β). According to one embodiment, the pharmaceutical composition of the present invention is formulated for oral and / or parenteral administration. Preferably, the pharmaceutical composition is formulated for intravenous administration. According to a particularly preferred embodiment, the pharmaceutical composition is formulated as an aqueous solution. The pharmaceutical composition is preferably stable for a long period of time, i.e., 5 days to 12 months, preferably 5 days to 1 month. The present invention also relates to an iron complex having general formula (I) or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition, for use as a contrast agent for magnetic resonance imaging (MRI). According to a preferred embodiment, the iron complex having general formula (I) or a pharmaceutically acceptable salt thereof, or the aforementioned pharmaceutical composition, is administered at a dose of 0.005 to 0.5 mmol / kg, preferably 0.01 to 0.3 mmol / kg.

[0023] Advantageously, as shown in the Examples section, when used as an MRI contrast agent, the iron complex or its salt, or the pharmaceutical composition exhibits performance in terms of contrast of acquired images (T1-weighted images) equivalent to that obtained using a gadolinium-based complex (gadopentetic acid, Gd-DTPA, trade name Magnevist) commonly used in the art (under the same experimental conditions and at the same dosage). Furthermore, as already described, the high thermodynamic stability of the complex or its pharmaceutically acceptable salt of the present invention is particularly advantageous because, when the complex or its salt is administered to a patient, preferably in the form of a pharmaceutical composition, preferably intravenously, for use as an MRI contrast agent, the complex or its salt maintains its structural integrity. Without wishing to be bound by any particular theory, it can be said that, precisely due to the above-mentioned thermodynamic stability, the iron complex having general formula (I) of the present invention or its pharmaceutically acceptable salt does not interfere with the endogenous pool of iron ions or other ions present in the patient's body, does not induce a Fenton-type reaction, and is therefore particularly advantageous for application as an MRI contrast agent. The present invention further relates to a method for in situ preparation of an iron complex having the aforementioned general formula (I) or a pharmaceutically acceptable salt thereof. In the present invention, "in situ preparation" means that the iron complex or a pharmaceutically acceptable salt thereof is produced by mixing appropriate ingredients at the time of oral and / or parenteral administration to a patient or a few minutes before. Therefore, the method of the present invention preferably comprises the steps of: (i) General formula (II) [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, C1-C5 alkoxyl; R3 is selected from H, C1-C5 alkyl, C1-C5 hydroxyalkyl, C1-C5 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from the following: H, C1-C5 alkyl), wherein said at least one group is preferably located at the 4-position of the aromatic ring of said aryl; R4 and R5 are simultaneously or independently selected from H, C1-C4 alkanoyl, aroyl optionally substituted with at least one group selected from the following: COOH, C1-C2 alkyl, C1-C2 alkoxyl, OH, wherein said at least one group is preferably located at the 4-position of the aromatic ring of said aroyl. A compound having the formula (ii) with an iron compound capable of providing Fe(III) ions, preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, ammonium iron sulfate, iron carbonate, until an iron complex having the general formula (I) is formed; or (iii) mixing an inorganic or organic base (preferably selected from the group consisting of alkali metal or alkaline earth metal salts, amines, aminoalcohols (wherein the aminoalcohols are preferably selected from the group consisting of tris(hydroxymethyl)aminomethane, glucosamine, glucamine, and N-methylglucamine (meglumine)) with a compound having general formula (II) until a pharmaceutically acceptable salt of the compound is formed, followed by mixing with an iron compound capable of providing Fe(III) ions (preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, iron ammonium sulfate, and iron carbonate) until a pharmaceutically acceptable salt of the iron complex having general formula (I) is formed. The method comprises the steps of:

[0024] According to one embodiment of the method of the present invention, the amino alcohol is meglumine. According to a preferred embodiment of the method of the present invention, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, and C1-C3 alkoxyl. According to another preferred embodiment of the method of the present invention, R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl) optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl), and the at least one group is preferably located at the 4-position of the aromatic ring of the aryl.

[0025] Preferably, according to a preferred embodiment of the method of the present invention, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl), and the at least one group is preferably located at the 4-position of the aromatic ring of the aryl.

[0026] According to another preferred embodiment of the method of the present invention, R1 and R2 are both located at the 5-position of the aromatic ring. According to a particularly preferred embodiment of the method of the present invention, R3 is selected from the following: aryl (wherein the at least one group is preferably located at the 4-position of the aryl aromatic ring) optionally substituted with at least one group selected from COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl). Preferably, R3 is selected from aryl (wherein the at least one group is preferably located at the 4-position of the aryl aromatic ring) optionally substituted with at least one group selected from COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl). According to a particularly preferred embodiment of the method of the present invention, R1 and R2 are both at the 3-position of the aromatic ring or both at the 5-position of the aromatic ring and both are H; R3 is an aryl substituted with a COOH group at the 4-position of the aromatic ring. According to a particularly preferred embodiment, the method of the present invention preferably comprises, upon oral and / or parenteral administration: (i) General formula (II) [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are both H; R3 is an aryl substituted with a COOH group at the 4-position of the aromatic ring; R4 and R5 are simultaneously or independently selected from H, C1-C4 alkanoyl, aroyl optionally substituted with at least one group selected from the following: COOH, C1-C2 alkyl, C1-C2 alkoxyl, OH, wherein said at least one group is preferably located at the 4-position of the aromatic ring of said aroyl. A compound having the formula (iii) mixing the compound having the general formula (II) with an inorganic or organic base selected from the group consisting of alkali metal or alkaline earth metal salts, amines, and amino alcohols (wherein the amino alcohols are preferably selected from the group consisting of tris(hydroxymethyl)aminomethane, glucosamine, glucamine, and N-methylglucamine (meglumine)) until a pharmaceutically acceptable salt of the compound is formed, followed by mixing with an iron compound. Preferably, the iron compound capable of providing Fe(III) ions to form a pharmaceutically acceptable salt of the iron complex having formula (Ia) can be selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, ammonium iron sulfate, and iron carbonate. According to one embodiment of the method of the present invention, the amino alcohol is meglumine.

[0027] The present invention also relates to a method for in situ preparation of the pharmaceutical composition. In the present invention, "in situ preparation" means that the pharmaceutical composition is produced by mixing appropriate ingredients at the time of, or minutes before, oral and / or parenteral administration to a patient. Therefore, the in situ preparation method of the pharmaceutical composition of the present invention preferably comprises, at the time of oral and / or parenteral administration, mixing the iron complex having the general formula (I) or a pharmaceutically acceptable salt thereof obtained according to the method described above with (iv) mixing with one or more additives, diluents and / or pharmaceutically acceptable vehicles. The additives are preferably selected from the group consisting of NaCl, HCl, NaOH, sulfuric acid and its sodium salts, phosphoric acid and its sodium salts, citric acid and its sodium salts, ascorbic acid, sodium ascorbate, sodium carbonate, disodium carbonate, EDTA, and benzalkonium chloride. The diluents are preferably selected from the group consisting of water for injection, saline, dextrose solution, ethanol, and propylene glycol. The pharmaceutically acceptable vehicles are preferably selected from the group consisting of dextrose, mannitol, dextran, and cyclodextrins (α, γ, and HP-β). The present invention further relates to a kit for in situ preparation of an iron complex having general formula (I) or a pharmaceutically acceptable salt thereof according to the above-mentioned method. The kit comprises at least two separate containers, (i) a first container contains a compound having the general formula (II); (ii) A second container contains an iron(III) compound.

[0028] The compound having general formula (II) and the iron(III) compound are as described above. According to one embodiment of the present invention, the kit optionally comprises a third container containing one or more additives, diluents and / or pharmaceutically acceptable vehicles for the preparation of the pharmaceutical composition described above. According to a particularly preferred embodiment of the present invention, the kit comprises one or more additives, diluents and / or pharmaceutically acceptable vehicles for the preparation of the pharmaceutical composition described above, wherein the one or more additives, diluents and / or pharmaceutically acceptable vehicles are contained in at least one of two separate containers (i)-(ii). According to a particularly preferred embodiment of the present invention, the kit comprises at least three separate containers: (i) a first container comprises a compound having the general formula (II); (ii) a second container comprises an iron(III) compound; and (iii) A third container contains an inorganic or organic base.

[0029] The compound having the general formula (II), the iron(III) compound, and the inorganic or organic base are as described above. According to a particularly preferred embodiment of the present invention, the kit comprises one or more additives, diluents and / or pharmaceutically acceptable vehicles for the preparation of the aforementioned pharmaceutical compositions, said one or more additives, diluents and / or pharmaceutically acceptable vehicles being contained in at least one of three separate containers (i)-(iii).

[0030] According to a particularly preferred embodiment, the present invention provides a compound of general formula (I) [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, C1-C5 alkoxyl; R3 is selected from H, C1-C5 alkyl, C1-C5 hydroxyalkyl, C1-C5 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl), wherein the at least one group is preferably located at the 4-position of the aromatic ring of the aryl). or a pharmaceutically acceptable salt thereof, and one or more additives, diluents and / or pharmaceutically acceptable vehicles.

[0031] Preferably, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl), and the at least one group is preferably located at the 4-position of the aromatic ring of the aryl.

[0032] Preferably, R1 and R2 are both located at the 5-position of the aromatic ring. Preferably, R3 is selected from COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl), and aryl (wherein the at least one group is preferably located at the 4-position of the aryl aromatic ring) optionally substituted with at least one group selected from H, C1-C5 alkyl, preferably C1-C2 alkyl. According to a particularly preferred embodiment, the iron complex has the general formula (I) in which R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring and are simultaneously H; R3 is an aryl substituted at the 4-position of the aromatic ring with a COOH group, i.e., the following formula (Ia): [ka] is an iron complex having the formula:

[0033] Preferably, the pharmaceutical composition of the present invention contains the iron complex having the general formula (I) (or (Ia)) or a pharmaceutically acceptable salt thereof in the form of a racemic or enantiomer-enriched mixture. Preferably, the pharmaceutically acceptable salt is a salt of the iron complex having the above general formula (I) (or (Ia)) with an inorganic or organic base, preferably selected from the group consisting of alkali metal or alkaline earth metal salts, amines, and aminoalcohols (the aminoalcohols are preferably selected from the group consisting of tris(hydroxymethyl)aminomethane, glucosamine, glucamine, and N-methylglucamine (meglumine), preferably N-methylglucamine (meglumine)). According to a preferred embodiment of the present invention, the pharmaceutically acceptable salt is obtained by reacting the iron complex having the general formula (I) (or (Ia)) with meglumine. Preferably, the pharmaceutical composition of the present invention is formulated as an aqueous solution.

[0034] The present invention also relates to a compound of the general formula (I) for use as a contrast agent for magnetic resonance imaging (MRI). [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, C1-C5 alkoxyl; R3 is selected from H, C1-C5 alkyl, C1-C5 hydroxyalkyl, C1-C5 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl), wherein the at least one group is preferably located at the 4-position of the aromatic ring of the aryl). or a pharmaceutically acceptable salt or pharmaceutical composition thereof.

[0035] Preferably, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl), and the at least one group is preferably located at the 4-position of the aromatic ring of the aryl.

[0036] Preferably, R1 and R2 are both located at the 5-position of the aromatic ring. Preferably, R3 is aryl (wherein the at least one group is preferably located at the 4-position of the aryl aromatic ring) optionally substituted with at least one group selected from COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl). According to a particularly preferred embodiment, the iron complex is an iron complex having general formula (I) in which R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring and simultaneously H; and R3 is aryl substituted at the 4-position of the aromatic ring with a COOH group, i.e., the following formula (Ia): [ka] is an iron complex having the formula:

[0037] The present invention also provides a compound of general formula (I): [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, C1-C5 alkoxyl; R3 is selected from H, C1-C5 alkyl, C1-C5 hydroxyalkyl, C1-C5 carboxyalkyl, aryl optionally substituted with at least one group selected from COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl), and wherein the at least one group is preferably located at the 4-position of the aryl aromatic ring). The present invention relates to a pharmaceutically acceptable salt obtained from the reaction of an iron complex having the formula:

[0038] Preferably, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl), and the at least one group is preferably located at the 4-position of the aromatic ring of the aryl.

[0039] Preferably, R1 and R2 are both located at the 5-position of the aromatic ring. Preferably, R3 is aryl (wherein the group is located at the 4-position of the aryl aromatic ring) optionally substituted with at least one group selected from COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl). According to one embodiment, the pharmaceutically acceptable salt is an iron complex having general formula (I) in which R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring and both are H; and R3 is aryl substituted at the 4-position of the aromatic ring with a COOH group, i.e., the following formula (Ia): [ka] with meglumine.

[0040] The present invention also provides an iron complex having the general formula (I) or a pharmaceutically acceptable salt thereof, Mixed with one or more additives, diluents and / or pharmaceutically acceptable vehicles, preferably for oral and / or parenteral administration. A method for in situ preparation of the above pharmaceutical composition, comprising the steps of: The iron complex having the general formula (I) or a pharmaceutically acceptable salt thereof preferably exhibits the following properties upon oral and / or parenteral administration: (i) General formula (II): [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl; R3 is selected from H, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 hydroxyalkyl, preferably C1-C3 hydroxyalkyl, C1-C5 carboxyalkyl, preferably C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl), wherein said at least one group is preferably present in the 4-position of the aromatic ring of the aryl; R4 and R5 are simultaneously or independently selected from H, C1-C4 alkanoyl, aroyl optionally substituted with at least one group selected from the following: COOH, C1-C2 alkyl, C1-C2 alkoxyl, OH, wherein said at least one group is preferably located at the 4-position of the aromatic ring of said aroyl. A compound having the formula (ii) with an iron compound capable of providing Fe(III) ions, preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, ammonium iron sulfate, iron carbonate, until an iron complex having the general formula (I) is formed; or (iii) preferably obtained according to a method comprising the step of mixing a compound having the general formula (II) with an inorganic or organic base, preferably selected from the group consisting of alkali metal or alkaline earth metal salts, amines, amino alcohols (wherein the amino alcohol is preferably selected from the group consisting of tris(hydroxymethyl)aminomethane, glucosamine, glucamine, N-methylglucamine (meglumine)), until a pharmaceutically acceptable salt of the compound is formed, and then mixing with an iron compound capable of providing Fe(III) ions, preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, iron ammonium sulfate, iron carbonate, until a pharmaceutically acceptable salt of the iron complex having the general formula (I) is formed, Regarding the preparation method.

[0041] Preferably, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from the following: H, C1-C2 alkyl), and the at least one group is preferably located at the 4-position of the aromatic ring of the aryl.

[0042] Preferably, R1 and R2 are both located at the 5-position of the aromatic ring. Preferably, R3 is aryl (wherein the at least one group is preferably located at the 4-position of the aromatic ring) optionally substituted with at least one group selected from COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl), The present invention also relates to a method for the in situ preparation of a pharmaceutically acceptable salt of a complex having the above general formula (I) with meglumine, which method preferably comprises, upon oral and / or parenteral administration: (i) A compound having the general formula (II) [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl; R3 is selected from H, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 hydroxyalkyl, preferably C1-C3 hydroxyalkyl, C1-C5 carboxyalkyl, preferably C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl), wherein said at least one group is preferably present in the 4-position of the aromatic ring of the aryl; R4 and R5 are simultaneously or independently selected from H, C1-C4 alkanoyl, aroyl optionally substituted with at least one group selected from the following: COOH, C1-C2 alkyl, C1-C2 alkoxyl, OH, wherein said at least one group is preferably located at the 4-position of the aromatic ring of said aroyl. and a compound having the formula: (iii) N-methylglucamine (meglumine) is mixed until a pharmaceutically acceptable salt of the compound having the general formula (II) is formed, and then mixed with an iron compound capable of providing Fe(III) ions, preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, ammonium iron sulfate, and iron carbonate, until a pharmaceutically acceptable salt of the iron complex having the general formula (I) is formed. The present invention relates to a method comprising the steps of:

[0043] Preferably, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C2 alkyl) (wherein the at least one group is preferably located at the 4-position of the aryl aromatic ring). Preferably, R1 and R2 are both located at the 5-position of the aromatic ring. Preferably, R3 is aryl optionally substituted with a group selected from COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2, (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl), and the group is preferably located at the 4-position of the aromatic ring of the aryl. The present invention also provides compounds, preferably when administered orally and / or parenterally, that: (i) A compound having the general formula (II) [ka] [In the formula, R1 and R2 are both at the 3-position of the aromatic ring or both at the 5-position of the aromatic ring and are both H; R3 is an aryl substituted with a COOH group at the 4-position of the aromatic ring; R4 and R5 are simultaneously or independently selected from H, C1-C4 alkanoyl, aroyl optionally substituted with at least one group selected from the following: COOH, C1-C2 alkyl, C1-C2 alkoxyl, OH, wherein said at least one group is preferably located at the 4-position of the aromatic ring of said aroyl. and a compound having the formula: (iii) N-methylglucamine (meglumine) is mixed with the compound having the general formula (II) until a pharmaceutically acceptable salt of the compound is formed, and then mixed with an iron compound capable of providing Fe(III) ions, preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, ammonium iron sulfate, and iron carbonate, until a pharmaceutically acceptable salt of the iron complex having the general formula (I) is formed. The present invention relates to a method for the in situ preparation of a pharmaceutically acceptable salt of an iron complex having the general formula (Ia) and meglumine, comprising the steps of:

[0044] Furthermore, the present invention preferably provides, upon oral and / or parenteral administration: (i) General formula (II) [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl; R3 is selected from H, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 hydroxyalkyl, preferably C1-C3 hydroxyalkyl, C1-C5 carboxyalkyl, preferably C1-C3 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl, preferably C1-C2 alkyl), wherein said at least one group is preferably present in the 4-position of the aromatic ring of the aryl; R4 and R5 are simultaneously or independently selected from H, C1-C4 alkanoyl, aroyl optionally substituted with at least one group selected from the following: COOH, C1-C2 alkyl, C1-C2 alkoxyl, OH, wherein said at least one group is preferably located at the 4-position of the aromatic ring of said aroyl. A compound having the formula (ii) with an iron compound capable of providing Fe(III) ions, preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, ammonium iron sulfate, iron carbonate, until an iron complex having the general formula (I) is formed; or (iii) mixing with an inorganic or organic base, preferably selected from the group consisting of alkali metal or alkaline earth metal salts, amines, amino alcohols (wherein the amino alcohol is preferably selected from the group consisting of tris(hydroxymethyl)aminomethane, glucosamine, glucamine, and N-methylglucamine (meglumine)), until a pharmaceutically acceptable salt of the compound having the general formula (II) is formed, followed by mixing with an iron compound capable of providing Fe(III) ions, preferably selected from the group consisting of iron oxide, iron hydroxide, iron chloride, iron sulfate, iron citrate, iron fumarate, iron gluconate, iron tartrate, iron ammonium sulfate, and iron carbonate, until a pharmaceutically acceptable salt of the iron complex having the general formula (I) is formed. According to a method comprising the steps of: [ka] [In the formula, R1 and R2 are both located at the 3-position of the aromatic ring or both located at the 5-position of the aromatic ring, and are simultaneously or independently selected from H, halogen, C1-C5 alkyl, C1-C5 alkoxyl; R3 is selected from H, C1-C5 alkyl, C1-C5 hydroxyalkyl, C1-C5 carboxyalkyl, aryl optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, C1-C5 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from H, C1-C5 alkyl), wherein the at least one group is preferably located at the 4-position of the aromatic ring of the aryl). or a pharmaceutically acceptable salt thereof, the kit comprising at least two separate containers, (i) a first container contains a compound having the general formula (II); (ii) the second container contains an iron compound; Regarding the kit.

[0045] Preferably, R1 and R2 are both located at the 3-position of the aromatic ring, or both located at the 5-position, and are simultaneously or independently selected from H, halogen, C1-C3 alkyl, and C1-C3 alkoxyl; R3 is selected from H, C1-C3 alkyl, C1-C3 hydroxyalkyl, C1-C3 carboxyalkyl, and aryl (said at least one group is located at the 4-position of the aryl aromatic ring) optionally substituted with at least one group selected from COOH, halogen, C1-C3 alkyl, C1-C3 alkoxyl, OH, NZ2, and CONZ2 (wherein Z is simultaneously or independently selected from H and C1-C2 alkyl). Preferably, R1 and R2 are both located at the 5-position of the aromatic ring. Preferably, R3 is aryl (said at least one group being present at the 4-position of the aromatic ring) optionally substituted with at least one group selected from the following: COOH, halogen, C1-C5 alkyl, preferably C1-C3 alkyl, C1-C5 alkoxyl, preferably C1-C3 alkoxyl, OH, NZ2, CONZ2 (wherein Z is simultaneously or independently selected from: H, C1-C5 alkyl, preferably C1-C2 alkyl). According to a particularly preferred embodiment, the iron complex is an iron complex having general formula (I) in which R1 and R2 are both present at the 3-position of the aromatic ring or both present at the 5-position of the aromatic ring and both are H, and R3 is an aryl substituted at the 4-position of the aromatic ring with a COOH group, i.e., formula (Ia): [ka] is an iron complex having the formula:

[0046] The present invention also provides a kit comprising one or more additives, diluents and / or pharmaceutically acceptable vehicles for the preparation of the above pharmaceutical composition, the one or more excipients, diluents and / or pharmaceutically acceptable vehicles are contained in at least one of two separate containers (i)-(ii), or alternatively, the kit comprises at least three separate containers; where (i) a first container comprises a compound having the general formula (II); (ii) a second container comprising an iron compound; (iii) a third container comprises an inorganic or organic base; The kit optionally comprises one or more additives, diluents and / or pharmaceutically acceptable vehicles for the preparation of the pharmaceutical composition of the present invention, wherein the one or more additives, diluents and / or pharmaceutically acceptable vehicles are contained in at least one of three separate containers (i)-(iii); Regarding the kit. [Example]

[0047] Example 1 - Fe(DFX) 2 Preparation of meglumine salt of The [Fe(DFX)2Meg3] complex was prepared according to the following procedure. 0.2 mmol of DFX (PM = 373.73; 75 mg) was dispersed in 100 mL of HO. The resulting suspension was completely dissolved with a 5 M aqueous solution of meglumine (N-methyl-D-glucamine, MEG) and salted with heating and stirring until the pH reached approximately 9. 0.1 mmol of FeCl3 (4 mL of a 25 mM solution) was then added, and the pH of the resulting solution was adjusted to approximately 8 by adding a 5 M solution of meglumine. The resulting solution was heated to 60 °C and maintained with stirring for 1 h. The solution was then filtered through a Buchner filter and lyophilized to yield a red solid. The resulting complex was analyzed and characterized by HPLC with a Waters Alliance Separation Module equipped with a 2998 PDA detector. The analysis was performed using a 10-minute isocratic run (flow rate 1 mL / min; injection volume: 10 μL of a 200 μM solution; column: Atlantis RPC18; eluent: 35% buffer (50 mM ammonium acetate, 10 mM tetrabutylammonium hydrogen sulfate), 45% methanol, and 20% acetonitrile; wavelength 467 nm; t R= 2.7 min). The presence of the complex was confirmed by mass spectrometry using a Waters 3100 Mass Detector system with ESI ionization (-) by syringe pump (direct infusion) and a 2:1 water / methanol eluent. Analysis of the mass spectral peaks (m / z = 798.3 and m / z 398.8) identified complex C. 42 H 27 This corresponds to the theoretical mass of FeN6O8: m / z = MH / 1 = 798.13, m / z = M-2H / 2 = 398.6. In order to prove the effectiveness of the salt of the complex thus obtained (hereinafter simply referred to as Fe(DFX)2) as an MRI contrast agent, various experiments and tests were carried out as shown in the following examples.

[0048] Example 2 - Fixed Field Relaxometric Measurements (1 T): Comparison with Prior Art Gd-DTPA and Fe-DTPA Complexes Fixed-field relaxometric measurements were performed using the [Fe(DFX)2Meg3] complex obtained in Example 1 and compared with two prior art complexes, Gd-DTPA and Fe-DTPA. The results obtained in measurements in human serum and in water are shown in Table 1 below. [Table 1]

[0049] Example 3 - Fe(DFX) 2 1 / T of 1 1 H-NMRD profile As shown in FIG. 1, the 1 / T1(R1) of the Fe(DFX)2 complex obtained in the examples 1 H-NMR profiles were analyzed in water and human serum at 25°C over the Larmor frequency range of 0.01 to 80 MHz, and 1 / T2 (R2) profiles were analyzed over the Larmor frequency range of 20 to 80 MHz. The 1 / T1 (R1) profiles recorded in water and serum coincided up to a frequency of approximately 10 MHz, but an increase in relaxivity was observed in the profile recorded in serum, which was much more pronounced than for the complex in water. This phenomenon is due to the binding of the complex to albumin in serum, which results in an increase in the size of the system and a longer molecular reorientation time (τ R) is due to the longer T2 / T1 values. As expected, the 1 / T2 values ​​are always higher than the 1 / T1 values ​​across the entire frequency range tested (20–80 MHz). The R2 / R1 ratio remains approximately 1.4 in both water and serum.

[0050] Example 4 - Stability and relaxivity measurements with pH changes The stability of the Fe(DFX)2 complex obtained according to Example 1 was tested in water at varying pH. The complex of the present invention dissolved in water was shown to be stable (no precipitation was recorded) over the pH range tested (6-10). Furthermore, as shown in Figure 2, the relaxivity measured in a fixed magnetic field (B0 = 0.5 T) was found to be constant over the pH range tested (6-10), suggesting that no structural changes occurred that would alter the relaxivity.

[0051] Example 5 - Measurement of stability and relaxivity with temperature change For solutions of the Fe(DFX)2 complex obtained in the same manner as in Example 1, the increase in the relaxivity R1 was measured in PBS (phosphate buffered saline) and serum under a fixed magnetic field (B0 = 0.5 T) at various temperatures. As can be seen from Figure 3, the R1 value gradually decreased with increasing temperature in both serum and PBS. This trend is due to the fact that the correlation time of paramagnetic relaxation shortens with increasing temperature, resulting in a decrease in the R1 value.

[0052] Example 6 - Stability testing in human serum The stability of the Fe(DFX)2 complex of the present invention obtained according to Example 1 in serum was tested by measuring the relaxivity at 0.5 T and 25°C for solutions maintained at 4°C and 37°C for up to 6 days after preparation. The values ​​obtained were compared with those obtained in a similar test performed in PBS. As shown in Figure 4, the r1 values ​​were essentially constant for solutions maintained at both 4°C and 37°C. Therefore, it can be concluded that the Fe(DFX)2 complex is stable in PBS and serum at the temperatures and times tested.

[0053] Example 7 - Binding to albumin The binding of the Fe(DFX)2 complex of the present invention obtained according to Example 1 to human serum albumin (HSA-human serum albumin) was tested by measuring the water proton relaxation time (R1 = 1 / T1) values ​​for solutions containing 0.5 mM Fe(DFX)2 and increasing concentrations of protein (ranging from 0.07 to 2.0 mM) in PBS. The trend shown in Figure 5 indicates a strong interaction between Fe(DFX)2 and albumin. A change in the slope of the binding curve occurs at an Fe(DFX)2:albumin ratio of 3:1. This means that three Fe(DFX)2 molecules bind to three different sites on the protein. The increase in R1 at albumin concentrations above 0.17 mM is due to nonspecific binding and increased solution viscosity.

[0054] Example 8 - Fe(DFX) 2 MRI images using Gd-DTPA complexes and comparison with prior art Gd-DTPA complexes The contrast enhancement (En%) produced by administration (0.1 mmol / kg) of the Fe(DFX)2 complex of the present invention obtained according to Example 1 was measured and compared with that produced by administration of a Gd-DTPA complex (known under the trade name Magnevist) at the same dose and under the same experimental conditions. Measurements were performed in vivo using mice inoculated with tumor cells (TSA) under fixed magnetic fields of 3 T and 7 T. Images were acquired when the subcutaneous tumors reached approximately 1–2 cm in size (i.e., approximately 15–20 days after inoculation). As can be seen from Figures 6–8, overall similarities were observed between the Fe(DFX)2 complex and Gd-DTPA in terms of the contrast produced in various organs / tissues. Major differences were noted with respect to the kidney and bladder, indicating faster renal excretion of Gd-DTPA compared with the complex of the present invention. In contrast, a slower "washout" of Fe(DFX)2 was observed in the tumor region compared to Gd-DTPA, and the complexes of the present invention demonstrated sustained MRI signal enhancement (En%, "enhancement") in the tumor region for up to 60 minutes after administration under fixed magnetic fields at both 7 T and 3 T.

[0055] Example 9 - Blood Excretion After administration of Fe(DFX)2 or Gd-DTPA at a dose of 0.1 mmol / kg to mice, plasma iron (Fe 3+ ) (values ​​corrected for endogenous iron) or gadolinium (Gd 3+ The time course of Fe(DFX)2 concentrations was measured by ICP-MS. Fe(DFX)2 exhibits behavior similar to that of a "blood pool agent," i.e., angiographic contrast agent. However, as shown in Figure 9, the Fe(DFX)2 concentration in the blood 24 hours after administration is close to zero.

Claims

1. The following formula (Ia): 【Chemistry 1】 1. A contrast agent for magnetic resonance imaging (MRI), comprising an iron complex having the formula:

2. The contrast agent of claim 1, wherein the pharmaceutically acceptable salt is a salt of meglumine with an iron complex having formula (Ia):

3. The following formula (Ia): 【Chemistry 2】 or a pharmaceutically acceptable salt thereof, and one or more additives, diluents and / or pharmaceutically acceptable vehicles, for use as a contrast agent for magnetic resonance imaging (MRI).

4. 4. The pharmaceutical composition of claim 3, wherein the pharmaceutically acceptable salt is a salt of an iron complex having formula (Ia) and meglumine.

5. 5. The pharmaceutical composition of claim 3 or 4, formulated for oral or parenteral administration.

6. The pharmaceutical composition of claim 5 formulated for intravenous administration.

7. A pharmaceutical composition according to claim 5 or 6 formulated as an aqueous solution.

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