Process for the preparation of nitride complexes of transition m

Details Process for the preparation of nitride complexes of transition m Process for the preparation of nitride complexes of transition m

1993-01-21

1995-03-21

Stoll, Robert L.

Drug, bio-affecting and body treating compositions

Radionuclide or intended radionuclide containing; adjuvant...

Attached to antibody or antibody fragment or immunoglobulin;...

534 10, 534 14, 556 45, 423249, 423409, 424165, C07F 1300, C01B 2106

Patent

active

053993390

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a process for the preparation of transition metal complexes, more particularly usable as radiopharmaceutical products or for the synthesis of novel radiopharmaceutical products.
More specifically, it relates to the preparation of nitride complexes of transition metals having a part M.tbd.N, in which M represents a transition metal.
It is pointed out that the term transition metal is understood to mean a metal, whose layer d is partly filled in the conventional degree of oxidation of said metal. These are metals of periods III to XII of the periodic table of elements with 18 columns. Examples of such metals are Tc, Ru, Co, Pt, Fe, Os, Ir, W, Re, Cr, Mo, Mn, Ni, Rh Pd, Nb and Ta.
The invention more particularly relates to the preparation of nitride complexes of radioactive transition metals usable as radiopharmaceutical products for diagnosis or therapy.
Among the complexes usable for diagnosis, particular reference is made to complexes of technetium 99 m. The complexes usable for therapy can e.g. be rhenium complexes.
Radiopharmaceutical products using the radionucleide .sup.99m Tc are compounds which are frequently used in nuclear medicine for diagnosis as a result of the physical and chemical characteristics of said radionuclide.
Thus, the latter only gives a gamma emission, has an optimum gamma energy for external detection (140 keV) and a short physical half-life (6.02 h), so that the patient is only given a low irradiation dose. Moreover, the cost of this radio-element is not very high and it is commercially available. Finally, the richness of technetium chemistry makes it possible to obtain a wide range of radiopharmaceutical products.
Thus, as stated by E. DEUTSCH et al in Progr. Inorg. Chem. (Australia), vol. 30, pp. 76-106, 1983, technetium can form very varied complexes with numerous ligands, at oxidation states ranging from VII to -I and coordination numbers between 4 and 9. Among the numerous complexes of said document, reference is made to complexes of .sup.99m Tc and .sup.99 Tc in oxidation state V having a part Tc.tbd.N.
Complexes of this type can be prepared by the process described by J. BALDAS et al in J. Chem. Soc. Dalton Trans., 1981, pp. 1798-1801; in Int. J. Appl. Radiat. Isot., 36, 1985, pp. 133-139 and in international patent application WO85/03063. This process firstly consists of preparing a compound of formula R.sup.+ [.sup.99m Tc.tbd.NX.sub.4 ], in which R.sup.+ is a cation such as sodium or ammonium and X represents a halogen atom such as Cl or Br and then reacting said compound with an appropriate ligand for obtaining the complex of .sup.99m Tc usable as a radiopharmaceutical product.
The complex R.sup.+ [.sup.99m Tc.tbd.NX.sub.4 ]- is of interest, because it is very stable to hydrolysis and can be used without modification of the component Tc.tbd.N for substitution reactions with other ligands, which makes it possible to obtain a considerable diversity of technetium complexes.
The process known at present for the preparation of the intermediate compound R.sup.+ [.sup.99m TCNX.sub.4 ]- consists of reacting a pertechnetate such as sodium pertechnetate with sodium nitride and a halogenated hydracid such as hydrochloric acid.
For carrying out this reaction, dry evaporation takes place of a sodium pertechnetate solution (.sup.99m Tc) using a rotary evaporator, followed by the addition to the dry residue of sodium nitride and concentrated hydrochloric acid. Refluxing takes place for approximately 5 min in order to complete the reduction and destroy the nitride excess, followed by further dry evaporation using a rotary evaporator. This gives a residue containing the compound R.sup.+ (.sup.99m Tc.tbd.NCl.sub.4)-.
It is difficult to apply this process to the manufacture of kits for medical use, because it takes a long time and has at least three stages in which a rotary evaporator is used twice, which is not easy in a nuclear medicine hospital department. Moreover, it is difficult to use this process for producing medical kits, because the sterility and

REFERENCES:
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Kaden et al., Isotopenpraxis, "Nitridokomplexe des Technetium (V)", vol. 17 (1981) pp. 174-175.
Abram et al., Inorg Chim Acta, 109 (1985) "Lipophilic Technetium Complexes . . . " pp. L9-L11.
Abram et al., J. Radioanal. Nuc. Chem., vol. 102, No. 2 (1986) "Lipophilic Techetium Complexes . . . " pp. 309-320.
International Journal of Radiation/Applications & Instrumentation Part A, vol. 39, No. 3, 1988, Pergamon Journals Ltd., (Marsh Barton, Exetor, GB); C. M. Kennedy et al: "A Formate Based Precursor for the Preparation of Technetium Complexes", pp. 213-225.

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