AU570507B2 - Chemical compounds - Google Patents

Description

CHEMICAL COMPOUNDS

The present invention relates to new compounds, to myocardial imaging compositions containing such compounds and to the use of such myocardial imaging compositions.

Radioiodinated fatty acids useful as myocardial imaging agents are complex molecules. As is known, the iodine in the molecule provides the imaging. The remainder of the molecule provides the framework for transport of the iodine atom. However, the structural arrangement of the molecule is important in providing various desirable features such as iodine stability, heart uptake and heart retention. Additionally, the agents should not substantially interfere with the heart's normal mechanism of metabolizing acids.

These myocardial imaging agents need to have favorable radioactivity concentration ratios for target to non-target tissues. The blood, lungs and liver represent major potential sources of background radiation which can interfere with the diagnostic quality of heart images. Thus, heart/blood, heart/lung and heart/liver ratios of radioactivity must be favorable. Additionally, these agents should have a satisfactory residence time in the heart to permit multiple examinations.

An object of the present invention is to provide a radioiodinated fatty acid myocardial imaging agent. Another object of this invention is to provide such an imaging agent having superior heart uptake, but acceptable myocardial residence time.

This invention relates to 15-(4-halophenyl)pentadecanoic acid through 19-(4-halophenyl)nonadecanoic acid (HMPA) having a methyl or ethyl group on one of the backbone carbons that does not occupy position 1-3; radioactive imaging isotopes thereof, and pharmaceutically acceptable salts of such isotopes. Prefered acids include 15-(4-iodophenyl)-9-methylpentadecanoic acid (IMPA), 15-(4-iodophenyl)-5-methylpentadecanoic acid (IMPA-2), and 15-(4-iodophenyl)-10-methylpentadecanoic acid (IMPA-3). Preferred imaging isotopes include iodine isotopes such as 123_I and 131_l. 77_Br and 18_F are also preferred. Preferred pharmaceutically acceptable salts include sodium, potassium, calcium and ammonium.

The radioactive imaging isotopes of HMPA and pharmaceutically acceptable salts thereof are useful as myocardial imaging agents. Non-radioactive HMPA's are useful as. intermediates to form the radioactive imaging isotopes of HMPA.

A further feature of the present invention is a myocardial imaging composition containing a radioactive imaging isotope of HMPA or pharmaceutically acceptable salt thereof together with a pharmaceutically acceptable radiological vehicle.

Pharmaceutically acceptable radiological vehicles include those that are suitable for injection such as human serum albumin (HSA), aqueous buffer solutions, e.g., tris(hydroxymethyl)aminomethane (and its salts), phosphate, citrate, bicarbonate, etc., sterile water for injection, physiological saline, and balanced ionic solutions containing chloride and/or bicarbonate salts of normal blood plasma cations such as Ca, Na, K and Mg. Other buffer solutions are described in Remington's Practice of Pharmacy, Eleventh Edition for example on page 170.

The concentration of the imaging agent of the present invention in the pharmaceutically acceptable vehicle is a sufficient amount to provide satisfactory imaging. For example, when using aqueous solutions the concentration is about 0.3 to about 6 mg/ml based on an IMPA/HSA molar ratio of about 0.1 to about 2.0.

The myocardial imaging composition is administered so that the imaging agent of the present invention remains in the living animal body for about 1 to about 3 hours, although both shorter and longer residence periods are normally acceptable. The composition may thus be formulated for imaging conveniently in vials or ampoules containing 1 to 10 ml. of an aqueous solution.

The myocardial imaging compositions may be used in the usual way in imaging procedures. For example, a sufficient amount of the myocardial imaging composition to provide adequate imaging is injected into the subject and then the subject is scanned with a suitable machine, for example a gamma camera.

HMPA's may be prepared in the usual manner by those skilled in the art. For example, alkyl substituted, ω -(4-iodophenyl) fatty acids can be prepared by the following reactions: An appropriate ω -phenyl-oxo-fatty acid can be reacted with a wittig reagent to give an alkylene substituted, ω -phenylfatty acid. Reduction of the alkylene group yields an alkyl substituted ω -phenylfatty acid. Thallation with thallium(III) trifluoro- acetate followed by treatment with potassim iodide yields the desired alkyl substituted ω-(4-iodophenyl) fatty acid.

EXAMPLES

All temperature designations are in degrees centigrade.

EXAMPLE 1 1. Preparation of 2-Benzoylcylcohexanone (2)

A solution of 1 (33.45g, 0.2 mol) and triethylamine

(20.24g, 0.2 mol) in dry CHCI₃ (75 ml) were placed into a 500 ml flask equipped with a thermometer, an addition funnel, a mag stirring bar and a N₂ gas inlet. A solution of benzoyl chloride (28.11g, 0.2 mol) in dry CHCI₃ (25 ml) were added dropwise over 40 minutes to the stirring reaction mixture. The temperature rose to 55°C and was cooled to 35ºC with a water bath. The reaction was stirred for 4 hrs at 35°C by heating with an oil bath. The addition funnel was replaced with a reflux condensor and 20% HCl (100 ml) were added. The reaction mixture was heated at 80ºC for 5 hrs and was stirred at room temperature for 10.5 hrs. The layers were separated and the aqueous layer was extracted with CHCI₃ (2 x 100 ml). The combined CHCI3 solutions were washed with H₂O (6 x 100 ml), 1N HCl (100 ml), H₂O (100 ml), 1N NaOH (100 ml), H₂O (100 ml). After drying over Na₂SO₄, the solvent was removed to give 40.61g of yellow solid (100% yield). Tic showed one spot. The ir spectrum and nmr spectra were consistent with the assigned structure, 2. 2. Preparation of 7-Phenyl-7-oxoheptanoic Acid ( 3 )

Diketone 2 (21.99g, 0.108 mol) and KOH (17.63g, 0.314 mol) in H₂O (88 ml) were placed into a 500 ml flask equipped with a reflux condenser and a mag stirring bar. The reaction mixture was heated to reflux with a 120°C oil bath for 25 minutes. After cooling to room temperature, it was acidified with concentrated HCl (30 ml). H₂O (100 ml) was added and the aqueous mixture was extracted with ethyl ether (3 x 100). The combined ethyl ether extracts were washed with H₂O (2 x 50 ml) and saturated NaCl solution (50 ml). After drying over Na₂SO₄. the solvent was removed to give 22.07 g of crude ketoacid (92.6% yield). The product was one spot on tic. The ir spectrum was consistent with the assigned structure, 3. ^τ5ne ketoacid was crystallized from MeOH/H₂O to give a white crystalline product (39% yield) whose m.p. was 83.5-84°C (lit. 83-84ºC).

3. Preparation of 7-Phenylheptanoic Acid ( 4 )

Ketoacid 3 (8g, 0.036 mol), KOH (2.40g, 0.036 mol) and triethanolamine (30 ml) were placed into a 250 ml flask equipped with a mechanical stirrer, a reflux condenser and thermometer. The mixture was heated with a 140ºC oil bath. After a complete solution formed, the solution was cooled to 100ºC. Hydrazine (11.63g, 0.363 mol) was added through the condenser and the mixture was heated to 140ºC. After 1.5 hrs, KOH (7.19g, 0.109 mol) and triethanolamine (20 ml) were added. The condenser was removed and the reaction mixture was rapidly heated to 190°C. After stirring for 4 hrs at 190-196ºC, the reaction mixture was cooled to 100ºC and H₂O (200 ml) was added. After standing overnight at room temperature, H₂O (400 ml) was added and the solution was acidified with concentrated HCl (60 ml). The aqueous mixture was extracted with ethyl ether (2 x 200 ml and 2 x 100 ml). The combined ethyl ether extracts were washed with 10% HCl (2 x 100 ml), H₂O (2 x 100 ml) and sat. NaCl solution (50 ml). After drying over Na₂SO₄, the solvent was removed to give

7.66g of crude acid (102% yield). The crude acid was distilled bulb to bulb (vac. 0.28 mm, bp 114°C) to give 6.98g of acid 4 (93% yield). NE calc. 206.27, found 205.1. The acid was one spot on tlc. Its ir spectrum and nmr spectra were consistent with the assigned structure, 4. 4. Preparation of 7-Phenylheptanoyl Chloride ( 5 )

Acid (4) (27.97g, 0.136 mol) and SOCl₂ (30 ml, 48.93g, 0.411 mol) were placed into a 500 ml flask equipped with a reflux condenser, a drying tube, and a mag stirring bar. The reaction mixture was placed into a 60ºC oil bath. After 1.5 hrs, toluene (25 ml) was added and the excess SOCl₂ and toluene was removed on the roto evaporator. Toluene (50 ml) was added and was stripped off. This step was repeated. The residue was distilled bulb to bulb (vac. 0.45 mm to 0.2 mm, bp 100-100ºC) to give 30.89g of water white oil (97% yield). The ir spectrum was consistent with the assigned structure, 5.

5. Preparation of 8-Bromooctan-1-01 ( 1 )

Br ( CH₂ ) ₇-COOH + BH₃-THF -----------> Br ( CH₂ ) ₈-OH

6 7

C₈H _{1 5}BrO₂ C₈H _{1 7}BrO

Mwt . 223 .12 209 . 14

Acid (6) (45.0g, 0.201 mol) and dry THF (130 ml) were placed into a 1L flask equipped with a N₂ gas inlet, a mag stirring bar and an addition funnel. The solution was cooled with an ice bath. BH₃-THF (242 ml, 0.242 mol) was added over 20 minutes while controlling the gas evolution. The bath was removed and the reaction mixture was stirred at room temperature for 1.8 hrs. A mixture of THF/H₂O (965 ml/65 ml) was carefully added to consume the excess BH3. K₂CO₃ (51.89g, 0.375 mol) was carefully added and the mixture was stirred for 2 hrs. The layers were separated. The organic solution was stripped on the roto evaporator. The residue, the aqueous layer and H₂O (500 ml) were combined and extracted with ethyl ether (4 x 250 ml). The combined ethyl ether extract was washed with H₂O (2 x 250 ml) and sat. NaCl solution (200 ml). After drying over Na₂SO₄, the solvent was removed to give 36.57g of crude alcohol 7 (87% yield). It was distilled bulb to bulb (vac. 0.2 mm, bp 75-85°C) to give 32.19g of water white oil (76% yield). The product was one spot on tlc. Its ir spectrum was consistent with its proposed structure, 7. 6. Preparation of 2- ( 8-Bromooctyloxy ) oxacyclohexane ( 8 )

Alcohol 7 (35.2g, 0.169 mol), dihydropyran (38.6 ml, 35.47g, 0.42 mol) and dry CH₂Cl₂ (500 ml) were placed into a 1L flask equipped with a drying tube and a magnetic stirring bar. p-Toluenesulfonic acid (3.21g, 0.0169 mol) and CH₂Cl₂ (180 ml) were added. The reaction mixture quickly turned dark red-purple. After stirring for 2.5 hrs, 'the reaction mixture was added dropwise to a well stirred solution of NaHCO₃ (30g, 0.36 mol) in H₂O (680 ml). The layers were separated. The CH₂Cl₂ solution was washed with H₂O (2 x 100 ml) and sat. NaCl solution (100 ml). After drying over Na₂SO₄, the solvent was removed to give 82.05g of dark oil (166% yield). It was chromatographed on silica gel (500g) eluting with mixtures of hexane/CHCl₃ to give 37.24g of oil (75% yield). The oil was distilled bulb to bulb (vac 0.25 mm, bp 95-105°C) to give 36.73g of THP ether 8 (74% yield). The THP ether was one spot on tlc. Its ir spectra and nmr spectrum were consistent with the assigned structure, 8. 7. Preparation of 15-Phenyl-9-0xopentadecan-l-ol (9)

Mg (2.91g, 0.120 mol) was placed in a 250 ml flask fitted with a N₂ sweep. The flask and the Mg were flamed for 2 minutes with a propane torch. After cooling, the flask was equipped with a reflux condenser, a thermometer, a mag stirring bar and a rubber septum. Dry THF (13 ml) and

1,2-dibromoethane (0.22 ml, 0.48g, 0.0026 mol) was added and the flask was placed into an 80°C oil bath. Bromide 8 (29.17g, 0.0998 mol) in dry THF (24 ml) was added. The reaction .began and the flask was removed from the bath. A water bath was used to keep the reaction temperature between 60°C and 70°C. After 15 minutes the reaction slowed and dry THF (42 ml) was added. The reaction flask was placed into a 60°C oil bath for 15 minutes. Acid chloride 5 (22.73g, 0.0998 mol) in dry THF (105 ml) was placed in a 500 ml flask equipped with a N₂ gas inlet, a mechanical stirrer and a rubber septum. This solution was cooled with a dry ice/isopropyl alcohol bath. Using a syringe, the grignard solution was added dropwise to the cold, stirring acid chloride solution over 25 minutes. An additional 10 ml of dry THF wash were added. The thick white reaction mixture was stirred in the dry ice/ isopropyl alcohol bath for 53 minutes. It was removed from the bath and allowed to warm to room temperature over 1.5 hrs. The excess solvent was removed on the roto evaporator. The residue was poured into 5% NaHCO₃ solution (400 ml) and was extracted with ethyl ether (3 x 200 ml). The combined ethyl ether extracts were washed with 5% NaHCO₃ solution (100 ml), H₂O (2 x 100 ml) and sat. NaCl solution (100 ml). After drying over Na₂SO₄, the solvent was removed to give 39.64g of oil ( 98.6% yield ) . MeOH ( 350 ml ) and IN HCl ( 69 ml ) were added to the oil and it was refluxed for one hour In a 70°C oil bath. The excess solvent was removed on the roto evaporator. H₂O (250 ml) was added to the residue and the aqueous mixture was extracted with ethyl ether (200 ml and 2 x 100 ml). The combined ethyl ether extracts were washed with H₂O (2 x 100 ml) and sat. NaCl solution (100 ml). After drying over Na₂SO₄, the solvent was removed to give 34.32g of oily solid. It was distilled bulb to bulb (vac 0.4 to 0.25 mm, bp 90ºC) to give 4.07g of distillate and leaving 27.53g of solid (86% yield).

The solid residue contained the desired keto alcohol. The distillation residue from three reactions was combined (total 65.9g, theoretical yield 71.27g) and was chromatographed on silica gel (700g) eluting with hexane/CHCl₃ mixtures to give 17.98g of ketoalcohol 9

(25.2% yield). The purified product was one major spot on tlc. Its ir spectrum and nmr spectra were consistent with the assigned structure, 9.

Preparation of 10-Hydroxy-2-(6-phenylhexyl)-1-decene (11)

Phosphonium bromide 10 (41.0g, 0.115 mol) in dry THF (450 ml) was placed into a 2L flask equipped with a N₂ gas inlet, a mechanical stirrer and a rubber septum. The mixture was cooled with an ice bath. Using a dry syringe, n-BuLi/hexane (88.8 ml, 0.1135 mol) was slowly added.

Most of the solids dissolved to give a red-orange solution. The cooling bath was removed. After stirring for 50 minutes, an additional 1 ml of n-BuLi/hexane

(0.0013 mol) was added. A small amount of solid remained in the reaction mixture. After 40 minutes, a solution of keto alcohol 9 (17.81g, 0.056mol) in dry THF (100 ml) was added. An additional 26 ml of THF wash were added. Dry

DMSO (99 ml) was added. The thick suspension was stirred for 16 hrs at room temperature. The yellow suspension was added to H₂O (1 L) containing concentrated HCl (150 ml).

The aqueous mixture was extracted with ethyl ether (1 L and 3 x 250 ml). The combined ethyl ether extracts were washed with H₂O (3 x 250 ml) and sat. NaCl solution (2 x

100 ml). After drying over Na₂SO₄, the solvent was removed to give 33.6g of yellow solid (190% yield). It was chromatographed on Waters C-18 reverse phase packing

(700g) eluting with water/MeOH mixtures to give 11.65g of olefin 11 (66% yield). The purified olefin was one major peak on HPLC and one spot on tlc. Its ir spectrum and nmr spectra were consistent with its assigned structure, 11. 9. preparation of 9-Methyl-1 5-phenylpentadecan-l-ol ( 1 2)

10% Pd/C (11.65g) and absolute EtOH (300 ml) were placed into a 1 L hydrogenation bottle. Olefin 11 (11.65g, 0.037 mol) in absolute EtOH (160 ml) was added. The mixture was hydrogenated at 20 psi on a shaker hydrogenation apparatus. After 24 hrs. the catalyst was filtered off and washed with MeOH (2 x 100 ml). The combined filtrate and wash were concentrated to give 10.75g of alcohol 12 (92% yield). The reduction product was one major peak on HPLC and one spot on tlc. Its ir spectrum and nmr spectra were consistent with its assigned structure, 12.

1 0. Preparation o f 9-Methyl- 1 5-phenylpentadecanoic Acid ( 13 )

Alcohol 12 (10.63g, 0.033 mol) and acetone (110 ml) were placed in a 500 ml flask containing a mag stirring bar. Jones Reagent was prepared by dissolving CrO₃ (35g, 0.35 mol) in 250 ml of H₂O. After cooling with an ice bath, concentrated H₂SO₄ (30.5 ml) was carefully added. The solution was warmed to room temperature (total volume 0.288 L, 1.22 M/L). Jones Reagent (50 ml) was added slowly to the alcohol/acetone solution. The reaction mixture was stirred at room temperature for 45 minutes. An additional 6 ml of Jones Reagent was added. After another 1.5 hrs, isopropanol (10 ml) was added to consume the excess oxidizing agent. H₂O (500 ml) and ethyl ether (1.5 L) were added. The layers were separated. The aqueous layer was extracted with ethyl ether (100 ml). The combined ethyl ether extracts were washed with H₂O (2 x 500 ml) and saturated NaCl solution (200 ml). After drying over Na₂SO₄, the solvent was removed to give 11.2g of oil. It was chromatographed on Waters C-18 reverse phase packing (700g) eluting with water/MeOH mixtures to give 8.25g of acid 12 (74% yield). The purified acid was one major peak on HPLC. Its ir spectrum and nmr spectra were consistent with its assigned structure, 13. 1 1 . Preparation of 1 5- ( 4-Iodophenyl ) -9-methylpentadecanoic Acid ( 1 4 ) IMPA

Tl(TFA)₃ (13.05g, 0.024 mol) was weighed into a 200 ml flask in a N₂ filled glove bag. The flask was equipped with a N₂ gas inlet, a rubber spetum and a mag stirring bar. Dry trifluoroacetic acid (18 ml) and acid 13 (7.83g, 0.0235 mol) in dry trifluoroacetic acid (13 ml) were added. An additional 6 ml of dry trifluoroacetic acid wash were added. The flask was covered with aluminum foil to protect the reaction from light and the reaction was stirred at room temperature for 4 days. The reaction was transferred to a 500 ml flask using 1,2-dichloroethane (100 ml). The solvent was removed on a roto evaporator. 1,2-Dichloroethane (100 ml) was added and then stripped off. This step was repeated. KI (19.54g, 0.118 mol) in H₂O (230 ml) was added to the residue. A reflux condenser was added and the mixture was refluxed in a 100ºC oil bath for 5 hrs. Sodium metabisulfite (3.7g, 0.019 mol) was added and the mixture was refluxed for an additional 2 hrs. The yellow mixture was acidified with concentrated HCl (10 ml) and extracted with ethyl ether (2 x 200 ml and 2 x 100 ml). The combined ethyl ether extracts were washed with H₂O (2 x 100 ml) and saturated NaCl solution (100 ml). After drying over Na₂SO₄, the solvent was removed to give 12.72g of crude product. It was chromatographed on Waters C-18 reverse phase packing (700g) eluting with water/MeOH mixtures to give three fractions as follows: HPLC Chrom Purity

Wt. Yield O/P Isomers Total

1. 7.2g 67% 4.81%/93.79% 98.61%

2. 1.2g 11% 4.49%/94.30% 98.79%

3. 1.2g 11% 91.1%

1. and 2. were one spot on tic.

Its ir spectrum and nmr spectra were consistent with the assigned structure, 14.

Elemental Analysis for C₂₂H₃₅IO₂

Calc. Found

C 57.64 57.77

H 7.70 7.56

I 27.6 27.58

EXAMPLE 2 RADIOIODINATION OF IMPA

In a vial are placed IMPA (3 mg), and Na¹³¹ι (20 mCi). The vial is sealed with a rubber stopper and heated in an oil bath at 140°C for 2-3 hrs.

The vial is cooled, the contents dissolved in methanol and purified by HPLC (reversed phase C-18 column, 5 um x 250 mm fitted with UV and radiometric detectors; solvent: 90% MeOH, 3.6% HOAc, 6.4% H₂O) to yield ¹³¹I-IMPA (843 ng, 900 uCi, specific activity 1.3 mCi/mg).

¹²³I-IMPA was prepared in a similar manner by substituting Na¹²³i for Na¹³¹l.

EXAMPLE 3 COMPLEXATION OF IMPA WITH HSA

A solution of ¹³¹I-IMPA (843 ug), as prepared in Example 2, was evaporated to dryness and to the residue was added a 4% solution of HSA (25 cc). Similarly, a solution of ¹²³I-IMPA (843 ug), as prepared in Example 2, was evaporated to dryness and to the residue was added a 4% solution of HSA (25 cc).

EXAMPLE 4

The following pharmacological studies were conducted on IMPA, prepared by the method of Example 1. Material was radiolabeled with ¹³¹I, ¹²⁵I or ¹²³I according to methods described in Example 2. For comparative purposes, radioiodinated 15-(4-iodophenyl)pentadecanoic acid (IPPA; 13.67 mCi/mg) and 14-(4-iodoρhenyl)-3-methyltetradecanoic acid (IPMTA; 6.8 mCi/mg) were also tested in some of the studies. Prior to administration to animals, radioiodinatd fatty acids were complexed with 4% human serum albumin (HSA) or, where indicated, with 0.4% HSA. All formulations contained 5% v/v of ethanol except as noted.

1. Biodistribution of ¹³¹I-IMPA, ¹³¹I-IPPA and ¹³¹I-IMPTA in Rats

Groups of 3-4 female Sprague-Dawley rats, with body weights ranging from 156-239 g, received intravenous injections of 20-36 uCi/kg of ¹³¹ι-IMPA (specific activity, 1.3 mCi/mg), ¹³¹i-IPPA (13.67 mCi/mg) or ¹³¹I-IMPTA (6.8 mCi/mg). The 1³¹I-IMPA formulation contained no ethanol.

Rats were sacrificed at intervals of 5 and 45 minutes after dosing and radioactivity concentrations were determined by gamma scintillation spectrometry in blood, heart, liver, lungs, kidneys, muscle and thyroid. Results were as follows: Time

After Tissue Radioactivi ,ty (mean % dose/g)

Test Inj. Skeletal

Substance (Min) Heart Blood Liver Lung Kidney Muscle Thy

¹³¹I-IMPA 5 4.65 0.88 2.43 1.16 0.91 0.57 0.9

¹³¹I-IPPA 3.23 0.62 2.92 1.00 0.88 0.43 0.9

¹³¹I-IPMTA 2.13 0.97 5.52 1.00 1.04 0.31 1.2

¹³¹I-IMPA 45 3.57 1.11 1.17 1.15 1.78 0.54 4.3

¹³¹I-IPPA 2.12 0.90 1.74 0.99 0.98 0.32 2.7

¹³¹I-IPMTA 1.83 1.24 3.23 0.77 1.50 0.28 5.0

Levels of radioactivity in the heart were as great, if not greater, with ¹³¹I-IMPA than with the other two fatty acids. There was no significant degree of deiodination of any of the fatty acid as reflected in the thyroid levels which increase dramatically wit time when deiodination occurs. Furthermore, excellent heart/nontarget tissue ratios were observed for ¹³¹I-IMPA as indicated in the following table:

Time After

Test Injection Heart/Non-Target Tissue Ratio (Mean) Substance (Min) Heart/Blood Heart/Liver Heart/Lung 1³¹I-IMPA 5 5.28 1.91 4.01 1³¹I-IPPA 5.34 1.11 3.25 1³¹I-IPMTA 2.21 0.39 2.13

¹³¹I-IMPA 45 3.22 3.05 3.10 1³¹I-IPPA 2.43 1.22 2.16 1³¹I-IPMTA 1.48 0.57 2.41

As a measure of retention in the heart, the ratio of the myocardial radioactivity in rats sacrificed 45 minutes after injection to that in rats sacrificed 5 minutes after injection was determined. Test Myocardial Retention Index

Substance (Heart ¹³¹I at 45 min/Heart ¹³¹I at 5 min)

¹³¹I-IMPA 0.77

¹³¹I-IPPA 0.66

¹³¹I-IPMTA 0.86

It appeared that ¹³¹I-IMPA was cleared from the heart more rapidly than ¹³¹I-IPMTA but less rapidly than 1³¹I-IPPA.

2. Gamma Camera Imaging with IMPA, IPPA and IPMTA in Dogs

A computerized gamma camera system was used for myocardial imaging studies with ¹³¹I-IPPA, ¹³¹I-IPMTA and ¹³¹I- or 1²³I-IMPA in mongrel dogs. Dogs, male or female, weighing 8.0-11.0 kg, received 0.25-1.0 mCi of radiolabeled fatty acid and imaging was conducted for 60-64 minutes. One of the dogs receiving ¹²³I-IMPA was fasted for 20 hours prior to dosing. Dogs were sacrificed at the conclusion of the imaging period and heart, blood, liver and lung samples were assayed for radioactivity using gamma scintillation spectrometry.

All three fatty acids showed good initial uptake in heart and liver. With IPPA, heart images faded considerably over a 30-minute period. With IMPA, images of the heart were persistent for one hour, but considerable clearance was observed during the imaging period. IPMTA images were the most persistent, with little clearance from the myocardium over the imaging period.

Tissue radioactivity levels and heart/non-target tissue levels at sacrifice were as follows: Tissue Radioactivity (mean % dose/g)

Number and Heart/Non-Target Tissue Ratios

Test of Heart/ Heart/ Heart/ Substance Dogs Heart Blood Liver Lung Blood Liver Lung

¹³¹I-or

¹²³I-IMPA 2 0.050 0.020 0.043 0.034 2.50 1.16 1.47

¹²³I-IMPA (Fasted Dog) 1 0.092 0. 025 0 . 047 0. 029 3. 68 1 . 96 3 . 1 7

¹³¹I-IPPA 3 0.030 0. 01 2 0. 043 0. 022 3. 02 0. 96 1 . 62

¹³¹I-IPMTA 1 0. 073 0. 01 1 0. 044 0 . 01 0 6. 64 1 . 66 7. 30

In unfasted dogs, IMPA was retained longer in the heart than IPPA but not as long as IPMTA. Fasting appeared to increase the myocardial uptake of IMPA.

3. Biodistribution of ¹³¹l-IMPA Formulations with Different IMPA/HSA Molar Ratios

In order to determine if the myocardial uptake of IMPA was dependent on the molar ratio of the fatty acid/albumin complex, a rat biodistribution study was conducted with ¹²⁵ I-IMPA complexed with 0.4% and 4.0% HSA at molar ratios ranging from 0.001-10. Groups of six female Sprague-Dawley rats, body weights 150-211 g, received intravenous injections of 2 ml/kg (0.7-8.7 uCi/kg) of 8 different formulations of ¹²⁵I-iMPA. Rats were sacrificed 5 minutes after dosing and radioactivity was determined by gamma scintillation spectrometry in heart, blood, liver, lungs, kidneys, skeletal muscle and thyroid. Results were expressed as % dose/g and heart/blood, heart/liver and heart/lung ratios were calculated. A one-way analysis of variance with Duncan's multiple range test was used for statistical comparisons between treatment groups. A probability level of p<0.05 for Type I error was used the criterion for significance. Approximate

Lot % HSA IMPA/HSA Specific Activity

Number (w/v) Molar Ratio (uCi/umol IMPA)

001 -A 4.0 0.001 595

001-B 4.0 0.01 672

001-C 4.0 0.1 68.0

001-D 4.0 1.0 6.70

001-E (1) 0.4 10.0 -

001-F 0.4 1.0 67.6

001-G 0.4 0.1 671

001-H 0.4 2.0 35.2

(1) Lot 001-E contained particulate after filtration.

Approximate specific activity was not determined after filtration.

Biodistribution data and selected heart/non-target tissue ratios are presented in the following two tables:

Tissue Radioactivity (Mean Percent Dose/g)

Lot

Number Blood Heart Liver Lung Kidney Muscle Thyroid

001-A 1.19 3.66 2.66 1.27 1.38 0.46 1.66

001-B 1.30 2.84 2.81 1.14 1.51 0.43 1.44

001-C 1.18 3.92 3.18 1.24 1.30 0.50 1.11

001-D 1.10 3.27 3.26 1.27 1.21 0.45 0.93

001-E 0.63 2.05 2.58 28.13 0.86 0.26 0.54

001-F 1.06 3.64 2.70 1.20 1.37 0.44 1.20

001-G 0.95 3.60 2.59 1.18 1.24 0.44 1.14

001-H 0.92 3.95 2.70 1.17 1.22 0.47 1.18

Least significant differences for tissue uptake are summarized as follows:

Blood = 0.21 Lung = 1.96 Thyroid = 0.53 Heart = 0.75 Kidney = 0.36 Liver = 0.20 Muscle - 0.12 Lot Heart/Non-Target Tissue Ratio (Mean)

Number Heart/Blood Heart/Liver Heart/Lung

001-A 3.10 1.39 2.88

001-B 2.23 1.02 2.49

001-C 3.35 1.28 3.20

001-D 3.10 1.02 2.58

001-E 3.33 0.80 0.07

001-F 3.45 1.39 3.03

001-G 3.99 1.39 3.09

001-H 4.32 1.48 3.38

Least significant differences for tissue ratios are summarized as follows:

Heart/Blood = 1.00 Heart/Liver = 0.30 Heart/Lung = 0.58

Lot 001-E was observed to contain particulate matter and showed extensive lung uptake. All other lots demonstrated good heart uptake. However, lot 001-B had less heart uptake than most of the other formulations and higher blood levels than some of the lots. There were some significant differences in liver uptake between the test lots but no apparent correlation based on IMPA/HSA molar ratio. When 0.4% HSA was used in the vehicle (as opposed to 4% HSA), there was a tendency for blood levels of radioactivity to be lower and consequently for heart/blood ratios to be higher. The overall conclusion from the study was that the IMPA/HSA molar ratio does not appear to be a critical determinant of myocardial uptake of IMPA, except when one exceeds the binding capacity of the HSA giving rise to a colloidal material (formulation 001-E). 4. Biodistribution of ¹²⁵I-IMPA in Fasted Rats.

The effect of fasting on myocardial uptake of IMPA was examined in a biodistribution study of groups of six control (nonfasted), twenty four-hour fasted and seventy two-hour fasted female Sprague-Dawley rats. Rats were of similar weights prior to fasting but ranges observed at dosing were as follows: nonfasted 162-203 g, 24-hour fasted 133-165 g and 72-hour fasted 110-145 g. Rats received 2 ml/kg ( 22 uCi/kg) intravenous injections of 1²⁵I-IMPA and were sacrificed 5 minutes after injection. Gamma scintillation spectrometry was used to assay radioactivity in heart, blood, liver, lungs, kidneys, skeletal muscle and thyroid. Results were expressed as % dose/g tissue. A one-way analysis of variance and Duncan's multiple range test were used for statistical comparisons with a probability value of 0.05 for Type I error chosen as the criterion for significance.

It has been reported that a 72-hour fast is required for rats to reach basal serum chemistry values. Fasting for 72-hours increased heart uptake of ¹²⁵I- IMPA and resulted in higher heart to blood ratios as demonstrated in the tables below. On the other hand, a 24-hour fast appeared to depress heart uptake and gave lower heart/blood ratios than nonfasted animals.

Tissue Tissue Reidioatrtivity (Mean % dose/g) or Fluid Nonfasted Fasted 24 Hour Fasted 72 Hour

Blood 1.01 1.07 1.02

Kidney 1.38 1.24 1.54

Liver 2.81(c) 3.07(c) 3.75(a,b)

Muscle 0.57(c) 0.64(c) 0.93(a,b)

Lung 1.38(c) 1.38(c) 1.79(a,b)

Thyroid 0.76 0.89 0.81

Heart 4.38(c) 3.74(c) 5.31(a,b) (a) - Significant difference from nonfasted group

(b) - Significant difference from 24-hour fasted group

(c) - Significant difference from 72-hour fasted group Heart/Non-Target Tissue Ratio (Mean)

Parameter Nonfasted Fasted 24 Hour Fasted 72 Hour

Heart/Blood 4.36(b) 3.64(a,c) 5.43(b) Heart/Liver 1.56 1.27 1.42 Heart/Lung 3.17 2.75 2.97

(a) - Significant difference from nonfasted group

(b) - Significant difference from 24-hour fasted group

(c) - Significant difference from 72-hour fasted group

5. Effects of Ethanol Concentration on the Biodistribution of 1²³I-IMPA.

Formulations of ¹²³I-IMPA with IMPA/HSA molar ratios of 1 were prepared using 4% HSA and ethanol concentrations of 0, 2, 5 or 12%, v/v. Groups of four female Sprague-Dawley rats (body weight range of 190-226 g) received 12 uCi/kg of one of the 1²³I-IMPA formulations (specific activity of 4.8 uCi/umol) and were sacrificed 5 minutes after injection. Radioactivity was determined in heart, blood, liver, lungs, skeletal muscle, kidneys and thyroid using gamma scintillation spectrometry. Statistical comparisons between treatment groups were made using a one-way analysis of variance and Duncan's multiple range test. A probability of less than 0.05 for Type I error was used as the criterion for significance.

The concentration of ethanol in ¹²³I-IMPA formulations did not affect the biodistribution in rats as evidenced by the following two tables:

Concentration of Ethanol Tissue (% v/v) Heart Blood Liver Lung Kidney Muscle Thyroid

0 3.23 0.97 2.66 1.10 1.00 0.41 1.45

2 3.57 0.97 2.81 1.13 1.01 0.35 1.10

5 3.12 0.86 2.72 1.06 0.88 0.36 1.55

12 3.17 0.94 2.79 1.09 0.94 0.32 1.56

Ethanol Concentration Heart/Non-Target Tissue Ratio (Mean)

(% v/v) Heart/Blood Heart/Liver Heart/Lung

0 3.43 1.24 2.93 2 3.84 1.28 3.26

5 3.72 1.16 2.92 12 3.39 1.14 2.91 EXAMPLE 5

1 . Preparation of 12-Hydroxy-4- ( 6-phenylhexyl ) -3- dodecene ( 1 6 )

Sodium hydride (57%, 0.72g, 7.54 mmol), dry DMSO (20 ml) and t-butanol (0.022g, 0.3 mmol) were placed into a 100 ml flask equipped with a N₂ gas inlet, a mag stirring bar and a rubber septum. Phosphonium bromide 15 (3.02g, 7.85 mmol) dissolved in DMSO (10 ml) was added using a dry syringe. Gas evolution was observed as the mixture was stirred at room temperature for 2.5 hours. A solution of 9 (1.0g, 3.14 mmol) in DMSO (10 ml) was added to the dark orange reaction mixture. The mixture was stirred for 25.5 hours at room temperature under N₂. The reaction mixture was added to H₂O (360 ml) containing concentrated HCl (40 ml). The aqueous mixture was extracted with ethyl ether (200 ml and 2x100 ml). The combined ethyl ether extracts were washed with H₂O (3x100 ml) and sat. NaCl solution (2x50 ml). After drying over Na₂SO₄, the solvent was removed to give 2.63g of yellow oil. It was chromatographed on Waters C-18 reverse phase packing (200g) eluting with mixtures of water and MeOH to give 1.48g of oily olefin 16 (109% yield). The purified olefin was one major peak on HPLC. Its NMR spectra were consistent with its assigned structure 16. 2. Preparation of 1 5-Phenyl-9-propylpentadecan- 1 -ol ( 17 )

10% Pd/C (1.4g) and absolute EtOH (25 ml) were placed into a 250 ml hydrogenation bottle. Olefin 16 (1.4g, 4.06 mmol) in absolute EtOH (25 ml) was added. The mixture was hydrogenated at 20 psi on a shaker hydrogenation apparatus. After 24 hrs, the catalyst was filtered off and washed with MeOH (75 ml). The combined filtrate and wash were concentrated to give 0.78g of alcohol 17 (55% yield). The reduction product was one spot on tlc. Its nmr spectra were consistent with its asigned structure, 17.

3. Preparation of 15-Phenyl-9-propylpentadecanoic Acid

Alcohol 17 (0.78g, 2.25 mmol) and acetone (8 ml) were placed in a 25 ml flask containing a mag stirring bar. Jones Reagent was prepared by dissolving CrO₃ (35g, 0.35 mmol) in 250 ml of H₂O. After cooling with an ice bath, concentrated H₂SO₄ (30.5 ml) was carefully added. The solution was warmed to room temperature (total volume 0.288L, 1.22M/L). Jones Reagent (3.2 ml) was added slowly to the alcohol/acetone solution. The reaction mixture was stirred at room temperature for 1.5 hours. Isopropanol (1 ml) was added to consume the excess oxidizing agent. H₂O (100 ml) and ethyl ether (100 ml) were added. The layers were separated. The aqueous layer was extracted with ethyl ether (100 ml). The combined ethyl ether extracts were washed with H₂O (3x50 ml) and saturated NaCl solution (2x50 ml). After drying over Na₂SO₄, the solvent was removed to give 0.72g of oil. It was chromatographed on silica gel (75g) eluting with hexane/CHCl₃ mixtures to give 0.56g of acid 18 (69% yield). The purified acid was one spot on tlc. Its nmr spectra were consistent with its assigned structure, 18. 4. Preparation of 15-(4-Iodophenyl)-9-propylpentadecanoic Acid (19) MP-553

Tl(TFA)₃ (0.87g, 1.60 mmol) was weighed into a 25 ml flask in a N₂ filled glove bag. The flask was equipped with a N₂ gas inlet, a rubber septum and a mag stirring bar. Dry trifluoroacetic acid (1 ml) and acid 18 (0.56g, 1.55 mmol) in dry trifluoroacetic acid (6 ml) were added. An additional 6 ml of dry trifluoroacetic acid wash were added. The flask was covered with aluminum foil to protect the reaction from light and the reaction was stirred at room temperature for 3 days. The reaction was transferred to a 250 ml flask using 1,2-dichloroethane (25 ml). The solvent was removed on a roto evaporator. 1,2-Dichloroethane (25 ml) was added and then stripped off. This step was repeated. KI (1.33g, 8 mmol) in H₂O (83 ml) was added to the residue. A reflux condenser was added and the mixture was refluxed in a 100°C oil bath for 5 hrs. Sodium metabisulfite (0.3g, 1.58 mmol) was added and the mixture was refluxed for an additional 2 hrs. The yellow mixture was acidified with concentrated HCl (5 ml) and extracted with ethyl ether (3x100 ml). The combined ethyl ether extracts were washed with H₂O (3x50 ml) and saturated NaCl solution (50 ml). After drying over Na₂SO₄, the solvent was removed to give 0.65g of crude product. It was chromatographed on silica gel (75g) eluting with CHCI₃ to give 0.58g of purified material. The material was purified by preparative HPLC (EM, Prep 10 column C-18) eluting with a mixture of MeOH/H₂O/HOAc (930/06/5) to give 0.29g of solid. HPLC showed that it was 95.6% pure. It was chromatographed on silica gel (30g) eluting with CHCl₃ to give 0.24g of low melting acid 19. It was one spot on tlc. HPLC showed that it contained 93.05% para isomer and 5.6% ortho isomer. Its ir spectrum and nmr spectra were consistent with the assigned structure, 19. High resolution mass spec.; calculated for C₂₄H₃₉IO₂ 486.1995, found 486.1994.

EXAMPLE 6

1 . Preparation of Phosphonium Salt ( 20 )

Triphenylphosphine (5.3g, 20.24 mmol) and 9-bromononoic acid (4.8g, 20.24 mmol) were placed into a 250 ml flask equipped with a mechanical stirrer and a N₂ gas inlet. It was placed into an 85°C oil bath and the mixture was stirred at 85°C for 21 hrs. under N₂. After cooling the gummy product was dissolved in CHCI₃ (20 ml) and the solution added dropwise into ethyl ether (200 ml) which was stirring rapidly. A white gum formed. The solvent was poured off and the gum was dried under vacuum. This step was repeated three times. The gum was dried at 100°C under high vacuum to give 9.45g of phosphonium salt 20 (94% yield). It was one spot on tic.

2. Preparation of Ethyl 3-Oxo-8-phenyloctanoate ( 21 )

Ethyl hydrogen malonate (17.6g, 133.4 mmol), dry THF (135 ml) and dry CH₂Cl₂ (55 ml) were placed into a 1 L flask equipped with a mag stirring bar, a drying tube, a thermometer and an addition funnel. The solution was cooled with an ice bath. Isopropylmagnesium chloride/THF (2 molar, 135 ml, 270 mmol) was added over 10 minutes while keeping the reaction temperature between 35°C and 45°C. The mixture was cooled to 10°C and the bath was removed. After 30 minutes the reaction was placed into an ice bath. A solution of 6-phenylhexanoyl chloride (11.35g, 53.4 mmol) in CHCI₃ (26 ml) was added over 5 minutes while keeping the reactions temperature between 3° and 8°C. The bath was removed and the reaction was stirred for 3.5 hours. It was carefully poured into 1 N HCl (400 ml) as gas evolved. The .aqueous mixture was extracted into ethyl ether (2x200 ml and 100 ml). The combined ethyl ether extracts were washed with H₂O (2x100 ml) and sat. NaCl solution (2x50 ml). After drying over Na₂SO₄, the solvent was removed to give 33.13g of oil. The crude product was distilled bulb to bulb (120°C to 130°C, 0.2 mm) to give 12.0g of ketoacid 21 (80% yield). It was one spot on tlc. Its ir spectrum and nmr spectra were consistent with its structure, 21. 3. Preparation of 7-Phenylheptan-2-one ( 22 )

Ketoester 21 (7.0g, 26.7 mmol), H₂O (16 ml), trifluoroacetic acid (49 ml) and THF (21 ml) were placed into a flas equipped with a mag stirring bar and a reflux condenser. The reaction was refluxed for 17 hours. The excess solvent was removed under vacuum and the residue was added to a 5% solution of NaHCO₃ (500 ml). The aqueous mixture was extracted into ethyl ether (200 ml and 2x100 ml). The combined extracts were washed with H₂O (100 ml and 2x50 ml) and sat. NaCl solutions (50 ml). After drying over Na₂SO₄, the solvent was removed to give 5.72g of crude product. It was distilled bulb to bulb (75°C to 90°C, 0.15 mm) to give 4.88g of ketone 22 (96% yield). It was one spot on tic. Its ir spectrum and nmr spectra were consistent with the assigned structure, 22.

4. Preparation of 10-Methyl-15-phenylpentadec-8-enoic Acid

Sodium hydride (57%, 0.57g, 6.3 mmol) was placed into a 100 ml flask equipped with a N₂ gas inlet, a mag stirring bar and a rubber septum. It was washed with hexane and dried. Phosphonium bromide 20 (1.5g, 3 mmol) dissolved in DMSO (3 ml) was added using a dry syringe. DMSO (1 ml) and THF (3 ml) were added. Gas evolution was observed and the mixture was stirred at room temperature for 17 hours. A solution of 22 (0.38g, 2 mmol) in THF (1.5 ml) was added to the mixture. THF (1.5 ml) was added and the mixture was stirred for 19.5 hours at room temperature under N₂. Two reaction mixtures were combined and added to H₂O (360 ml) containing concentrated HCl (40 ml). The aqueous mixture was extracted with ethyl ether (200 ml and 2x100 ml). The combined ethyl ether extracts were washed with H₂O (3x100 ml) and sat. NaCl solution (2x50 ml). After drying over Na₂SO₄, the solvent was removed to give 3.06g of yellow oil. Two reaction products were combined (5.09g total) and were chromatographed on silica gel (200g) eluting with hexane/CHCl₃ fixtures to give 1.67g of material. It was chromatographed on Waters C-18 reverse phase packing (180g) eluting with water/MeOH mixtures to give 0.91g of product (35% yield). Its nmr spectrum showed an olefin proton at 5.1 ppm and no triphenylphosphine oxide. This material was used as is in the next reaction. 5. Preparation of 10-Methyl-15-ρhenylpentadecanoic Acid

10% Pd/C (1.8g) and acetic acid (30 ml) were placed into a 250 ml hydrogenation bottle. Olefin 23 (0.91g, 2.75 mmol) acetic acid (6 ml) was added. The mixture was hydrogenated at 20 psi on a shaker hydrogenation apparatus. After 5 day the catalyst was filtered off and washed with MeOH and CHCI₃. The combined filtrate and wash were concentrated to give 1.0g of acid 24 (92% yield). It was chromatographed on silica gel (100g) eluting with hexane/CHCl₃ mixtures to give 1.05g of product (115% yield). The purified product was one spot on tic. Its nmr spectra were consistent with its assigned structure, 24.

6. Preparation of 15-(4-Iodophenyl)-10-methylpentadecanoic Acid (25), MP-563.

Tl(TFA)₃ (1.8g, 3.32 mmol) was weighed into a 25 ml flask in a N₂ filled glove bag. The flask was equipped with a N₂ gas inlet, a rubber septum and a mag stirring bar. Dry trifluoroacetic acid (2 ml) and acid 24 (1.05g, 3.16 mmol) in dry trifluoroacetic acid (1 ml) were added. An additional 2 ml of dry trifluoroacetic acid wash were added. The flask was covered with aluminum foil to protect the reaction from light and the reaction was stirred at room temperature for 3 days. The reaction was transferred to a 200 ml flask using 1 ,2-dichloroethane (25 ml). The solvent was removed on a roto evaporator. 1,2-Dichloroethane (25 ml) was added and then stripped off. This step was repeated. KI (2.76g, 16.6 mmol) in H₂O (32.5 ml) was added to the residue. A reflux condenser was added and the mixture was refluxed in a 100ºC oil bath for 5 hrs. Sodium metabisulfite (0.52g, 2.55 mmol) was added and the mixture was refluxed for an additional 1 hour. The yellow mixture was acidified with concentrated HCl (5 ml) and extracted with ethyl ether (3 x 100 ml). The combined ethyl ether extracts were washed with H₂O (3 x 50 ml) and saturated NaCl solution (50 ml). After drying over Na₂SO₄, the solvent was removed to give 3.21g of crude product. It was chromatographed on silica gel (200g) eluting with hexane/CHCl₃ mixtures to give 1.12g of oil. It was chromatographed on Waters C-18 reverse phase packing (200g) eluting with water/MeOH mixtures to give 0.49g of MP-563 (33% yield). It was one spot on tic. HPLC showed that it was 97.8% para isomer and 1.3% ortho isomer. Its ir spectrum and nmr spectra were consistent with the assigned structure, 25.

Elemental Analysis for C₂₂H₃₅IO₂

Calc Found

C 57. 64 57. 67

H 7. 70 7. 73

I 27 . 68 27. 54

EXAMPLE 7

Triphenylphosphine (6.6g, 25.2 mmol) and 1-bromo-10phenyldecane (7.12g, 24 mmol) were placed into a 250 ml flask equipped with a mechanical stirrer and a N₂ gas inlet. It was placed into an 85°C oil bath and the mixture was stirred at 85°C for 21 hours. After cooling the gummy product was dissolved in CHCI₃ (20 ml) and the solution added dropwise into ethyl ether (200 ml) which was stirring rapidly. A white gum formed. The solvent was poured off and the gum was dried under vacuum. This step was repeated three times. The gum was dried at 100°C under high vacuum to give 10.95g of phosphonium salt 26 (81% yield).

2. Preparation of 5-Methyl-15-phenylρentadec-5-enoic Acid (28)

Phosphonium bromide 26 (8.98g, 16 mmol) in dry THF (75 ml) was placed into a 500 ml flask equipped with a N₂ gas inlet, a mag stirring bar and a rubber septum. The mixture was cooled with an ice bath. Using a dry syringe, n-BuLi/ hexane (14.8 ml, 17.7 mmol) was slowly added. Most of the solids dissolved to give a red-orange solution. After 1 hour, a solution of ketoester 27 (1.6g, 10.7. ml) in dry THF (3 ml) was added. An additional 2 ml of THF wash were added. The mixture was stirred and warmed to room temperature. After about 1 hour, the reaction mixture was added to H₂O (500 ml). The aqueous mixture was extracted with ethyl ether (1 L and 3x250 ml). The combined ethyl ether extracts were washed with H₂O (3x250 ml) and sat. NaCl solution (2x100 ml). After drying over Na₂SO₄, the solvent was removed to give 8.55g of oil. It was dissolved in MeOH (90 ml) and 1N NaOH solution (30 ml). The mixture was refluxed for 2 hours and then it was stirred for 16 hours at room temperature. The excess solvent was removed and the residue was extracted with ethyl ether (3x100 ml). The combined ethyl ether extracts were washed with H₂O (3x100 ml) and sat. NaCl solution (50 ml). After drying over Na₂SO₄, the solvent was removed to give 4.7g of crude product. It was chromatographed on silica gel (150g) eluting with hexane/CHCl₃ mixtures to give 4.04g of product. This was combined with other reaction products (4.78g total). They were chromatographed on Waters C-18 reverse phase packing (150g) eluting with water/MeOH mixtures to give 1.88g of olefin 28. Although a mixture on HPLC, their nmr spectra were consistent with their assigned structure, 28.

3. Preparation of 5-Methyl- 15-phenylpentadecanoic Acid

10 Pd/C (1.8g) and acetic acid (50 ml) were placed into a 250 ml hydrogenation bottle. Olefin 28 (1.88g, 5.6 mmol) in acetic acid (25 ml) was added. The mixture was hydrogenated at 20 psi on a shaker hydrogenation apparatus. After 4 days the catalyst was filtered off and washed with MeOH and CHCI₃. The combined filtrate and wash were concentrated to give 1.68g of acid. It was chromatographed on silica gel (150g) eluting with hexane/CHCl₃ mixtures to give 1.6g of acid, 29 (85% yield). It was one major spot on tic and one major peak on HPLC. Its nmr spectra were consistent with its assigned structure, 29.

4. Preparation of 15-(4-Iodoρhenyl)-5-methylpentadecanoic Acid (30) MP-568

Tl₂O₃ (2.3g, 5.04 mmol), CF₃(CF₂)₂CO₂H(9.2 ml, 81.5 mmol) and H₂O (1.15 ml, 63.8 mmol) were placed into a 50 ml flask equipped with a reflux condenser, a N₂ gas inlet, a rubber septum and a mag stirring bar. The flask was covered with aluminum foil and was heated at 100°C for 19 hours under N₂. This solution was added to acid 29 (1.6g, 4.8 mmol) in a 250 ml flask equipped with a rubber septum and a mag stirring bar. An additional 1.4 ml of CF3(CF₂)₂CO₂H wash were added. The flask was covered with aluminum foil to protect the reaction from light and the reaction was stirred at room temperature for 52 hours. The reaction was transferred to a 250 ml flask using 1,2-dichloroethane (50 ml). The solvent was removed on a roto evaporator. 1,2-Dichloroethane (50 ml) was added and then stripped off. This step was repeated. KI (4.2g, 25.2 mmol) in H₂O (82 ml) was added to the residue. A reflux condenser was added and the mixture was refluxed in a 100°C oil bath for 5 hours. Sodium metabisulfite (1.8g, 9.2 mmol) was added and the mixture was refluxed for an additional 2 hours. The yellow mixture was acidified with concentrated HCl (5 ml) and extracted with ethyl ether (2x100 ml). The combined ethyl ether extracts were washed with H₂O (3x50 ml) and saturated NaCl solution (50 ml). After drying over Na₂SO₄, the solvent was removed to give 2.35g of crude product. It was chromatographed on silica gel (150g) eluting with hexane/CHCl₃ mixture to give 1.93g of product. This material was chromatographed on Waters C-18 reverse phase packing (180g) eluting with water/MeOH mixtures to give 1.70g of product. It was crystallized from hexane to give 0.75g of acid 30 (36% yield). It was one spot on tic. HPLC showed that it contained 95.4% para isomer and 2.7% ortho isomer. Its ir spectrum and nmr spectra were consistent with the assigned structure 30. High resolution mass spec.; calculated for C₂₂H₃₅IO₂ 458.1683, found 458.1691.

EXAMPLE 8

The compounds set forth in the table below were tested in accordance with the procedure of Example 4.

Time After Test Injection Heart/Non-Target Tissue Ratio (Mean) Substance (Min) Heart/Blood Heart/Liver Heart/Lung

¹³¹l-IMPA-2 5 2.93 1.43 3.39

¹³¹I-IMPA-3 5 4.16 1.12 2.56

¹³¹I-IMPA-2 45 2.28 2.87 3.10

¹³¹I-IMPA-3 45 2.76 1.36 2.65

Claims (13)

WHAT I S CLAIMED :

1. A compound selected from the group consisting of 15-(4-iodophenyl) pentadecanoic acids having a methyl or ethyl group on one of the backbone carbons that does not occupy position 1-3, radioactive iodine imaging isotopes thereof and pharmaceutically acceptable salts of such acid and said isotopes.

2. A compound selected from the group consisting of radioactive imaging isotopes of the acids of Claim 1.

3. A compound selected from the group consisting of the radioactive imaging isotopes of 15-(4-iodophenyl)-9methylpentadecanoic acid, 15-(4-iodophenyl)-5-methylpentadecanoic acid and 15-(4-iodophenyl)-10-methylpentadecanoic acid and pharmaceutically acceptable salts thereof.

A compound according to Claim 2 wherein the iodine isotope is ¹³¹I or ¹²³I.

5. A compound according to Claim 4 wherein the isotope is an isotope of 15-(4-iodophenyl)-9-methylpentadecanoic acid and pharmaceutically acceptable salts thereof.

6. A myocardial imaging composition containing a compound selected from the group consisting of radioactive iodine imaging isotopes αf acids of Claim 1 and pharmaceutically acceptable salts thereof in a sufficient amount to provide satisfactory myocardial imaging together with a pharmaceutically acceptable vehicle.

7. A composition according to Claim 6 wherein the acids are selected from the group consisting of 15-(4-iodophenyl)-5-methylpentadecanoic acid, 15-(4-iodophenyl)-9methylpentadec'anoic acid and 15-(4-iodophenyl)-10-methylpentadecanoic acid.

8. A composition according to Claim 7 wherein the isotope is ¹³¹I or ¹²³I.

9. A composition according to Claim 8 wherein the acid is 15-(4-iodophenyl)-9-methylpentadecanoic acid.

10. In a method for myocardial imaging wherein a myocardial imaging composition containing a myocardial agent in a pharmaceutically acceptable vehicle is injected in a sufficient amount to provide adequate imaging and thereafter imaging carried out, the improvement comprising or utilizing as the myocardial imaging composition a compound selected from the group consisting of radioactive iodine imaging isotopes of Claim 1 and pharmaceutically acceptable salts thereof In a sufficient amount to provide satisfactory imaging together with a pharmaceutically acceptable vehicle .

11. A method of Claim 10 wherein the acid is selected from the group consisting of 15-(4-iodophenyl)-5-methylρentadecanoic acid and 15-(4-iodophenyl)-10-methylpentadecanoic acid.

12 A method according to Claim 11 wherein the isotope is ¹³¹I or ¹²³I.

13. A method according to Claim 12 wherein the acid is

15-(4-iodophenyl)-9-methylpentadecanoic acid.