Method of preparing a radiolabelled technetium complex and kit f

Details Method of preparing a radiolabelled technetium complex and kit f Method of preparing a radiolabelled technetium complex and kit f

1992-08-21

1993-12-07

Stoll, Robert L.

Drug, bio-affecting and body treating compositions

Radionuclide or intended radionuclide containing; adjuvant...

534 14, A61K 4902

Patent

active

052681637

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a method of preparing a radiolabelled technetium complex by bringing Tc-99m in the form of a pertechnetate solution in a complex-forming reaction with a compound of the general formula ##STR2## wherein R.sub.1 -R.sub.12 each independently represents a hydrogen atom, a C.sub.1 -C.sub.4 alkyl group, a carboxy group, or a carboxy(C.sub.1 -C.sub.4 >alkyl group; R.sub.9 +R.sub.10 and R.sub.11 +R.sub.12 each independently represent an oxo or imino function; carboxy(C.sub.1 -C.sub.4)alkyl group; NH--Z--CO--NH--.sub.m --COOH, wherein: alkylidene group, and R.sub.1 -R.sub.13 and B is or comprises a carboxy group; and or both R.sub.3 +R.sub.4 and R.sub.7 +R.sub.8 or both R.sub.5 +R.sub.6 and R.sub.7 +R.sub.8 represent oxo functions, if A is an amino group and B is a group of the formula NH--Z--CO--NH--.sub.m Z--COOH.
If Z is a substituted alkylene, cycloalkylene or alkylidene group, said group is substituted with one or more substituents selected from phenyl; phenyl substituted with.. one or more substituents selected from hydroxy, halogen and substituted phenoxy; hydroxy; mercapto; thio; methylthio; carboxy; imino; amino; amido; imidazolyl; and indolyl.
Such a complex-forming reaction as defined above, starting, however, from a compound of formula I wherein optionally mercapto groups are protected, is described in European patent application publ. no. 173424. According to this patent publication, Tc-99m mercaptoacetyltriglycine is prepared by heating a mixture of benzoyl mercaptoacetyltriglycine, an exchange ligand, a SN(II) salt as a reducing agent and a Tc-99m pertechnetate solution in a boiling water bath for five minutes. According to European patent application, publ. no. 250013, related compounds like Tc-99m mercaptoacetylglycylserylglycine are prepared in a corresponding manner, viz. by heating the S-benzoyl mercapto compound together with a SN(II) salt, Tc-99m pertechnetate and a buffer solution (pH 5.0) in a boiling water bath for 10 minutes. According to this latter European patent publication such technetium-99m complexes can also be prepared starting from the corresponding ethyl ester, viz. by heating said ester in a boiling water bath in the presence of sodium dithionite as a reducing agent in the presence of a base, apparently to saponify the ester to the correspondingg acid. As a matter of fact, however, SN(II) salts are preferred to dithionite as reducing agent in the labelling reaction with Tc-99m pertechnetate, because dithionite is not sufficiently stable under the normal storage conditions and therefore less attractive for pharmaceutical purposes.
In various respects the reaction conditions for the preparation of the radiolabelled technetium complex, as described in the above patent publications, are unsatisfactory. Usually the labelling reaction is carried out by the user himself, applying Tc-99m pertechnetate from .3 molybdenum-technetium generator that is at his disposal. It stands to reason that such operations to be carried out with radioactive material under aseptic conditions, which operations should often be performed in a clinic or clinical laboratory, should be as simple as possible to avoid any risks as to contamination of the pharmaceutical composition to be prepared and as to accidental radioactive contamination of the environment. Use of a boiling water bath for performing the above reaction is therefore a disadvantage. It would be highly favorable to be able to perform said complexforming reaction at room temperature. Such favorable reaction conditions, however, should not be to the detriment of the reaction time. Preferably the labelling reaction should result in the desired product in a high yield only after 5 to 10 minutes at room temperature. Another disadvantage is the application of a so-called transfer agent, also defined as transfer ligand or exchange ligand, which is generally used to perform the desired complex-forming reaction. Although the labelling yield may sometimes be improved by using such a transfer agent, said agent will contaminate t

REFERENCES:
patent: 4571430 (1986-02-01), Byrne et al.
patent: 4849511 (1989-07-01), Verbruggen
patent: 4925650 (1990-05-01), Nosco et al.

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