WO1999042139A2

WO1999042139A2 - Hydroxyethyl starch conjugate, method for the production thereof and pharmaceuticals containing the same

Info

Publication number: WO1999042139A2
Application number: PCT/EP1999/000853
Authority: WO
Inventors: Peter Mareski; Johannes Platzek; Bernd Radüchel; Ulrich Niedballa; Hanns-Joachim Weinmann
Original assignee: Schering Aktiengesellschaft
Priority date: 1998-02-20
Filing date: 1999-02-09
Publication date: 1999-08-26
Also published as: DE19808079A1; WO1999042139A3; AU2832899A

Abstract

The invention relates to novel hydroxyethyl starch conjugates and their use in medical diagnosis.

Description

Hydroxyethyl starch conjugates, processes for their preparation and pharmaceutical compositions containing them

The invention relates to the subject matter characterized in the patent claims, that is to say new hydroxyethyl starch conjugates, agents containing these compounds, the use of the complexes in diagnosis and therapy and methods for producing these compounds and agents.

The contrast media currently used clinically for the modern imaging methods magnetic resonance imaging (MRI) and computed tomography (CT) [Magnevist®, Pro Hance®, Ultravist® and Omniscan®] are distributed throughout the extracellular space of the body (intravascular space and interstitium) about 20% of the body volume

Extracellular MRI contrast agents were first used clinically successfully in the diagnosis of cerebral and spinal disease processes, since this results in a very special situation with regard to the regional distribution area. In the brain and spinal cord, extracellular contrast agents in healthy tissue cannot leave the intravascular space due to the blood-brain barrier. In pathological processes with a disturbance of the blood-brain barrier (e.g. malignant tumors, inflammation, demyelinating diseases, etc.), regions with increased blood vessel permeability (permeability) for these extracellular contrast agents (Schmiedl et al., MRI of blood -brain barπer permeabi ty in astrocytic giiomas: application of small and large molecular weight contrast media, Magn. Reson. Med. 22: 288, 1991). By taking advantage of this vascular permeability disorder, diseased tissue can be identified with high contrast to the healthy tissue

However, there is no such permeability barrier for the contrast media mentioned above outside the brain and spinal cord (Canty et al, First-pass entry of nonionic contrast agent mto the myocardial extravascular space Effects on radiographic estimate of transit time and blood volume Circulation 84. 2071 , 1991) The concentration of the contrast medium is no longer dependent on the vascular permeability, but only on the size of the extracellular space in the corresponding tissue It is not possible to demarcate the vessels from the surrounding interstitial space when using this contrast medium

A contrast medium that is distributed exclusively in the vasal space (vascular space) would be desirable especially for the imaging of vessels. Such a blood pool agent should make it possible to use MRI to differentiate between well-perfused and poorly perfused tissue and thus also diagnose ischemia infarcted tissue could be differentiated from the surrounding healthy or ischemic tissue due to its anemia, if a vasal contrast medium is used. This is particularly important when it comes to differentiating a heart attack from an ischemia, for example

So far, most of the patients who are suspected of having cardiovascular disease (this disease is the most common)

Cause of death in the western industrialized countries), undergo invasive diagnostic examinations In angiography, X-ray diagnostics with the aid of iodine-containing contrast media are currently used primarily. These examinations have various disadvantages, they are associated with the risk of radiation exposure, as well as with inconvenience and stress , which come mainly from the fact that the iodine-containing contrast media, compared to NMR contrast media, must be used in a much higher concentration

There is therefore a need for NMR contrast media which can mark the vasal space (blood pool agent). These compounds are to be distinguished by good tolerability and high activity (high increase in signal intensity in MRI)

The approach to using at least some of these problems

To date, complexing complexes that are bound to macro- or biomolecules has only been successful to a very limited extent

For example, the number of paramagnetic centers in the complexes described in European Patent Applications No. 0 088 695 and No. 0 150 844 is not sufficient for satisfactory imaging Increasing the number of required metal units by multiple introduction of complexing units into a macromolecular biomolecule is associated with a non-tolerable impairment of the affinity and / or specificity of this biomolecule [J Nucl Med 24, 1158 (1983)]

Macromolecules can generally be suitable as contrast media for angiography. Albumm-GdDTPA (Radiology 1987, 162 205) eg 24 hours after intravenous injection in the rat, however, shows an accumulation in the liver tissue that accounts for almost 30% of the dose. In addition, in 24 hours only 20% of the dose eliminated

The macromolecule polylysine-GdDTPA (European patent application, publication no. 0 233 619) also proved to be suitable as a blood pool agent. However, due to the production process, this compound consists of a mixture of molecules of different sizes. In excretion experiments in the rat, it was shown that this macromolecule is excreted unchanged via the kidney by glomerular filtration. Due to its synthesis, polylysine-GdDTPA can also contain macromolecules that are so large that they cannot pass through the capillaries of the kidney during glomerular filtration and thus remain in the body

The polymers described in European Patent Application No. 0 430 863 already represent a step on the way to biood-pooi agents, since they no longer have the heterogeneity in terms of size and molar mass which is characteristic of the aforementioned polymers. However, they still leave nothing to be desired Open with regard to complete elimination, tolerability and / or effectiveness

The in EP 0326226, EP 0166755, EP0184899, WO 95/24225, US-4,986,980, WO 92/07259, US-5,336,762, WO 85/05554, US-4,822,594, US-5,250,672, WO 91/10908, WO 87/02893 , WO 92/17214, WO 94/27498, US-5,271, 929, WO 92/21017, US-5,271, 924 WO 94/08629 US-5,364 613, US-5,368,840, US-5,401, 491, US-5,512,294, Compounds disclosed in EP 0535668, WO 95/14491, US Pat. No. 5,679,810, US Pat. No. 5,593,658, US Pat. No. 5,583,206, EP 0271180 and EP 0481526 have disadvantages in terms of suitability as blood-pool contrast media, particularly with regard to chemical stability, water solubility, excretion behavior and / or tolerance on Carboxymethyldextrandeπvate as described in Bioconjug Chem 1998, 94-99 also have inadequate excretion behavior and a too low tolerance for use as a contrast agent

The object was therefore to provide new diagnostic means, especially for the detection and localization of vascular diseases, which do not have the disadvantages mentioned. This object is achieved by the present invention

It has been found that hydroxyethyl starch conjugates of the general formula I

where n for the numbers 200 to 1,500 and

R for a hydrogen atom or in each case independently of one another for the radicals a ₁ = - (CH2) 2θH, a ₂ = -CH2COOH, 8 3 =

- (CH ₂ ) 2θCH ₂ COOH, a 4 = -CH ₂ CONHK or a 5 = - (H2) 2θCH2CONHK with K have the meaning of a metal complex or a complexing agent, with the proviso that statistically 0.02 to 1 per monomer unit , 5 residues a - | and 0.02 to 2.5 residues a 2 and 0.02 to 1.5 residues a 3 and 0.02 to 2.5 residues a 4 and 0.02 to 1.5 residues a 5 substitute the hydroxyl hydrogens, where the carboxyl groups that may be present in the molecule are replaced by cations of inorganic and / or organic bases, amino acids or amino acid amides, surprisingly excellent for the production of NMR and X-ray diagnostics, in particular for displaying the vasal space (ie as a blood pool agent) without the aforementioned To have disadvantages

K represents a radical of the general formula II

₍ " _}

wherein

Z independently of one another for a hydrogen atom or a

Metal ion equivalent of atomic numbers 20-29, 39, 42, 44 or 57-83,

A for the groups -CH2CH (OH) - or -CHR ¹ CONH-, where R ^{1 represents} a hydrogen atom or the methyl group,

B for a C- | -C20- ^{A |} kylene chain which is optionally interrupted by 1 - 3 -CONH-, 1 -3 -NHCO-, 1 -3 -NH-, 1 -3 -CO-, 1 phenylene group (s) or 1 -5 oxygen atoms or which is optionally substituted by 1 -3 -OH or 1 -3 - (CH2) θ-3 "COOH groups.

N preferably stands for the numbers 240 to 750.

If K is a metal complex, then at least two of the radicals Z are metal ion equivalents of atomic numbers 20-29, 39, 42, 44 or 57-83, preferably the atomic numbers of paramagnetic metals. Gadolinium is particularly preferred.

The monomer unit of the hydroxyethyl starch conjugates according to the invention preferably contains statistically 0.05 to 1 radicals a 4 and 0.05 to 1 radicals a 5.

B is preferably one of the radicals

-CH ₂ -

-CH ₂ CH ₂ -

- (CH ₂ ) ₃ -

-CH ₂ CH2-0-CH ₂ CH2- - (CH ₂ -CH2-O) 2-CH ₂ CH2-

-CH ₂ NHCOCH ₂ -

-CH ₂ NHCO-CH ₂ CH ₂ -

-CH ₂ CONHCH ₂ CH ₂ -

-CH2CONHCH2CH2CH2-

CH2-CO-NH-C6H4-O-CH2-CH2-

The hydroxyethyl starch conjugates according to the invention have the desired properties described at the outset

They accumulate in areas with increased vascular permeability, e.g. in tumors. allow statements about the perfusion of tissues, give the possibility to determine the blood volume in tissues, to selectively shorten the relaxation times or densities of the blood, and to visualize the permeability of the blood vessels. Such physiological information is not possible through the use of extracellular contrast agents, e.g. Gd-DTPA [Magnevist®], to be obtained From these points of view, there are also the areas of application in the modern imaging methods magnetic resonance imaging and computed tomography, more specific diagnosis of malignant tumors, early therapy control in cytostatic, anti-inflammatory or vasodilative therapy, early detection of underperfused areas (e.g. in the myocardium), angiography for vascular diseases, and detection and diagnosis of (sterile or infectious) inflammation

Another advantage over extracellular contrast media such as Gd-DTPA [Magnevist®] is that the higher effectiveness as a contrast agent for magnetic resonance imaging (higher relaxivity) must be emphasized, which leads to a significant reduction in the diagnostically necessary dose. At the same time, the contrast agents according to the invention can be used as solutions Isoosmolar to the blood and thereby reduce the osmotic load on the body, which is reflected in a reduced toxicity of the substance (higher toxic threshold). Lower doses and higher toxic threshold lead to a significant increase in the safety of contrast medium applications in modern imaging methods In comparison to the macromolecular contrast agents based on carbohydrates, eg dextran (European patent application, publication no. 0 326 226), which generally only carry about 5% of the signal-enhancing paramagnetic cation, the polymer complexes according to the invention have a content of generally about 20% of the paramagnetic cation. Thus, the macromolecules according to the invention bring about a very much higher signal amplification per molecule, which at the same time means that the dose required for nuclear spin tomography is considerably smaller compared to other macromolecular contrast agents

With the hydroxyethyl starch conjugates according to the invention, it is surprisingly possible to use compounds with a molecular weight above the renal function threshold as a blood pool agent

Compared to the other polymer compounds mentioned in the prior art, the hydroxyethyl starch conjugates according to the invention are distinguished by improved excretion behavior, greater effectiveness, greater stability and / or better tolerance

A further advantage of the present invention is that complexes with hydrophilic, macrocyclic, high molecular weight ligands have now become accessible. This makes it possible to control the compatibility and pharmacokinetics of these polymer complexes by chemical substitution

The hydroxyethyl starch conjugates according to the invention are prepared by the processes known to the person skilled in the art by base-catalyzed etherification of commercially available hydroxyethyl starches - preferably with a degree of substitution of 0.5 - with haloacetic acids, preferably

Chloroacetic acid (see B Bioconjug Chem 1998, 94-99). The acids obtained in this way are activated (for example as an active ester) with the desired amino group-containing macrocyclic complexes or complexing agents by methods known in the art (for example Houben-Weyl, methods of organic chemistry, Georg Thieme Verlag, Stuttgart, Volume E 5 1985 633) preferably water-soluble carbodimides such as EDCI are used. The macrocyclic complexes or complexing agents required for this are according to the regulations disclosed in WO 95/17451 and WO 97/02051

In the case of reaction with complexing agents, the desired metals are introduced by the methods known to the person skilled in the art, as disclosed, for example, in German Offenlegungsschnft 34 01 052, by adding the metal oxide or a metal salt (for example the nitrate, acetate, carbonate, Chloride or sulfate) of the element of atomic numbers 20 - 29, 39, 42, 44, 57 - 83 dissolved or suspended in water and / or a lower alcohol (such as methanol, ethanol or isopropanol) and with the solution or suspension of the equivalent amount of complex-forming ligands and then, if desired, existing acidic hydrogen atoms of the acid groups substituted by cations of inorganic and / or organic bases, amino acids or amino acid amides

The neutralization takes place with the aid of inorganic bases (for example hydroxides, carbonates or bicarbonates) of for example sodium, potassium, lithium, magnesium or calcium and / or organic bases such as primary, secondary and tertiary nurses, for example

Ethanolamine, morpholine, glucamine, N-methyl and N, N-dimethylglucamine, as well as basic amino acids such as lysine, arginine and ornithine or amides of originally neutral or acidic amino acids such as hippuric acid, glycacetamide

To prepare the neutral complex compounds, for example, the acidic complex salts in aqueous solution or suspension can be added with as much of the desired base that the neutral point is reached. The solution obtained can then be evaporated to dryness in vacuo. It is often advantageous to add the neutral salts formed of water-miscible solvents, such as, for example, lower alcohols (methanol, ethanol, isopropanol and others), lower ketones (acetone and others), polar ethers (tetrahydrofuran, dioxaπ, 1, 2-dimethoxyethane and others) to precipitate and are easy to isolate and to obtain easily cleanable systems It has proven to be particularly advantageous to add the desired base already during the complex formation of the reaction mixture and thereby to save one process step If the acidic complex compounds contain several free acidic groups, it is often expedient to prepare neutral mixed salts which contain both inorganic and organic cations as counterions

This can be done, for example, by using the complex-forming

Reacts ligands in aqueous suspension or solution with the oxide or salt of the element providing the central ion and half the amount of an organic base required for neutralization, isolates the complex salt formed, cleans it if desired and then adds the required amount of inorganic base for complete neutralization The order of adding the base can also be reversed

The pharmaceutical compositions according to the invention are also prepared in a manner known per se by using the complex compounds according to the invention

- if necessary with the addition of the additives customary in galenics - suspended or dissolved in an aqueous medium and then the suspension or solution optionally sterilized. Suitable additives are, for example, physiologically acceptable buffers (such as tromethamine), additions of complexing agents or weak complexes (such as diethylene) - tπaminpentaacetic acid or its Ca complex) or - if necessary - electrolytes such as sodium chloride or - if necessary - antioxidants such as ascorbic acid

If suspensions or solutions of the agents according to the invention in water or physiological salt solution are desired for enteral administration or other purposes, they are mixed with one or more auxiliary agents (for example methyl cellulose, lactose, mannitol) and / or tenside which are common in galenics (s) [for example lecithins, Tween®, Myrj®] and / or flavoring (s) for flavor correction [for example essential oils] mixed

In principle, it is also possible to prepare the pharmaceutical compositions according to the invention without isolating the complex salts. In any case, particular care must be taken to carry out the chelation so that the salts and salt solutions according to the invention are practically free of non-complexed, toxic-acting metal ions This can be ensured, for example, with the aid of color indicators such as xylenol orange through control titrations during the production process. The invention therefore also relates to processes for the preparation of the complex compounds and their salts. As a last resort, cleaning of the isolated complex salt remains

The pharmaceutical compositions according to the invention preferably contain 1 μmol - 1.3 mol / l of the complex salt and are generally dosed in amounts of 0.0001 - 5 mmol / kg. They are intended for enteral and parenteral administration. The complex compounds according to the invention are used

Application for NMR and X-ray diagnostics in the form of their complexes with the ions of the elements with atomic numbers 21 - 29, 39, 42, 44 and 57 - 83

The agents according to the invention meet the diverse requirements for suitability as contrast agents for magnetic resonance imaging. Thus, after oral or parenteral application, they are excellently suited to improve the meaningfulness of the image obtained with the aid of the magnetic resonance tomograph. Furthermore, they show the high effectiveness, which is necessary to burden the body with the smallest possible amount of foreign substances and the good tolerability which is necessary to maintain the non-vasive character of the examinations

The good water solubility and low osmolahtate of the agents according to the invention make it possible to produce highly concentrated solutions so that the

To keep the volume load of the circulation within reasonable limits and to compensate for the dilution through body fluid, that is, NMR diagnostics must be 100 to 1000 times more water-soluble than for NMR spectroscopy. Furthermore, the agents according to the invention not only have high stability in vitro, but also a surprisingly high stability in vivo, so that a release or an exchange of those not covalently bound in the complexes

- toxic in itself - ions take place extremely slowly within the time in which the new contrast agents are completely excreted again

In general, the agents according to the invention are used for use as NMR diagnostics in amounts of 0.0001-5 mmol / kg, preferably 0.005- 0.5 mmol / kg, dosed. Details of the application are described, for example, in H.J. Weinmann et al., Am. J. of Roentgenology 142, 619 (1984).

Particularly low doses (below 1 mg / kg body weight) of organism-specific NMR diagnostics can be used, for example, to detect tumors and heart attacks.

Furthermore, the complex compounds according to the invention can advantageously be used as susceptibility reagents and as shift reagents for in vivo NMR spectroscopy.

The compounds according to the invention are surprisingly also suitable for differentiating malignant and benign tumors in areas without a blood-brain barrier.

They are also characterized by the fact that they are completely eliminated from the body and are therefore well tolerated.

The agents according to the invention are outstandingly suitable as X-ray contrast agents, in particular for computed tomography (CT), whereby it should be emphasized that they show no signs of the anaphylaxis-like reactions known from the iodine-containing contrast agents in biochemical-pharmacological examinations. They are particularly valuable for digital subtraction techniques due to their favorable absorption properties in areas with higher tube voltages.

In general, the agents according to the invention for use as X-ray contrast media are dosed in amounts of 0.1 to 5 mmol / kg, preferably 0.25 to 1 mmol / kg, in analogy to, for example, meglumine diatrizoate.

Details of the use of X-ray contrast media are discussed, for example, in Barke, X-ray contrast media, G. Thieme, Leipzig (1970) and P. Thurn, E. Bücheier "Introduction to X-ray diagnostics", G. Thieme, Stuttgart, New York (1977).

Overall, it has been possible to synthesize new complexing agents, metal complexes and metal complex salts, which open up new possibilities in diagnostic and therapeutic medicine. The following examples serve to explain the subject of the invention in more detail:

example 1

Polyamide of O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7, 10-tπs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 40 KD / Degree of substitution on gadolinium complex K 0.2)

a) Sodium-O-carboxymethyl-hydroxyethyl-strong (dSQM = 1, 1)

10.0 g (56.5 mmol) of 40 kD hydroxyethyl starch (ds HE ⁼ ° _> ^{5 /} commercially available from Gerindus) are suspended in 200 ml of dimethyl sulfoxide and with vigorous stirring with a total of 16.0 ml (172.8 mmol) Sodium hydroxide) of a 32% aqueous sodium hydroxide solution was added dropwise at room temperature. After a reaction time of 2 hours at room temperature, a total of 7.64 g (80.8 mmol) of chloroacetic acid was added to the solution of the hydroxyethyl-strong poly-alcoholate formed Reaction solution is stirred for 3 hours at 65 ° C. After cooling to 5 ° C., a mixture of 1000 ml of isopropanol / 500 ml of tetrahydrofuran / 500 diethyl ether is added and the precipitated solid is filtered off, the solid reaction product thus obtained is then washed three times with 150 ml of isopropanol and dried in vacuo at 30 ° C. The colorless reaction product is then dissolved in 350 ml of distilled water while cooling with ice and vigorous stirring, by adding the aqueous product solution thus obtained with 10% aqueous hydrochloric acid, a pH of 10.0 is set and the volume is made up to a total volume of 500 ml with distilled water. After three times of ultrafiltration against distilled water through a YM10 ultrafiltration membrane (AMICON ®) the remaining residue is freeze-dried. 12.46 g of the title compound are obtained as an amorphous, colorless powder

Water content (Karl Fischer) 8.55%

The method of Eyler Klug and Diephuis is used to determine the degree of substitution of the hydroxyethyl starch obtained with sodium carboxymethyl functions [RW Eyler, ED Klug, F Diephuis, Anal Chem, 19, 24 (1947), see also JW Green in Methods in Carbohydrate Chemistry, Vol III, 322, (1963)] according to which a degree of substitution of ds ^ = 1, 1 is present in the product Elemental analysis (calculated on anhydrous substance above C 40.60 H 4.85 Na 9.29 found C 40.82 H 4.93 Na 9.18

b) polyamide of O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 0- (2-hydroxy-3-aminopropyl) -4,7, 10-tπs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 40 KD / degree of substitution on gadolinium complex K 0.2)

A solution of 8.17 g (30 mmol) of the title compound from Example 1 a is dissolved in 200 ml of water and at room temperature with 3 42 g (5 97 mmol) of the gadolinium complex of 10- (2-hydroxy-3- aminopropyl) -4,7,10- trιs (carboxymethyl) -1, 4,7, 10-tetraazacyclododecane, 1 N aqu hydrochloric acid is added to pH 6.5. A total of 1 14 g (5 97 mmol) EDCI is then added in portions After the EDCI addition has ended, the mixture is stirred for a further 12 hours at room temperature. The pH is brought to pH 7.2 by adding 1 N aqueous sodium hydroxide solution. The reaction solution is then made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM 3 ultrafiltration membrane (AMICON ®), the remaining residue is freeze-dried

10.99 g of the title compound are obtained as an amorphous, colorless powder, water content (Karl-Fischer) 6.53% Gd determination (AAS) 9 45%

(Plasma) 14.1 l / mmol sec

Elemental analysis (calculated on anhydrous substance) over C 39 94 H 5.03 N 3.70 Gd 8.30 Na 5.46 found C 40.02 H 5, 12 N 3.60 Gd 8.37 Na 5.55

Example 2

Polyamide made from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-amiπopropyl) -4 7, 10-tπs (carboxymethyl) - _-j ₅ _

1, 4,7,10-tetraazacyclododecane (backbone 40 KD / degree of substitution on gadolinium complex K 0.7)

a) Sodium-O-carboxymethyl-hydroxyethyl-strong (dSQM = 1, 5)

10.0 g (56.5 mmol) of 40 kD hydroxyethyl starch (ds HE = 0.5, commercially available from Gerindus) are suspended in 200 ml of dimethyl sulfate and with vigorous stirring with a total of 21.0 ml (226.8 mmol) Sodium hydroxide) of a 32% aqueous sodium hydroxide solution was added dropwise at room temperature. After a reaction time of 2 hours at room temperature, a total of 10.41 g (110.2 mmol) of chloroacetic acid was added to the solution of the hydroxyethyl-strong polyalcoholate formed Reaction solution is stirred for 3 hours at 65 ° C. After cooling to 5 ° C., a mixture of 1000 ml of isopropanol / 500 ml of tetrahydrofuran / 500 diethyl ether is added and the precipitated solid is filtered off, the solid reaction product thus obtained is then washed three times with 150 ml of isopropanol and dried in vacuo at 30 ° C. The colorless reaction product is then dissolved in 350 ml of distilled water while cooling with ice and vigorous stirring is achieved by moving the water so obtained

Product solution with 10% aqueous hydrochloric acid set a pH of 10 0 and made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM10 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 26 g of the title compound as an amorphous, colorless powder, water content (Karl Fischer) 8.55%

The method of Eyler, Klug and Diephuis is used to determine the degree of substitution of the obtained hydroxyethyl starch with sodium carboxymethyl functions [RW Eyler, ED Klug, F Diephuis, Anal Chem, 19, 24 (1947), see also JW Green in Methods in Carbohydrate Chemistry , Vol III, 322, (1963)], according to which a degree of substitution of dSQM ⁼ 1, 5 is present in the product ^{, iUV} -16- PCT / EP99 / 00853

Elemental analysis (calculated on anhydrous substance above C 39.48 H 4.47 Na 11, 34 found C 39.37 H 4.59 Na 11, 47

b) polyamide of O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7, 10-trιs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 40 KD / degree of substitution on gadolinium complex K 0.7)

A solution of 2 74 g (9.0 mmol) of the title compound from Example 1a is dissolved in 200 ml of water and at room temperature with 3.42 g (5.97 mmol) of the gadolinium complex of 10- (2-hydroxy- 3-aminopropyl) -4,7,10-trιs (carboxymethyl) -1, 4,7,10-tetraazacyclododecane are added. 1 N aqu. Hydrochloric acid to pH 6.5. A total of 1.14 g (5.97 mmol) of EDCI is then added in portions. After the EDCI addition has ended, a further 12

Stirred for hours at room temperature. The pH is brought to 7.2 by adding 1 N aqueous sodium hydroxide solution. The reaction solution is then made up to a total volume of 500 ml with distilled water. After three times of ultrafiltration against distilled water through a YM 3 ultrafiltration membrane (AMICON ®) the remaining residue is freeze-dried

5.73 g of the title compound are obtained as an amorphous, colorless powder, water content (Karl-Fischer) 8.5% Gd determination (AAS) 16.20% Ti relaxivity (H2O) 16.3 l / mmol sec (plasma) 16 , 1 l / mmol sec

Elemental analysis (calculated on anhydrous substance) over C 38.81 H 5 03 N 7.23 Gd 16.24 Na 2.71 found C 38.69 H 5.10 N 7.30 Gd 16.35 Na 2.82

Example 3

Polyamide made from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7,10-trιs (carboxymethyl) - 1, 4,7, 10-tetraazacyclododecane (backbone 40 KD / Degree of substitution on gadolinium complex K 0 3) a) Sodium-O-carboxymethyl-hydroxyethyl-strong (dsςM ^{= 2} - ³ )

10.0 g (56.5 mmol) of 40 kD hydroxyethyl starch (ds HE ⁼ ° _> ^5! Commercially available from Gerindus) are suspended in 200 ml of dimethyl sulfoxide and with vigorous stirring with a total of 31.3 ml (337.9 mmol) Sodium hydroxide) of a 32% aqueous sodium hydroxide solution is added dropwise at room temperature. After a reaction time of 2 hours at room temperature, a total of 15.96 g (168.9 mmol) of chloroacetic acid is added in portions to the solution of the hydroxyethyl-strong poly-alcoholate formed Reaction solution is stirred for 3 hours at 65 ° C. After cooling to 5 ° C., a mixture of 1000 ml of isopropanol / 500 ml of tetrahydrofuran / 500 diethyl ether is added and the precipitated solid is filtered off, the solid reaction product thus obtained is then washed three times with 150 ml of isopropanol and dried in vacuo at 30 ° C. The colorless reaction product is then dissolved in 350 ml of distilled water under ice and vigorous stirring, a pH value of 10.0 is set by adding 10% aqueous hydrochloric acid to the aqueous product solution obtained in this way, and the volume is made up to a total volume of 500 ml with distilled water. After three times of ultrafiltration against distilled water using a YM10 ultrafiltrate tion membrane (AMICON®), the remaining residue is freeze-dried. 14.17 g of the title compound are obtained as an amorphous, colorless powder, water content (Karl-Fischer) 7.7%

The method of Eyler, Klug and Diephuis is used to determine the degree of substitution of the obtained hydroxyethyl starch with sodium carboxymethyl functions [RW Eyler, ED Klug, F Diephuis, Anal Chem, 19, 24 (1947), see also JW Green in Methods in Carbohydrate Chemistry , Vol III, 322, (1963)], according to which there is a degree of substitution of dsQM ^~ ^{2-3 in the} product

Elemental analysis (calculated on anhydrous substance over C 38 51 H 3 98 Na 14.61 found C 38.64 H 4.11 Na 14.74 _-.

b) polyamide of O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7, 10-tπs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 40 KD / degree of substitution on gadolinium complex K 0.3)

A solution of 7.24 g (20.0 mmol) of the title compound from Example 3a is dissolved in 200 ml of water and at room temperature with 3 42 g (5.97 mmol) of the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) ) -4,7,10- tπs (carboxymethyl) -1, 4,7, 10-tetraazacyclododecane are added. 1 N aqu. Hydrochloric acid to pH 6.5 A total of 1 14 g (5 97 mmol) of EDCI is then added in portions. After the EDCI addition has ended, the mixture is stirred for a further 12 hours at room temperature. The pH is brought to pH 7.2 by adding 1 N aqueous sodium hydroxide solution is then made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM 3 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 10.51 g of the title compound is obtained as an amorphous, colorless powder water content ( Karl-Fischer) 6.8% Gd determination (AAS) 8.89% T- | -Relaxιvιtat (H2O) 14.9 l / mmol sec (plasma) 15.3 l / mmol sec

Elemental analysis (calculated on anhydrous substance) over C 37.93 H 4 48 N 3.97 Gd 8.92 Na 8.69 found. C 40.00 H 4.56 N 4.07 Gd 9.01 Na 8.79

Example 4

Polyamide from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7, 10-trιs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 100 KD / Degree of substitution on gadolinium complex K 0.25)

a) sodium ⁱ -O-carboxymethyl-hydroxyethyl-strong (d ^S QM ⁼ 1.1)

10.0 g (56 5 mmol) of 100 kD hydroxyethyl starch (ds HF. ⁼ 0.5 / commercially available from Gerindus) are dissolved in 200 ml of dimethyl sulfoxide suspended and mixed vigorously with a total of 16 ml (172.8 mmol of sodium hydroxide) of a 32% aqueous sodium hydroxide solution at room temperature after vigorous stirring. After a reaction time of 2 hours at room temperature, the solution of the hydroxyethyl starch poly-alcoholate formed with a total of 7. 64 g (80.8 mmol)

Chloroacetic acid added in portions. The reaction solution thus obtained is stirred for 3 hours at 65 ° C. After cooling to 5 ° C., a mixture of 1000 ml of isopropanol / 500 ml of tetrahydrofuran / 500 diethyl ether is added and the precipitated solid is filtered off, and the solid reaction product thus obtained is then filtered three times Each 150 ml of isopropanol is washed and dried in vacuo at 30 ° C. The colorless reaction product is then dissolved in 350 ml of distilled water. With ice cooling and vigorous stirring, a pH of 10 0 is obtained by adding 10% aqueous hydrochloric acid to the aqueous product solution thus obtained adjusted and made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM10 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 12.63 g of the title compound is obtained as an amorphous, colorless powder water content (Karl-Fischer ) 6.8%

The method of Eyler, Klug and Diephuis is used to determine the degree of substitution of the obtained hydroxyethyl starch with sodium carboxymethyl functions [RW Eyler, ED Klug, F Diephuis, Anal Chem, 19, 24 (1947), see also JW Green in Methods in Carbohydrate Chemistry Vol III, 322, (1963)], according to which a degree of substitution of dsςM ⁼ 1, 1 is present in the product

Elemental analysis (calculated on anhydrous substance above C 40.60 H 4.85 Na 9.29 found C 40.47 H 4.98 Na 9.38

b) polyamide of O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4 7 IO-trιs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 100 KD / Degree of substitution

Gadolinium complex K 0.25) A solution of 6.53 g (24 mmol) of the title compound from Example 4a is dissolved in 200 ml of water and at room temperature with 3.42 g (5.97 mmol) of the gadolinium complex of 10- (2-hydroxy-3 -amιnopropyl) -4,7,10- trιs (carboxymethyl) -1,4,7,10-tetraazacyclododecane are added. 1 N aqu. Hydrochloric acid to pH 6.5. A total of 1 14 g (5.97 mmol) of EDCI is then added in portions. After the EDCI addition has ended, the mixture is stirred for a further 12 hours at room temperature. The pH is adjusted by adding 1 N aqu. Sodium hydroxide solution brought to pH 7.2. The reaction solution is then made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM 3 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 9.68 g of the title compound are obtained as an amorphous, colorless powder, water content (Karl-Fischer), 8.6% Gd determination ( AAS) 9.70% T- | Relaxation (H2O) 15.3 l / mmol sec (plasma) 16.0 l / mmol sec

Elemental analysis (calculated on anhydrous substance) calc .. C 39.83 H 5.06 N 4.32 Gd 9.69 Na 4.82 found / C 39.91 H 5.15 N 4.40 Gd 9.58 Na 4.90

Example 5

Polyamide made from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7,10-tπs (carboxymethyl) -1,4,7,10-tetraazacyclododecane (backbone 100 KD / Degree of substitution on gadolinium complex K 0.32)

a) Sodium-O-carboxymethyl-hydroxyethyl-strong (dsςM = 1.6)

10.0 g (56.5 mmol) of 100 kD hydroxyethyl starch (ds HE ⁼ °. ^{5 s} commercially! Available from Gerindus) are suspended in 200 ml of dimethyl sulfate and with vigorous stirring with a total of 23.0 ml (248.4 mmol on

Sodium hydroxide) of a 32% aqueous sodium hydroxide solution is added dropwise at room temperature. After a reaction time of 2 hours at room temperature, the solution of the hydroxy- ethyl strong poly-alcoholate with a total of 11.1 1 g (1 17 6 mmol) of chloroacetic acid added in portions. The reaction solution thus obtained is stirred for 3 hours at 65 ° C. After cooling to 5 ° C., a mixture of 1000 ml of isopropanol / 500 ml of tetrahydrofuran is added / 500 diethyl ether added, filtered off from the precipitated solid, the solid reaction product thus obtained was then washed three times with 150 ml of isopropanol and dried in vacuo at 30 ° C. The colorless reaction product was then dissolved in 350 ml of distilled water. The mixture was cooled with ice and vigorous stirring The aqueous product solution thus obtained is adjusted to a pH of 10.0 with 10% aqueous acidic acid and topped up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water through a YMI O ultrafiltration membrane (AMICON ®), the remaining residue freeze-dried 13.12 g of the title verb are obtained indorph as an amorphous, colorless powder

Water content (Karl Fischer) 8.3%

The method of Eyler, Klug and Diephuis is used to determine the degree of substitution of the obtained hydroxyethyl starch with sodium carboxymethyl functions [RW Eyler, ED Klug, F Diephuis, Anal Chem, 19, 24 (1947), see also JW Green in Methods in Carbohydrate Chemistry , Vol III, 322, (1963)], according to which there is a degree of substitution of dsQM ⁼ 1.6 i product

Elemental analysis (calculated on anhydrous substance above C 39.24 H 4.39 Na 11.78 found C 39.39 H 4.51 Na 11.90

b) polyamide of O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4.7 I O-tπs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 100 KD / degree of substitution on gadolinium complex K 0.32)

A solution of 5.93 g (19 0 mmol) of the title compound from Example 5a is dissolved in 200 ml of water and at room temperature with 3 42 g (5 97 mmol) of the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) ) -4 7 10- tπs (carboxymethyl) -1 4 7 10-tetraazacyclododecane are added. 1 N is added aqu hydrochloric acid to pH 6.5 A total of 1.14 g (5 97 mmol) EDCI is then added in portions. After the EDCI addition has ended, the mixture is stirred for a further 12 hours at room temperature. The pH is brought to pH 7.2 by adding 1 N aqueous sodium hydroxide solution The reaction solution is then made up to a total volume of 500 ml with distilled water. After three times of ultrafiltration against distilled water over a YM 3 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 9.03 g of the title compound are obtained as an amorphous, colorless powder Water content (Karl-Fischer) 6.3% Gd determination (AAS) 10.41%

Relaxation (H ^~ 2θ) 16.2 l / mmol sec (plasma) 16 4 l / mmol sec

Elemental analysis (calculated on anhydrous substance) over C 38.89 H 4.77 N 4.64 Gd 10.42 Na 6.09 found C 39.00 H 4.86 N 4.71 Gd 10.50 Na 6.16

Example 6

Polyamide from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4.7, 1 O-tπs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone 40 KD / Degree of substitution on gadolinium complex K 0.5)

a) Natπum-O-carboxymethyl-hydroxyethyl-strong (dscM ^{= 2} _> 5)

10.0 g (56.5 mmol) of 100 kD hydroxyethyl starch (ds HE ⁼ °, 5 / commercially available from Gerindus) are suspended in 200 ml of dimethyl sulfate and with vigorous stirring with a total of 35.0 ml (378.0 mmol) Sodium hydroxide) of a 32% aqueous sodium hydroxide solution is added dropwise at room temperature. After a reaction time of 2 hours at room temperature, a total of 17.35 g (183.6 mmol) of chloroacetic acid is added in portions to the solution of the hydroxyethyl-strong poly-alcoholate formed Reaction solution is stirred for 3 hours at 65 ° C. After cooling to 5 ° C., a mixture of 1000 ml isopropanol / 500 ml tetrahydrofuran / 500 diethyl ether is added precipitated solid filtered off, the solid reaction product thus obtained then washed three times with 150 ml of isopropanol and dried in vacuo at 30 ° C. The colorless reaction product is then dissolved in 350 ml of distilled water. While cooling with ice and stirring vigorously, the aqueous solution thus obtained is added

Product solution adjusted to a pH of 10.0 with 10% aqueous hydrochloric acid and made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM10 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 14.17 g of the title compound are obtained as an amorphous, colorless powder. Water content (Karl Fischer): 9.2%

The method of Eyler, Klug and Diephuis is used to determine the degree of substitution of the hydroxyethyl starch obtained with Nathum carboxymethyl functions [R.W. Eyler, E.D. Klug, F. Diephuis, Anal. Chem., 19, 24 (1947); see. also: J.W. Green in Methods in Carbohydrate Chemistry, Vol III, 322, (1963)], according to which a degree of substitution of dsQM = 2.5 is present in the product.

Elemental analysis (calculated on anhydrous substance calc .: C 37.51 H 3.80 Na 14.96 found: C 37.44 H 3.87 Na 15.09

b) polyamide from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7, 10-tris (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone: 100 KD / degree of substitution on gadolinium complex K: 0.5)

A solution of 4.61 g (12.0 mmol) of the title compound from Example 6a is dissolved in 200 ml of water and at room temperature with 3.42 g (5.97 mmol) of the gadolinium complex of 10- (2-hydroxy -3-aminopropyl) -4,7,10-tris (carboxymethyl) -1,4,7,10-tetraazacyclododecane. The pH is adjusted to 6.5 with 1 N aqueous hydrochloric acid, and a total of 1.14 g (5.97 mmol) of EDCI is then added in portions. After the EDCI addition has ended, the mixture is stirred for a further 12 hours at room temperature. The pH is adjusted by adding 1 N aqu. Sodium hydroxide solution brought to pH 7.2. The reaction solution is then made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM 3 ultrafiltration membrane (AMICON ®), the remaining residue is freeze-dried. 7.71 g of the title compound are obtained as an amorphous, colorless powder

Water content (Karl Fischer). 6.8% Gd determination (AAS) - 10.1% T- | relaxivity (H2O) 16.6 l / mmol-sec (plasma) 16.7 l / mmol sec

Elemental analysis (calculated on anhydrous substance) calc .. C 37.79 H 4.56 N 5.37 Gd 12.07 Na 7.06 found. C 37.91 H 4.66 N 5.28 Gd 12.18 Na 7.17

Example 7

Polyamide made from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7, 10-trιs (carboxymethyl) - 1, 4,7,10-tetraazacyclododecane (backbone. 200 KD / Degree of substitution on gadolinium complex K. 0.25)

a) Natπum-O-carboxymethyl-hydroxyethyistarke (dSQM ⁼ 1 _> ² )

10.0 g (56.5 mmol) of 200 kD hydroxyethyl starch (ds HE ⁼ °, ^{5 l} commercially available from Gerindus) are suspended in 200 ml of dimethyl sulfate and with vigorous stirring with a total of 17.4 ml (187.9 mmol) Sodium hydroxide) of a 32% aqueous sodium hydroxide solution was added dropwise at room temperature. After a reaction time of 2 hours at room temperature, a total of 8.33 g (88.2 mmol) of chloroacetic acid was added to the solution of the hydroxyethyl starch polyalcoholate formed. The reaction solution thus obtained is stirred for 3 hours at 65 ° C. After cooling to 5 ° C, a mixture of 1000 ml of isopropanol / 500 ml of tetrahydrofuran / 500 diethyl ether is added and the precipitated solid is filtered off, and the solid reaction product thus obtained is then filtered three times, each time with 150 ml of isopropanol and washed in Vacuum dried at 30 ° C. The colorless reaction product is then dissolved in 350 ml of distilled water. With ice cooling and vigorous stirring, a pH of 10.0 is set by adding 10% aqueous hydrochloric acid to the aqueous product solution obtained in this way, and the mixture is made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM10 ultrafiltration membrane (AMICON ®), the remaining residue is freeze-dried. 12.84 g of the title compound are obtained as an amorphous, colorless powder. Water content (Karl Fischer): 7.9%

The method of Eyler, Klug and Diephuis is used to determine the degree of substitution of the hydroxyethyl starch obtained with sodium carboxymethyl functions [R.W. Eyler, E.D. Klug, F. Diephuis, Anal. Chem., 19, 24 (1947); see. also: J.W. Green in Methods in Carbohydrate Chemistry, Vol III, 322, (1963)], according to which a degree of substitution of dSQM = 1, 2 is present in the product.

Elemental analysis (calculated on anhydrous substance calc .: C 39.44 H 4.37 Na 12.05 found: C 39.57 H 4.51 Na 12, 14

b) polyamide from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7,10-ths (carboxymethyl) -

1, 4.7, 10-tetraazacyclododecane (backbone: 200 KD / degree of substitution on gadolinium complex K: 0.25)

A solution of 6.87 g (24.0 mmol) of the title compound from Example 7a is dissolved in 200 ml of water and at room temperature with 3.42 g (5.97 mmol) of the gadolinium complex of 10- (2-hydroxy-3-aminopropyl ) -4.7, 10- tris (carboxymethyl) -1, 4.7, 10-tetraazacyclododecane. It is made with 1 N aqu. Hydrochloric acid to pH 6.5. A total of 1.14 g (5.97 mmol) of EDCI is then added in portions. After the EDCI addition has ended, the mixture is stirred for a further 12 hours at room temperature. The pH is adjusted by adding 1 N aqu. Sodium hydroxide solution brought to pH 7.2. The reaction solution is then made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water using a YM 3 ultrafiltrate tion membrane (AMICON ®), the remaining residue is freeze-dried. 9.85 g of the title compound are obtained as an amorphous, colorless powder.

Water content (Karl Fischer): 7.4%. Gd determination (AAS): 7.59%

T <| relaxation (H2θ): 16.0 l / mmol-sec (plasma): 16.2 l / mmol-sec

Elemental analysis (calculated on anhydrous substance): calc .: C 39.64 H 4.98 N 4.23 Gd 9.50 Na 5.28 found: C 39.78 H 5.11 N 4.30 Gd 9.36 Na 5 , 41

Example 8

Polyamide from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7,10-tris (carboxymethyl) -1,4,7,10-tetraazacyciododecane (backbone: 200 KD / Degree of substitution on gadolinium complex K: 1, 1)

a) Sodium-O-carboxymethyl-hydroxyethyl starch (dscM = ² _> 3)

10.0 g (56.5 mmol) of 40 kD hydroxyethyl starch (ds HE ⁼ °, 5 / commercially available from Gerindus) are suspended in 200 ml of dimethyl sulfate and a 32 with a total of 32.5 ml (351, 0 mmol of sodium hydroxide) with vigorous stirring % aqueous sodium hydroxide solution was added dropwise at room temperature. After a reaction time of 2 hours at room temperature, a total of 15.96 g (168.9 mmol) of chloroacetic acid are added to the solution of the hydroxyethyl starch polyalcoholate formed in portions. The reaction solution thus obtained is stirred at 65 ° C. for 3 hours. After cooling to 5 ° C., a mixture of 1000 ml of isopropanol / 500 ml of tetrahydrofuran / 500 diethyl ether is filtered off from the precipitated solid, the solid reaction product thus obtained is then washed three times with 150 ml of isopropanol and dried in vacuo at 30 ° C. The colorless reaction product is then dissolved in 350 ml of distilled water. While cooling with ice and stirring vigorously, the aqueous solution thus obtained is added Product solution with 10% aqueous hydrochloric acid set a pH of 10.0 and made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM10 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 14.23 g of the title compound are obtained as an amorphous, colorless powder. Water content (Karl Fischer) 7.7%

The method of Eyler, Klug and Diephuis is used to determine the degree of substitution of the hydroxyethyl starch obtained with sodium carboxymethyl functions [RW Eyler, ED Klug, F Diephuis, Anal. Chem, 19, 24 (1947); see also. JW Green in Methods in Carbohydrate Chemistry, Vol III, 322, (1963)], according to which there is a degree of substitution of dscM ⁼ ^{2-3 in the} product.

Elemental analysis (calculated on anhydrous substance calc. - C 38.51 H 3.98 Na 14.61 found. C 38.62 H 4.05 Na 14.70

b) polyamide made from O-carboxymethyl-hydroxyethyl starch and the gadolinium complex of 10- (2-hydroxy-3-aminopropyl) -4,7,10-trιs (carboxymethyl) -1,4,7,10-tetraazacyclododecane (backbone 200 KD / degree of substitution on gadolinium complex K 1, 1)

A solution of 3.98 g (11.0 mmol) of the title compound from Example 8a is dissolved in 200 ml of water and at room temperature with 3.42 g (5.97 mmol) of the gadolinium complex of 10- (2-hydroxy -3-aminopropyl) -4,7,10-tris (carboxymethyl) -1,4,7,10-tetraazacyclododecane. The pH is adjusted to 6.5 with 1 N aqueous hydrochloric acid. A total of 1.14 g (5.97 mmol) of EDCI is then added in portions. After the EDCI addition has ended, stirring is continued for a further 12 hours at room temperature. The pH is adjusted by adding 1 N aqu. Sodium hydroxide solution brought to pH 7.2. The reaction solution is then made up to a total volume of 500 ml with distilled water. After three times ultrafiltration against distilled water over a YM 3 ultrafiltration membrane (AMICON®), the remaining residue is freeze-dried. 9.52 g is obtained the title compound as an amorphous, colorless powder, water content (Karl Fischer) 5.9% Gd determination (AAS): 18.18% T- _| -Relaxivity (H2O): 17.5 l / mmol-sec (plasma): 17.9 l / mmol-sec

Elemental analysis (calculated on anhydrous substance): calc .: C 38.08 H 4.92 N 8.06 Gd 18.10 Na 2.89 found: C 38.17 H 4.99 N 8.00 Gd 18.27 Na 2.98

Claims

O 99/42139-29 claims

1. Hydroxyethyl starch conjugates of the general formula

where n for the numbers 200 to 1,500 and

R for a hydrogen atom or in each case independently of one another for the radicals a * = - (CH ₂ ) 2θH, a ₂ = -CH2COOH, a $ =

- (CH2) 2θCH2COOH, a 4 = -CH ₂ CONHK or a 5 =

- (CH2) 2θCH2CONHK with K are the meaning of a metal complex or a complexing agent, with the proviso that statistically 0.02 to 1.5 residues a -j and 0.02 to 2.5 residues a 2 and 0 per monomer unit, 02 to 1.5 residues a 3 and 0.02 to 2.5 residues a 4 and 0.02 to 1.5 residues a 5 substitute the hydroxyl hydrogens, the carboxyl groups which may be present in the molecule being cations of inorganic and / or organic Bases, amino acids or amino acid amides are replaced.

2. Compounds of general formula I according to claim 1, characterized in that K represents a radical of general formula II

stands,

wherein

Z independently of one another for a hydrogen atom or a

Metal ion equivalent of atomic numbers 20-29, 39, 42, 44 or 57-83,

A for the groups -CH2CH (OH) - or -CHR CONH-, where R1 represents a hydrogen atom or the methyl group,

B for a C- | -C20-alkylene chain, which is optionally interrupted by 1 - 3 -CONH-, 1 -3 -NHCO-, 1 -3 -NH-, 1 -3 -CO-, 1 phenylene group (s) or 1-5 oxygen atoms or the is optionally substituted by 1 -3 -OH or 1-3 - (CH2) θ-3 "COOH groups.

3. Compounds of general formula I according to claim 1, characterized in that n stands for the numbers 240 to 750.

4. Compounds of general formula I according to claim 2, characterized in that at least two of the radicals Z are metal ion equivalents of the atomic numbers of paramagnetic metals.

5. Compounds of general formula I according to claim 4, characterized in that the radicals Z are metal ion equivalents of gadolinium.

6. Compounds of general formula I according to claim 1, characterized in that statistically 0.05 to 1 radicals a 4 and 0.05 to 1 radicals a 5 are present per monomer unit.

7. Compounds of general formula I according to claim 2, characterized in that B represents one of the radicals -CH ₂ -

-CH ₂ CH ₂ -

- (CH ₂ ) ₃ -

-CH ₂ CH2-0-CH ₂ CH ₂ -

- (CH ₂ -CH2-0) 2-CH ₂ CH2-

-CH ₂ NHCOCH2-

-CH ₂ NHCO-CH ₂ CH ₂ -

-CH ₂ CONHCH ₂ CH ₂ -

-CH ₂ CONHCH ₂ CH ₂ CH2-

CH2-CO-NH-C6H ₄ -0-CH ₂ -CH ₂ -

stands.

8. Pharmaceutical compositions containing at least one hydroxyethyl starch conjugate of the general formula I according to claim 1, optionally with the additives customary in galenics.

9. Use of at least one hydroxyethyl starch conjugate according to claim 1 for the preparation of agents for X-ray diagnosis (conventional methods and computed tomography).

10. Use of at least one hydroxyethyl starch conjugate according to claim 1 for the preparation of agents for NMR diagnostics.

11. Use of at least one hydroxyethyl starch conjugate according to claim 9 or 10 as a blood pool diagnostic.

2. A process for the preparation of the pharmaceutical composition according to claim 8, characterized in that the hydroxyethyl starch conjugates dissolved or suspended in water or physiological saline, optionally with the additives customary in galenics, are brought into a form suitable for enteral or parenteral administration .