Note: Descriptions are shown in the official language in which they were submitted.
WO92/11232 2 ~ 9 ~ 71 ~ PCT/EP9~2~68
.
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-- 1 ~ i
CHELATING AGENTS
The present invention relates to chelat.in~ agents,
more particularly aminopolycarboxylic acid chelants, and
metal chelates thereof and the use of such chelating
agents and chelates in diagnostic imaging, radiotherapy
or heavy metal detoxification, and in particular as
hepatobiliary contrast agents.
Medical uses of chelating agents are well
established, for example as stabilizers for
pharmaceutical preparations, as antidotes for poisonous
heavy metal species and as agents for the
administration, in chelate form, of metal ions for
radiotherapy or diagnostic ima~ing, e.g. X-ray, magnetic
resonance imaging (MRI), ultrasound or scintigraphy.
Aminopolycarboxylic acids and derivatives thereof
(hereinafter referred to as APCAs) are well known as
particularly effective chelants and are described in a
wide range of publications, for example in US-A-2407645
(Bersworth), EP-A-71564 (Schering), EP-A-130934
(Schering), EP-A-165728 (Nycomed), US-A-4647447
(Schering), US-A-4826673 (Mallinckrodt), US-A-4639365
(Sherry), EP-A-26305s (Schering), EP-A-230893 (Bracco),
EP-A-325762 (Bracco), WO-A-86/06605 (Lauffer), US-A-
4746507 (Salutar), EP-A-290047 (Salutar), WO-A-90/01024
(Mallinckrodt), US-A-4687659 (Salutar) and EP-A-299795
(Nycomed) and in the documents cited in these patent
publications.
Thus, for example, EP-A-71564 describes
paramagnetic metal chelates, for which the chelating
agent is nitrilotriacetic acid (NTA),
N,N,N',N'-ethylenediaminetetraacetic acid (EDTA),
N-hydroxyethyl-N,N',N'-ethylenediaminetriacetic acid
(HEDTA), N,N,N',N",N"-diethylenetriaminepentaacetic acid
(DTPA) and N-hydroxyethylimino-diacetic acid, as being
suitable as contrast agents for MRI, contrast being
.. .. : . , ~, . ........... . . ........... :~
:
WO~/11232 ~ ~ 9 ~ 7 12 PCT/E~Y~/0~46~
achieved by the effect of the magnetic field of the
paramagnetic species (e.g. Gd(III)) with the chelatin~
agents serving to reduce the to~icity and to assist
administration of the paramagnetic species.
Amongst the particular metal chelates disclosed by
EP-A-71564 was -the dimeglumine salt of GdDTPA, the use
of which as an MRI contrast agent has recently received
much attention.
To improve stability, water solubility and
selectivity, relative to the APCA chelating agents
described in EP-A-71564, Schering in EP-A-130934
proposed the partial substitution for the N-attached
carboxyalkyl groups of alkyl, alkoxyalkyl,
alkoxycarbonylalkyl or alkylaminocarbonylalkyl groups,
where any amide nitrogens may themselves carry
polyhydroxy-alkyl ~roups.
For reduced toxicity, Salutar Inc, in for example
US-A-4687659, has proposed the use as MRI contrast
agents of chelates of paramagnetic metal ions and
bisamides of DTPA, in particular DTPA-bismethylamide
~n the same patent, Salutar suggested that for imaging
of the liver chelates of DTPA-bisthigher alkyl-amides)
might be used.
In this field of hepatobiliary MRI contrast agents
Nycomed, in EP-A-165728, have also proposed the use of
paramagnetic chelates of certain anilide group-
containing iminodiacetic acids and Lauffer in WO-A-
86/0660S has suggested the use of paramagnetic chelates
of various benzene ring containing chelants, e.g.
ethylene-bis-(2-hydroxyphenyl glycine) (EHPG), bist2-
hydroxybenzyl)-ethylenediamine diacetic acid (HBED),
benzo- and dibenzo-DTPA and triaza and tetraaza
macrocycles which carry a fused benzene ring.
Still further APCA chelants for use in preparing
MRI contrast agents have been proposed by Bracco in EP-
A-230893 and EP-A-325762. These for the most par-t carry
aryl or aralkyl substituents on the alkylene part of one
- . ::, - ,. . :, , : .. '
:, ,.: . , . .: . - . . ,
WO92/11232 PCr/~ 6~
2 0 9 ~ ~J 1 ?
-- 3
or more of the nitrogen-attached carboxyalkyl complex-
forming moieties. Among the chelates covered is
GdBOPTA, in which the chelant BOPTA has a DTPA structure
with one N3 carboxymethyl replaced by a 2-benzyloxy-l-
carboxy-ethyl group. GdBOPTA has been described by
Vittadini et al in CMR '89, MRl9 as a liver~-specific ~RI
contrast agent.
Schering in EP-A-263059 have proposed a further
range of DTPA and EDTA amide chelants for use in
preparing MRI contrast agents. While commenting on the
high lipophilicity of the DTPA-bisamides proposed by
Salutar in WO-A-86/02841 (equivalent to US-A-4687659
discussed above), Schering have exemplified such
compounds as GdDTPA-bispentylamide, GdDTPA-bisbutylamide
and GdDTPA-phenylamide as well as chelates of further
DTPA-alkylamides in which the alkyl moieties are
substituted by hydrophilic groupings such as hydroxyl
and alkoxy groups.
There is however a general and continuing need Eor
APCA chelants which form metal chelates of reduced
toxicity, improved stability, improved water solubility
or improved biodistribution (e.g. enhanced tissue or
organ specificity).
We now propose certain improved chela~ing agents,
in particular amide derivatives of APCAs.
Viewed from one aspect therefore the invention
provides chelants of formula I
HOOC CH2 ~ . ~ CH2COOH
NCH2CH2 [ NCH2CH2 ] nN ~ ( I )
R10CCH2 ~ CH2COR
CH2COOH
(wherein n is 0 or l;
one group R1 is a group NR11R14 where R11 is a hydroxyl or
alkoxy group or a group -L-Cy or -O-L-Cy, and R14 is a
hydrogen atom, an alkyl group or a group -L-Cy, and the
: . . ,. :: , :,. . , . :-
W092/11232 PCT/E~ 2~
2~S7~2
-- 4
other group R1 is a hydroxyl group or a group NR1lR14; L
is a bond or a straight-chain or branched saturated or
unsaturated alkylene group optionally interrupted by a
carbocyclic or heterocyclic saturated or unsa~urated
group and optionally attached to the Cy group by a
peptid~ or carbonyl link and optionally substituted ~y
further Cy groups or by aminocarbonyl, acyl or acylamino
groups; and Cy is a cyclic lipophilic group, eg a
carbocyclic or heterocyclic saturated or unsaturated
group itself optionally carrying one or more fused
carbocyclic or heterocyclic saturated or unsaturated
rings and optionally substituted by halogen atoms (eg
iodine, chlorine or bromine), alkyl, al~ylamino,
dialkylamino, carbamoyl, N-alkylcarbamoyl, acetamido, N-
alkylacetamido and carbocyclic or heterocyclic saturated
or unsaturated groups; with the provisos that in any
NR11R14 group one of R11 and R14 group comprises a L-Cy
group and that where n is 1 at least one R1 is other than
phenylamine, benzylamine or methoxybenzylamine) and
metal chelates and salts thereof.
Unless speci~ied otherwise, all alkyl or alkylene
moieties in the compounds of the invention preferably
contain up to ~0, particularly preferably up to 6,
carbon atoms. The lipophilic Cy groups and the other
cyclic rings in the compounds of formula I are
particularly preferably mono or polycyclic groups
containing 5 to 7 ring members in each ring, the rings
if heterocyclic containing up to 3, preferably 1 or 2,
non-adjacent ring heteroatoms selected from 0, N and S.
Preferred such rir.gs include benzene, pyridine,
pyrimidine, pyrazine, 1,3-oxazine, 1,4-oxazine, 1,3-
thiazine, 1,4-thiazine, pyrrole, imidazole, 1,3-oxazole,
1,3-thiazole, furan, thiophene, piperidine, piperazine,
morpholine, perhydro-1,4-thiazine and pyrrolidine.
Thus particular examples of lipophilic Cy groups
include groups of formula Ia to Ie
,
.: : . . :
; : ; :, . , ,., : :
.:. :: . .: :,
:. , .: : , ~ :.
WO 92/11232 2 3 9 8 ~12 P~lER~ 2A68
~;
- 5 -
R ~ R s ~:
R 3 ~ R 6 ~) y \~X "
R R7 ( I b) ( I c) , :
( la)
/N
R 9 ( I d )
and other condensed a'cyclic rings
(where R3 to R8 is each independently a bond or a
hydrogen or halogen atom or an alkyl, alkylamino, .
dialkylamino, carbamoyl, N-alkylcarbamoyl, acetamido or
N-alkylacetamido group or two adjacent groups from R3 to
R8 together form a C25 alkylene or azaalkylene bridge,
the point of attachment to L being a carbon of said
bridge or one of said groups R3 to R8; X is nitrogen or
CH and Y is CH or nitrogen; X' is CH2, NH, oxygen,
sulphur or a bond; X" is nitrogen, oxygen or sulphur and
Y" is CH or nitrogen; and R9 is a bond or hydrogen, alkyl
or aralkyl, eg benzyl; such rings preferably not having
ring heteroatoms at adjacent ring positions).
The linker moiety L is conveniently a branched or
linear alkylene chain, eg such that LCy is of formula
--(CHRt)k--(CO)a--(NR1)b-(CO)C--R10
where k is 0-10, especially 1 to 8, more especially 1 to
... ... . .. . . . . ..
WO9~tll232 PCT/E~
2~987 l2 ~
-- 6 --
6; a, b and c are O or l, the sum of a and c being 0 or
l; each R10 is a hydrogen atom, an alkyl group, an
optionally esterified carboxyl group or a group Cy, at
least one and preferably only one being a group Cy, and
one or more CHR10 moieties may optionally be replaced by
a 5-7 membered saturated homo or heterocyclic ring.
The carboxyl groups in the compounds of formula I
may, for example, be in the form of carboxylate salt
groups, for example groups of formula -COOMt (where ~t
is a monovalent cation or a fraction of a polyvalent
cation, for example an ammonium or substituted ammonium
ion or a metal ion, for example an alkali metal or
alkaline earth metal ion). Particularly preferably, Mt
is a cation deriving from an organic base, for example
meglumine.
It is also particularly preferred that the number
of the ion-forming carboxyl groups in the compounds of
formula I be chosien to equal the valency of the me-tal
species to be chelated by the compound of formula I.
Thus, for example, where Gd(III) i5 to be chelated, the
chelating agent of formula I preferably contains three
ion-forming -COOH or -COOM~ groups. In this way, the
metal chelate will be formed as a neutral species, a
form preferred since the osmotic pressures in
concentrated solutions of such compounds are low and
since their toxicities relative to their ionic analogues
are significantly reduced.
Preferably the compounds of the invention contain
two -L-Cy groups and particularly preferred compounds
according to the invention include the chelants of
formula II
A
HooccH2NCH2CH2 [NC~2CH2) n NCH2CH (II)
R13NRlSCocH2 CH2COOH CH2coNR1sR13
(where n is 0 or l, R1s is hydrogen or methyl
., . : : : . :: :: , . . :: .:: :
WO~2/11232 2 0 9 ~ 7 1 2 PCTIEWI/0~68
-- 7
and R13 is a group selected from benzyl, 2-phenyl-ethyl,
1-phenyl-ethyl, pyrid-4-yl, pyrid-3-yl, pyrid-2-yl, 3-
morpholino-propyl, N-benzyl-piperidin-4-yl and inda~yl
groups and iodinated such groups), and the metal
chelates and salts thereof.
The chelant compounds of the invention may be
prepared by amidation, eg analogously to EP-A-130934
(Schering~ and US-A-4687~59 (Salutar) of EDTA or DTPA or
an activated or protected derivative thereof (eg an acid
anhydride or bisanhydride) with an amine compound of
formula III
HNR11'R14' (III)
(where R11 and R14 are groups R11 and R14 as hereinbefore -
defined or protected such groups), followed where
necessary by deprotection.
As protecting groups, conventional protecting
groups may be used, for example groups such as are
described by T.W. Greene in "Protective Groups in
Organic Synthesis", John Wiley & Sons, 1981.
Alternatively the compounds may be prepared in two
or more stages, in the first reacting DTPA, EDTA or a
derivative thereof to introduce one or two NR11 R14
groups (~here one of R11 and R14' is a group R11 or R1b
and the other is a Cy-free analogues of R11 or R14) and
in a second stage to introduce the Cy groups, eg by a
peptide condensation reaction.
The amidation reactions are preferably performed in
the liquid phase. Thus for example a solution of the
amine in a solvent such as water, dipolar aprotic
solvents, such as acetonitrile, N-methylpyrrolidone, N-
methylmorpholine, dimethylformamide, dimethylacetamide,
dimeth~vl sulfoxide, tetrahydrofuran and the like or
mixtures thereof is prepared. The anhydride is added in
portions or optionally dissolved in a dipolar aprotic
anhydrous solvent such as acetonitrile, N-
,, , .: ~ : . ;~, , . ~ . :
. .: :: :: . : , ~.:. :
:
WO92/11232 2 ~ 9 37 ~ 2 PCT/EP~ $ ~
- 8 -
methylpyrrolidone, N-methylmorpholine,
dimethylformamide, dimethylacetamide, dimethyl
sulfoxide, tetrahydrofuran and the like or mi~tures
thereof. The reaction mixture is stirred under a
nitrogen atmosphere for a period ranging between 0.5
hour and 3 days, preferably between l hour and 24 hoursO
The reaction temperatures generally range between about
0C and 100C, temperatures of about 20C to 80OC being
preferred. For solvents with a low boiling point (l00C
or less) the reaction mixture can eventually be
evaporated to dryness. For the solvents with higher
boiling points, further solvents such as for example
diethylether may be added and/or cooling may be used to
precipitate the product.
Thus for example the bisamide chelants may be
prepared by amidation as follows:
a) the amine of formula III is dissolved in a dry
polar aprotic solvent, e.g. acetonitrile or chloroform,
in a ratio of about l:l0 w:v amine:solvent. The
bisanhydride of DTPA (or EDTA) (0.5 equivalents to the
amine~ is added as dry powder in portions, with thorough
stirring, and the reaction is allowed to proceed
overnight. In the case of less reactive amines such as
for example 2-aminopyridine, extensive refluxing may be
necessary. In most cases the product precipitates from
the reaction mixture and can be collected by filtration.
Otherwise the product can be precipitated by addition of
diethyl ether and/or by cooling.
In the case of the bis-amides with non-heterocyclic
side groups, the product may be puri~ied as follows: the
precipitate from à) is dissolved in deionized water, and
if necessary the pH is adjusted to 8-l0 using dilute
NaOH. The pH is then adjus~ed to 3-3.5 with dilute HCl,
and the precipitate is collected by filtration.
Chelants of formula I may be used as the basis for
bifunctional chelants or for polychelant compounds, that
~. : , ... . ... .
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WO92/11232 2 a ~ ~ 7 ~ /E~
'
_ 9 _ :
is compounds containing several independent chelant
groups, by substituting for a hydrogen atom or hydroxyl
group a bond or linkage to a macromolecule or polymer~
e.g. a tissue specific biomolecule or a backhone polymer
such as polylysine or polyethyleneimine which may carry
several chelant groups and may itself be attached to a
macromolecule to produce a bifunctional-polychelantO
Such macromelecular derivatives of the compounds of
formula I and the salts and metal chelates t~ereof fo:~m
a further aspect of the present invention. -
The linkage of a compound of formula I to a
macromolecule or backbone polymer may be effected by any
of the conventional methods such as the carbodiimide
method, the mixed anhydride procedure of Krejcarek et
al. (see Biochemical and Biophysical Research
Communications 77: 581 (1977)), the cyclic anhydride
method of Hnatowich et al. (see Science 220: 613 (1983)
and elsewhere), the backbone conjugation techniques oE
Meares et al. (see Anal. Biochem. 142: 68 (1984) and
elsewhere) and Schering (see EP-A-331616 for example)
and by the use of linker molecules as describéd for
example by Nycomed in W0-A-89/06979.
Formation of salts and chelates of the chelants of
the invention may again be performed in a conventional
manner.
The chelating agents of the present invention are
particularly suitable for use in detoxification or in
the formation of me~al chelates, chelates which may be
used for example in or as contrast agents for in vivo or
in vitro magnetic resonance (MX), X-ray or ultrasound
diagnostics (e.g~ MR imaging and MR spectroscopy), or
scintigraphy or in or as therapeutic agents for
radiotherapy, and such metal chelates form a
particularly important embodiment of the present
invention.
Salts or chelate comple~es of the compounds of the
invention containing heavy metal ions are particularly
: . . . : , .,
- . . : . . ., , ~ , :
WO92/11232 PCT/EP~ 2~
2 ~ ~ r~ g 2 1~ 1
)
-- 10 --
useful in diagnostic imaging or therapy. Especially
preferred are salts or complexes with metals of atomic
numbers 20-32, 42 44, 49 and 57 to 83, particularly Gd,
Dy and Yb.
For use as an MR-diagnostics contrast agent, the
chelated metal ion is particularly suitably a
paramagnetic ion, the metal conveniently bein~ a
transition metal or a lanthanide, preferably having an
atomic number of 21-29, 42, 44 or 57-71. Metal chelates
in which the metal species is Eu, Gd, Dy, Ho, Cr, Mn or
Fe are especially preferred and Gd3 , Mn2 and Dy3 are
particularly preferred. For such use, the paramagnetic
metal species is conveniently non-radioactive as
radioactivity is a characteristic which is neither
required nor desirable for MR-diagnostics contrast
agents. For use as X-ray or ultrasound contrast agenks,
the chelated metal species is preferably a heavy metal
species, for example a non-radioactive metal with an
atomic number greater than 37, preferably greater than
50, e.g. Dy3 . For use in scintigraphy and radiotherapy,
the chelated metal species must of course be radioactive
and any conventional complexable radioactive metal
isotope, such as 99mTc or lllIn for example, may be
used. For radiography, the chelating agent may be in
the form of a metal chelate with for example 67Cu, l53Sm
or 90Y
For use in detoxification of heavy metals, the
chelating agent must be in salt form with a
physiologically acceptable counterion, e.g. sodium,
calcium, ammonium, zinc or meglumine, e.g. as the sodium
salt of the chelate of the compound of formula I with
zinc or calcium.
Where the metal chelate carries an overall charge,
such as is the case with the prior art Gd DTPA, it will
conveniently be used in the form of a salt with a
physiologically acceptable counterion, for example an
a~monium, substituted ammonium, alkali metal or alkaline
. . ~
.: ~
W092/11232 2 ~ P~T1~ 2~ t
earth metal cation or an anion deriving from an
inorganic or organic acid. In this regard, meglumine
salts are particularly preferred.
Viewed from a further aspect, the present invention
provides a diagnostic or therapeutic agent comprising a
metal chelate, whereof the chelating entity is the
residue of a compound of formula I or salt thereof,
together with at least one pharmaceutical or veterinary
carrier or excipient, or adapted for formulation
therewith or for inclusion in a pharmaceutical
formulation for human or veterinary use~
Viewed from another aspect, the present invention
provides a detoxification agent comprising a chelatin~
agent according to the invention in the form of salt
with a physiologically acceptable counterion, together
with at least one pharmaceutical or veterinary carrier
or excipient, or adapted for formulation therewith or
for inclusion in a pharmaceutical formulation for human
or veterinary use.
The diagnostic and therapeutic agents of the
present invention may be formulated with conventional
pharmaceutical or veterinary formulation aids, for
example stabilizers, antioxidants, osmolality adjusting
agents, buffers, pH adjusting agents, etc. and may be in
a form suitable for parenteral or enteral
administration, for example injection or infusion or
administration directly into a body cavity having an
external escape duct, for example the gastrointestinal
tract, the ~ladder or the uterus. Thus the agent of the
present invention may be in a conventional
pharmaceutical administration form such as a tablet,
capsule, powder, solution, suspension, dispersion,
syrup, suppository, etc; however, solutions, suspensions
and dispersions in physiologically acceptable carrier
media, for example water for injections, will generally
be pre~erred.
The compounds according to the invention may
-
. . , , . ~ ~ . . ~ ..................... . .
. . . :, , . ~ .:
W092/ll~32 2 0 9 o 7 ~ ~ PC~ 102468
- 12 -
therefore be formulated for administration using
physiologically acceptable carriers or excipients in a
manner fully within the skill of the art. For example,
the compounds, optionally with the addition of
pharmaceutically acceptable excipients, may be suspended
or dissolved in an aqueous medium, with the resulting
solution or suspension then being sterilized. Suitable
additives include, for example, physiologically
biocompatible buffers (as for example, tromethamine
hydrochloride), additions ~e.g., O.Ol to lO mole
percent) of chelants (such as, for example, DTPA, a
DTPA-bisamide or non-complexed chelants of formula I) or
calcium chelate complexes (as for example calcium DTPA~
CaNaDTPA-bisamide, calcium salts or chelates of chelants
of formula I), or, optionally, additions (e.g., 1 to 50
mole percent) of calcium of sodium salts (for example,
calcium chloride, calcium ascorbate, calcium gluconate
or calcium lactate combined with metal chelate complexes
of chelants formula I and the like).
If the compounds are to be formulated in suspension
form, e.g., in water or physiological saline for oral
administration, a small amount of soluble chelate ma~ be
mixed with one or more of the inactive ingredients
traditionally present in oral solutions and/or
surfactants and/or aromatics for flavouring.
For MRI and for X-ray imaging of some portions of
the bod~ the most preferred mode for administering metal
chelates as contrast agents is parenteral, e.g.,
intravenous administration. Parenterally administrable
forms, e.g., intra~enous solutions, should be sterile
and free from physiologically unacceptable agents, and
should have low osmolality to minimize irritation of
other adverse effects upon administration, and thus the
contrast medium should preferably be isotonic or
slightly hypertonic. Suitable vehicles include aqueous
vehicles customarily used for administering parenteral
solutions such as Sodium Chloride Injection, Ringer's
: , .: . ., - .. . . .
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WO 92/11232 2 ~ ~ s; r~ 3 ~E~
~,) A ~ : .
-- 13 --
Injection, Dextrose Injection, Dextrose and Sodium
Chloride Injection, Lactated Ringer's Injection and
other solutions such as are described in Remingtonls
Pharmaceutical Sciences, 15th ed., Easton: Mack
Publishing Co., pp. 1405-1412 and 1461-1487 (1975) and
The National Formulary XIV, 14th ed. Washington:
American Pharmaceutical Association (1975). The
solutions can contain pre~ervatives, antimicrobial
agents, buffers and antioxidants conventionally used for
parenteral solutions, excipients and other additives
which are compatible with the chelates and which will
not interfere with the manufacture, storage or use of
products.
Where the diagnostic or therapeutic agent comprises
a chelate or salt of a toxic metal species, e.g. a
heavy metal ion, it may be desirable to include within
the formulation a slight excess of the chelating agent,
e.g. as discussed by Schering in DE-A-3640708, or more
preferably a slight excess of the calcium salt of such a
chelating agent.
For MR-diagnostic examination, the diagnostic agent
of the present invention, if in solution, suspension or
dispersion form, will generally contain the metal
chelate at concentration in the range 1 micromole to 1~5
mole per litre, preferably 0.1 to 700mM. The diagnostic
agent may however be supplied in a more concentrated
form for dilution prior to administration. The
diagnostic agent of the invention may conveniently be
administered in amounts of from 10 3 to 3 mmol of the
metal species per kilogram of body weight, e.g. about
mmol Gd/kg bodyweight.
For X-ray examination, the dose of the contrast
agent should generally be higher and for scintigraphic
examination the dose should generally be lower than for
MR examination. For radiotherapy and detoxification,
conventional dosages may be used.
Viewed from a further aspect, the present invention
, , : ::,: ~ . , ; .,
.: . , , . : . :,
:~. . . . . . . .
W092/11232 PCT/E~ 2~
2~9~71~ ~ ~
- 1~ -
provides a method of generating enhanced images of the
human or non-human animal body, especiall~ the liver,
which method comprises administering to said body a
diagnostic agent according to the present invention and
generating an X ray, MR-diagnostics, ultrasound or
scintigraphic image of at least a part thereof.
Viewed from a further aspect, the present invention
provides a method of radiotherapy practised on the human
or non-human animal body, which method comprises
administering to said body a chelate of a radioactive
metal species with a chelating agent according to the
invention.
Viewed from a further aspect, the present invention
provides a method of heavy metal detoxification
practised on the human or non-human animal body, which
method comprises administering to said body a chelating
agent according to the invention in the form of a salt
with a physiologically acceptable counterion.
Viewed from a yet further aspect, the present
invention also provides the use of the compounds,
especially the metal chelates, according to the
invention for the manufacture of diagnostic or
therapeutic agents for use in methods of image
generation, detoxification or radiotherapy practised on
the human or non-human animal body.
Viewed from a still further aspect, the present
invention provides a process for the preparation of the
metal chelates of the invention which process comprises
admixing in a solvent a compound of formula I or a salt
te~g. the sodium salt) or chelate thereof together with
an at least sparingly soluble compound of said metal,
for example a chloride, oxide or carbonate.
Viewed from a yet still further aspect, the present
invention provides a process for the preparation of the
diagnostic or therapeutic agent of the present
invention, which comprises admixing a metal chelate
according to the invention, or a physiologically
acceptable salt thereof, together with at least one
: . , :,; .;.;, , .
W092/11232 2 ~ ~ 71 2
- 15 - !
pharmaceutical or veterinary carrier or excipient.
Viewed from a yet still further aspect, the present
invention provides a process for the preparation of the
detoxification agent of the invention, which comprises
admixing a chelating agent according to the invention in
the form of a salt with a physiologically acceptable
counterion together with at least one pharmaceutical or
veterinary carrier or excipient.
The disclosures of all of the documents mentioned
herein are incorporated by reference.
The present invention will now be illustrated
further by the following non-limiting Examples. All
ratios and percentages given herein are by weight and
all temperatures are in degrees Celsius unless otherwise
indicated.
Example 1
3.6,9,12-Tetraaza-6,9-bis(carboxvmethyl)-4,11-dioxo-
2,13-diphenvltetradecane
EDTA-bis(anhydride) l.O g (3.9 mmol) was gradually added
to a stirred solution of l-phenylethylamine 0.9 g (708
mmol) in dried acetonitrile (40 ml) at ambient
temperature and under a nitrogen atmosphere. The
solution was heated to reflux temperature (85C) and
refluxed for 20 hours. The mixture was then cooled, and
the precipitate which had formed was isolated by
filtration and dried.
Yield 1.5g (77.1%),
The crude solid was dissolved in 20 ml water to which
was added lN NaOH to bring the pH to 10. After
adjusting the pH with HCl (2N) to 3.5, the precipitate r
formed was filtered off and dried, and the title
compound was isolated.
Yield 1.06g (54.6%)
Melting point: 187-l90~C.
WO~2/11232 2 ~ 9 ~ PC~ g~
- 16 -
Example 2
3,6,9.12,15-Pentaaza-6,9L12-tris(carboxymethYl~-4,14-
dioxo-1,17-diPhenylheptadecane
DTPA-bis(anhydride) l.0 g (2.8 mmol) was gradually added
to a stirred solution of 2-phenylethylamine 0.68 g (5O6
mmol) in dried chloroform (85 ml) at ambient
temperature. The stirred solution was left for 16 hours
at ambient temperature. The precipitate which formed
was isolated by filtration and dried. The crude product
was then purified by reprecipitation as described in
Example l.
Yield: 0.89 g (53 %)
Melting point: 95-98C.
Example 3
2,5,8 ! 11, 14-Pentaaza-5,8,11-tris(carboxymethvl)-3,13
dioxo-1,15-bis(~Yrid-2-yl)pentadecane
. . .
DTPA-bis(anhydride) l.0 g (2.8 mmol) was gradually added
to a stirred solution of 2-aminomethylpyridine 0.61 g
(5.6 mmol) in dried chloroform at ambient temperature.
The stirred solution was left for 42 hours at ambient
temperature. The precipitate formed was isolated by
filtration and dried~ `'
Yield: 74.5%
Melting point: 107-110C.
Example 4
1,4,7,10,13-Pentaaza-4,7,10-triscarboxymethYl-2,12-
dioxo-1,13_bis(N benzvl-piperidin-4-yl)tridecane
DTPA-bis(anhydride) 1.0 g (2.8 mmol) was gradually added
.,. . , . ., . . : , . . ~ .
-: ' , ,: ", ,' ', ', : ' `: ; ' ` : ' '
. ' ' .' .,'. . , : ' ,: ' , ' ` ''
W092/1123Z 2 ~ 9 8 ~
- 17 -
to a stirred solution of 4-amino-1-benzylpiperidine 1.07
g (5.6 mmol) in dried chloroform (85 ml) at a~bient
temperature. The solution was then heated to reflux
temperature. The solution was refluxed with stirring
overnight under a nitrogen atmosphere. The solution was
then evaporated until 25-30 ml remained. ,~ubseque~tly
ether (120ml) was added, and the precipitate was
filtered off and dried.
Yield: 93.2g
Example 5
1,4,7.10,13-Pentaaza-4,7,10-tris(carboxymethYl)-2,12-
dioxo-1,13-bis(indan-2-ylLtridecane
DTPA-bis(anhydride) 0.88 g (2.48 mmol) was gradually
added to a stirred solution of 2-aminoindane 0.66 g
(4.955 mmol) in dried acetonitrile (40 ml) at ambient
temperature. The solution was heated to reflux
temperature (85C) and refluxed under a nitrogen
atmosphere ~or 4 hours. The reaction mixture was
subsequently cooled, and the solution was decantedO T~e
crude solid thereby obtained was dissolved in water with
lN NaOH added to bring the pH to 13. After adjusting
the pH with HC1 (lN) to 3.5, the precipitate formed was
filtered off and dried.
Yield: 47.2%
Example 6
1,4,7 10-Tetraaza-4,7-bis(carboxymethyl)-2,9-dioxo 1,10-
bis~indan-2-yl~decane
EDTA-bis(anhydride) 0.38 g (1.46 mmol) was gradually
added to a stirred solution of 2-aminoindane 0.39 g
(2.93 mmol) in dried chloroform (30 ml) at ambient
: .. - . .; .. ...
.
.. ,~
~. , : ~::
: ' ,, .. , ,: . , ' ~ ::
2~9.~ 2
WO92/~1232 P~ 8
- 18 -
temperature. After 24 hours the precipitate formed was
isolated by filteration and dried. The crude product
was then purified by reprecipitation as described in
Example 1.
Yield: 0.43 g (56.4%)
Melting point: 199.5-202C
Exam~le 7
2.5,8,11-Tetraaza-5,8-bis(carboxymethYl)-3,10-dioxo-
1,12-diphenyldodecane
EDTA-bis(anhydride) 1.0 g (3.9 mmol) was gradually added
to a stirred solution of benzylamine 0.83 g (3.9 mmol)
in dried chloroform (85 ml) at ambient temperature. The
solution was heated to reflux temperature (70C) and
refluxed under a nitrogen atmosphere for 19 hours. The
reaction mixture was subsequently cooled, and the
precipitate formed was filtered off and dried.
Yield: 1.69 g (92.09%) -
Melting point: 139-141C
Example 8
1,4,7,10-Tetraaza-4,7-bis(carboxy~thvl)-2,9-dioxo-1,10
bis~Dvrid-2-yl)decane
lg (3,9 mmol) EDTA-bis(anhydride) was gradually under
stirring to acetonitrile (33 ml) heated to boiling. The
mixture was refluxed for 1/2 h and 0.73g (1.1 mmol) 2-
aminopyridine dissolved in 7 ml acetonitrile was
gradually added.
The reaGtion mlxture was refluxed under nitrogen
atmosphere for 40 hours, subsequently cooled to ambient
temperature and the precipitate formed was filtered off
.
. .,
WO9~/ll232 2 ~ ~ ~ 712 PCT/EP9~/024~8
- 19 -
and dried.
Yield: 92.8%
Melting point: 215-217 C.
Exam~le 9
1,4,7,10,13-Pentaaza-4,7,10-tris(carboxy~ethYl)-2,12
dioxo-1.13-bis(N-benzYlpiperidin-4-yl)tridecane
DTPA-bis(anhydride) 1.0 g ~2.8 mmol) was gradually added
to a stirred solution of 4-amino-1-benzylpiperidine
1.07 g (5.6 mmol) in dried chloroform (100 ml) at
ambient temperature. The stirred solution was left at
ambient temperature for 66 hours. Then about 50% of the
chloroform was evaporated off. Ether (50 ml) was then
added, and the precipitate formed was filtered off and
dried.
Yield: 92.8%
Example 10
..
1,4.7,10-Tetraaza-4,7-bis~carboxvmethYl)-2,9-dioxo-1,10-
bis(N-benzylpiperidin-4-yl)decane
DTPA-bis(anhydride) 1.0 g (3.9 mmol) was gradually added
to a stirred solution of 4-amino-1-benzylpiperidine
1.48 g (7.8 mmol? in dried chloroform (85 ml) at ambient
temperature. The stirred solution was left for 18 hours
at ambient temperature. The solution was evaporated
until 25-30 ml remained. Subsequently ether (2 x 100
ml) was added. The precipitate formed was isolated by
filtration and dried.
Yield: 91.9%
Melting point: 105-111C.
. .
. . ~
W092/11232 PCT/EP9~f~46~
2~8 ~ 1 2
- 20 -
Example 11
3,6,9,12-Tetraaza-6,9-bis(carboxymethyl)-4,11-dioxo-
1,14-diphenvltetradecane
EDTA~bis(anhydrïde) 1.0 g (3.9 mmol) was gradually added
to a stirred solution of 2-phenylethylamine 0.9 g (7.8
mmol) in dried acetonitrile (40 ml) at ambient
temperature under a nitrogen atmosphere. The solution
was heated to reflux temperature (85C) and refluxed for
17 hours. The reaction mixture was subsequently cooled,
and the precipitate formed was isolated by filtration
and dried.
Yield: 1.7 g (87.8%)
.....
ExamPle 12
.~
4.7,10.13,16-Pentaaza-7,10,13-tris(carboxymethYl)-5,15-
dioxo-l,19-bis(morpholino)nonadecane
DTPA-bis(anhydride) 1.0 g (2.8 mmol) was gradually added
to a stirred solution of N-(3-aminopropyl)morpholine
0.81 g (5.6 mmol) in dried chloroform (85 ml) at ambient
temperature. The solution was stirred for 27 hours and
then refluxed under a nitrogen atmosphere for 69 hours.
The solution was evaporated until 25-30 ml remained.
Subsequently ether (12Oml) was added, The precipitate
formed was isolated by filtration and dried.
Yield: 93.9%
ExamDle 13
2.5,8,11,14-Pentaaza-5,8,11-tris(carboxymethyl)-3,15-
dioxo-1,15-bis(pYrid-3-yl~pentadecane
DTPA-bis(anhydride) 1.0 g (2.8 mmol) was gradually added
. , , ................... . : ~
, .. ..
.
WO92/11232 2~9~712 ~f`~51/~'~,6~ 1
- 21 -
to a stirred solution of 3-aminomethylpyridine 0.61 g
(5.6 mmol) in dried acetonitrile (40 ml) at ambient
temperature. The solution was stirred for 84 hours~
The precipitate formed was isolated by filtration and
dried.
Yield: 87.6%
ExamPle 14
2,5,8,11-Tetraaza-5~8-bis(carboxymethyl)-3,10-dioxo~
1.12- bis(pyrid-3-yl~dodecane
EDTA-bis(anhydride) 1.0 g (3.9 mmol) was gradually added
to a stirred solution of 3-aminomethylpyridine 0.84 g
(7.8 mmol) in dried chloroform (85 ml) at ambient
temperature. The precipitate formed was isolated b~
filtration and dried.
Yield: 97.8% '
Melting point: 212-216C
Example 15
2,5.8,11-Tetraaza-5,8-bis(carboxymethyl)-3.10-dioxo-
1,12- bisrpyrid-2-yl)dodecane
EDTA-bis(anhydride) 1.0 g (3.9 mmol) was gradually added
to a stirred solution of 2-aminomethylpyridine 0.84 g
(7.8 mmol) in dried chloroform (120 ml) at ambient
temperature. The stirred solution was left for 16 hours
at ambient temperature. The solution was evaporated
until 25-30 ml remained. Subsequently ether (50 ml) was
added. The precipitate formed was isolated by
filteration and dried.
Yield: 98.4%
Melting point: 73-81C.
.
.... . ...
.~ , , . : . . :~ . .: . : : , , . :
:: , ' : .' ' .,, ,:. ,., . :.: .
WO92/11232 2 ~ 9 8 .~ ~ 2 PCT/EP9~ 4~ ~
- 22 -
Example 16
3,6 9 12-Tetraaza-2 13-bis(benzyloxycarbonyl)-6,9-
bis(carboxymethyl)-4~11-dioxo-1~14-diPhenyltetradecane
EDTA-bis(anhydride) (0.4 g, 1.56 mmol) was added in
portions to a solution of H-Phe-OBzl-HCl (0.91 g, 3.12
mmol) and triethylamine (0.32 g, 3.12 mmol) in
chloroform (50 ml). The reaction mixture was stirred at
ambient temperature for 20 hours before the white
precipitated product was collected by filtration and
dried under vacuum at 50C.
Yield: 0.83 g (69%),
Melting point: 174-178C
Elemental analysis:
calculated: C 65.78 H 6.05, N 7.30
found: C 65.53, H 6.15, N 7.14
1H NMR (DMSO): ~ 8.32 (d, J 8.06 Hz, 2H), 7.5-7.08 (m,
20H), 5.10 (s, 4H), 4.70-4.50 (m, 2H), 3.50-2.41 (m,
16H).
Example l?
3,6,9 r 12 15-Pentaaza-2 16-bis(benzyloxycarbonyl)-6,9.12-
tris(carboxymethyl)-4,14-dioxo-1 17-diPhenylhe~tadecane
DTPA-bis(anhydride) (0.56 g, 1.56 mmol) was added in
portions to a solution of H-Phe-OBzl-HCl (0.91 g, 3.12
mmol) and triethylamine (0.32 g, 3.12 mmol) in
chloroform (50 ml). The reaction mixture was refluxed
under N2 for 24 hours before the white precipitated
product was collected by filtration and dried under
vacuum at 50~C.
Yield: 1.1 g (81%),
Melting point: 120-126C
1H NMR (DMSO): ~ 8.45 (d, J 7.78 Hz, 2H), 7.50-7.05 (m,
20H), 5.10 (s, 4H), 4.70 4.50 (m, 2H), 3.70-2.60 (m,
. ' :, .' ' , ' .,'
-.
W092/11232 2~ 7~ PCT/~ 2~$
- 23 -
22H).
.
Example 18
3.6 9.12-Tetraaza-2.13_dicarboxY 6.9-bislcarbQxYmethy
4.11-dioxo-1,14-diPhenyltetradecane
LioH tO.34 g, 14.3 mmol) was added to a suspension of
EDTA-bis(benzylphenylalanyl)amide (1.1 g, 1.43 mmol) in
a mixture of methanol/water (3:1, 44 ml). After 2 hours
the TLC showed that the hydrolysis was completed.
Methanol was removed under reduced pressure and the
reaction mixture acidified to pH 3.5 with 2N HCl. The
product was collected by filtration and dried under '~
vacuum at 50C.
Yield: 0.89 g,
Melting point: 115-120C
H NMR (DMSO): ~ 8.22 (d, J 7.4 Hz, 2H), 7.50-7.08 (mr 1
OH), 4.61-4.35 (m, 2H), 3.40-2.40 (m, 16H).
Example 19
3.6 9,12 15-Pentaaza-2 16-dicarboxy-6 9.12-
tris(carboxymethvl)-4 14-dioxo-1 17-diphen~lheptadecane
LioH (0.30 g, 12.7 mmol) was added to a suspension of
DTPA-bis(benzylphenylalanyl)amide (1.1 g, 1.27 mmol) in
a mixture of methanol/water (3:1, 44 ml). After 2 hours
the TLC showed that the hydrolysis was completed. The
solvent was removed under reduced pressure and the
residue dried under vacuum at 50C to give l.Q4 g of
crude product.
1H NMR (DMSO): ~ 8.49 (d, J 1.6 Hz, 2H), 7.40-7.00 (m, 1
OH), 4.43-4.20 (m, 2H), 3.61-2.55 (m, 22H).
: ::~ :. . . , ,: . ,,
WO9-/llZ32 2 0 9 ~ 7 12 PC~/EP9~/~246~ l
24 -
ExamPle 20
3 ! 6,9,12-Tetraaza-6,9-bis(carboxYmethYl)-4,11-dioxo-
1,14-bis(pyrid-2-YlLtetradecane
A solution of 2-(2-aminoethyl)pyridine (0.95 g, 7O8
mmol) and EDTA-bis(anhydride) (1.0 g, 3.9 mmol) in 85 ml .
chloroform was stirred for 4 days at ambient
temperature. Most of the chloroform was evaporatedO
The rest (20-30 ml) was dissolved in 100 ml diethylether
to crystallize. The solid product was collected and
dried under reduced pressure to yield 88% product.
Melting point: 60-64OC
Elemental analysis:
Calculated: C 56.05 H 6.25
Found: C 55.88 H 6.25
lH NMR (200 MHz DMSO-d6) ~ ppm: 2.66 (s, 4H, t, 4H, J =
7.1 Hz), 3.20 (s, 4H), 3.33 (s, 4H), 3.4-4.6 (m, 4H),
7.1-7.3 (m, 4H), 7.6-7.8 (m, 2H), 8.10 (t, 2H, 5.7 Hz),
8.50 (d, 2H, J = 4.7 Hz).
Exam~le 21
3.6.9 12 15-Pentaaza-6 ~9 12-trisrcarboxYmethY1)-4.14-
dioxo-1 17-bis(PYrid-2-vl)heptadecane
2-(2-Aminoethyl)pyridine (0.68 g, 5.6 mmol) and DTPA-
bis(anhydride) (1.0 g, 2.8 mmol) were dissolved in 85 ml
chloroform. The mixture was stirred for 22 hours at
ambient temperature. The solid product was separated
from the solution by filtration before being dried in
vacuum to give 56% product.
Melting point: 110-118C
Elemental analysis:
Calculated: C 53.36 H 6.18
Found: C 57.58 H 6.46
1H NMR (200 MHz DMSO-d6) ~ ppm: 2.8-3.8 (m, 30H), 7.1-7.4
' ;' '. ~ ~: , " ' ;
'., . ;'' . ' ;' ', : '. ',
':
`
W092/1123Z PC~/EI~
2 ~ 2
- 25 -
(m, 4H), 7.6-7.8 (m, 2H), 8.1-8.3 (m, 2H), 8.49 (d, 2H,
4.8 Hz).
ExamPle 22
3,6 9~12-Tetraaza-2 13-dicarboxv-6,9-bis~carboxvmet~yl~ ¦
4.11-dioxo-1 14-bis(indol-3-vl~tetradecane
Triethylamine (On39 g, 3.9 mmol), tryptophanmethylester
(HCl) and EDTA-bis(anhydride~ (0.5 g, 1.95 mmol) were
dissolved in 70 ml chloroform. The suspension was
stirred for 21 hours at ambient temperature. The solid
product was collected by filtration and dried in vacuum
to give 83~ yield.
Melting point: 84-91C
Elemental analysis: ~ -
Calculated: C 53.30 H ~.46
Found: C 58.94 H 5.83
H NMR (200 MHz DMSO-d6) ~ ppm: 2.26 (3, 4H), 3.0-304 (m
14H), 3.60 (s, 6H), 4.5-4.7 (m, 2H), 6.95-7.15 (m, 4H)~
7.19 (d, 2H, J = 1.8 Hz), 7.37 (d, 2H, J = 7.5 Hz), 7052
(d, 2H, 7.7 Hz), 8.27 (d, 2H, J = 7.7 Hz).
Example 23
3 6 9~12-Pentaaza-2 16-dicarboxv-6 9~12-
tris(carboxYmeth~1)-4 14-dioxo-1 17-bis(indol-3-
yl)heptadecane
Triethylamine (0.57 g, 5.6 mmol), tryptophanmethylester
(HCl) (1.43 g, 5.6 mmol) and DTPA-bis(anhydride) (1.000
g, 2.8 mmol) were dissolved in 100 ml chloroform. The
mixture was refluxed in a nitrogen atmosphere for 3
days. Most of the chloroform was removed ~20-30 ml
left). 100 ml diethylether was added to the
concentrated solution. The crystalline product was
'; ` ; -
. , i , : !
WO92/11232 PCT/EP9FI/~2468
2~7 ~ 2,
- 26 -
collected by filtration, dissolved in basic aqueous
solution and recrystallized with 0.5 M HCl.
The identity of the product as the title compound was
verified by 1H and 13C NMR.
Example 24
3,6.9,12-Tetraaza-2,13-bis(methvloxYcarbonyll-6,9
bis(carboxymeth~l~4,11-dioxo-1,14-bis(indol-3-
Yl)tetradecane
Lithium hydroxide (14.4 mg, 0.61 mmol) was dissolved in
a 4.5 ml mixture of MeOH/H2O(3:1). 3,6,9,12-Tetraaza~
2,13,-bis(methyloxycarbonyl)-6,9-bis(carboxymethyl)-
4,11-dioxo-1,14-bis(indol-3-yl)tetradecane (60.0 mg, 8.7
x 102 mmol) was added and the solution was stirred for 8
hours. Methanol was removed, 2 ml water was added and
the pH was adjusted to 3.5 (0.5 M HCl). The solid
product was collected and dried in vacuo for 12 hoursO
The identity of the product as the title compound was
verified by lH NMR.
Exam~le 25
3.6,9,12,15-Pentaaza-2 16-bis(methYloxYcarbonYl)-6.9.12-
tris(carboxymethyl) 4,14-dioxo-1 17-bis(indol-3-
vl)heptadecane
Lithium hydroxide (0.32 g, 13.4 mmol) was dissolved in a
mixture of MeOH/H2O(3:l). 3,6,9,12,15-Pentaaza-2,16,-
bis(methyloxycarbonyl)-6,s,12-tris(carboxymethyl)-4,14-
dioxo-1,17-bis(indol-3-yl)heptadecane (1.33 g, 1.67
mmol~ was added and the solution was stirred for 6 hours
at ambient temperature. Methanol was evaporated and 10
ml water was added to the residual. The pH was adjusted
to 3.5 with 0.5 M HCl. The solid product was collected
, ', .: , . ; .: :-.: ~:.
WO92/11232 ~ 6~i 1
2 r
- 27 -
by filtration and dried to give 18% product.
Melting point: 158-160C
Elemental analysis:
Calculated: C 55.86 H 5.80
Found: C 56.45 H 5.67
1H NMR (200 MHz, DMSO-d6) ~ ppm: 2.5-3.6 (m, 22H), 4 4~
4.7 (m, 2H), 6.9-7.2 (m, 4H), 7.22 (s, 2H), 7.36 (d, 2H,
J = 7.5 Hz), 7.56 (d, 2H, J = 7.4 Hz), 8.27 (d, 2H, J =
8.1 Hz).
Example 26
General procedure for complexation w:ith Gadolinium (20
mM solution)
GdCl3 (1 mmol) in 4 ml water was dropwise added to a
solution of a chelant of formula I (where n is 1) (1
mmol) in 30 ml water, while the pH was kept at 5-6 by
adding 1 N NaOH. After addition the mixture was stirred
for 1/2 hour and diluted with water to 50 ml.
Exam~le 27
General ~rocedure for complexation with Man~anese (50 mM
solution)
MnCl2 (1.25 mmol) in 3 ml water was dropwise added to a
solution of a chelant of formula I (where n is 0) (1.25
mmol) in 15 ml water, while the pH was kept at 5-6 by
adding lN NaOH. After addition the mixture was stirred
for 1/2 hour and diluted with water to 25 ml.
:. , ~' ~' , :'
wO g2/1l232 2 0 9 ~ 7 ~ ~ PCT/EP91/02468
r .
- 28 -
Example 28
Relaxivitv of Gd and Mn chelates in water and AutonormR
measured at 37'C, 20 MHz on an IBM PC/20 Series NMR
Analyzer (Minispec).
I _ . .'
Water AutonormR
Chela~ing agent Metal l ,
(Example No.) _ rl (mM'' s'') r2 (mM'' s'') r1 (mM'~ s' ) ¦ :
1 Mn 3.3 2.8
2 Gd 3.4 5.8 _ 7.0 ¦ .
3 Gd 4.6 3.9 6.0
4 Gd 4.3 7.2 7.5
7 Mn 3.7 2.6
Mn 5.4 1.5
11 _ Mn 3.9 3.3
12 Gd 3.7 6.5 6.3 ~:
j 13 Gd 3.2 5.9 5.9
14 Mn 3.4 1 3.9
¦ 15 Mn 3.8 _ 3.0 _
l 19 Gd 8.0 2.1 7.1
¦ 20 _Mn 3.9 3.0 .
¦ 21 Gd 5.3 2.0 5.8 _
¦ 22 Mn 5.2 4.1
23 Gd 4 . 9 1 . 7 6 . 3 .
.. ~ ~ . . .... .. . ., .:
, ~ .
