WO1997000240A1

WO1997000240A1 - Formyl derivatives as nonionic contrast media

Info

Publication number: WO1997000240A1
Application number: PCT/US1996/010433
Authority: WO
Inventors: Milos Sovak; Ronald C. Terry; James Gordon Douglass, Iii; Allen Seligson; Jason Brown
Original assignee: Biophysica Foundation
Priority date: 1995-06-16
Filing date: 1996-06-13
Publication date: 1997-01-03
Also published as: JPH11502231A; NO975880L; KR19990022943A; AU6114396A; EP0855997A4; CA2229664A1; MX9710220A; EP0855997A1

Abstract

Carboxamide substituted N-formyl, N-alkyl or hydroxyalkyl triiodo anilides are provided. The subject composition have high iodine percentages and excellent water solubility, finding use as preferred embodiments for conventional nonionic contrast media.

Description

FORMYL DERIVATIVES AS NONIONIC CONTRAST MEDIA

INTRODUCTION

The field of this invention is nonionic contrast media.

Background The X-ray is the most often used diagnostic tool for the examination of various compartments of the body, such as the gastrointestinal tract, vascular system, and individual solid organs. These procedures are done in conjunction with iodinated contrast agents, due to the low inherent contrast differential within the tissues. Criteria for contrast media are that they are biologically inert; that they are capable of delineating anatomical detail accurately and consistently, that they provide accurate radiopacity; that they should have a high iodine content; and that they should be water soluble and should have reasonable osmolality at the concentrations at which they are administered. The demands on the contrast media employed varies with the nature of the examination. In addition, the media should be substantially homogenous, so as to avoid imaging artifacts and should not be affected by pH or other physiological conditions during their use.

In order to provide for water solubility, the nonionic contrast media have hydroxyalkyl constituents to enhance the hydrophilicity. However, the water solubility is to a great extent dependent upon the capability of the compounds to form isomeric mixtures in water solutions. In the nonionic contrast media involving hydroxyalkylated anilides, the isomeric mixtures are dependent upon the endo and exo isomerism of the substituted anilide group. For the most part, the acyl group bonded to the amino group is acetyl, glycolyic acid, or gly ceric acid, since such acyl group is stable and of relatively low molecular weight. There is substantial interest in developing new improved non-ionic contrast media, where the iodine content can be enhanced, as well as water solubility and the other factors indicated above.

Relevant Literature

U.S Patent Nos. of interest include 4,547,357; 4,021,481; 3,701,771; 4,364,921; and 4,341,756.

SUMMARY OF THE INVENTION Novel nonionic contrast media are provided, which are N-formylated, N- alkylated or -hydroxyalky lated triiodoanilides or bis-compounds, where the remaining positions on each ring are substituted with at least one carboxy group or an amino group. The subject compositions have high water solubility, good stability, and high iodine content. The subject compounds find use as contrast media in a wide variety of applications for X-ray and other non-invasive diagnosis.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS Novel nonionic contrast media are provided having excellent water solubility and high iodine content. The contrast media are characterized by having at least one N-formyl, N-alkyl or -hydroxyalkyl amino group bonded to a substituted triiodobenzene, either symmetrical or asymmetrical, usually symmetrical, where the remaining two sites have from zero to one substituted amino group and from one to two non-oxocarbonyl groups, particularly amides, more particularly unsubstituted or N-alkyl or N-hydroxyalkyl amides, mono- and di-substituted, i.e. from 0 to 2 alkyl (including hydroxyalkyl) substituents. The compounds may be monomeric or bis- dimers, joined by a bond, or more usually an alkylene linking group.

For the most part, the monomeric compounds of this invention will have fewer than 30 carbon atoms, usually fewer than 25 carbon atoms, preferably fewer than about 20 carbon atoms, usually having at least about 12 carbon atoms, more usually at least about 14 carbon atoms. The dimers may have twice the number of carbon atoms, usually up to twice the number of carbon atoms plus 5, more usually plus 3. Other than the formylated aniline nitrogen, the nitrogen atoms will be either mono- or disubstituted, usually monosubstituted when bonded to non-oxocarbonyl bonded to an annular carbon atom, while the nitrogen bonded to an annular carbon atom will be disubstituted, i.e. formylated and N-alkylated or -hydroxyalkylated. When two substituents are present on an amide nitrogen, usually one will be an oxyalkyl group and the other an alkyl group. (In referring to carboxamide and amide nitrogen, it is intended that the non-oxo-carbonyl carbon is bonded to an annular carbon atom, as distinguished from the formadinyl group, where the nitrogen is bonded to an annular carbon atom.)

One or both of the carboxamide nitrogens, may have from 1 to 2 hydroxyalkyl groups of from 2 to 4 carbon atoms and from 0 to 1 alkyl group of from 1 to 3 carbon atoms, preferably methyl.

For the most part, the compounds of this invention will have the following formula:

Wherein: a is 1 or 2, and b is 0 when a is one and 1 when a is 2; R¹ is alkyl of from 1 or 2 to 4 carbon atoms, usually more usually 1 to 3 carbon atoms, and 0 to 3, usually 0 or 1 to 3, more usually 0 or 1 to 2 hydroxyl groups, having hydroxyl at other than at the α-carbon atom, generally having from 1 to n - 1 hydroxyl groups, where n is the number of carbon atoms present in the group, wherein alkyl is usually of from 1 to 3 carbon atoms, preferably methyl;

R² may be the same or different from R¹, being hydrogen or coming within the definition of R¹;

R³ , when a is 1, is hydrogen or comes within the definition of R¹, at least one of R² and R³ having an hydroxyl group; when a is 2, either two of R³s, R's or Ws are taken together with Y to form a bridge between the two monomers;

Y is not present when a is 1 , and when a is 2, is a bridge comprising a bond or linking group of from 1 to 6 carbon atoms, usually of from 2 to 3, carbon atoms, normally aliphatic, usually saturated, particularly comprising one or more methylene groups, having from 0 to n-2 oxy groups, where n is the number of carbon atoms of the linking group;

Z is CONWR¹, NR'CHO or CONR²R³, preferably CONHR²; and

W is hydrogen when a is 1 or, when a is 2, is taken together with Y to form a bridge.

For the most part for the dimeric compounds, where Z is CONR²R³, R³ of each monomer is taken together with Y to form a bond or an alkylene group of from 1 to 6, usually 2 to 3, carbon atoms, and 0 to n-2 oxy groups, where n is the number of carbon atoms of the alkylene group. Where Z is CONWR¹, W is taken together with Y to form a bridge of an alkylene group of from 1 to 6, usually 2 to 3, carbon atoms, and 0 to n-2 oxy groups, where n is the number of carbon atoms of the alkylene group.

Hydroxyalkyl groups of interest include: hydroxyethyl; 2-hydroxypropyl; 1,3-dihydroxypropyl; 2, 3-dihydroxypropyl; 1, 3, 4-trihydroxybutyl; and 2, 3, 4- trihydroxybutyl.

Compounds of particular interest are triiodoisophthalamides, where the nitrogens of the carboxamide groups are substituted with 2,3-dihydroxypropyl, 1,3- dihydroxypropyl or hydroxyethyl or bis-hydroxyethyl, or a combination of methyl and 2,3-dihydroxypropyl or 1,3-dihydroxypropyl. Although they may be non- identical, preferably, both annular substituted carboxamide nitrogen atoms are identically substituted, and the anilide nitrogen is substituted with 2,3- dihydroxypropyl, or 2-hydroxyethyl.

Specific compounds of interest include: 5-N-(2,3-dihydroxypropyl) formylamido-2 ,4 , 6-triiodo-N , N ' -bis-(2 ,3-dihydroxypropyl)isophthalamide (BP-257) ; 5-N-(2-hydroxyethyl)formylamido-2,4,6-triiodo-N,N'-bis-(2,3- dihydroxypropyl)isophthalamide (BP-258); 5-N-(2,3-dihydroxypropyl) formylamido-2,4,6-triiodo-N-(2,3-dihydroxypropyl)-N'-(2-hydroxyethyl)- isophthalamide (BP-278); 5-N-(2,3-dihydroxypropyl)formylamido-2,4,6-triiodo-3- N-(2,3-dihydroxypropyl)-carbamoyl-benzamide (BP-256); and 5-N-(l- hydroxyethyl)forrnylamido-2,4,6-triiodo-N,N'-bis-(l,3- dihydroxypropyl)isophthalamide (BP-293) . The subject compounds may be prepared in accordance with conventional ways, except that the formylation is performed prior to the alkylation of the anilide nitrogen and the alkylation is carried out under conditions which avoids hydrolysis of the formanilide. Usually, the groups on the amide nitrogens will be present prior to the final alkylation. For formylation, activated formic acid may be employed, where the formic acid may be present as the mixed anhydride, where the mixed anhydride may be prepared in situ. Temperatures will generally be kept below about 30° C, preferably below about 25°C, and may be in the range of about 0 to 15°C. Usually, the formic acid will be added in excess, generally in at least about 5 fold molar excess, and may be from 10 to 20 fold molar excess. Where an anhydride is added, e.g. acetic anhydride, to the mixture to form the mixed anhydride, the formic acid will be present in at least stoichiometric amount and usually about 1.5 to 3 fold excess over the anhydride. Other mixed anhydrides may include benzoyl isobutyrl, benzyl carbonate, pivaloyl, etc. The work up of the product is conventional as described in the experimental section.

Of particular interest for hydroxyalkylation is the use of an alkylene oxide or alkylene oxide precursor, e.g. a 1 ,2-halohydroxyalkane. For the alkylation, the halohydrin is of particular interest, where the reaction is carried out in solution in a polar organic solvent at a basic pH, generally in excess of 10, preferably from about 11 to 13, where the reaction will be at an elevated temperature, generally at least 30° C, and less than about 60° C, usually less than about 50° C, preferably in the range of about 35 to 50° C. Basic salts may be added to enhance the reactivity of the halo group. Generally, the halohydrin will be in at least stoichiometric amount, preferably in excess, usually not greater than about 3 fold excess, more usually not greater than about 2.5 fold excess. The workup is conventional, the salts filtered, the filtrate acidified, followed by neutralization and purification of the residue. For use as contrast media, the subject compositions may be formulated in accordance with conventional ways, depending upon the particular application. For oral use, solutions in water are prepared either in advance or ad hoc from a mixture of the subject compound with lactose, citric acid, methylcellulose, and a detergent, particularly a nonionic detergent, such as Tween-80. For intestinal (rectal) use only methylcellulose (or other polysaccharide) and a detergent are used. The detergent will be present from about 0.1 to 1 weight percent of the composition (excluding water).

For X-ray computer tomography, the solution concentration of iodine will generally be in the range of about 5 to 15 mg I/ml, preferably about 10 mg I/ml; for plain radiography, about 200 to 400 mg I/ml, preferably 300 to 350 mg I/ml, will be employed. Generally, the fractions of the subject compounds in water will be from about 0.5 to 150% by weight/volume; for standard radiography the fraction will be from about 20 to 150% by weight/volume. The viscosity of the compositions for administration will be in the range of about 5 cps to 5000 cps, with the prefened range of about 10 to 1000 cps.

The subject compositions may be administered by any convenient means, depending upon the particular site or compartment to be investigated. Nonionic contrast media, as obvious from the relevant art literature, have found extensive use and the prior art compounds may be substituted with the subject compounds accordingly.

The following examples are offered by way of illustration and not by way of limitation.

EXPERIMENTAL 1. 5-N-formylamido-2,4,6-triiodo-N,N'-bis(2,3-dihydroxypropyl)isophthalamide. A. To a stirring suspension of 5-amino-2,4,6-triiodo-N,N'-bis(2,3- dihydroxypropyl) isophthalamide (10.0 g, 0.0158 mol) and formic acid (10.68 mL, 0.283 mol) in an ice bath was added acetic anhydride (13.44 mL, 0.142 mol) and the mixture allowed to stir overnight. The yellow, homogenous solution was concentrated on a rotary evaporator yielding a brownish foam. This was dissolved in EtOAc (100 mL) and extracted with 30% brine (60 mL). The solution was dried over MgSO₄ and concentrated on a rotary evaporator to a white foam. The solid was dissolved in MeOH (50 mL) basified with 30% NaOMe (7 mL) to pH = 12 and concentrated to 1/2 volume. After reconstitution with methanol, neutralization to pH = 7 with concentrated HCl, filtration, and solvent removal, a white foam was obtained. (70% yield)

B. Analysis:

1. TLC: Silica gel 60, F₂₅₄, 50% CHCl₃/50% methanol, UV detection @ 254 nm. Restarting material) = 0.53. Rf (product) = 0.47

2. HPLC: Alltech NH₂ econosphere, 4.6 x 250 mm, 5μ, 85% acetonitrile/ 15% H₂O, 1.5 mL/min, 254 nm detection, 30°C. Retention time (starting material) = 5.42 min. Retention time (product) = 8.61 min.

3. 1H NMR, product: DMSOdό; 10.3-10.0 ppm (m,lH), 8.5 ppm (m, 2H), 8.3 ppm (m,lH),5.2-4.4 ppm (m,4H), 3.7-3.1 (m, 10H).

2. 5-N-(2,3 dihydroxypropyl)-formylamido-2, 4,6-triiodo-N,N'-bis(2,3- dihydroxypropyl)isophthalamide (BP-257)

To a suspension of 5-N-formylamido-2,4,6-triiodo-N,N'-bis(2,3- dihydroxypropyl)isophthalamide (1.0 g, 1.17 mmol) and 5 mL MeOH was added Na₃PO₄.12 H₂O (1.30 g, 3.41 mmol) followed by 3-chloro-l,2-propandiol ( 0.23 mL, 2.73 mmol) in a single portion. The reaction mixture was maintained at pH 12 and 45 °C for 4 hours. The precipitated salts were filtered off and washed with dry MeOH. The filtrate was acidified to pH = 1.6 with concentrated HCl and stined overnight. The reaction was neutralized with sodium methoxide in methanol, filtered and concentrated on a rotary evaporator. 2 mL of isopropanol was added to the residue. The solids were filtered and dried. (75% yield). Following recrystallization from aqueous ethanol, BP-257 was > 99% pure. B. Analysis

1. TLC: Silica gel 60, F₂₅₄, 50% CHCl₃/50% methanol, UV detection @ 254 nm. Rf (starting material) = 0.47. Rf(product) = 0.39

2. HPLC: Alltech NH₂ econosphere, 4.6 x 250 mm, 5μ, 85% acetonitrile/ 15% H₂O, 1.5 mL/min, 254 nm detection, 30°C. Retention time (starting material) = 8.10 min. Retention times (product) = 12.13 min and 14.45 min.

3. Η NMR (BP-257): 8.6-8-4 ppm (m,2H), 8.4-7.9 ppm (d,lH), 4.9-4.5 ppm (m,4H), 4.0-3.1 ppm (m,15H).

3. 5-[N-(2,3-dihydroxypropyl)]formylamido-2,4,6-triiodo- N'-(2- hydroxyethyl)-N ' -(2 , 3-dihydroxypropyl)-isophthalamide [BP-278]

A 2 liter flask was charged with 5-[N-(2,3-diacetoxypropyl)]formylamido- 2,4,6-triiodo-3-[N-(2,3- diacetoxypropyl)]carbamoyl benzoyl chloride (74.29 g, 0.0807 moles), acetonitrile (296 mL) and ethanolamine (11.69 ml, 0.1937 moles). This mixture was stined for 2 hours at 25 °C and then neutralized to pH 8 with concentrated hydrochloric acid (2.69 mL, 0.0323 moles). After filtering salts, the filtrate was evaporated and vacuum dried to a yellow foam. It was partitioned between ethyl acetate (460 mL) and saturated sodium chloride (200 mL) and the aqueous layer was back extracted with ethyl acetate (100 mL), the ethyl acetate extracts were combined, dried over magnesium sulfate, and filtered. After solvent removal and drying, 73.97 g (97%) of the title compound was obtained. The reaction was repeated and the combined lots charged into a 1 liter flask (144.8 g, 0.1532 moles) with methanol (580 mL). 30% methanolic sodium methoxide (1.84 mL, 10.21 mmoles) was added dropwise at 25 °C. After 30 minutes the solution was concentrated to half- volume and then neutralized with Dowex 50 H-i- resin. The resin was filtered off and the solvent removed to give 117.2 g (95.4%) of the title compound [BP-278]. Analysis:

1. TLC: Silica gel 60, F₂₅₄, 40% methanol/60% CHC1₃, UV detection at 254 nm. Rf (BP-278) = 0.40

2. HPLC: Alltech C₈ Absorbosphere, 4.6x 250mm, 5 μ, 5% acetonitrile/95% 0.02 M KH₂PO₄, pH 3, 1.0 ml/min., 246 nm detection, 30° C. Retention times (BP-278) = isomer peaks at 8.95 min, 9.44 min. , and 11.97 minutes. 3. Η NMR, (BP-278; DMSOdό): 7.9 and 8.35 ppm (m, IH), 8.5 ppm

(m, 2H), 4.5 - 4.9 ppm (m, 5H), 3.3-3.9 ppm (m, 14H) 4. [N-(2 , 3-diacetoxypropyl)] formylamido-2 ,4 , 6-triiodo-3-[N-(2 , 3-dia cetoxypropyl)] carbamoyl benzoic acid [BP-256]

In a 5 L flask 5-amino-2,4,6-triiodo-3-[N-(2,3-dihydroxypropyl)] carbamoyl benzoic acid (947.8 g, 1.50 moles) and 95-97% formic acid (1.85 L) were stined at -1 to 10°C while acetic anhydride (1133 mL, 12.0 moles) was added dropwise over 6 hours, followed by stirring for 6 hours 20°C and a partial solvent removal. To the residue butyl acetate (1.5 L) was added. A white precipitate was filtered off, and vacuum dried to yield 970.7 g (91 %) of 5-formylamido-2,4,6-triiodo-3-[N-(2,3- diformyloxypropyl)] carbamoyl benzoic acid. In a 10 L flask charged with this compound (950 g, 1.33 moles), methanol (2.85 L) and a 30% methanolic sodium methoxide solution (478 mL, 2.65 moles), after stirring for 10 minutes at 25°C, acetic acid (76 mL, 1.33 moles) was added. The solution was reduced to half. Adding anhydrous ethanol (1.5 L) gave a white precipitate which was filtered, washed with ethanol, and vacuum dried, yielding 982.4 g of the sodium salt of 5- formylamido-2,4,6-triiodo-3-[N-(2,3-dihydroxypropyl)] carbamoyl benzoic acid and some salts. A 12 L flask was charged trisodium phosphate dodecahydrate (1366 g, 3.59 moles), 1,2-propanediol (1 L), and 3-chloro-l,2-propanediol (240 mL, 2.87 moles). After stirring at 40-45 °C for 30 minutes, a solution of the sodium salt of 5- formylamido-2,4,6-triiodo-3-[N-(2,3-dihydroxypropyl)] carbamoyl benzoic acid (980 g, 1.44 moles) in 1 ,2-propanediol (3 L), was added over 5 hours and the suspension stined 1.5 hours at 40-45°C, and filtered to remove salts. The filtrate was brought to pH 1 -5 with concentrated hydrochloric acid (250 mL) and stined for 16 hours at 25 °C to destroy residual glycidol. The solvent was removed and the product precipitated with isopropanol (2 L), filtered, washed with isopropanol, and vacuum dried, yielding 895.7 g (85% conected for salt content) of 5-[N-(2,3- dihydroxypropyl)]formylamido-2,4,6-triiodo-3-[N-(2,3- dihydroxypropyl)] carbamoyl benzoic acid. A 5 L flask was charged with this solid, ethyl acetate (0.8 L), pyridine (19.7 mL, 0.24 moles) and acetic anhydride (1.285 L, 13.6 moles). This mixture was stined for 4.5 hours at 50-60°C. The solvent was removed yielding an orange oil which was dissolved in butyl acetate (1.5 L) and treated with a solution of NaHCO₃ (102.5 g, 1.22 moles) in H₂O (2 L). The layers were separated and the aqueous layer extracted with butyl acetate (3 X 0.5 L). To the aqueous layer was added chloroform (1.5 L) followed by concentrated hydrochloric acid (22 mL, 0.26 moles). The organic layer was separated and the aqueous layer extracted with chloroform (1 L). The combined chloroform extracts were dried over magnesium sulfate, filtered and the solvent removed, yielding 845.7 g (77%). of 5- [N-(2 , 3-diacetoxypropyl)] formylamido-2 ,4 , 6-triiodo-3-[N-(2 , 3- diacetoxypropyl)]carbamoyl benzoic acid.

To a 1 L flask charged with 5-[N-(2,3-diacetoxypropyl)] formylamido-2,4,6- triiodo-3-[N-(2,3-diacetoxypropyl)] carbamoyl benzoic acid (102 g, 0.11 moles) and ethyl acetate (300 mL) was added thionyl chloride (41.2 mL, 0.57 moles) dropwise over 1.5 hours at 70° C. The solution was stined for 2.5 hours and the solvent removed yielding 106.6 g of 5-[N-(2,3-diacetoxypropyl)]formylamido-2,4,6-triiodo- 3-[N-(2,3-diacetoxypropyl)] carbamoyl benzoyl chloride. This compound was dissolved in acetonitrile (250 mL), and liquid ammonia added dropwise using a dry ice condenser. After 3 hours at 40°C the suspension was purged with nitrogen and filtered, dissolved in dichloromethane (250 mL) and the solution washed with 0.1 N hydrochloric acid (250 mL). The organic layer was dried over magnesium sulfate, filtered and the solvent removed, yielding 89.4 g (86%) of 5-[N-(2,3- diacetoxypropyl)]formylamido-2,4,6-triiodo-3-[N-(2,3-diacetoxypropyl)] carbamoyl benzamide. To a 1 L flask charged with this compound and methanol (500 mL) was added a 30% methanolic sodium methoxide solution (5.5 mL) to pH 13-14. When deacetylation was judged complete by TLC, the mixture was neutralized with Dowex 50 H+ to pH 5-6. The solvent was removed and the residue dissolved in H₂O, treated with resin, charcoal, and crystallized from boiling alcohol. The resultant BP-256 (80% crystallization yield) was > 99% pure by HPLC. Analysis:

1. TLC: Silica gel 60, F₂₅₄, 60% chloroform/30% methanol/10% acetic acid, UV detection @ 254 nm. Rf (BP-256) = 0.40

2. HPLC: Alltech C18 Absorbosphere, 4.6 x250 mm, 5 μ, 98% 0.02 M KH₂PO₄ pH 3, 2% acetonitrile, 1.0 mL/min, 246 nm detection, 30°C. Retention times (BP-256) = isomer peaks at 5.69, 6.11 , 7.26, 7.71, 9.54, and 10.00 minutes. 3. Η NMR (BP-256; DMSO-d6): 7.90 and 8.35 ppm (d, IH); 8.50 (m, IH); 7.99 and 7.72 ppm (m, 2H); 4.49-4.89 ppm (m, 4H); 3.20-3.96 ppm (m, 10H).

5. 5-[N-(2-hydroxyethyl)]formylamido-2,4,6-triiodo-N,N'-bis-(2,3-di hydroxypropyl)-isophthalamide [BP-258]

To a suspension of trisodium phosphate dodecahydrate (196.3 g, 0.52 moles) in 1,2-propanediol (800 mL) was added 2-chloroethanol (28.9 mL, 0.43 moles) in a single portion. After stirring for 30 minutes at 40°C, solid 5-N-formylamido-2,4,6- triiodo-N,N'-bis-(2,3-dihydroxypropyl)-is ophthalamide (152 g, 0.21 moles) was added over 2 hours. The pH was maintained at 11-12 and the mixture was heated at 40-45 °C for 4 hours. The precipitated salts were filtered off and washed with dry methanol. The filtrate was acidified to pH 1.6 with concentrated hydrochloric acid and stined for 3 hours to destroy the excess alkylating agent. The reaction mixture was neutralized with 30% methanolic sodium methoxide, and concentrated. Propyl alcohol (650 mL) was added, precipitating a solid which was filtered, washed with propanol, dissolved in water, and deionized with resins. After boiling with 5% charcoal, the product was dried and crystallized from isobutanol to yield 116.5 g (72.1 %) of 5-[N-(2-hydroxyethyl)]-formylamido-2,4,6-triiodo-N,N'-bis-(2,3- dihydroxypropyl)-isophthalamide [BP-258] . Analysis:

1. TLC: Silica gel 60,F₂₅₄, 60% n-butanol, 40% 5N HOAc. R_f (BP- 258 isomer) = 0.39 and 0.27.

2. HPLC: Alltech (C-18 Adsorbosphere, 4.6 X 250 mm, 5μ, 2% acetonitrile, 98%, 0.02 M KH₂PO₄, pH = 3, 1.0 mL/min, 246 nm detection, 30°C. Retention times (BP-258) = isomer peaks at 14.33 and 17.10 minutes.

3. 'H NMR (BP-258; DMSOdό): 7.86 and 8.4 ppm (m, IH), 8.5 ppm (m, 2H), 4.5 - 4.9 ppm (m, 5H), 3.0 - 3.9 (m, 14H).

6. 5-[N-(2-hydroxyethyl)]formylamido-2,4,6-triiodo-N,N'-bis-(l,3-di hydroxy- prop-2-yl)-isophthalamide [BP-293] A 2 L flask was charged with 5-amino-2,4,6-triiodo-N,N'-bis-(l,3- dihydroxy-prop-2-yl) isophthalamide (250.0 g, 0.355 moles) and formic acid (341 mL), stined at 0-10° C while acetic anhydride (233.6 g, 2.29 moles) was added dropwise over 1.6 hours. After stirring at RT for six hours, the solution was reduced and a solid precipitated with butyl acetate (800 mL), filtered and washed with butyl acetate. The solid was vacuum dried, yielding 299.1 g (99.8%) 5-N- formylamido-2,4,6-triiodo-N,N'-bis-(l ,3-diformyloxy-prop-2- yl)- isophthalamide. This compound was charged into a 2 L flask with methanol (1200 mL), and 30% methanolic sodium methoxide (89.3 mL). After stirring for 20 minutes at 0-10°C, the solution was reduced to half volume and acetic acid (29.8 g, 0.496 moles) was added. A white solid was precipitated with isopropanol (500 mL), filtered, washed with isopropanol, and vacuum dried. The product was re-suspended in methanol (1000 mL), heated at 60°C for 30 minutes, cooled to 20°C, filtered, washed with methanol, and vacuum dried to yield 216.4 g (83.4%) of 5-formylamido-2,4,6- triiodo-N,N'-bis-(l,3-dihydroxy-prop-2-yl)- isophthalamide.

A 2 L flask was charged with trisodium phosphate dodecahydrate (194.8 g, 0.513 moles), propylene glycol (850 mL), and (33.0 g, 0.409 moles) 2-chloro ethanol (33.0 g, 0.409 moles). After stirring at 40-45 °C for 1 hour, solid 5-N- formylamido-2 , 4 , 6-triiodo-N , N ' -bis-( 1 , 3-dihydroxy-2-prop-2-yl)- isophthalamide (150 g) was added over 30 minutes. The suspension was stined for 4 hours at 40- 45°C, allowed to cool, filtered, and the salts washed with propylene glycol. The filtrate was acidified to pH 1.5-2.0 with 12 M hydrochloric acid to destroy residual ethylene oxide. After neutralization to pH 7 with 30% methanolic sodium methoxide, the solution was concentrated, and a solid precipitated with propyl alcohol, filtered, washed with propyl alcohol, and vacuum dried. After dissolving in water, deionization with resins and boiling with 5% charcoal, the product was crystallized from n-butanol to yield 115.3 g (72.49%) of 5-[N-(2-hydroxyethyl)] formylamido-2,4,6-triiodo-N,N'-bis-(l ,3-dihydroxy-prop-2-yl)-is ophthalamide [BP- 293]. Analysis:

1. TLC: Silica gel 60, F₂₅₄, 60% n-butanol, 40% 5N HOAc. R_f (BP- 293 isomers) = 0.60 and 0.33. 2. HPLC: Alltech C_I8 Adsorbosphere, 4.6 X 250 mm, 5μ, 5% methanol/95% 0.02 M KH₂PO₄, pH = 3, 1.0 mL/min., 246 nm detection, 30°C. Retention times (BP-293) = isomer peaks at 9.54 and 10.75 minutes.

3. Η NMR (BP-293; DMSOdό): 7.85 and 8.4 ppm (m, 14), 8.25 ppm (m, 2H), 4.4 - 5.0 ppm (m, 5H), 3.3-4.0 (m, 14H).

7. Physicochemical Properties of Contrast Media

Compound % Iodine Centipoise @ Centipoise @ Centipoise @ ^"300 mg l/mL ^"350 mg l/mL "370 mg l/mL @ 37 °C @ 37 °C . @ 37 °C

BP-257 47.20 5.1 1 (a) 8.48(b) 10.46(m)

BP-278 49.00 4.23(c) 6.89(d) 9.9

BP-256 51 .90 4.84(j) 5.95(k) ---

BP-258 49.00 4.82(e) 7.23(f) ---

BP-293 49.00 4.72(g) 7.68(h) lohexol 46.40 6.10 (i) 10.60 (i) 13.5 (i) lopamidol 49.00 4.50 (i) — ---

Compound % Iodine Osmolality @ Osmolality @ Osmolality @ ^• 300 mg l/mL ^"350 mg 1/mL ^" 370 mg 1/mL

BP-257 47.20 589(a) 790 (b) 880

BP-278 49.00 562(c) 683(d) 740

BP-256 51 .90 386(1) 423 (k) —

BP-258 49.00 550 (e) 744 (f) —

BP-293 49.00 527 (g) 629 (h) --- lohexol 46.40 690 (i) 880 (i) 920 (i) lopamidol 49.00 700 (i) 800 (i) --- a = 289.6 mg 1/mL f = 346.1 mg l/mL k = 349.3 mg l/mL b = 357.4 mg 1/mL 9 = 294.6 mg l/mL l = 300.1 mg l/mL c = 288.5 mg 1/mL h = 353.5 mg l/mL m = 373.1 mg l/mL d = 351 .1 mg l/mL i = published value e = 300.0 mg l/mL 308.9 mg l/mL 8. Toxicity of Contrast Media in Balb/C Mice

Compound LD50 Control (@350 mg l/ml)

BP-257 18 g l/kg lohexol: 17 g l/kg

BP-278 18-19 g l/kg loxilan: 16-17 g l/kg

BP-256 14-15 g l/kg lohexol: 16-17 g l/kg

BP-258 17-18 g l/kg lohexol: 16-17 g l/kg

BP-293 16 g l/kg lohexol: 15-16 g l/kg BP-258: 16-17 g l/kg

9. Renal and Hepatic Effects of BP-257 and BP-258 Iodinated Contrast Media in Rabbits The kidney and liver effects of a single iv bolus injection of BP-257 or BP-

258 at 5g Iodine/kg were evaluated in rabbits and compared to those of lohexol at the same dose. Young female rabbits were injected in the ear vein using 350 mg Iodine/ml drug solutions. Blood samples were collected within 15 minutes prior to drug injections, two hours, 24 hours and six days after treatment. Serum creatinine, BUN, SGPT/ALT and SGOT/AST levels were estimated at these time periods. The study showed that BP-257 and lohexol treatments resulted in normal serum creatinine and BUN levels, indicating that neither of these drug treatments have toxic renal effects at any of the examined time periods. In addition, they showed that while BP-258 treatment has no renal deleterious effects up to 24 hours post-treatment, six days after injections, all animals treated with BP-258 had elevated serum creatinine and BUN levels.

The animals liver function tests show no alterations in serum SGPT and SGOT enzymes, indicating that none of the studied drug treatments causes liver damage.

In accordance with the subject invention, novel compositions are provided which find use as nonionic contrast media. The subject compositions have a high iodine content while having excellent high water solubility and low osmolality to provide excellent properties for general use as non-ionic contrast media. All publications and patent applications cited in this specification are herein incoφorated by reference as if each individual publication or patent application were specifically and individually indicated to be incoφorated by reference.

Although the foregoing invention has been described in some detail by way of illustration and example for puφoses of clarity of understanding, it will be readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A nonioinic contrast media N-formyl, N-alkyl or -hydroxylalkyl symmetrically triiodo substituted anilide of from about 12 to 30 carbon atoms, wherein the remaining two sites are substituted with up to 2 carboxamides and up to 1 formamidyl , wherein each carboxamide nitrogen has from 0 to 2 N-alkyl or N- hydroxyalkyl substituents, and each formamidyl nitrogen has 0 to 1 N-alkyl or hydroxyalkyl groups, said alkyl groups are of from 1 to 3 carbon atoms and said hydroxyalkyl groups are of from 2 to 4 carbon atoms and 1 to 3 hydroxyl groups, or the dimer thereof, wherein a nitrogen from each formamide or carboxamide is joined by a bond or linking group.

2. An anilide according to Claim 1, wherein said remaining two sites are substituted with N-hydroxyalkyl annular carbon substituted carboxamides, and said hydroxyalkyl groups are of from 2 to 3 carbon atoms.

3. A compound of the formula:

wherein: a is 1 or 2, and b is 0 when a is one and 1 when a is 2; R¹ is alkyl of from 1 to 4 carbon atoms and 0 to 3 hydroxyl groups, having hydroxyl at other than at the α-carbon atom;

R³ , when a is 1 , is hydrogen or comes within the definition of R¹, at least one of R² and R³ having an hydroxyl group; when a is 2, either two R³s, R^!s or Ws are taken together with Y to form a bridge between the two monomers;

Y is not present when a is 1 , and when a is 2, is a bridge comprising a bond or linking group of from 1 to 6 carbon atoms, having from 0 to n-2 oxy groups, where n is the number of carbon atoms of the linking group;

Z is CONWR¹, NR'CHO or CONR²R³; and

4. A compound according to Claim 3, wherein a is 1 and R² is hydrogen or 1 ,3- or 2,3-dihydroxypropyl, R¹ is 1,3- or 2,3-dihydroxypropyl or 2- hydroxyethyl, and R³ is hydrogen.

5. A compound according to Claim 3, wherein a is 1 and R² is hydrogen or 1,3- or 2,3-dihydroxypropyl, R¹ is 1,3- or 2,3-dihydroxypropyl or 2- hydroxyethyl, and R³ is methyl.

6. A compound of the formula:

wherein:

R¹ is of from 2 to 4 carbon atoms and 1 to 3 hydroxyl groups;

R² is hydrogen or alkyl of from 1 to 3 carbon atoms and 0 to 2 hydroxyl groups;

R³ or W is taken together with Y;

Y is a bond or alkylene group of from 1 to 6 carbon atoms and n-2 oxy groups, wherein n is the number of carbon atoms of said alkylene group; and Z is CONWR¹ or CONHR²; when not taken together with Y, R³ is hydrogen or methyl or W is hydrogen.

7. A compound according to Claim 6, wherein Z is CONHR², wherein R² is 1,3- or 2,3-dihyroxypropyl, R¹ is 1,3- or 2,3-dihydroxypropyl or 2- hydroxyethyl.

8. A compound selected from the group consisting of: 5-N-(2,3- dihydroxypropyl)formylamido-2,4,6-triiodo-N,N'-bis-(2,3- dihydroxypropyl)isophthalamide; 5-N-(2-hydroxyethyl)formylamido-2,4,6-triiodo- N,N'-bis-(2,3-dihydroxypropyl)isophthalamide; 5-N-(2,3- dihydroxypropyl)formylamido-2,4,6-triiodo-N-(2,3-dihydroxypropyl)-N'-(2- hydroxyethyl)-isophthalamide; 5-N-(2,3-dihydroxypropyl)formylamido-2,4,6- triiodo-3-N-(2,3-dihydroxypropyl)carbamoyl-benzamide, and 5-N-(2- hydroxyethyl)formylamido-2,4,6-triiodo-N,N'-bis(l,3- dihydroxypropyl)isophthalamide.

9. A non-ionic contrast media formulation comprising a compound according to Claim 1 , in an amount to provide for x-ray contrast when administered to a mammalian host, and a physiologically acceptable canier.

10. A non-ionic contrast media formulation comprising a compound according to Claim 3, in an amount to provide for x-ray contrast when administered to a mammalian host, and a physiologically acceptable carrier.

11. A non-ionic contrast media formulation comprising a compound according to Claim 6, in an amount to provide for x-ray contrast when administered to a mammalian host, and a physiologically acceptable carrier.

12. In a method for obtaining an x-ray of an organ employing a contrast medium to provide contrast, the improvement which comprises: using a compound according to Claim 1 as said contrast medium.