U.S. patent application number 12/478531 was filed with the patent office on 2010-09-09 for pendant fatty acid imaging agents.
This patent application is currently assigned to Molecular Insight Pharmaceuticals, Inc.. Invention is credited to John W. BABICH.
Application Number | 20100228012 12/478531 |
Document ID | / |
Family ID | 28791911 |
Filed Date | 2010-09-09 |
United States Patent
Application |
20100228012 |
Kind Code |
A1 |
BABICH; John W. |
September 9, 2010 |
PENDANT FATTY ACID IMAGING AGENTS
Abstract
The disclosure provides pendant fatty acid compounds for use in
diagnostic imaging, (particularly the cardiovascular system), as
well as kits comprised of the same. The disclosure also provides
for a method administering a imaging agent with a high specificity
for the myocardium.
Inventors: |
BABICH; John W.; (North
Scituate, MA) |
Correspondence
Address: |
FOLEY & LARDNER LLP
111 HUNTINGTON AVENUE, 26TH FLOOR
BOSTON
MA
02199-7610
US
|
Assignee: |
Molecular Insight Pharmaceuticals,
Inc.
|
Family ID: |
28791911 |
Appl. No.: |
12/478531 |
Filed: |
June 4, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11599159 |
Nov 13, 2006 |
7556794 |
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12478531 |
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10405094 |
Apr 1, 2003 |
7179444 |
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11599159 |
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60368933 |
Apr 1, 2002 |
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Current U.S.
Class: |
534/14 |
Current CPC
Class: |
A61K 51/0402 20130101;
A61K 51/0487 20130101; C07F 13/005 20130101; A61K 51/0478
20130101 |
Class at
Publication: |
534/14 |
International
Class: |
C07F 13/00 20060101
C07F013/00 |
Claims
1. An imaging agent represented by the structure 1: ##STR00020##
wherein R.sub.1, R.sub.4, R.sub.5, and R.sub.6 are each
independently selected from an alkyl, alkenyl or a bond; R.sub.2 is
selected from the group consisting of a hydrogen, a primary amine,
a secondary amine, a tertiary amine, an alkyl group, a substituted
alkyl group, an aryl group, and a substituted aryl group; R.sub.3
is selected from the group consisting of a hydrogen, an alkyl, a
hydroxyl, a keto ester, an alkoxy, a halide, and an amine; R.sub.7
is selected from a metal chelating moiety bound to a metallic
carbonyl ligand; wherein the stereochemical configuration of a
compound represented by 1 may be R, S, at the stereocenters; or a
mixture of these configurations, and the pharmaceutically
acceptable salts, esters, amide's, and prodrugs thereof.
Description
RELATED APPLICATION INFORMATION
[0001] This application is a continuation application of and claims
priority to and the benefit of U.S. patent application Ser. No.
10/405,094 filed on Apr. 1, 2003, which claims priority to U.S.
Provisional Patent Application No. 60/368,933 filed Apr. 1, 2002,
the entire teachings of which are incorporated herein by
reference.
BACKGROUND
[0002] Every year, seven million Americans arrive in emergency
rooms complaining of chest pain indicating a possible heart attack.
Identifying which patients are actually having a heart attack and
require hospitalization can be challenging. More than 40% of
emergency room chest pain patients, estimated at more than 3
million, are admitted to hospitals unnecessarily at an estimated
annual cost of $10-$13 billion. These unnecessary hospitalizations
may be avoided if better diagnostic tests existed for emergency
room use. As pointed out in the NIH's 1997 National Heart Attack
Alert Program Report on Diagnostic Technologies for Acute Cardiac
Ischemia, there have been no diagnostic tests to-date that have
been shown by controlled clinical trials to improve emergency room
decision-making in actual practice. Unstable angina is also part of
the population arriving at the emergency room. Approximately 6 out
of 10,000 individuals suffer from unstable angina, or approximately
150,000 Americans.
[0003] Fatty acids are the primary source of energy for the heart
muscle under normal conditions of blood flow and oxygen delivery.
In ischemia, when blood flow is diminished under stress, the heart
lacks an adequate supply of oxygen to utilize fatty acids
efficiently. Instead, the heart shifts from fatty acid metabolism
to glucose. This change occurs immediately after heart muscle
ischemia. Hence, a radiolabeled fatty acid would be of value for
clinical evaluation of ischemic heart disease and
cardiomyopathies.
[0004] There have been numerous attempts to measure fatty acid
metabolism in the heart using radiolabeled fatty acids. Although
C-11 labeled fatty acids are a true tracer for fatty acids, the
complicated metabolic profile and consequent pharmacokinetic
modeling has kept it from being applied widely. Many fatty acids
have been radiolabeled, but those that are metabolically trapped
are superior to those that are metabolized. This may be analogous
to a situation with 2-fluoro-2-deoxyglucose (FDG), a glucose
analog, which is a more widely used than C-11 glucose because
metabolic trapping leads to easier analysis by virtue of the
simpler pharmacokinetic modeling. Other fatty acids have been used,
for example, BMIPP ((15-p-iodophenyl)-methylpentadecanoic acid).
BMIPP is an 123-iodine labeled fatty acid analog for imaging heart
disease using conventional nuclear medicine cameras. BMIPP may be
used to image ischemic areas of the heart soon after the ischemic
event and has the added value of being able to image the ischemic
muscle even several days after injury to the myocardium.
[0005] Radiolabeled fatty acids may be useful in evaluating the
efficacy of beta-blocker therapy in patients with dilated
cardiomyopathy (DCM) and ACE inhibitor therapy in congestive heart
failure patients. These radiolabeled fatty acids have been shown to
demonstrate clinical utility in the evaluation of cardiac disease,
including acute myocardial infarction (AMI), unstable angina (UA),
prediction of functional recovery of ischemic myocardium,
prediction of future cardiac events, and assessment of therapy in
patients with heart failure.
[0006] A metabolically blocked radiolabeled fatty acid may be a
superior tracer to catabolizable fatty acid and therefore a Tc-99m
labeled fatty acid may be of greater value than known labeled fatty
acids. Early attempts to label fatty acids with Tc-99m resulted in
radiopharmaceuticals that were not true fatty acid tracers. These
attempts by other investigators have, in general, been directed at
omega-labeled fatty acids. However, none of the omega labeled fatty
acids have been shown to trace fatty acid metabolism, while some
had either low heart-to-blood ratios and others exhibited low
uptake in the myocardium.
SUMMARY
[0007] The present disclosure provides novel radiopharmaceutical
agents for diagnostic imaging. The imaging agents of the disclosure
are radionuclide containing analogs of fatty acids and are
particularly suitable for cardiovascular imaging.
[0008] In one aspect, the imaging agent comprises a compound
represented by the formula:
##STR00001##
wherein:
[0009] R.sub.1, R.sub.4, R.sub.5, and R.sub.6 are each
independently selected from an alkyl, alkenyl or a bond;
[0010] R.sub.2 is selected from the group consisting of a hydrogen,
a primary amine, a secondary amine, a tertiary amine, an alkyl
group, a substituted alkyl group, an aryl group, and a substituted
aryl group;
[0011] R.sub.3 is selected from the group consisting of a hydrogen,
an alkyl, a substituted alkyl, a hydroxyl, a keto ester, an alkoxy,
a halide, and an amine;
[0012] R.sub.7 is selected from a metal chelating moiety bound to a
metallic carbonyl ligand; and the stereochemical configuration of a
compound represented by 1 may be R or S at the stereocenters; or a
mixture of these configurations, and the pharmaceutically
acceptable salts, esters, amides, and prodrugs thereof.
[0013] In an embodiment, a composition is provided that comprises
compound 1; wherein the compound is a R stereoisomer, and the
composition is of more than about 75% isomeric purity. In another
embodiment, a composition is provided that comprises compound 1;
wherein the compound is a S stereoisomer, and the composition is of
more than about 75% isomeric purity.
[0014] In an embodiment, R.sub.3 is a methyl group or CF.sub.3. In
another embodiment, R.sub.3 is bound to the C-3 position relative
to the carboxyl end of compound 1. In yet another embodiment,
R.sub.3 is bound to the C5, C7 or C9 position. In an embodiment,
the metallic carbonyl ligand is a radionuclide carbonyl
compound.
[0015] In another embodiment, R.sub.7 is selected from a metal
chelating moiety bound to a metallic carbonyl ligand wherein the
metallic carbonyl ligand comprises a low oxidation state metal. In
yet another embodiment, the metallic carbonyl ligand is a
.sup.99mTc-carbonyl compound or rhenium carbonyl compound. In yet
another embodiment, the metallic carbonyl ligand is a
.sup.99mTc-tricarbonyl compound or a rhenium tricarbonyl
compound.
[0016] In another aspect, the imaging agent comprises the compound
represented by the formula:
##STR00002##
wherein
[0017] R.sub.1, R.sub.4, R.sub.5, and R.sub.6 are each
independently selected from an alkyl, alkenyl or a bond;
[0018] R.sub.2 is selected from the group consisting of a hydrogen,
a primary amine, a secondary amine, a tertiary amine, an alkyl
group, a substituted alkyl group, an aryl group, and a substituted
aryl group;
[0019] R.sub.3 is selected from the group consisting of a hydrogen,
an alkyl, a hydroxyl, a keto ester, an alkoxy, a halide, and an
amine;
[0020] R.sub.7 is selected from;
##STR00003##
[0021] R.sub.8 is selected from the group 0, H, OH, alkoxy, or
O-alkyl;
[0022] R.sub.9 is any heterocycle;
[0023] R.sub.10 and R.sub.11 are each independently selected from
the group of hydrogen, alkyl or substituted alkyl;
[0024] R.sub.12 is selected from the group of aryl, alkyl, or
heterocycle; the stereochemical configuration of a compound
represented by 2 may be R or S, at the stereocenters; or a mixture
of these configurations, and the pharmaceutically acceptable salts,
esters, amides, and prodrugs thereof.
[0025] In an embodiment, R.sub.3 is selected from a methyl group or
a substituted methyl group. In another embodiment R.sub.3 is
CH.sub.3 or CF.sub.3. In another embodiment, R.sub.3 is bound to
the C-3 position relative to the carboxyl end of compound 2. In yet
another embodiment, R.sub.3 is bound to the C5, C7, or C9
position.
[0026] In another embodiment, R.sub.8 is O.
[0027] In another aspect, the disclosure provides an imaging agent
comprising the compound represented by:
##STR00004##
wherein
[0028] R.sub.3 is H or alkyl;
[0029] R.sub.7 is selected from
##STR00005##
[0030] R.sub.8 is selected from the group consisting of 0, H, OH,
alkoxy, or O-alkyl;
[0031] m is an integer between 0 and 12 inclusive;
[0032] n is an integer between 0 and 12 inclusive;
[0033] p is an integer between 0 and 12 inclusive; and
the stereochemical configuration of a compound represented by 3 may
be R or S, at the stereocenters; or a mixture of these
configurations, and the pharmaceutically acceptable salts, esters,
amides, and prodrugs thereof.
[0034] In one embodiment, R.sub.8 is O.
[0035] In another aspect, the imaging agent comprises a compound
represented by the formula:
##STR00006##
wherein:
[0036] R.sub.7 is selected from
##STR00007##
[0037] R.sub.8 is selected from the group 0, H, OH, alkoxy, or
O-alkyl;
[0038] m is an integer selected from 0 to 12;
[0039] p is an integer selected from 0, 1, 2, 4, 6 or 8; and
the stereochemical configuration of a compound represented by 4 may
be R or S, at the stereocenters; or a mixture of these
configurations, and the pharmaceutically acceptable salts, esters,
amides, and prodrugs thereof.
[0040] In one embodiment, m is an integer selected from 0, 1 or 2.
In another embodiment, R.sub.8 is O.
[0041] In another aspect the disclosure provides methods for using
imaging agents to identify a lesion. In an embodiment, the lesion
is in a cardiovascular system. In an exemplary embodiment, the
detection of the lesion may be used in diagnosing or effectively
treating myocardial infarction, unstable angina, heart failure, and
ischemic myocardium. In an embodiment, the compounds of the instant
disclosure have high specificity for the myocardium when
administered to a subject in vivo. The fatty acid complex disclosed
herein may show a heart to blood ratio of at least about 3 to 1 and
at least about 0.3% ID/g heart retention within about 60 min of
administration. The disclosure also provides for a method of
identifying a cardiovascular lesion comprising: administering an
imaging agent to a subject; wherein said imaging agent shows a
heart to blood ratio of at least about 3 to 1 and at least about
0.3% ID/g heart retention within about 60 minutes of
administration.
[0042] A further aspect of this disclosure contemplates kits
including subject compounds and a pharmaceutically acceptable
carrier, and optionally instructions for their use. Uses for such
kits include therapeutic management and medical imaging
applications.
[0043] These and further embodiments of the present disclosure, and
their features and characteristics will be apparent from the
following description, drawings, and claims.
BRIEF DESCRIPTION OF FIGURES
[0044] FIG. 1 depicts a compound of the present disclosure.
[0045] FIG. 2 depicts a synthetic route to compounds of the present
disclosure.
[0046] FIG. 3 shows a comparison of heart/blood ratios for
compounds of the present disclosure.
[0047] FIG. 4 shows a mass spectrum for a compound of the present
disclosure.
DETAILED DESCRIPTION
1. Overview
[0048] In general, the present disclosure is based on the
identification of compounds that may be useful for medical imaging.
The compounds comprise a metal chelating agent bound to a
radionuclide carbonyl ligand, which is pendantly bound to a fatty
acid. The compounds may be particularly useful for monitoring
alterations in fatty acid metabolism or utilization.
2. Definitions
[0049] For convenience, before further description of the present
invention, certain terms employed in the specification, examples
and appended claims are collected here. These definitions should be
read in light of the remainder of the disclosure and understood as
by a person of skill in the art. Unless defined otherwise, all
technical and scientific terms used herein have the same meaning as
commonly understood by a person of ordinary skill in the art.
[0050] The articles "a" and "an" are used herein to refer to one or
to more than one (i.e., to at least one) of the grammatical object
of the article. By way of example, "an element" means one element
or more than one element.
[0051] The terms "comprise" and "comprising" are used in the
inclusive, open sense, meaning that additional elements may be
included.
[0052] The term "including" is used to mean "including but not
limited to". "Including" and "including but not limited to" are
used interchangeably.
[0053] The term "alkyl" refers to the radical of saturated
aliphatic groups, including straight-chain alkyl groups,
branched-chain alkyl groups, cycloalkyl (alicyclic) groups, alkyl
substituted cycloalkyl groups, and cycloalkyl substituted alkyl
groups. In an embodiment, a straight chain or branched chain alkyl
has 30 or fewer carbon atoms in its backbone (e.g.,
C.sub.1-C.sub.30 for straight chain, C.sub.3-C.sub.30 for branched
chain), and in one embodiment, 20 or fewer. Likewise, cycloalkyls
have from 3-10 carbon atoms in their ring structure, and in one
embodiment, have 5, 6 or 7 carbons in the ring structure.
[0054] Moreover, the term "alkyl" (or "lower alkyl") as used
throughout the specification, examples, and claims is intended to
include both "unsubstituted alkyls" and "substituted alkyls", the
latter of which refers to alkyl moieties having substituents
replacing a hydrogen on one or more carbons of the hydrocarbon
backbone. Such substituents can include, for example, a halogen, a
hydroxyl, a carbonyl (such as a carboxyl, an alkoxycarbonyl, a
formyl, or an acyl), a thiocarbonyl (such as a thioester, a
thioacetate, or a thioformate), an alkoxyl, a phosphoryl, a
phosphonate, a phosphinate, an amino, an amido, an amidine, an
imine, a cyano, a nitro, an azido, a sulfhydryl, an alkylthio, a
sulfate, a sulfonate, a sulfamoyl, a sulfonamido, a sulfonyl, a
heterocyclyl, an aralkyl, or an aromatic or heteroaromatic moiety.
It will be understood by those skilled in the art that the moieties
substituted on the hydrocarbon chain can themselves be substituted,
if appropriate. For instance, the substituents of a substituted
alkyl may include substituted and unsubstituted forms of amino,
azido, imino, amido, phosphoryl (including phosphonate and
phosphinate), sulfonyl (including sulfate, sulfonamido, sulfamoyl
and sulfonate), and silyl groups, as well as ethers, alkylthios,
carbonyls (including ketones, aldehydes, carboxylates, and esters),
--CF.sub.3, --CN and the like. Exemplary substituted alkyls are
described below. Cycloalkyls can be further substituted with
alkyls, alkenyls, alkoxys, alkylthios, aminoalkyls,
carbonyl-substituted alkyls, --CF.sub.3, --CN, and the like.
[0055] The term "aralkyl", as used herein, refers to an alkyl group
substituted with an aryl group (e.g., an aromatic or heteroaromatic
group).
[0056] The terms "alkenyl" and "alkynyl" refer to unsaturated
aliphatic groups analogous in length and possible substitution to
the alkyls described above, but that contain at least one double or
triple bond respectively.
[0057] Unless the number of carbons is otherwise specified, "lower
alkyl" as used herein means an alkyl group, as defined above, but
having from one to ten carbons, and in one embodiment, from one to
six carbon atoms in its backbone structure. Likewise, "lower
alkenyl" and "lower alkynyl" have similar chain lengths. In an
embodiment, alkyl groups are lower alkyls. In an embodiment, a
substituent designated herein as alkyl is a lower alkyl.
[0058] The term "aryl" as used herein includes 5-, 6- and
7-membered single-ring aromatic groups that may include from zero
to four heteroatoms, for example, benzene, pyrrole, furan,
thiophene, imidazole, oxazole, thiazole, triazole, pyrazole,
pyridine, pyrazine, pyridazine and pyrimidine, and the like. Those
aryl groups having heteroatoms in the ring structure may also be
referred to as "aryl heterocycles" or "heteroaromatics." The
aromatic ring can be substituted at one or more ring positions with
such substituents as described above, for example, halogen, azide,
alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl,
amino, nitro, sulfhydryl, imino, amido, phosphonate, phosphinate,
carbonyl, carboxyl, silyl, ether, alkylthio, sulfonyl, sulfonamido,
ketone, aldehyde, ester, heterocyclyl, aromatic or heteroaromatic
moieties, --CF.sub.3, --CN, or the like. The term "aryl" also
includes polycyclic ring systems having two or more cyclic rings in
which two or more carbons are common to two adjoining rings (the
rings are "fused rings") wherein at least one of the rings is
aromatic, e.g., the other cyclic rings can be cycloalkyls,
cycloalkenyls, cycloalkynyls, aryls and/or heterocyclyls.
[0059] The terms ortho, meta and para apply to 1,2-, 1,3- and
1,4-disubstituted benzenes, respectively. For example, the names
1,2-dimethylbenzene and ortho-dimethylbenzene are synonymous.
[0060] The term "heteroatom" as used herein means an atom of any
element other than carbon or hydrogen. Exemplary heteroatoms are
boron, nitrogen, oxygen, phosphorus, sulfur and selenium.
[0061] The terms "heterocyclyl" or "heterocyclic group" refer to 3-
to 10-membered ring structures, and in one embodiment, 3- to
7-membered rings, whose ring structures include one to four
heteroatoms. Heterocycles can also be polycycles. Heterocyclyl
groups include, for example, thiophene, thianthrene, furan, pyran,
isobenzofuran, chromene, xanthene, phenoxathiin, pyrrole,
imidazole, pyrazole, isothiazole, isoxazole, pyridine, pyrazine,
pyrimidine, pyridazine, indolizine, isoindole, indole, indazole,
purine, quinolizine, isoquinoline, quinoline, phthalazine,
naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine,
carbazole, carboline, phenanthridine, acridine, pyrimidine,
phenanthroline, phenazine, phenarsazine, phenothiazine, furazan,
phenoxazine, pyrrolidine, oxolane, thiolane, oxazole, piperidine,
piperazine, morpholine, lactones, lactams such as azetidinones and
pyrrolidinones, sultams, sultones, and the like. The heterocyclic
ring can be substituted at one or more positions with such
substituents as described above, as for example, halogen, alkyl,
aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, amino, nitro,
sulfhydryl, imino, amido, phosphonate, phosphinate, carbonyl,
carboxyl, silyl, ether, alkylthio, sulfonyl, ketone, aldehyde,
ester, a heterocyclyl, an aromatic or heteroaromatic moiety,
--CF.sub.3, --CN, or the like.
[0062] The terms "polycyclyl" or "polycyclic group" refer to two or
more rings (e.g., cycloalkyls, cycloalkenyls, cycloalkynyls, aryls
and/or heterocyclyls) in which two or more carbons are common to
two adjoining rings, e.g., the rings are "fused rings". Rings that
are joined through non-adjacent atoms are termed "bridged" rings.
Each of the rings of the polycycle can be substituted with such
substituents as described above, as for example, halogen, alkyl,
aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, amino, nitro,
sulfhydryl, imino, amido, phosphonate, phosphinate, carbonyl,
carboxyl, silyl, ether, alkylthio, sulfonyl, ketone, aldehyde,
ester, a heterocyclyl, an aromatic or heteroaromatic moiety,
--CF.sub.3, --CN, or the like.
[0063] The term "carbocycle", as used herein, refers to an aromatic
or non-aromatic ring in which each atom of the ring is carbon.
[0064] As used herein, the term "nitro" means --NO.sub.2; the term
"halogen" designates --F, --Cl, --Br or --I; the term "sulfhydryl"
means --SH; the term "hydroxyl" means --OH; and the term "sulfonyl"
means --SO.sub.2--.
[0065] The terms "amine" and "amino" are art-recognized and refer
to both unsubstituted and substituted amines, e.g., a moiety that
can be represented by the general formula:
##STR00008##
wherein R.sub.9, R.sub.10 and R'.sub.10 each independently
represent a group permitted by the rules of valence.
[0066] The term "acylamino" is art-recognized and refers to a
moiety that can be represented by the general formula:
##STR00009##
wherein R.sub.9 is as defined above, and R'.sub.11 represents a
hydrogen, an alkyl, an alkenyl or --(CH.sub.2).sub.m--R.sub.8,
where m and R.sub.8 are as defined above.
[0067] The term "amido" is art recognized as an amino-substituted
carbonyl and includes a moiety that can be represented by the
general formula:
##STR00010##
wherein R.sub.9, R.sub.10 are as defined above. In an exemplary
embodiment an amide will not include imides which may be
unstable.
[0068] The term "carbonyl" is art recognized and includes such
moieties as can be represented by the general formula:
##STR00011##
wherein X is a bond or represents an oxygen or a sulfur, and
R.sub.11 represents a hydrogen, an alkyl, an alkenyl,
--(CH.sub.2).sub.m--R.sub.8 or a pharmaceutically acceptable salt,
R'.sub.11 represents a hydrogen, an alkyl, an alkenyl or
--(CH.sub.2).sub.m--R.sub.8, where m and R.sub.8 are as defined
above. Where X is an oxygen and R.sub.11 or R'.sub.11 is not
hydrogen, the formula represents an "ester". Where X is an oxygen,
and R.sub.11 is as defined above, the moiety is referred to herein
as a carboxyl group, and particularly when R.sub.11 is a hydrogen,
the formula represents a "carboxylic acid". Where X is an oxygen,
and R'.sub.11 is hydrogen, the formula represents a "formate". In
general, where the oxygen atom of the above formula is replaced by
sulfur, the formula represents a "thiolcarbonyl" group. Where X is
a sulfur and R.sub.11 or R'.sub.11 is not hydrogen, the formula
represents a "thiolester." Where X is a sulfur and R.sub.11 is
hydrogen, the formula represents a "thiolcarboxylic acid." Where X
is a sulfur and R.sub.11' is hydrogen, the formula represents a
"thiolformate." On the other hand, where X is a bond, and R.sub.11
is not hydrogen, the above formula represents a "ketone" group.
Where X is a bond, and R.sub.11 is hydrogen, the above formula
represents an "aldehyde" group.
[0069] The terms "alkoxyl" or "alkoxy" as used herein refers to an
alkyl group, as defined above, having an oxygen radical attached
thereto. Representative alkoxyl groups include methoxy, ethoxy,
propyloxy, tert-butoxy and the like. An "ether" is two hydrocarbons
covalently linked by an oxygen. Accordingly, the substituent of an
alkyl that renders that alkyl an ether is or resembles an alkoxyl,
such as can be represented by one of --O-alkyl, --O-alkenyl,
--O-alkynyl, --O--(CH.sub.2).sub.m--R.sub.8, where m and R.sub.8
are described above.
[0070] The terms triflyl, tosyl, mesyl, and nonaflyl are
art-recognized and refer to trifluoromethanesulfonyl,
p-toluenesulfonyl, methanesulfonyl, and nonafluorobutanesulfonyl
groups, respectively. The terms triflate, tosylate, mesylate, and
nonaflate are art-recognized and refer to trifluoromethanesulfonate
ester, p-toluenesulfonate ester, methanesulfonate ester, and
nonafluorobutanesulfonate ester functional groups and molecules
that contain said groups, respectively.
[0071] The abbreviations Me, Et, Ph, Tf, Nf, Ts, Ms represent
methyl, ethyl, phenyl, trifluoromethanesulfonyl,
nonafluorobutanesulfonyl, p-toluenesulfonyl and methanesulfonyl,
respectively. A more comprehensive list of the abbreviations
utilized by organic chemists of ordinary skill in the art appears
in the first issue of each volume of the Journal of Organic
Chemistry; this list is typically presented in a table entitled
Standard List of Abbreviations. The abbreviations contained in said
list, and all abbreviations utilized by organic chemists of
ordinary skill in the art are hereby incorporated by reference.
[0072] Analogous substitutions can be made to alkenyl and alkynyl
groups to produce, for example, aminoalkenyls, aminoalkynyls,
amidoalkenyls, amidoalkynyls, iminoalkenyls, iminoalkynyls,
thioalkenyls, thioalkynyls, carbonyl-substituted alkenyls or
alkynyls.
[0073] As used herein, the definition of each expression, e.g.
alkyl, m, n, etc., when it occurs more than once in any structure,
is intended to be independent of its definition elsewhere in the
same structure.
[0074] It will be understood that "substitution" or "substituted
with" includes the implicit proviso that such substitution is in
accordance with permitted valence of the substituted atom and the
substituent, and that the substitution results in a stable
compound, e.g., which does not spontaneously undergo transformation
such as by rearrangement, cyclization, elimination, etc.
[0075] As used herein, the term "substituted" is contemplated to
include all permissible substituents of organic compounds. In a
broad aspect, the permissible substituents include acyclic and
cyclic, branched and unbranched, carbocyclic and heterocyclic,
aromatic and nonaromatic substituents of organic compounds.
Illustrative substituents include, for example, those described
herein above. The permissible substituents can be one or more and
the same or different for appropriate organic compounds. For
purposes of this disclosure, the heteroatoms such as nitrogen may
have hydrogen substituents and/or any permissible substituents of
organic compounds described herein which satisfy the valences of
the heteroatoms. This disclosure is not intended to be limited in
any manner by the permissible substituents of organic
compounds.
[0076] The term "electron-withdrawing group" is recognized in the
art, and denotes the tendency of a substituent to attract valence
electrons from neighboring atoms, i.e., the substituent is
electronegative with respect to neighboring atoms. A quantification
of the level of electron-withdrawing capability is given by the
Hammett sigma (.sigma.) constant. This well known constant is
described in many references, for instance, J. March, Advanced
Organic Chemistry, McGraw Hill Book Company, New York, (1977
edition) pp. 251-259. The Hammett constant values are generally
negative for electron donating groups (.sigma.[P]=-0.66 for
NH.sub.2) and positive for electron withdrawing groups
(.sigma.[P]=0.78 for a nitro group), .sigma.[P] indicating para
substitution. Exemplary electron-withdrawing groups include nitro,
acyl, formyl, sulfonyl, trifluoromethyl, cyano, chloride, and the
like. Exemplary electron-donating groups include amino, methoxy,
and the like.
[0077] The phrase "protecting group" as used herein means temporary
substituents which protect a potentially reactive functional group
from undesired chemical transformations. Examples of such
protecting groups include esters of carboxylic acids, silyl ethers
of alcohols, and acetals and ketals of aldehydes and ketones,
respectively. The field of protecting group chemistry has been
reviewed (Greene, T. W.; Wuts, P. G. M. Protective Groups in
Organic Synthesis, 2.sup.nd ed.; Wiley: New York, 1991).
[0078] Certain compounds of the present disclosure may exist in
particular geometric or stereoisomeric forms. The present
disclosure contemplates all such compounds, including cis- and
trans-isomers, R- and S-enantiomers, diastereomers, (D)-isomers,
(L)-isomers, the racemic mixtures thereof, and other mixtures
thereof, as falling within the scope of the disclosure. Additional
asymmetric carbon atoms may be present in a substituent such as an
alkyl group. All such isomers, as well as mixtures thereof, are
intended to be included in this disclosure.
[0079] If, for instance, a particular enantiomer of a compound of
the present disclosure is desired, it may be prepared by asymmetric
synthesis, or by derivation with a chiral auxiliary, where the
resulting diastereomeric mixture is separated and the auxiliary
group cleaved to provide the pure desired enantiomers.
Alternatively, where the molecule contains a basic functional
group, such as amino, or an acidic functional group, such as
carboxyl, diastereomeric salts are formed with an appropriate
optically-active acid or base, followed by resolution of the
diastereomers thus formed by fractional crystallization or
chromatographic means well known in the art, and subsequent
recovery of the pure enantiomers.
[0080] Contemplated equivalents of the compounds described above
include compounds which otherwise correspond thereto, and which
have the same general properties thereof (e.g., functioning as
precursors), wherein one or more simple variations of substituents
are made which do not adversely affect the efficacy of the compound
to function as precursors of radiolabelled compounds. In general,
the compounds of the present disclosure may be prepared by the
methods illustrated in the general reaction schemes as, for
example, described below, or by modifications thereof, using
readily available starting materials, reagents and conventional
synthesis procedures. In these reactions, it is also possible to
make use of variants which are in themselves known, but are not
mentioned here.
[0081] For purposes of this disclosure, the chemical elements are
identified in accordance with the Periodic Table of the Elements,
CAS version, Handbook of Chemistry and Physics, 67th Ed., 1986-87,
inside cover. Also for purposes of this disclosure, the term
"hydrocarbon" is contemplated to include all permissible compounds
having at least one hydrogen and one carbon atom. In a broad
aspect, the permissible hydrocarbons include acyclic and cyclic,
branched and unbranched, carbocyclic and heterocyclic, aromatic and
nonaromatic organic compounds which can be substituted or
unsubstituted.
[0082] The phrase "pharmaceutically acceptable" is art-recognized.
In certain embodiments, the term includes compositions, polymers
and other materials and/or dosage forms which are, within the scope
of sound medical judgment, suitable for use in contact with the
tissues of human beings and animals without excessive toxicity,
irritation, allergic response, or other problem or complication,
commensurate with a reasonable benefit/risk ratio.
[0083] The phrase "pharmaceutically acceptable carrier" is
art-recognized, and includes, for example, pharmaceutically
acceptable materials, compositions or vehicles, such as a liquid or
solid filler, diluent, solvent or encapsulating material, involved
in carrying or transporting any subject composition, from one
organ, or portion of the body, to another organ, or portion of the
body. Each carrier must be "acceptable" in the sense of being
compatible with the other ingredients of a subject composition and
not injurious to the patient. In certain embodiments, a
pharmaceutically acceptable carrier is non-pyrogenic. Some examples
of materials which may serve as pharmaceutically acceptable
carriers include: (1) sugars, such as lactose, glucose and sucrose;
(2) starches, such as corn starch and potato starch; (3) cellulose,
and its derivatives, such as sodium carboxymethyl cellulose, ethyl
cellulose and cellulose acetate; (4) powdered tragacanth; (5) malt;
(6) gelatin; (7) talc; (8) cocoa butter and suppository waxes; (9)
oils, such as peanut oil, cottonseed oil, sunflower oil, sesame
oil, olive oil, corn oil and soybean oil; (10) glycols, such as
propylene glycol; (11) polyols, such as glycerin, sorbitol,
mannitol and polyethylene glycol; (12) esters, such as ethyl oleate
and ethyl laurate; (13) agar; (14) buffering agents, such as
magnesium hydroxide and aluminum hydroxide; (15) alginic acid; (16)
pyrogen-free water; (17) isotonic saline; (18) Ringer's solution;
(19) ethyl alcohol; (20) phosphate buffer solutions; and (21) other
non-toxic compatible substances employed in pharmaceutical
formulations.
[0084] The term "pharmaceutically acceptable salts" is
art-recognized, and includes relatively non-toxic, inorganic and
organic acid addition salts of compositions, including without
limitation, analgesic agents, therapeutic agents, other materials
and the like. Examples of pharmaceutically acceptable salts include
those derived from mineral acids, such as hydrochloric acid and
sulfuric acid, and those derived from organic acids, such as
ethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid,
and the like. Examples of suitable inorganic bases for the
formation of salts include the hydroxides, carbonates, and
bicarbonates of ammonia, sodium, lithium, potassium, calcium,
magnesium, aluminum, zinc and the like. Salts may also be formed
with suitable organic bases, including those that are non-toxic and
strong enough to form such salts. For purposes of illustration, the
class of such organic bases may include mono-, di-, and
trialkylamines, such as methylamine, dimethylamine, and
triethylamine; mono-, di- or trihydroxyalkylamines such as mono-,
di-, and triethanolamine; amino acids, such as arginine and lysine;
guanidine; N-methylglucosamine; N-methylglucamine; L-glutamine;
N-methylpiperazine; morpholine; ethylenediamine;
N-benzylphenethylamine; (trihydroxymethyl)aminoethane; and the
like. See, for example, J. Pharm. Sci., 66:1-19 (1977).
[0085] The term "prophylactic or therapeutic" treatment is
art-recognized and includes administration to the host of one or
more of the subject compositions. If it is administered prior to
clinical manifestation of the unwanted condition (e.g., disease or
other unwanted state of the host animal) then the treatment is
prophylactic, i.e., it protects the host against developing the
unwanted condition, whereas if it is administered after
manifestation of the unwanted condition, the treatment is
therapeutic (i.e., it is intended to diminish, ameliorate, or
stabilize the existing unwanted condition or side effects
thereof).
[0086] A "radionuclide" refers to molecule that is capable of
generating a detectable image that can be detected either by the
naked eye or using an appropriate instrument, e.g. positron
emission tomography (PET), and single photon emission tomography
(SPECT). Radionuclides useful within the present disclosure include
penetrating photon emitters including gamma emitters and X-ray
emitters. These rays accompany nuclear transformation such as
electron capture, beta emission and isomeric transition.
Radionuclides useful include those with photons between 80 and 400
keV and positron producers, 511 keV annihilation photons and
acceptable radiation doses due to absorbed photons, particles and
half life. Radionuclides include radioactive isotopes of an
element. Examples of radionuclides include .sup.123I, .sup.125I,
.sup.99mTc, .sup.18F, .sup.68Ga, .sup.62Cu, .sup.111In, .sup.131I,
.sup.186Re, .sup.188Re, .sup.90Y, .sup.212Bi, .sup.211At,
.sup.89Sr, .sup.166Ho, .sup.153Sm, .sup.67Cu, .sup.64Cu,
.sup.100Pd, .sup.212Pb, .sup.109Pd, .sup.67Ga, .sup.94Tc,
.sup.105Rh, .sup.95Ru, .sup.177Lu, .sup.170Lu .sup.11C, and
.sup.76Br.
[0087] A "subject" shall mean a human or animal e.g. a non-human
mammal (e.g. rat, mouse, cat, dog, horse, sheep, cow, monkey),
avian, or amphibian.
3. Compounds
[0088] In one aspect, the imaging agent comprises a compound
represented by the formula:
##STR00012##
wherein
[0089] R.sub.1, R.sub.4, R.sub.5, and R.sub.6 are each
independently selected from an alkyl, alkenyl or a bond;
[0090] R.sub.2 is selected from the group consisting of a hydrogen,
a primary amine, a secondary amine, a tertiary amine, an alkyl
group, a substituted alkyl group, an aryl group, and a substituted
aryl group;
[0091] R.sub.3 is selected from the group consisting of a hydrogen,
an alkyl, a substituted alkyl, a hydroxyl, a keto ester, an alkoxy,
a halide, and an amine;
[0092] R.sub.7 is selected from a metal chelating moiety bound to a
metallic carbonyl ligand; wherein a stereochemical configuration of
a compound represented by 1 may be R or S at the stereocenters; or
a mixture of these configurations, and the pharmaceutically
acceptable salts, esters, amides, and prodrugs thereof.
[0093] In an embodiment, a composition is provided that comprises
compound 1; wherein the compound is a R stereoisomer, and the
composition is of more than about 75%, more than about 80%, or even
more than about 90% isomeric purity. In another embodiment, a
composition is provided that comprises compound 1; wherein the
compound is a S stereoisomer, and the composition is of more than
about 75% more than about 80%, or even more than about 90% isomeric
purity. In an exemplary embodiment, the purity of composition
comprising a stereoisomer is such that the desired heart to blood
ratio, or heart intake, is obtained.
[0094] In an embodiment, R.sub.3 is a methyl group or CF.sub.3. In
another embodiment, R.sub.3 is bound to the C-3 position relative
to the carboxyl end of compound 1. In yet another embodiment,
R.sub.3 is bound to the C5, C7 or C9 position. In an embodiment,
the metallic carbonyl ligand is a radionuclide carbonyl
compound.
[0095] In an embodiment, the metallic carbonyl ligand is a
radionuclide carbonyl compound. In another embodiment, R.sub.7 is
selected from a metal chelating moiety bound to a metallic carbonyl
ligand wherein the metallic carbonyl ligand comprises a low
oxidation state metal. In a further embodiment, the radionuclide
carbonyl compound is a .sup.99mTc-carbonyl compound. In another
further embodiment, the radionuclide carbonyl compound is a
.sup.99mTc-tricarbonyl compound. In one embodiment, the metallic
carbonyl compound is rhenium-carbonyl compound.
[0096] Any suitable metal chelating moiety or structure may be used
to provide a covalent or other association with a radionuclide
carbonyl or Tc (1) or and Tc(V) ligand. Examples of metal chelating
agents include a substituted or unsubstituted N.sub.2S.sub.2
structure, a N.sub.4 structure, an isonitrile, a hydrazine, a
triaminothiol, a chelating agent with a hydrazinonicotinic acid
group, a phosphorus group, phosphinothiols, thioesters, thioethers,
a picolineamine monoacetic acid, a pyridine or bipyridyl based
compound, and a substituted or unsubstituted cyclopentadienyl Some
examples of low oxidization state metals include metals with an
oxidation state less than or equal to about 4, for example Tc(I),
Re(I), and Cu(0).
[0097] Metallic carbonyl ligands of the present disclosure include
radioisotopic gallium, indium and copper (e.g. .sup.68Ga,
.sup.67Ga, .sup.111In, .sup.62Cu, .sup.64Cu) in addition to
technetium (.sup.99mTc) and rhenium. The properties of the Group
VII metals technetium and rhenium are very similar due to their
periodic relationship. It is anticipated that the metals will
demonstrate similar reaction chemistry, which is often the case for
the thiol, nitrogen, and oxo-chemistry of these two metals.
Likewise, perrhenate and pertechnetate have very similar reaction
behaviors. The similar reductions of the M(VII) oxo species allow
for easy substitution of the nonradioactive rhenium as a model for
the medicinally useful technetium-99m, which routinely uses reduced
.sup.99mTcO.sub.4.
[0098] In another aspect, the imaging agent comprises the compound
represented by the formula:
##STR00013##
wherein
[0099] R.sub.1, R.sub.4, R.sub.5, and R.sub.6 are each
independently selected from an alkyl, alkenyl or a bond;
[0100] R.sub.2 is selected from the group consisting of a hydrogen,
a primary amine, a secondary amine, a tertiary amine, an alkyl
group, a substituted alkyl group, an aryl group, and a substituted
aryl group;
[0101] R.sub.3 is selected from the group consisting of a hydrogen,
an alkyl, a hydroxyl, a keto ester, an alkoxy, a halide, and an
amine;
[0102] R.sub.7 is selected from:
##STR00014##
[0103] R.sub.8 is selected from the group O, H, OH, alkoxy, or
O-alkyl;
[0104] R.sub.9 is any heterocycle;
[0105] R.sub.10 and R.sub.11 are each independently hydrogen, alkyl
or substituted alkyl;
[0106] R.sub.12 is selected from the group of aryl, alkyl, or
heterocycle; the stereochemical configuration of a compound
represented by 2 may be R or S, at the stereocenters; or a mixture
of these configurations, and the pharmaceutically acceptable salts,
esters, amides, and prodrugs thereof.
[0107] In one embodiment, the compound 2 is a R stereoisomer of
more than about 75% isomeric purity. In another embodiment, the
compound 2 is a S stereoisomer of more than about 75% isomeric
purity.
[0108] In an embodiment, R.sub.3 is selected from a methyl group or
a substituted methyl group. In another embodiment R.sub.3 is
CH.sub.3 or CF.sub.3. In another embodiment, R.sub.3 is bound to
the C-3 position relative to the carboxyl end of compound 2. In yet
another embodiment, R.sub.3 is bound to the C5, C7, or C9
position.
[0109] In another embodiment, R.sub.8 is O.
[0110] In another aspect, the disclosure provides an imaging agent
comprising the compound represented by:
##STR00015##
wherein
[0111] R.sub.3 is H or alkyl;
[0112] R.sub.7 is selected from
##STR00016##
[0113] R.sub.8 is selected from the group O, H, OH, alkoxy, or
O-alkyl;
[0114] m is an integer between 0 and 12 inclusive;
[0115] n is an integer between 0 and 12 inclusive;
[0116] p is an integer between 0 and 12 inclusive; and
the stereochemical configuration of a compound represented by 3 may
be R or S, at the stereocenters; or a mixture of these
configurations, and the pharmaceutically acceptable salts, esters,
amides, and prodrugs thereof.
[0117] In an embodiment, a composition is provided that comprises
compound 3; wherein the compound is a R stereoisomer, and the
composition is of more than about 75%, more than about 80%, or even
more than about 90% isomeric purity. In another embodiment, a
composition is provided that comprises compound 3; wherein the
compound is a S stereoisomer, and the composition is of more than
about 75% more than about 80%, or even more than about 90% isomeric
purity. In an exemplary embodiment, the purity of composition
comprising a stereoisomer is such that the desired heart to blood
ratio, or heart intake, is obtained.
[0118] In one embodiment, R.sub.8 is O.
[0119] In another aspect, the imaging agent comprises a compound
represented by the formula:
##STR00017##
wherein
[0120] R.sub.7 is selected from
##STR00018##
[0121] R.sub.8 is selected from the group 0, H, OH, alkoxy, or
O-alkyl;
[0122] m is an integer selected from 0 to 12;
[0123] p is an integer selected from 0, 1, 2, 4, 6 or 8; and
the stereochemical configuration of a compound represented by 4 may
be R or S, at the stereocenters; or a mixture of these
configurations, and the pharmaceutically acceptable salts, esters,
amides, and prodrugs thereof.
[0124] In one embodiment, m is an integer selected from 0, 1 or 2.
In another embodiment, R.sub.8 is O.
[0125] In an embodiment, the compound 4 is a R stereoisomer of more
than about 75% isomeric purity. In another embodiment, the compound
4 is a S stereoisomer of more than about 75% isomeric purity.
[0126] In one embodiment, the compounds of the present disclosure
have high specificity for the myocardium when administered to a
subject in vivo. In one embodiment, the fatty acid complex may show
a heart-to-blood ratio of at least about 3 to 1, at least about 6
to 1. In one embodiment, the fatty acid complex may show a heart
retention rate of at least 0.5% ID/g within about 60 min of
administration.
[0127] Compounds of the present disclosure that contain a
beta-methyl group may have a higher retention of radioactivity and
may prevent in vivo beta-oxidation from occurring on the molecule
and thus prolong myocardial retention of the Tc-fatty acid. In one
embodiment, the chain length of fragment A will remain
constant.
[0128] The chain length of the fatty acid may have a dramatic
effect on heart uptake. Addition of a Tc-chelator moiety and a
carbon linker to the fatty acid also may have an effect on the
overall lipophilicity of the molecule; however, it is not clear how
this change influences the transport of the fatty acid into
myocardial cells. In one embodiment, the relationship between chain
length and chelating group may be optimized by varying the length
of the fatty acid backbone from C-16 to C-20. This structural
variation, shown by fragment B, may be accomplished synthetically
by using alkyl bromides of different carbon lengths.
[0129] Attaching the Tc-metal core via a carbon linker to the fatty
acid may minimize transport interference into myocardial cells. In
fragment C, (FIG. 1) the carbon spacer may be lengthened from m=2,
to m=4 and 6 to determine if moving the metal cluster further away
from the fatty acid backbone may improve heart accumulation.
[0130] In one embodiment, the type of metal core on the fatty acid
influences the heart-to-blood ratio. Since attachment of the
chelator to the fatty acid is performed synthetically in the last
remaining steps, other chelate moieties may be used. These
chelators, represented by fragment D, will include the PAMA
(picolineamine monoacetic acid), MAMA(N.sub.2S.sub.2) ligands, and
cyclopentadienyl ligands. For example, representative compounds may
be:
##STR00019##
[0131] The Tc-cyclopentadienyl system (Cp) may be prepared by
methods known in the art. The overall size of this Tc-complex is
smaller than the Tc-PAMA, and importantly, Tc-Cp does not contain
nitrogen atoms, which may influence lung accumulation.
[0132] Synthesis of fragment A containing the beta-methyl group may
be done using a modified approach. This route involves preparing
2-methyloctanoic acid 8-trityl ether and then converting the
alpha-methyl carboxylic acid to 3-methylnonanoic acid 9-trityl
ether via hydrolysis of a nitrile intermediate.
[0133] Attachment of alkyl chain B to the beta-methyl fragment A
may comprise use of a Grignard addition, prepared from the
appropriate alkyl bromide, to the aldehyde of A. Oxidation of the
resultant alcohol furnishes the ketone, which can now undergo
nucleophilic addition of a lithium acetylide to give the tertiary
alcohol. Dehydration of the product using methane sulfonyl chloride
and base affords the enyne. Removal of the trityl group using
p-toluene sulfonic acid in methanol gives the alcohol, which is
then oxidized by Jones' Reagent to the carboxylic acid.
Hydrogenation of the corresponding methyl ester and bromination of
the resultant alcohol provides the bromo methyl ester. The chelate
moiety is now attached to the bromo-pendant fatty acid ester. The
two stereogenic centers created in the molecule will produce a
mixture consisting of two diasteromers which may be separated by
HPLC.
[0134] The .sup.99mTc-labeled fatty acids may be synthesized using
a standard .sup.99mTcO.sub.4-- reduction with tin dichloride, as
well as, employing the convenient
[.sup.99mTc(CO).sub.3(H.sub.2O.sub.3)]+ precursor.
[0135] The .sup.99mTc (I) precursor may be prepared from
.sup.99mTcO.sub.4-- in saline and CO at normal pressure.
[0136] Pharmacokinetic characterization was accomplished by
radiometric analysis of heart, blood, lung, kidney, liver and other
tissue at various times following administration of the 99
mTc-labeled fatty acid analogs to rats. A comparison of heart
uptake and pharmacokinetic characteristics of the 99 mTc-fatty
acids with those of [1-123]-(15-p-iodophenyl)-methylpentadecanoic
acid (I-BMPPA) was performed in Sprague Dawley rats (male, 90-130
grams). Six new compounds were evaluated at up to four time points
each (5, 15, 60, and 120 minutes) with a minimum of three animals
per time point. Non-anesthetized animals were injected with 20-50
.mu.Ci in 100 .mu.l via the tail vein and sacrificed at increasing
time points post injection. The organs were excised and counted in
a gamma counter. Experiments were also conducted to compare the
effects of injection media using 10% ethanol, 10% bovine serum
albumin and 7% ursodeoxycholic acid on distribution.
[0137] The nature of the injection media was found to have a
significant effect on the heart uptake of BMIPP with ethanol
showing almost 75% less in the heart than observed with
ursodeoxycholic acid. Consequently, compounds were studied with
various media to screen out effects of the solublizing agent. The
99 mTc-labeled C18P.MAMA appears to have the greatest heart
accumulation (Table 1); however, this value is distorted by the
high blood retention. The iodinated agent BMIPP has high extraction
into the heart but slow blood clearance with gradual washout from
the heart, liver and kidneys. The 99 mTc-labeled C18P.PAMA shows a
maximal heart accumulation of about 0.36% per organ at 30 minutes
decreasing to 0.13% at 60 minutes. By contrast the clinical agent
123I-BMIPP gives an uptake in the heart of 3.49 and 1.62 percent
per organ at 15 and 60 minutes, respectively, in the rat. The
myocardial clearance rate is greater for C18P.PAMA, which does not
have a beta-methyl group to inhibit metabolism. The more rapid
clearance of these two compounds compared to humans could be due to
higher metabolic rates or increased beta-oxidation in the rat.
TABLE-US-00001 TABLE 1 Percent injected dose per gram of Tc-99m
agents in the rat at 15-min post injection. BMIPP P.PAMA P.MAMA
I.PAMA T.PAMA T.MAMA Blood 1.30 .+-. 0.19 0.09 .+-. 0.02 1.56 .+-.
0.17 0.07 .+-. 0.01 0.32 .+-. 0.13 0.20 .+-. 0.04 Heart 4.60 .+-.
0.63 0.34 .+-. 0.06 0.66 .+-. 0.11 0.03 .+-. 0.01 0.31 .+-. 0.0
0.13 .+-. 0.02 Lung 1.83 .+-. 0.22 0.34 .+-. 0.08 0.97 .+-. 0.14
0.05 .+-. 0.01 0.26 .+-. 0.06 0.15 .+-. 0.08 Liver 2.97 .+-. 0.56
3.91 .+-. 0.61 1.17 .+-. 0.13 0.39 .+-. 0.07 6.80 .+-. 3.38 1.38
.+-. 0.20 Kidneys 4.09 .+-. 0.82 0.37 .+-. 0.04 3.76 .+-. 0.44 0.63
.+-. 0.06 2.71 .+-. 1.38 2.28 .+-. 0.29
[0138] Even with its greater accumulation in the heart, the
heart-to-blood ratio for BMIPP, an indicator of image resolution,
is only 2.2 and 1.6 at 15 and 60 minutes compared with 4.8 and 5.1
for C18P.PAMA. FIG. 3 shows a comparison of heart/blood ratios for
some Tc compounds. The liver activity goes from 19.7 to 7.2 percent
per organ in 45 minutes for BMIPP and from 32.3 to 5.1 for the
C18P.PAMA during the same period indicating better target to
background ratios for the surrounding organ.
[0139] The type and position of the technetium metal core on the
fatty acid may have an effect on heart accumulation and blood
clearance. Attaching the Tc-metal core via a carbon linker to the
fatty acid apparently may minimize interference with transport into
myocardial cell. The heart retention of C18P.PAMA and C18P.MAMA
gradually decreased with time, slower than blood clearance, which
can mean they are undergoing beta-oxidation as a normal fatty
acid.
[0140] Knock-out mice may be used to analyze the radiolabeled fatty
acids. To date, investigators have depended on heart- to -blood
ratios and uptake in the heart as markers of fatty acid behavior.
The transmembrane protein CD36 has been identified in isolated cell
studies as a putative transporter of long chain fatty acids. Key
enzymes such as long chain acyl-CoA synthetase and diacylglycerol
acyltransferase were similar in heart tissue from wild type and CD
36 knock out mice. This transporter membrane may also represent an
important control site for fatty acid metabolism in vitro by
regulating fatty acid esterification at the level of diacylglycerol
acyltransferase by determining fatty acyl-CoA supply.
4. Dosage and Administration
[0141] The imaging agents of the disclosure may be used in
accordance with the methods of the disclosure by those of skill in
the art, e.g., by specialists in nuclear medicine, to image
cardiovascular tissue in a mammal or to detect cardiovascular
lesions in a mammal. Some cardiovascular lesions are evident when a
dark spot appears within the image, for example, within a labeled
heart, indicating the presence of necrotic tissue. Alternatively, a
carcinomic lesion might be detectable as a brighter spot within the
image, indicating a region of enhanced metabolism at the site of a
tumor. A particularly useful imaging approach employs more than one
imaging agent to perform simultaneous studies. For example,
simultaneous studies of perfusion and metabolic function would
allow study of coupling and uncoupling of flow and metabolism, thus
facilitating determinations of tissue viability after a cardiac
injury. Such determinations may be useful in diagnosis of cardiac
ischemia, cardiomyopathy, tissue viability, hybrinating heart, and
other heart abnormalities.
[0142] The imaging agents of the disclosure may be used in the
following manner. An effective amount of the imaging agent (from 1
to 50 mCi) may be combined with a pharmaceutically acceptable
carrier for use in imaging studies. In accordance with the
disclosure, "an effective amount" of the imaging agent of the
disclosure is defined as an amount sufficient to yield an
acceptable image using equipment which is available for clinical
use. An effective amount of the imaging agent of the disclosure may
be administered in more than one injection. Effective amounts of
the imaging agent of the disclosure will vary according to factors
such as the degree of susceptibility of the individual, the age,
sex, and weight of the individual, idiosyncratic responses of the
individual and dosimetry. Effective amounts of the imaging agent of
the disclosure will also vary according to instrument and
film-related factors. Optimization of such factors is well within
the level of skill of a person skilled in the art.
[0143] As used herein, "pharmaceutically acceptable carrier"
includes any and all solvents, dispersion media, coatings,
antibacterial and antifungal agents, isotonic agents, absorption
delaying agents, and the like. The use of such media and agents for
pharmaceutically active substances is well known in the art. The
imaging agent of the disclosure may further be administered to an
individual in an appropriate diluent or adjuvant, co-administered
with enzyme inhibitors or in an appropriate carrier such as human
serum albumin or liposomes. Supplementary active compounds can also
be incorporated into the imaging agent of the disclosure.
Pharmaceutically acceptable diluents; include saline and aqueous
buffer solutions. Adjuvants contemplated herein include
resorcinols, non-ionic surfactants such as polyoxyethylene oleyl
ether and nhexadecyl polyethylene ether. Enzyme inhibitors include
pancreatic trypsin inhibitor, diethylpyrocarbonate, and trasylol.
Liposomes include water-in-oil-in-water CGP emulsions as well as
conventional liposomes (Strejan et al. (1984) J. Neuroimmunol. 7,
27).
[0144] In one embodiment, the imaging agent of the disclosure is
administered parenterally as injections (intravenous, intramuscular
or subcutaneous). The imaging agent may be formulated as a sterile,
pyrogen-free, parenterally acceptable aqueous solution. The
preparation of such parenterally acceptable solutions, having due
regard to pH, isotonicity, stability, and the like, is within the
skill in the art. Certain pharmaceutical compositions of this
disclosure suitable for parenteral administration comprise one or
more imaging agents in combination with one or more
pharmaceutically acceptable sterile powders which may be
reconstituted into sterile injectable solutions or dispersions just
prior to use, which may contain antioxidants, buffers,
bacteriostats, solutes which render the formulation isotonic with
the blood of the intended recipient or suspending or thickening
agents. A formulation for injection should contain, in addition to
the cardiovascular imaging agent, an isotonic vehicle such as
sodium chloride solution, Ringer's solution, dextrose solution,
dextrose and sodium chloride solution, lactated Ringer's solution,
dextran solution, sorbitol solution, a solution containing
polyvinyl alcohol, or an osmotically balanced solution comprising a
surfactant and a viscosity-enhancing agent, or other vehicle as
known in the art. The formulation used in the present disclosure
may also contain stabilizers, preservatives, buffers, antioxidants,
or other additives known to those of skill in the art.
[0145] The amount of imaging agent used for diagnostic purposes and
the duration of the imaging study will depend upon the nature and
severity of the condition being treated, on the nature of
therapeutic treatments which the patient has undergone, and on the
idiosyncratic responses of the patient. Ultimately, the attending
physician will decide the amount of imaging agent to administer to
each individual patient and the duration of the imaging study.
5. Kits
[0146] In another embodiment, the disclosure provides a kit for
imaging which comprises one or more of the imaging agents described
above, in combination with a pharmaceutically acceptable solution
containing a carrier such as human serum albumin or an auxiliary
molecule such as mannitol or gluconate. Human serum albumin for use
in the kit of the disclosure may be made in any way, for example,
through purification of the protein from human serum or through
recombinant expression of a vector containing a gene encoding human
serum albumin. Other substances may also be used as carriers in
accordance with this embodiment of the disclosure, for example,
detergents, dilute alcohols, carbohydrates, and the like. In one
embodiment, a kit according to the disclosure may contain from
about 1 to about 30 mCi of an imaging agent. In another embodiment,
a kit may contain the unlabeled fatty acid stereoisomer which has
been covalently or non-covalently combined with a chelating agent,
and an auxiliary molecule such as mannitol, gluconate, and the
like. The unlabeled fatty acid stereoisomer/chelating agent may be
provided in solution or in lyophilized form. The radionuclide, for
example, .sup.99mTc from a commercially available
.sup.99Mo/.sup.99mTc generator, is combined with the unlabeled
fatty acid stereoisomer/chelating agent for a time and at a
temperature sufficient to chelate the radionuclide to the fatty
acid stereoisomer/chelating agent, and the imaging agent thus
formed is injected into the patient. The kits of the disclosure may
also include other components which facilitate practice of the
methods of the disclosure. For example, buffers, syringes, film,
instructions, and the like may optionally be included as components
of the kits of the disclosure.
EXEMPLIFICATION
[0147] The disclosure now being generally described, it will be
more readily understood by reference to the following examples
which are included merely for purposes of illustration of certain
aspects and embodiments of the present disclosure and are not
intended to limit the disclosure.
Example 1
Synthesis of [.sup.99mTc(CO).sub.3.eta.3-(Fatty Acid PAMA or Cp)]
Derivatives
[0148] Carbon monoxide is flushed for 20 minutes into a sealed vial
containing 18 mg each of Na.sub.2CO.sub.3 and NaBH.sub.4. Added to
the pressurized vial is 1 ml of TcO.sub.4.sup.- and the solution is
heated at 100.degree. C. for 30 minutes. After cooling the
solution, formation of
[Tc(CO).sub.3(H.sub.2O).sub.3(H.sub.2O).sub.3].sup.+ is examined by
HPLC. The [Tc(CO).sub.3(H.sub.2O).sub.3].sup.+ elutes at 3 minutes
while unreacted TcO.sub.4.sup.- has a retention time of 8 minutes.
Utilizing the method described for the synthesis of [99
mTc(CO).sub.3(H.sub.2O).sub.3].sup.+, 2 mg of the appropriate fatty
acid derivative is added to the dry vial before introducing the
Na.sub.2CO.sub.3 and NaBH.sub.4. The mixture is incubated at
100.degree. C. for 30 minutes, whereupon it is filtered and
analyzed via HPLC for product yield and purity.
Example 2
Synthesis of [.sup.99mTcO-(Fatty Acid MAMA)] Derivatives
[0149] Preparation of the Tc-99m-labeled MAMA and DADT derivatized
fatty acid complexes is achieved by adding 500 ul of a
Tc-99m-glucoheptate kit (Dupont) to a solution of the appropriate
derivatized fatty acid (2 mg/100 ul methanol) and 100 ul of DMSO.
The mixture is incubated at 100.degree. C. for 30 minutes,
whereupon it is filtered through a Millipore Millex-GV 0.22 .mu.m
filter and analyzed via HPLC for product yield and purity. The
radioactive product(s) elutes at >18 minutes.
Example 3
Preparation of C18 Pendant PAMA
[0150] Methyl 9-(1-bromopropane)octadecanoate (0.6 g, 1.4 mmol),
N-(2-methyl acetate) 2-aminomethylpyridine (0.42 g, 2.1 mmol), and
potassium carbonate (0.05 g) were stirred in DMF (10 mL) at 110-120
C for 2 hrs. The mixture was diluted with methylene chloride (50
mL) washed with water (3.times.) and dried. Chromatography on
silica gel (95:5 hexane/ethyl acetate) afforded 0.3 g (43%) of the
diester.
Example 4
Preparation of [Re(CO).sub.3(Fatty Acid PAMA)]
[0151] In a 100 mL flask is placed
[NEt.sub.4][ReBr.sub.3(CO.sub.3)] (0.053 g, 0.0680 mmol) in 10 mL
of distilled water. To the stirring solution is added the pendant
PAMA acid (0.040 g, 0.0816 mmol) in 1 mL of methanol. The solution
immediately changed its appearance from clear and colorless to
cloudy white upon addition. The reaction mixture is heated at
80.degree. C. for 4 hours then stirred at room temperature for 12
hours. After being evaporated to dryness the mixture is purified
using a silica column (10% methanol: 90% methylene chloride). The
resulting product was dissolved in methanol and analyzed by mass
spectroscopy, with a MW of 759.2. (FIG. 4)
Example 5
Preparation of [ReO(Fatty Acid MAMA)]
[0152] In a 100 mL flask is placed [ReOCl.sub.3(PPh.sub.3).sub.2]
(0.050 g, 0.0600 mmol) in 10 mL of methanol. To the stirring
solution is added the pendant MAMA acid (0.034 g, 0.0661 mmol) in 1
mL of methanol. The solution immediately changed its appearance
from cloudy green to brown upon addition of triethylamine (0.012 g,
0.120 mmol). The reaction mixture is refluxed for 4 hours then
vacuumed to dryness. The mixture is purified using a silica column
(20% acetone: 80% chloroform).
EQUIVALENTS
[0153] While specific embodiments of the subject invention have
been discussed, the above specification is illustrative and not
restrictive. Many variations of the invention will become apparent
to those skilled in the art upon review of this specification. The
full scope of the invention should be determined by reference to
the claims, along with their full scope of equivalents, and the
specification, along with such variations.
[0154] Unless otherwise indicated, all numbers expressing
quantities of ingredients, reaction conditions, parameters,
descriptive features and so forth used in the specification and
claims are to be understood as being modified in all instances by
the term "about." Accordingly, unless indicated to the contrary,
the numerical parameters set forth in this specification and
attached claims are approximations that may vary depending upon the
desired properties sought to be obtained by the present
invention.
[0155] All publications and patents mentioned herein, including
those items listed below, are hereby incorporated by reference in
their entirety as if each individual publication or patent was
specifically and individually indicated to be incorporated by
reference. In case of conflict, the present application, including
any definitions herein, will control.
[0156] Also incorporated by reference are the following:
PUBLICATIONS
[0157] Alberto, R. J. Label. Cpd. Rad. 2001, 44, 54-6; ibid. Lee, B
C. 535-7; Knapp et al J. Med. Chem. 1984, 27, 390-7; Schubiger J.
Am. Chem. Soc. 1998, 120, 7987-8;
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