Patent Publication Number: US-2004058984-A1

Title: Stabilization of radiopharmaceutical compositions using hydrophilic thioethers and hydrophilic 6-hydroxy chromans

Description:
[0001] The present invention relates to novel stabilizers of radiopharmaceutical compositions used for diagnosis and therapy. In particular, the invention relates to use of a hydrophilic thioether, a hydrophilic 6-hydroxy-chroman derivative, or a combination of a hydrophilic thioether with a hydrophilic 6-hydroxy-chroman derivative, to increase the shelf-life of diagnostic and therapeutic radiopharmaceuticals.  
       [0002] A number of radionuclides are routinely employed in nuclear medicine, both as diagnostic agents and as therapeutics. For example,  99m Tc,  111 In,  18 F, and  201 Tl are employed as diagnostic imaging agents, and  131 I,  32 P,  89 Sr, and  153 Sm are in therapeutic use. In addition, nuclides such as  186 Re,  188 Re,  212 Bi,  213 Bi,  90 Y,  67 Cu,  192 Ir,  165 Dy, and  117m Sn have been proposed as potential therapeutic agents. Such radionuclides are administered in the form of radiopharmaceutical compositions, which generally include a chelator for the nuclide. Radiopharmaceuticals may additionally include a targeting molecule such as a monoclonal antibody, an antibody fragment, or a receptor ligand. The availability of radiopharmaceuticals has significantly advanced diagnosis and treatment of a variety of diseases.  
       [0003] Chemical decomposition may limit a radiopharmaceutical&#39;s shelf life by decreasing the radiochemical purity of the agent over time. For example, a radiopharmaceutical containing  99m Tc,  186 Re, or  188 Re may be susceptible to oxidation of the nuclide itself. In addition, the radiation emitted from a radionuclide can break chemical bonds of other components of the composition, thus causing autoradiolysis. Autoradiolysis is a particular problem when the radiopharmaceutical contains higher energy nuclides, such as β-emitters (e.g.,  186 Re,  188 Re,  90 Y,  131 I) and α-emitters (e.g.  213 Bi,  212 Bi,  211 At,  225 Ac,  223 Ra).  
       [0004] Thus many radiopharmaceuticals require stabilizers to maximize shelf life. Such stabilizers must be non-toxic and must be able to maintain the product&#39;s radiochemical purity for an acceptable shelf-life as well as during use. In addition, an acceptable radiopharmaceutical stabilizer must not interfere with delivery of the radionuclide to the target site. Methods for stabilizing radiopharmaceuticals by adding gentisates are disclosed, for example, in U.S. Pat. Nos. 4,232,000; 4,233,284; 4,497,744; 5,384,113. Stabilization of radiopharmaceuticals using ascorbic acid is disclosed in U.S. Pat. Nos. 5,393,512 and 5,011,676, in WO 97/28181 and in WO 98/33531. Hydroquinone stabilizers of radiopharmaceuticals is disclosed in U.S. Pat. No. 4,229,427. Other compounds such as reductic acid, erythorbic acid, p-aminobenzoic acid, 4-hydroxybenzoic acid, nicotinic acid, nicotinamide, 2,5-dihydroxy-1,4-benzenedisulfonic acid, tartaric acid, inositol, and the like, have also been used to stabilize radiopharmaceutical compositions.  
       [0005] U.S. Pat. No. 5,384,113 discloses a method of preventing autoradiolysis of peptides radiolabeled with  111 In using gentisic acid or gentisyl alcohol. In addition to preventing autoradiolysis of peptides by  111 In, the method of U.S. Pat. No. 5,384,113 is proposed to prevent autoradiolysis of peptides by  67 Ga,  169 Yb,  125 I,  123 I, and  201 Tl. Two radiolabelled peptides,  111 In-DTPA-octreotide and  123 I-LHRH, were tested for autoradiolysis prevention. A monoclonal antibody, NR-Lu-10, labeled with  186 Re was also specifically exemplified.  
       [0006] As indicated in Example 1, infra, the present inventors have found that that when added as a component in radiopharmaceutical kit formulations, gentisic acid decreases the radiochemical purity of some  99m Tc-labelled peptides, and thus is not useful as a stabilizer of some radiolabeled peptides. A need exists, therefore, for additional stabilizers of radiopharmaceuticals. A particular need exists for stabilizers of radiopharmaceuticals containing less than 70 amino acids linked by peptide bonds.  
       [0007] Methionine residues in proteins and polypeptides are known to oxidize to methionine sulfoxide. U.S. Pat. No. 5,272,135 discloses a method of inhibiting oxidation of a liquid or semi-liquid composition of a polypeptide containing at least one methionine residue by adding between 0.01% w/v to 0.3% w/v methionine to the composition. U.S. Pat. No. 5,272,135 teaches that the method disclosed therein is effective with a variety of polypeptides, including epidermal growth factor, insulin-like growth factor I, nerve growth factor, transforming growth factor alpha precursor, transforming growth factor beta precursor, transforming growth factor beta, fibroblast growth factor, vaccinia growth factor, platelet derived growth factor, or methionine containing biologically active fragments or precursors of such growth factors. However, the data presented in U.S. Pat. No. 5,272,135 are limited to addition of methionine to inhibit oxidation of methionine residues present in epidermal growth factor. Lam, et al. (1997)  J. Pharm. Sci.  86, 1250-1255 disclose the use of methionine to stabilize the recombinant humanized monoclonal antibody rhuMAb HER2 in liquid formulations to prevent oxidation of methionine residues.  
       [0008] U.S. Pat. No. 5,358,708 discloses a method for increasing the storage stability of an aqueous formulation of granulocyte-macrophage colony stimulating factor or an interleukin by addition of a stabilizing amount of methionine, listidine, or mixtures thereof. U.S. Pat. No. 5,358,708 also discloses that chemical differences among proteins causes different proteins to become inactivated during storage at different rates and under different conditions. U.S. Pat. No. 5,358,708 further discloses that the storage-prolonging effects of methionine and histidine are not equivalent with different proteins, and that mixtures of amino acids exhibit different effects as the ratio varies, as the identity of the protein is changed, and/or as concentrations are altered.  
       [0009] WO 97/14430 discloses use of hydrophilic thioethers as antioxidants to prolong storage stability of aqueous formulations of proteins and peptides. The only data presented in WO 97/14430 relate to insulin-like growth factor I, a 70-amino acid peptide containing three disulfide bonds. WO 97/14430 further discloses that common antioxidants such as ascorbic acid, sodium thiosulfate, glutathione, or sodium bisulfite increased oxidation of IGF-1 or even precipitated the protein.  
       [0010] U.S. Pat. Nos. 3,947,473; 4,003,919; 4,018,799; and 4,026,907 disclose a variety of antioxidant hydrophilic 6-hydroxy-chroman compounds as intermediates in preparation of optically active α-tocopherol. U.S. Pat. No. 4,511,685 discloses hydrophilic 6-hydroxy-chroman derivatives and use of such derivatives to stabilize polypropylene compositions. U.S. Pat. Nos. 4,847,267 and 4,970,216 disclose use of one such hydrophilic 6-hydroxy-chroman, hydrophilic 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid alone or in combination with sulfur compounds, including glutathione or cysteine, as a skin treatment composition to inhibit generation of free radicals in the skin.  
       [0011] It has now been surprisingly found that the radiolabelling efficiency and shelf-life of peptide and non-peptide radiopharmaceutical compositions may be significantly increased by addition of a stabilizing amount of a hydrophilic thioether, a stabilizing amount of a hydrophilic 6-hydroxy-chroman derivative, or a stabilizing amount of a mixture of a hydrophilic thioether and a hydrophilic 6-hydroxy-chroman.  
       [0012] In the first aspect of this invention, the radiolabelling efficiency and shelf life of the radiopharmaceutical compositions are increased by the addition of a hydrophilic thioether.  
       [0013] In one embodiment of this first aspect, the invention provides a composition comprising a radiopharmaceutical precursor and a stabilizing amount of a hydrophilic thioether.  
       [0014] In another embodiment of this first aspect, the invention provides a method of stabilizing a radiopharmaceutical comprising the steps of:  
       [0015] a) combining a precursor of said radiopharmaceutical with a stabilizing amount of a hydrophilic thioether in a container; and  
       [0016] b) adding a radionuclide to the container.  
       [0017] In another embodiment of this first aspect, the invention provides a kit comprising a sealed vial containing a predetermined quantity of a radiopharmaceutical precursor and a stabilizing amount of a hydrophilic thioether.  
       [0018] In a second aspect of this invention, the radiolabelling efficiency and shelf life of the radiopharmaceutical compositions are increased by the addition of a hydrophilic 6-hydroxy-chroman derivative.  
       [0019] In one embodiment of this second aspect, the invention provides a composition comprising a radiopharmaceutical precursor and a stabilizing amount of a hydrophilic 6-hydroxy-chorman derivative.  
       [0020] In another embodiment of this second aspect, the invention provides a method of stabilizing a radiopharmaceutical comprising the steps of:  
       [0021] a) combining a precursor of said radiopharmaceutical with a stabilizing amount of a hydrophilic 6-hydroxy-chroman derivative in a container; and  
       [0022] b) adding a radionuclide to the container.  
       [0023] In another embodiment of this second aspect, the invention provides a kit comprising a sealed vial containing a predetermined quantity of a radiopharmaceutical precursor and a stabilizing amount of a hydrophilic 6-hydroxy-chroman derivative.  
       [0024] In the third aspect of this invention, the radiolabelling efficiency and shelf life of the radiopharmaceutical compositions are increased by the addition of a hydrophilic thioether and a hydrophilic 6-hydroxy-chroman derivative.  
       [0025] In one embodiment of this third aspect, the invention provides a composition comprising a radiopharmaceutical precursor, a hydrophilic thioether, and a hydrophilic 6-hydroxy-chroman.  
       [0026] In another embodiment of this third aspect, the invention provides a method of stabilizing a radiopharmaceutical comprising the steps of:  
       [0027] a) combining a precursor of said radiopharmaceutical with a stabilizing amount of a mixture of a hydrophilic thioether and a hydrophilic 6-hydroxy-chroman in a container; and  
       [0028] b) adding a radionuclide to the container.  
       [0029] In another embodiment of this third aspect, the invention provides a kit comprising a sealed vial containing a predetermined quantity of a radiopharmaceutical precursor and a stabilizing amount of a mixture of a hydrophilic thioether and a hydrophilic 6-hydroxy-chroman.  
       [0030] As defined herein, a “radiopharmaceutical” or “radiopharmaceutical composition” comprises a radionuclide, a chelator, and optionally a targeting moiety or domain.  
       [0031] In accordance with the invention, a “precursor” of a radiopharmaceutical is defined as comprising an unlabelled, that is, non-radioactive, reagent which may be a chelator or a chelator covalently linked to a targeting moiety or domain.  
       [0032] A “targeting moiety or domain” as defined herein as a moiety or domain capable of binding specifically to a site within a mammalian body such as a receptor on a cell surface. Targeting moieties or domains within the scope of the present invention include but are not limited to antibodies, antibody fragments such as Fab or F(ab)′ 2  fragments, epitope binding complementarity determining regions derived from antibodies, peptides, growth factors or receptor binding fragments thereof, hormones, steroids, receptor binding nucleic acids, receptor binding carbohydrates including monosaccharides, disaccharides, and oligosaccharides, receptor-binding lipids, benzodiazepines, receptor binding antibiotics, and the like.  
       [0033] A “stabilizing amount” is defined herein as that amount of hydrophilic thioether, hydrophilic 6-hydroxy-chroman or hydrophilic thioether/hydrophilic 6-hydroxy-chroman mixture sufficient to maintain the radiochemical purity, as measured by known methods such as those disclosed in the examples below, of a radiopharmaceutical composition relative to that of the radiopharmaceutical composition without the additive for at least 3 hours. Preferably, a clinically acceptable radiochemical purity for a radiopharmaceutical is at least 80% of the labelled undegraded radiopharmaceutical. More preferably, a clinically acceptable radiochemical purity for a radiopharmaceutical is at least 85% of the labelled undegraded radiopharmaceutical. Most preferably, a clinically acceptable radiochemical purity for a radiopharmaceutical is at least 90% of the labelled undegraded radiopharmaceutical.  
       [0034] Preferably, a stabilizing amount of hydrophilic thioether is in the range of about 0.1% (w/v) to about 1.5% (w/v). More preferably, a stabilizing amount of hydrophilic thioether is in the range of about 0.4% (w/v) to about 1.0% (w/v). More preferably, a stabilizing amount of hydrophilic thioether is in the range of about 0.5% (w/v) to about 1.0% (w/v).  
       [0035] A “hydrophilic thioether” is defined in accordance with the present invention as a compound having the general structure:  
       R—S—CH 2 C(R 1 R 2 R 3 )  
       [0036] wherein:  
       [0037] R is C 1  to C 4  alkyl or a C 1  to C 4  alkyl containing at least one hydrophilic group selected from —COOH, —NH 2 , —NHR 4 , —NR 4   2 , —OH, —SO 2 R 4 , —SOR 4 , SO 3 H, —CONH 2 , —CONH 4 , —CONR 4   2 , —COOR 4 , —OR 4 , —SR 4 , —NO 2 , —SO 2 NH 2 , —SO 2 NHR 4 , and —SO 2 NR 4   2 , with the proviso that, when R is methyl, the hydrophilic group is not NH 2 , NHR 4 , NR 4   2  or OH;  
       [0038] R 1 , R 2 , and R 3  are each independently selected from the group consisting of H, —COOH, —NH 2 , —NHR 4 , —NR 4   2 , —OH, —SO 2 R 4 , —SOR 4 , —SO 3 H, —CONH 2 , —CONHR 4 , —CONR 4   2 , —COOR 4 , —OR 4 , —SR 4 , —NO 2 , —SO 2 NH 2 , —SO 2 NHR 4 , —SO 2 NR 4   2 , C 1  to C 4  alkyl, and a C 1  to C 3  alkyl containing at least one hydrophilic group selected from —COOH, —NH 2 , —NHR 4 , —NR 4   2 , —OH, —SO 2 ; —SO 3 R 4 , —SO 3 H, —CONH 2 , —CONHR 4 , —CONR 4   2 , —COOR 4 , —OR 4 , —SR 4 , —NO 2 , —SO 2 NH 2 , —SO 2 NHR 4 , and —SO 2 NR 4   2 , with the proviso that only one of R 1 , R 2 , and R 3  is —NH 2 , NHR 4 , NR 4   2  or OH; and  
       [0039] R 4  is selected from the group consisting of C 1  to C 3  alkyl;  
       [0040] and with the further proviso that the hydrophilic thioether comprise at least one of said hydrophilic groups. Specific hydrophilic thioethers of the present invention include  D -methionine,  L -methionine,  D -ethionine,  L -ethionine, 3-methylthio-1,2-propanediol, methyl-3-(methylthio)propionate, 2-(ethylthio)ethylamine-HCl, 2-(methylthio)-ethanol, buthionine, S-methyl- L -cysteine, S-methyl- D -cysteine,  D -methioninol,  L -methioninol, and the like. Preferably, the hydrophilic thioether used in the compositions of the invention is methioninol, 2-(ethylthio)-ethylamine.HCl, 3-methythio-1,2-propanediol, or methionine. More preferably, the hydrophilic thioether used in the compositions of the invention is 2-(ethylthio)-ethylamine.HCl or methionine. Most preferably, the hydrophilic thioether used in the compositions of the invention is  L -methionine.  
       [0041] A “hydrophilic 6-hydroxy-chroman derivative” is defined in accordance with the present invention as having a formula:  
                 
 
       [0042] wherein  
       [0043] one of Y and Z is selected from the group consisting of O, S, C═O, and (CHR 3 ) n  where n is an integer from 0-3, and the other of Y and Z is selected from the group consisting of C═O and (CHR 3 ) n  where n is an integer from 0 to 3;  
       [0044] each R 3  group is independently selected from the group consisting of H, alkyl, halogen, —OR 4 , —SO 3 H, —SO 3 R 4 , —S(O) m R 4 , —COOR 4 , —NO 2 , —CONH m (R 4 ) 2-m , —NH m (R 4 ) 2-m , —COR 4 , —CH 2 OR 4 , —COR 5 , —SO 2 NH m (R 4 ) 2-m , —R 5 , and —CH 2 R 5 , where m is an integer from 0 to 2;  
       [0045] R 4  is H or C 1  to C 3  alkyl; and  
       [0046] R 5  is selected from the group consisting of a monosaccharide, a disaccharide, and a hydrophilic peptide sequence of up to 5 amino acids comprising at least one hydrophilic amino acid residue.  
       [0047] Preferably, Y is (CH 2 ) and Z is (CH 2 ). Exemplary hydrophilic 6-hydroxy-chroman derivatives of the present invention include 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox®, available from Aldrich Chemical Co., (Milwaukee, Wis., USA); 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid-4-sulfonic acid; 6-hydroxy-2,5,7,8-tetramethylchroman-3-hydroxy-2-carboxylic acid; 6-hydroxy-2,5,7,8-tetramethylchroman-2-glucosamine, having a structure:  
                 
 
       [0048] and 6-hydroxy-2,5,7,8-tetramethylchroman-2-(carboxy-seryl-seryl-serylamide), having the structure:  
                 
 
       [0049] Preferably, the hydrophilic 6-hydroxy-chroman derivative of the present invention is a water soluble vitamin E derivative. More preferably, the hydrophilic 6-hydroxy-chroman derivative of the invention is a 6-hydroxy-2,5,7,8-tetramethyl-2-carboxylic acid derivative having —CH 2  at the 3- and 4-positions and a hydrophilic substituent at the 2-position. Most preferably, the hydrophilic 6-hydroxy-chroman derivative of the invention is 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.  
       [0050] Any radiopharmaceutical may be stabilized by addition of a hydrophilic thioether, a hydrophilic 6-hydroxy-chroman or a mixture of a hydrophilic thioether and a hydrophilic 6-hydroxy-chroman as taught herein. Ligand-type radiopharmaceuticals which do not comprise a targeting moiety or domain, such as Tc 99m MAG3 (TechnoScan®, Mallinkrodt Medical, Inc., St. Louis, Mo., USA), may be stabilized in accordance with the present invention. In addition, radiopharmaceuticals comprising any kind of targeting moiety or domain may be stabilized in accordance with the present invention.  
       [0051] Recently a new class of radiopharmaceuticals has been developed which target a radiolabel to a particular tissue, disease site, or organ through a small receptor-specific molecule, which may be a peptide, a β-glucan, a benzodiazepine, or other small molecule. Such radiopharmaceuticals are disclosed and claimed, for example, in commonly assigned U.S. Pat. Nos. 5,508,020; 5,225,180; 5,405,597; 5,443,815; 5,552,525; 5,561,220; 5,620,675; 5,645,815; 5,654,272; 5,681,541; 5,711,931; 5,714,579; 5,716,596; 5,736,122; 5,770,179; 5,783,170; 5,788,960; 5,807,537; 5,807,538; 5,811,394; 5,814,297; 5,814,298; 5,814,299; 5,820,845; 5,820,846; 5,830,856; 5,833,942; 5,843,401; 5,843,403; 5,849,260; 5,849,261; 5,851,509; 5,866,097; 5,871,711; 5,932,189; 5,951,964; 5,955,426; 5,976,496; 5,997,844; 6,007,792; 6,017,509; 6,017,512; 6,028,056; 6,051,206; 6,074,627; 6,086,850; 6,171,178 and; 6,241,960; and in commonly assigned copending U.S. patent application Ser. Nos. 08/236,402; 08/253,973; 08/721,443; and 09/553,494. These new agents comprise a chelator covalently linked to the receptor-specific targeting moiety or domain, and a radiolabel complexed with the chelator. A kit for making one such agent, ACUTECT®, has received approval in the U.S. for scintigraphic imaging of acute deep vein thrombosis. A second kit, NEOTECT®, has been approved in the U.S. for imaging malignant lung tumors. The stabilizers of the present invention are particularly suitable for use with radiopharmaceuticals which comprise chelators covalently linked to peptide, β-glucan, benzodiazepine, or other small targeting molecules as described in the commonly assigned patents and copending applications listed above.  
       [0052] In general, radiopharmaceuticals containing precursors in which a targeting moiety or domain is covalently linked to a monoamine, diamide, single thiol containing chelator such as those disclosed in commonly assigned copending U.S. patent application Ser. No. 08/253,973 and in WO 95/33497 are stabilized using a hydrophilic thioether, a hydrophilic 6-hydroxy-chroman or a mixture of a hydrophilic thioether and a hydrophilic 6-hydroxy-chroman in accordance with this invention. In addition, radiopharmaceuticals containing precursors in which a targeting moiety or domain is covalently linked to a bisamine bisthiol (BAT) chelator such as those disclosed in commonly assigned U.S. Pat. Nos. 5,780,007; 5,776,428; 5,720,934; 5,922,303; 5,965,107; 6,086,849; and 6,093,383 and in WO 93/21962 may be stabilized in accordance with the present invention.  
       [0053] The stabilizers of the present invention may also be used for radiopharmaceuticals comprising targeting molecules covalently linked to any chelator, such as the diamine monoamide thiol chelators and the triamine thiol chelators described in U.S. Pat. No. 5,688,485 and the triamide thiols disclosed in U.S. Pat. No. 5,091,514.  
       [0054] The stabilizers of the invention are preferably employed to increase the shelf life of radiopharmaceuticals comprising a targeting moiety covalently linked to a peptide metal chelator having a formula  
       C(pgp) S -(aa)-C(pgp) S    
       [0055] wherein (pgp) S  is H or a thiol protecting group and (aa) is an amino acid. Such chelators are disclosed and claimed in commonly assigned U.S. Pat. Nos. 5,654,272; 5,681,541; 5,788,960; and 5,811,394.  
       [0056] The stabilizers of the invention may also be employed to increase the shelf life of radiopharmaceuticals comprising a targeting moiety covalently linked to a peptide metal chelator having a formula selected from the group consisting of:  
                 
 
       [0057] wherein  
       [0058] X is H or a protecting group;  
       [0059] (amino acid) is any amino acid; and  
                 
 
       [0060] wherein  
       [0061] X is H or a protecting group;  
       [0062] (amino acid) is any amino acid.  
       [0063] Such chelators are disclosed and claimed in commonly assigned U.S. Pat. Nos. 5,720,934; 5,776,428; 5,780,007; 6,086,849 and 6,093,383.  
       [0064] More preferably, the stabilizers of the invention are used to increase the shelf life of radiopharmaceuticals comprising a targeting moiety covalently linked to a peptide metal chelator comprising a single thiol having a formula:  
       A-CZ(B)-[C(R′R″)] n —X  
       [0065] wherein  
       [0066] A is H, HOOC, H 2 NOC, (peptide)-NHOC, (peptide)-OOC or R″″;  
       [0067] B is H, SH, —NHR′″, —N(R′″)-(peptide), or R″″;  
       [0068] X is H, SH, —NHR′″, —N(R′″)-(peptide) or R″″;  
       [0069] Z is H or R″″;  
       [0070] R′, R″, R′″ and R″″ are independently H or lower straight or branched chain or cyclic alkyl;  
       [0071] n is 0, 1 or 2;  
       [0072] and  
       [0073] where B is —NHR′″ or —N(R′″)-(peptide), X is SH, and n is 1 or 2;  
       [0074] where X is —NHR′″ or —N(R′″)-(peptide), B is SH, and n is 1 or 2;  
       [0075] where B is H or R″″, A is HOOC, H 2 NOC, (peptide)-NHOC, (peptide)-OOC, X is SH, and n is 0 or 1;  
       [0076] where A is H or R″″, then where B is SH, X is —NHR′″ or —N(′″)-(peptide) and where X is SH, B is —NHR′″ or —N(′″)-(peptide);  
       [0077] where X is H or R″″, A is HOOC, H 2 NOC, (peptide)-NHOC, (peptide)-OOC and B is SH;  
       [0078] where Z is methyl, X is methyl, A is HOOC, H 2 NOC, (peptide)-NHOC, (peptide)-OOC, B is SH and n is 0.  
       [0079] Such chelators are disclosed and claimed in commonly assigned U.S. Pat. Nos. 5,443,815; 5,807,537; 5,814,297; and 5,866,097.  
       [0080] Specific embodiments of the single thiol containing radiometal chelator stabilized in accordance with the present invention are described and claimed in commonly assigned copending U.S. patent application Ser. No. 08/236,402 and in WO 95/29708, and include chelators having the chemical formula:  
       R 1 —CO-(amino acid) 1 -(amino acid) 2 -Z  
       [0081] wherein (amino acid) 1  and (amino acid) 2  are each independently any primary α- or β-amino acid that does not comprise a thiol group, Z is a thiol-containing moiety selected from the group consisting of cysteine, homocysteine, isocysteine, penicillamine, 2-mercaptoethylamine and 3-mercaptopropylamine, and R 1  is lower (C 1 -C 4 ) alkyl, an amino acid, or a peptide comprising 2 to 10 amino acids. When Z is cysteine, homocysteine, isocysteine or penicillamine, the carbonyl group of said moiety is covalently linked to a hydroxyl group, a NR 3 R 4  group, wherein each of R 3  and R 4  are independently H or lower (C 1 -C 4 ) alkyl, an amino acid or a peptide comprising 2 to 10 amino acids.  
       [0082] Alternatively, a single thiol containing radiometal chelator stabilized in accordance with the present invention has a formula:  
       Y-(amino acid) 2 -(amino acid) 1 -NHR 2    
       [0083] wherein Y is a thiol-containing moiety that is cysteine, homocysteine, isocysteine, penicillamine, 2-mercaptoacetate or 3-mercaptopropionate, (amino acid) 1  and (amino acid) 2  are each independently any primary α- or β-amino acid that does not comprise a thiol group, and R 1  is H or lower (C 1 -C 4 ) alkyl, an amino acid or a peptide comprising 2 to 10 amino acids. When Y is cysteine, homocysteine, isocysteine or penicillamine, the amino group of said moiety is covalently linked to —H, an amino acid or a peptide comprising 2 to 10 amino acids.  
       [0084] Specific embodiments of the single thiol containing radiometal chelator are selected from the group consisting of:  
       [0085] -(amino acid) 1 -(amino acid) 2 -A-CZ(B)-{C(R 1 R 2 )} n —X},  
       [0086] -A-CZ(B)-{C(R 1 R 2 )} n —X}-(amino acid) 1 -(amino acid) 2 ,  
       [0087] -(a primary α,ω- or β,ω-diamino acid)-(amino acid) 1 -A-CZ(B)-{C(R 1 R 2 )} n —X}, and  
       [0088] -A-CZ(B)-{C(R 1 R 2 )} n —X}-(amino acid) 1 -(a primary α,β- or α,ω-diamino acid) wherein the term “α,ω-diamino acid” represents an amino acid having an amine on the ac carbon atom and an amine on the carbon atom most distal from the ax carbon atom, the term “β,ω-diamino acid” represents an amino acid having an amine on the β carbon atom and an amine on the carbon atom most distal from the β carbon atom, and (amino acid) 1  and (amino acid) 2  are each independently any naturally-occurring, modified, substituted or altered α- or β-amino acid not containing a thiol group.  
       [0089] Specific single thiol-containing radiometal chelators stabilized in accordance with the invention have a formula selected from the group consisting of: -Gly-Gly-Cys-, Cys-Gly-Gly-, -(ε-Lys)-Gly-Cys-, (δ-Orn)-Gly-Cys-, -(γ-Dab)-Gly-Cys-, -(β-Dap)-Lys-Cys-, and -(β-Dap)-Gly-Cys-. (In these formulae, ε-Lys represents a lysine residue in which the ε-amino group, rather than the typical α-amino group, is covalently linked to the carboxyl group of the adjacent amino acid to form a peptide bond; δ-Orn represents an ornithine residue in which the δ-amino group, rather than the typical α-amino group, is covalently linked to the carboxyl group of the adjacent amino acid to form a peptide bond; γ-Dab represents a 2,4-diaminobutyric acid residue in which the γ-amino group is covalently linked to the carboxyl group of the adjacent amino acid to form a peptide bond; and β-Dap represents a 2,3-diaminopropionic acid residue in which the β-amino group is covalently linked to the carboxyl group of the adjacent amino acid to form a peptide bond.)  
       [0090] Most preferably, the stabilizers of the invention may be used to increase the shelf life of radiopharmaceuticals comprising a targeting moiety covalently linked to a monoamine, diamide, single thiol metal chelator such as those disclosed and claimed in commonly assigned copending U.S. patent application Ser. No. 08/253,973 and in WO 95/33497, and to increase the shelf life of radiopharmaceuticals comprising a targeting moiety covalently linked to a bisamide bisthiol metal chelator such as those disclosed and claimed in commonly assigned U.S. Pat. Nos. 5,780,007; 5,922,303; 6,086,849; and 6,093,383. Exemplary monoamine, diamide, single thiol chelators stabilized by a mixture of a hydrophilic thioether and a hydrophilic 6-hydroxy chroman have general formulae selected from the group consisting of:  
                 
 
       [0091] wherein n, m and p are each integers that are independently 0 or 1; each R′ is independently H, lower alkyl, C 2 -C 4  hydroxyalkyl, or C 2 -C 4  alkoxyalkyl, and each R is independently H or R″, where R″ is a substituted lower alkyl group, an unsubstituted lower alkyl group, or a phenyl not comprising a thiol group, and one R or R′ is L, where L is a bivalent linker linking the metal chelator to the targeting moiety and wherein when one R′ is L, NR′ 2  is an amine. In preferred embodiments, L is a C 1 -C 6  linear alkyl group; a branched chain alkyl group; a cyclic alkyl group; a carboxylic ester; a carboxamide; a sulfonamide; an ether; a thioether; an amine; an alkene; an alkyne; a 1,2-linked, optionally substituted benzene ring; a 1,3-linked, optionally substituted benzene ring; a 1,4-linked, optionally substituted benzene ring; an amino acid, or a peptide of 2 to about 10 amino acids, or combinations thereof. In preferred embodiments, R″ is a C 1 -C 6  linear allyl group; a branched alkyl group; a cyclic alkyl group; a —C q OC r —, —C q NHC r — or —C q SC r — group, where q and r are integers each independently 1 to 5 wherein the sum of q+r is not greater than 6; a (C 1 -C 6 ) alkyl-X, where X is a hydroxyl group; a substituted amine; a guanidine; an amidine; a substituted thiol group; a carboxylic acid; an ester; a phosphate group; a sulfate group; a phenyl group; a phenyl group substituted with a halogen, a hydroxyl, a substituted amine, a guanidine, an amidine, a substituted thiol, an ether, a phosphate group, or a sulfate group; an indole group; a C 1 -C 6  heterocyclic group containing 1 to 3 nitrogen, oxygen or sulfur atoms; or a combination thereof.  
       [0092] In a specific embodiment, the monoamine, diamide single thiol radiometal chelator stabilized in accordance with the invention may have a formula:  
                 
 
       [0093] wherein R 1  and R 2  are each independently H, lower alkyl, C 2 -C 4  hydroxyalkyl, or C 2 -C 4  alkoxyalkyl; R 3 , R 4 , R 5  and R 6  are independently H, substituted or unsubstituted lower alkyl or phenyl not comprising a thiol group; R 7  and R 8  are each independently H, lower allyl, lower hydroxyalkyl or lower alkoxyalkyl; L is a bivalent linker group and Z is a targeting moiety.  
       [0094] The monoamine, diamide single thiol radiometal chelator stabilized in accordance with the invention may alternatively have a formula:  
                 
 
       [0095] wherein R 1  and R 2  are each independently H, lower alkyl, C 2 -C 4  hydroxyalkyl, or C 2 -C 4  alkoxyalkyl; R 3 , R 4 , R 5  and R 6  are independently H, substituted lower alkyl, unsubstituted lower alkyl, phenyl, substituted phenyl not comprising a thiol group, and one of R 3 , R 4 , R 5  or R 6  is Z-L-HN(CH 2 ) n —, where L is a bivalent linker, Z is a targeting moiety, and n is an integer from 1 to 6; R 7  and R 5  are each independently H, lower alkyl, lower hydroxyalkyl, lower alkoxyalkyl; and X is an amino group, a substituted amino group or —NR 1 —Y, where Y is an amino acid, an amino acid amide, or a peptide comprising from 2 to 10 amino acids.  
       [0096] The mono amine, diamide single thiol radiometal chelator stabilized in accordance with the invention may alternatively have a formula:  
                 
 
       [0097] wherein R 1  and R 2  are each independently H, lower alkyl, lower hydroxyalkyl, or lower alkenylalkyl; R 3  and R 4  are independently H, substituted or unsubstituted lower alkyl or phenyl not comprising a thiol group; n is an integer from 1 to 6; L is a bivalent linker; and Z is a targeting moiety.  
       [0098] The monoamine, diamide single thiol radiometal chelator stabilized in accordance with the invention may alternatively have a formula:  
                 
 
       [0099] wherein L is a bivalent linker and Z is a targeting moiety.  
       [0100] Bisamide bisthiol metal chelators stabilized in accordance with the present invention preferably have a formula selected from the group consisting of:  
                 
 
       [0101] wherein  
       [0102] each R is independently H, CH 3  or C 2 H 5 ;  
       [0103] each (pgp) S  is independently a thiol protecting group or H;  
       [0104] m, n and p are independently 2 or 3;  
       [0105] A is linear or cyclic lower alkyl, aryl, heterocyclyl, a combination thereof or a substituted derivative thereof; and  
                 
 
       [0106] wherein  
       [0107] each R is independently H, CH 3  or C 2 H 5 ;  
       [0108] m, n and p are independently 2 or 3;  
       [0109] A is linear or cyclic lower alkyl, aryl, heterocyclyl, a combination thereof or a substituted derivative thereof;  
       [0110] V is H or —CO-peptide;  
       [0111] R′ is H or peptide;  
       [0112] and wherein when V is H, R′ is peptide; and when R′ is H, V is —CO-peptide.  
       [0113] For example, the stabilizers of the invention may be used to increase the shelf life of radiopharmaceuticals comprising the specific precursors set forth below:  
       [0114] GGCSIPPEVKFNKPFVYLI.amide (SEQ ID NO:1);  
       [0115] GGCSIPPEVKFNKPFVYLI (SEQ ID NO:2);  
       [0116] GGCGLF (SEQ ID NO:3);  
       [0117] RGCSIPPEVKFNKPFVYLI.amide (SEQ ID NO:4);  
       [0118] RGCGHRPLDKKREEAPSLRPAPPPISGGYR.amide (SEQ ID NO:5);  
       [0119] GGCRPKPQQFFGLM.amide (SEQ ID NO:6);  
       [0120] GGCFVYLI.amide (SEQ ID NO:7);  
       [0121] (acetyl.TKPRGG) 2 K(ε-K)GC.amide;  
       [0122] F D FYW D KTFT(ε-K)GC.amide;  
       [0123] acetyl.F D FYW D KTFT(ε-K)GC.amide;  
       [0124] acetyl.Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0125] acetyl-F D FYW D KTFTGGG(ε-K)GC.amide;  
       [0126] acetyl.F D FYW D KTFTGGG(ε-K)KC.amide;  
       [0127] acetyl.KKKKK.Nal D .Cpa.YW D KTFT(ε-K)GC.amide;  
       [0128] acetyl.D D F D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0129] acetyl.D D F D .Cpa.YW D KTC(ε-K)GCKK.amide;  
       [0130] acetyl.KKKKK.Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0131] acetyl.Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0132] acetyl-DDD.Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0133] acetyl.D D DF D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0134] (DTPA).F D FYW D KTFT(ε-K)GC.amide;  
       [0135] (DTPA).Nal D .Cpa.YW D KT.Nal.T(ε-K)GCKK.amide;  
       [0136] (DTPA).(ε-K)GCF D FYW D KTFT.amide;  
       [0137] (DTPA).(ε-K)GCF D .Cpa..YW D KTFT.amide;  
       [0138] (DTPA).F D .Cpa.YW D KTFT(ε-K)GC.amide;  
       [0139] (DTPA).Nal D .Cpa.YW D KTFT(ε-K)GC.amide;  
       [0140] (DTPA).Aca.F D .Cpa.YW D KTFT(ε-K)GC.amide;  
       [0141] (DTPA).Nal D .Cpa.YW D KT.Nal.T(ε-K)GCKK.amide;  
       [0142] (DTPA).Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0143]   CH   2   CO .FFW D KTFC (ε-K)GC.amide;  
       [0144]   CH   2   CO .FFW D KTFC KKKKK(ε-K)GC.amide;  
       [0145]   CH   2   CO .FFW D KTFC (ε-K)KKKKKGC.amide;  
       [0146] AKCGGGF D FYW D KTFT.amide;  
       [0147] AKCGGGF D YW D KTFT.amide;  
       [0148] DDDD.Nal D .Cpa.YW D KTFT(ε-K)GCKKKK.amide;  
       [0149] DDD.Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0150] Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0151] Trc.Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0152] Hca.Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0153] (Trc) 2 .Nal D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0154] KKKK.Nal D .Cpa.YW D KTFT(ε-K)GCDDDD.amide;  
       [0155] K D .Nal D .Cpa.YW D KTFT(ε-K)GCD.amide;  
       [0156] K D K.Nal D .Cpa.YW D KTFT(ε-K)GCDD.amide;  
       [0157] K D KK.Nal D .Cpa.YW D KTFT(ε-K)GCDDD.amide;  
       [0158] K D KK.Nal D .Cpa.YW D KTFT(ε-K)GCDD.amide;  
       [0159] K D KKK.Nal D .Cpa.YW D KTFT(ε-K)GCDD.amide;  
       [0160] K D KKK.Nal D .Cpa.YW D KTFT(ε-K)GCKDKD.amide;  
       [0161] K D KKKF D .Cpa.YW D KTF,Nal.(ε-K)GCDDDD.amide;  
       [0162] K(BAT).Nal D .C Me YW D KVC Me T.amide  
       [0163] K D DKD.Nal D .Cpa.YW D KTFT(ε-K)GCKDKD.amide;  
       [0164] KDKD.Nal D .Cpa.YW D KTFT(ε-K)GCKDKD.amide;  
       [0165] F D .Cpa.YW D KTC(ε-K)GCKK.amide;  
       [0166] F D .Cpa.YW D KTC(ε-K)GC.amide;  
       [0167] F D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0168] F D .Cpa.YW D K.Abu.Nal.T(ε-K)GC.amide;  
       [0169] F D .Cpa.YW D KTFTGGG(ε-K)GC.amide;  
       [0170] F D .Cpa.YW D KTFT(ε-K)GCR.amide;  
       [0171] (Trc-imide).Nal D .Cpa.YW D KTFT(ε-K)GCR.amide;  
       [0172] Trc.(Trc-imide).K.Nal D .Cpa.YW D KTFT(ε-K)GCRR.amide;  
       [0173] (Trc-imide) 2 K.Nal D .Cpa.YW D KTFT(ε-K)GCRR.amide;  
       [0174] (Trc-imide) 2 K.Nal D .Cpa.YW D KTFT(ε-K)GCR.amide;  
       [0175] D D DF D .Cpa.YWW D KTFT(ε-K)GCKK.amide;  
       [0176] D D F D .Cpa.YW D KTFT(ε-K)GCKK.amide;  
       [0177] F D FYW D KTFT(ε-K)GCKK.amide;  
       [0178] AKCGGGF D YW D KTFT.amide;  
       [0179] (2-ketogulonyl).Nal D .Cpa.YW D KTFT(8-K)GCKK.amide;  
       [0180] (2-ketogulonyl).F D .Cpa.YW D KTFT(ε-K)GC.amide;  
       [0181] cyclo- (N— CH   3 )FYW D KV.Hcy ( CH   2   CO .GC.Dap.Dap.amide);  
       [0182] cyclo- (N— CH   3 )FYW D KV.Hcy ( CH   2   CO .(γ-Dab)KCR.amide);  
       [0183] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO .KKKKK(ε-K)GC.amide);  
       [0184] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO ).(ε-K)GCK.amide;  
       [0185] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO .(β-Dap)KCR.amide);  
       [0186] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO .(β-Dap)KCK.amide);  
       [0187] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO .(δ-Orn)GCK.amide);  
       [0188] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO .(β-Dap)GCK.amide);  
       [0189] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO .K(ε-K)KCK.amide);  
       [0190] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO .(ε-K)GCKK.amide);  
       [0191] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO ).K(ε-K)GC.amide;  
       [0192] cyclo- (N—C 3 )FYW D KV.Hcy ( CH   2   CO ).(ε-K)GC.amide;  
       [0193] RGCQAPLYKKIIKKLLES (SEQ ID NO:8);  
       [0194] acetyl.KK(6-K)GCGCGGPLYKKIIKKLLES;  
       [0195] acetyl.KKKKKK(ε-K)GCGGPLYKKIIKKLLES;  
       [0196] (   CH   2   CO .Y D .Amp.GDC KGCG.amide) 2 ( CH   2   CO ) 2 K(ε-K)GC.amide;  
       [0197] (   CH   2   CO .Y D .Amp.GDC GGC Acm GC Acm GGC.amide) 2 ( CH   2   CO ) 2 K(ε-K)GC.amide;  
       [0198] (   CH   2   CO .Y D .Amp.GDC KGCG.amide) 2 ( CH   2   CO ) 2 K(ε-K)GC.amide;  
       [0199] {(   CH   2   CO .Y D .Amp.GDC GGCG.amide) ( CH   2   CO )} 2 K(—K)GC.amide;  
       [0200] (   CH   2   CO .Y D .Amp.GDC KGG) 2 K(ε-K)GC.β-Ala.amide;  
       [0201] (   CH   2   CO .Y D .Amp.GDC KKG) 2 K(ε-K)GC.β-Ala.amide;  
       [0202] {(   CH   2   CO .Y D .Amp.GDC G) 2 KG} 2 K(ε-K)GCG.amide;  
       [0203] (   CH   2   CO .Y D .Amp.GDC ) 2 K(ε-K)GCG.amide;  
       [0204] ({(   CH   2   CO .Y D .Amp.GDC GGC Acm GC Acm GGC.amide) ( CH   2   CO )} 2 .K) 2 K(ε-K)GCG.amide;  
       [0205] {(   CH   2   CO .Y D .Amp.GDC GGC Acm GC Acm GGC.amide) 2 ( CH   2   CO ) 2 K} 2 K(ε-K)GCG.amide;  
       [0206] (   CH   2   CO .Y D .Amp.GDC GGC Acm GC Acm GGC.amide) 2 ( CH   2   CO ) 2 K(ε-K)GC.amide;  
       [0207] HSDAVFTDNYTRLRKQMAVKKYLNSILN(ε-K)GC.amide;  
       [0208] HSDAVFTDNYTRLRKQMAVKKYLNSILNGGC.amide (SEQ ID NO:9);  
       [0209] AGCHSDAVFTDNYTRLRKQMAVKKYLNSILN.amide (SEQ ID NO:10);  
       [0210] HSDAVFTDNYTRLRKQMAVKKYLNSILNC(BAT).amide (SEQ ID NO:11);  
       [0211]   CH   2   CO .SNLST.Hhc VLGKLSC(BAT)ELHKLQTYPRTNTGSGTP.amide (SEQ ID NO:12);  
       [0212]   CH   2   CO .SNLST.Hhc VLGKLSQELHKLQTYPRTNTGSGTP(ε-K)GC.amide;    CH   2   CO .SNLST.Hhc VLGKLSC( CH   2   CO .GGCK.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0213]   CH   2   CO .SNLST.Hhc VLGKLSC( CH   2   CO .(β-Dap)KCK.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0214]   CH   2   CO .SNLST.Hhc VLGKLSC( CH   2   CO .(ε-K)GCE.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0215]   CH   2   CO .SNLST.Hhc VLGKLSC( CH   2   CO .GGCK.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0216]   CH   2   CO .SNLST.Hhc VLGKLSC( CH   2   CO .(β-Dap)KCK.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0217]   CH   2   CO .SNLST.Hhc VLGKLSC( CH   2   CO .(ε-K)GCE.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0218]   CH   2   CO .SNLST.Cys .LGKLSC( CH   2   CO .GGCK.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0219]   CH   2   CO .SNLST.Cys VLGKLSC( CH   2   CO .(β-Dap)KCK.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0220]   CH   2   CO .SNLST.Cys VLGKLSC( CH   2   CO .(ε-K)GCE.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0221] SNLST.Asu VLGKLSC( CH   2   CO . (β-Dap)KCK.amide)ELHKLQTYPRTNTGSGTP.amide;  
       [0222] SNLST.Asu VLGKLSC( CH   2   CO .(β-Dap)KCK.amide)ELHKLQTYPRTDVGAGTP.amide;  
       [0223] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Tyr-Cys-Thr(ol));  
       [0224] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Phe(4- F )-Cys-Thr(ol));  
       [0225] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Phe(4- NH   2 )-Cys-Thr-Ser);  
       [0226] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Dab-Cys-Thr);  
       [0227] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Phe(4- NH   2 )-Cys-Thr);  
       [0228] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Phe(4- NH   2 )-Cys-Thr(ol));  
       [0229] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-His-Cys-Thr(ol));  
       [0230] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Arg-Cys-Thr(ol));  
       [0231] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Gly-Cys-Lys- NH   2 );  
       [0232] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Ser-Cys-Thr(ol));  
       [0233] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Dab-Cys-Thr(ol));  
       [0234] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Gly-Cys-Thr(ol));  
       [0235] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Dab-Cys-Ser(ol));  
       [0236] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Gly-Gly-Cys-Lys- NH   2 );  
       [0237] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Gly-Gly-Cys-Arg- NH   2 );  
       [0238] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Ser-Cys-Lys- NH   2 );  
       [0239] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Ser-Cys-Arg- NH   2 );  
       [0240] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Ser-Cys-Lys-Thr(ol));  
       [0241] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Ser-Cys-Dap- NH   2 );  
       [0242] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Ser-Cys- NH ( CH   2   CH   2   O ) 2   CH   2   CH   2   NH   2 );  
       [0243] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Ser-Cys-Thr- NH ( CH   2   CH   2   O ) 2   CH   2   CH   2   NH   2 );  
       [0244] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Gly-Lys-Cys- NH   2 );  
       [0245] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Lys-Cys- NH   2 );  
       [0246] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Lys-Gly-Cys- NH   2 );  
       [0247] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Dab-Cys-Ser(ol));  
       [0248] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Dap-Cys- NH   2 );  
       [0249] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Gly-Gly-Cys-His- NH   2 );  
       [0250] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Gly-Gly-Cys-Phe(4- NH   2 )— NH   2 );  
       [0251] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Orn-Cys-Thr(ol));  
       [0252] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Dap-Cys-Thr(ol));  
       [0253] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Lys-Cys-Thr(ol));  
       [0254] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Ser-Ser-Cys- NHCH   2   CH   2   OCH   2   CH   2   NH   2 );  
       [0255] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -β-Dap-Lys-Cys- NH   2 );  
       [0256] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -δ-Orn-Gly-Cys- NH   2 ); and  
       [0257] cyclo- Tyr- D -Trp-Lys-Thr-Phe-( N—CH   3 )Hcy ( CH   2   CO -Thr-Gly-Gly-Cys- NH   2 ).  
       [0258] (Single-letter and three-letter abbreviations for amino acids can be found in G. Zubay,  Biochemistry  (2d. ed.), 1988 (MacMillan Publishing: New York) p.33; other abbreviations are as follows: Acm is acetamidomethyl; Mob is 4-methoxybenzyl; Abu is aminobutyric acid; F D  is  D -phenylalanine; W D  is  D -tryptophan; Y D  is  D -tyrosine; Aca is 6-aminohexanoic acid; Apc is S-(3-aminopropyl)cysteine; Hcy is homocysteine; Nal is 2-naphthylalanine; Cpa is 4-chlorophenylalanine; K D  is  D -lysine; D D  is  D -aspartate; Nal D  is  D -2-naphthylalanine; DTPA is diethylenetriaminepentaacetic acid; Trc is tricarballylic acid; Trc-imide is tricarballylic imide; and Hca is hexacarboxycyclohexane. ( . . . ) 2 K represents covalent linkage to both amino groups of lysine. Hcy( . . . ) represents covalent linkage to the sidechain sulfur atom of homocysteine. (N—CH 3 )F represents N-α-methyl-phenylalanine. Underlining between groups (e.g., as between the  CH   2   CO . group and cysteine (C) in    CH   2   CO .Y D RGDC ) represents a cyclic sulfide. Underlining between amino acids (e.g., as between the cysteines (C) in  CNPRGDC ) represents a cyclic disulfide bond. The term “cyclo” before an underlined sequence means an N-terminus-to-C-terminus cyclic sequence. The subscript X D  indicates the amino acid is in the  D -configuration; all other subscripts refer to amino acid sidechain protecting groups. ε-K, δ-Orn, γ-Dab, and β-Dap are defined as set forth above. Asu is 2-amino suberic acid, wherein the amino terminal amino acids of peptides containing an Asu residue are cyclized via an amide bond between the amino terminal amino group and the side chain carboxylic acid moiety of the Asu residue. BAT is N 6 , N 9 -bis(2-mercapto-2-methylpropyl)-6,9-diazanonanoic acid.  
       [0259] In accordance with the present invention, a hydrophilic 6-hydroxy-chroman derivative may also be used to stabilize labelld radiopharmaceutical precursors comprising a benzodiazepine derivative, such as those described in U.S. Pat. No. 6,171,578. In a preferred embodiment, a hydrophilic 6-hydroxy-chroman derivative such as 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid is used to stabilize radiolabelled 1-[(carboxyglycyl-glycyl-glycyl-cysteinamide)methyl]-4-(2-carboxyethyl)-7-[(4-amidinophenyl)methyl]-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione trifluoroacetate.  
       [0260] In addition, a hydrophilic thioether, or hydrophilic 6-hydroxy-chroman or a mixture of a hydrophilic thioether and a hydrophilic 6-hydroxychroman derivative may be used in accordance with the present invention to stabilize labelled radiopharmaceutical precursors comprising a targeting moiety or domain covalently linked to the known chelators 1,4,7,10-tetraazadodecanetetraacetic acid and derivatives thereof:  
                 
 
       [0261] where n is an integer that is 2 or 3 and where each R is independently H, C 1  to C 4  alkyl, or aryl and one R is covalently linked to the targeting moiety, and desferrioxamine.  
       [0262] A radiopharmaceutical comprising any radionuclide or radiometal may be stabilized in accordance with the present invention. For example, radiopharmaceuticals containing such nuclides as  125 I,  131 I,  211 At,  47 Sc,  67 Cu,  72 Ga,  90 Y,  153 Sm,  159 Gd,  165 Dy,  166 Ho,  175 Yb,  177 Lu,  186 Re,  188 Re,  212 Bi,  213 Bi,  68 Ga,  99m Tc,  111 In, and  123 I, and the like may be stabilized by addition of a hydrophilic thioether in accordance with the invention. The extent of stabilization of a particular radiopharmaceutical precursor when chelated to different radionuclides may vary. For example, a  99m Tc-labelled precursor may be stabilized to a greater extent than a  188 Re-labelled form of the same precursor.  
       [0263] The compositions of the invention are formulated as a sterile, pyrogen-free, parenterally acceptable aqueous solution which may optionally be supplied in lyophilized form and be reconstituted by the user. The compositions of the invention may be provided as components of kits which may include buffers, additional vials, instructions for use, and the like.  
       [0264] The pharmaceutical compositions of the invention comprises a radiopharmaceutical precursor in combination with a stabilizing amount of a hydrophilic thioether, a hydrophilic 6-hydroxy-chroman or a mixture of a hydrophilic thioether and hydrophilic 6-hydroxy-chroman, optionally with a pharmaceutically acceptable diluent or a carrier such as species appropriate albumin. As used herein, a “pharmaceutically acceptable diluent or carrier” may include any and all solvents, dispersion media, antibacterial and antifungal agents, isotonic agents, enzyme inhibitors, transfer ligands such as glucoheptonate, tartrate, citrate, or mannitol, and the like. The use of such media and agents for pharmaceutically active substances is well known in the art. For example, Sodium Chloride Injection and Ringer&#39;s Injection are commonly used as diluents. The preparation of such parenterally acceptable solutions, having due regard to pH, isotonicity, stability, and the like, is within the skill in the art.  
       [0265] In accordance with the method of this invention, radiopharmaceuticals are preferably administered intravenously in a single unit dose, either totally as a bolus or partly as a bolus followed by infusion over 1-2 hours. The amount of solution to be injected at unit dosage is from about 0.01 mL to about 10 mL, containing about 0.01 mCi to about 100 mCi of radioactivity, preferably from about 1 mCi to about 50 mCi. The amount of the radiopharmaceutical in the unit dose may range from about 0.1 to about 10 mg/kg body weight, After intravenous administration, the site is monitored, for example, by radioimaging in vivo if the radiopharmaceutical is a diagnostic agent.  
       [0266] The following examples are shown by way of illustration and not be considered as limitations. 
     
    
    
     EXAMPLE 1  
     Effect of Gentisic Acid on Radiochemical Purity of  99m Tc-labelled Depreotide  
     [0267] Gentisic acid (GA) was tested for its ability to stabilize the  99m Tc-labelled somatostatin receptor-binding peptide depreotide, which has the structure.  
                 
 
     [0268] This peptide is represented as:  
     [0269] cyclo (N— CH   3 )FYW D KV.Hcy. ( CH   2   CO .(β-Dap)KCK.amide)  
     [0270] in the listing set forth above.  
     [0271] Lyophilized kit vials were prepared containing depreotide, GA, and other components as described in Table 1. Formulations were adjusted to pH 7.4 or 8.5 (as noted) prior to lyophilization.  
                               TABLE 1                       Component   Control   GA I   GA II   GA III                  Depreotide   50 μg   50 μg   50 μg   50 μg       Sodium Glucoheptonate   25 mg   25 mg    5 mg   25 mg       Dihydrate 1         Edetate Disodium   100 μg    100 μg    100 μg    100 μg        Dihydrate 2         Stannous Chloride   50 μg   50 μg   50 μg   50 μg       Dihydrate 3         Gentisic Acid Sodium   —    1 mg    1 mg    1 mg       Salt Hydrate 4         pH   7.4   7.4   7.4   8.5                                                  
 
     [0272] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m  Tc sodium pertechnetate (Technelite® Molybdenum Mo99-Technetium Tc99m Generator, DuPont, Billerica, Mass.) containing approximately 50 mCi  99m Tc and heating in a boiling water bath for 10 minutes. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 2.  
                       TABLE 2                                      HPLC RCP (%)                                     Formulation   0.5 hr   3.5 hr   6.5 hr                                                 Control   94.5   88.3   86.4               94.2   92.1   90.8               94.5   91.7   90.1           (Average ± 1SD):   (94.4 ± 0.2)   (90.7 ± 2.1)   (89.1 ± 2.4)           GA I   82.4   79.4   77.2           GA II   29.1   25.1   20.5           GA III   0.9   0.7   0.6                      
 
     [0273] These results indicate that gentisic acid decreases the radiolabelling yield and the stability of  99m Tc-depreotide when included in formulated kits.  
     EXAMPLE 2  
     Stabilization of  99m Tc-Labelled Depreotide by  L -Methionine  
     [0274] Lyophilized kit vials were prepared containing depreotide,  L -methionine (Met), and other components as described in Table 3. All formulations were adjusted to pH 7.4 prior to lyophilization.  
                                       TABLE 3                       Component   Control   Met I   Met II   Met III   Met IV   Met V                  Depreotide    50 μg    50 μg    50 μg    50 μg    50 μg    50 μg       Sodium    5 mg    5 mg    5 mg    5 mg    5 mg    5 mg       Glucoheptonate       Dihydrate       Edetate   100 μg   100 μg   100 μg   100 μg   100 μg   100 μg       Disodium       Dihydrate       Stannous    50 μg    50 μg    50 μg    50 μg    50 μg    50 μg       Chloride       Dihydrate       L-Methionine   —    1 mg    2 mg    4 mg    5 mg    10 mg       USP 1                            
 
     [0275] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and heating in a boiling water bath for 10 minutes. Some of the formulations were also radiolabelled in a room temperature preparation (allowed to stand at rom temperature 30 minutes following reconstitution). Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 4.  
                       TABLE 4                                      HPLC RCP (%)                                 Formulation   Prep Type   0.5 hr   3.5 hr   6.5 hr                                         Control   Heated   91.9   85.0   80.7           Heated   —   81.6   79.3       (Average):       (91.9)   (83.3)   (80.0)           Rm Temp   94.8   87.6   78.2           Rm Temp   90.7   88.7   83.4       (Average):       (92.8)   (88.2)   (80.8)       Met I (1 mg)   Heated   95.9   91.5   89.5       Met II (2 mg)   Heated   95.2   93.2   90.5       Met III (4 mg)   Heated   95.9   93.5   92.2           Heated   92.4   88.5   87.4       (Average):       (94.2)   (91.0)   (89.8)           Rm Temp   90.4   90.0   89.4           Rm Temp   89.9   89.9   89.7           Rm Temp   91.4   87.9   83.1       (Average ± 1SD):       (90.6 ± 0.8)   (89.3 ± 1.2)   (87.4 ± 3.7)       Met IV (5 mg)   Heated   93.8   93.7   93.5           Heated   —   92.5   92.7       (Average):       (93.8)   (93.1)   (93.1)       Met V (10 mg)   Heated   94.5   94.6   92.6                  
 
     [0276] These results indicate that L-methionine increases the radiolabelling yield and the stability of  99m Tc-depreotide prepared from formulated kits which have been stored under normal conditions (≦−10° C.).  
     EXAMPLE 3  
     Stabilization of  99m Tc-Labelled Depreotide by L-Methionine in Lyophilized Kit Preparations; Accelerated Temperature (40° C.) Storage  
     [0277] Lyophilized kits were prepared containing depreotide, L-methionine (Met), and other components as described in Table 5. All formulations were adjusted to pH 7.4 prior to lyophilization. The kits were stored for one week at 40° C. Some kits were also stored at −10° C. as controls.  
                               TABLE 5                                   Component   Control   Met                          Depreotide   50 μg   50 μg           Sodium Glucoheptonate    5 mg    5 mg           Dihydrate           Edetate Disodium Dihydrate   100 μg    100 μg            Stannous Chloride Dihydrate   50 μg   50 μg           L-Methionine USP   —    5 mg                      
 
     [0278] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and incubation in a boiling water bath (10 min). Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 6.  
                       TABLE 6                                      HPLC RCP (%)                                     Formulation   Storage Temp   Prep Type   0.5 hr   3.5 hr   6.5 hr               Control   −10° C.   Heated   —   82.6   77.8             40° C.   Heated   —   82.6   79.0       Met     40° C.   Heated   76.5   78.0   77.6                  
 
     [0279] These results indicate that L-methionine does not stabilize  99m Tc-depreotide in lyophilized kits which have been stored at 40° C. prior to radiolabelling.  
     EXAMPLE 4  
     Stabilization of  99m Tc-Labelled Benzodiazepinedione Derivative by L-Methionine in Lyophilized Kit Preparations  
     [0280] L -methionine was tested for its ability to stabilize a  99m Tc-labelled glycoprotein IIb/IIIa receptor-binding benzodiazepinedione derivative 1-[(carboxyglycyl-glycyl-glycyl-cysteinamide)methyl]-4-(2-carboxyethyl)-7-[(4-amidinophenyl)methyl]-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione trifluoroacetate, having the structure.  
                   
     [0281] Lyophilized kit vials were prepared containing the benzodiazepinedione derivative and components as described in Table 7. All formulations were adjusted to pH 7.4 prior to lyophilization.  
                               TABLE 7                                   Component   Control   Met                          Derivative   40 μg   40 μg           Sodium   25 mg   25 mg           Glucoheptonate           Dihydrate           Edetate Disodium   100 μg    100 μg            Dihydrate           Stannous Chloride   50 μg   50 μg           Dihydrate           L-Methionine USP   —    5 mg                      
 
     [0282] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and heating in a boiling water bath for 10 minutes. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 8.  
                       TABLE 8                                      HPLC RCP (%)                                     Formulation   0.5 hr   3.5 hr   6.5 hr                                                 Control   93.2   90.1   88.0               93.6   94.5   88.8               92.4   89.2   88.1               85.0   86.1   82.3           (Average ± 1SD):   (91.0 ± 4.1)   (90.0 ± 3.5)   (86.8 ± 3.0)           Met (5 mg)   92.5   91.1   91.4               93.9   92.5   91.9               94.3   92.4   91.0               90.5   91.2   91.9           (Average ± 1SD):   (92.8 ± 1.7)   (91.8 ± 0.8)   (91.6 ± 0.4)                      
 
     [0283] These results indicate that L-methionine increases the radiolabelling yield and the stability of the  99m Tc-labelled benzodiazepinedione derivative prepared from formulated kits.  
     EXAMPLE 5  
     Stabilization of Tc  99m -Labelled Peptide by L-Methionine  
     [0284] L -methionine was tested for its ability to stabilize a  99m Tc-labelled glycoprotein IIb/IIIa receptor-binding peptide having the structure.  
                   
     [0285] This peptide is represented as:  
     [0286] (   CH   2   CO .Y D . Amp. GDC .KGCG.amide) 2 ( CH   2   CO ) 2 K(ε-K)GC.amide  
     [0287] in the listing set forth above.  
     [0288] Lyophilized kit vials were prepared containing the peptide (50 μg), sodium glucoheptonate dihydrate (10 mg), stannous chloride dihydrate (50 μg), and edetate disodium dihydrate (100 μg). The formulation was adjusted to pH 7.4 prior to lyophilization.  
     [0289] The lyophilized kits were radiolabelled with  99m Tc in the presence and absence of L-methionine. To the Met preparation was added 4 mg methionine (in 100 mL saline) and 100 JAL ethanol. To the control preparation was added 100 JIL ethanol and 100 JIL saline to account for the additional saline or ethanol added with the L-methionine. Both vials were then reconstituted with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and allowed to incubate for 30 minutes at room temperature. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 9.  
                       TABLE 9                                      HPLC RCP (%)                                     Preparation   0.5 hr   3.5 hr   6.5 hr                                                 Control   91.8   80.4   76.2           Methionine (4 mg)   96.7   96.9   96.2                      
 
     [0290] These results show that  L   -methionine increases the radiolabelling yield and the stability of the    99m Tc-peptide.  
     EXAMPLE 6  
     Stabilization of  99m Tc-Labelled Peptide Chelator by L-Methionine  
     [0291] L   -methionine was tested for its ability to stabilize a    99m Tc-labelled monoamine, diamide, single thiol peptide chelator having the structure.  
                   
     [0292] N-3-benzoyl-2,3-(S)-diaminopropionyl- L -lysinyl- L -cysteinyl- L -lysinyl Amide  
     [0293] Lyophilized kit “placebo” vials were prepared containing sodium glucoheptonate dihydrate, edetate disodium dihydrate, and stannous chloride dihydrate at the concentrations set forth in Table 1 (control formulation).  
     [0294] The peptide chelator was radiolabelled with  99m Tc in the presence and absence of  L -methionine. The peptide chelator was dissolved in water at a concentration of 1 mg/mL, and 50 μg (50 μL) of the peptide was added to each of three placebo vials. Ethanol and L-methionine were added to the control and methionine preparations as described in Example 5. In addition, 100 μL phosphate buffered saline (PBS) was added to each preparation. The vials were reconstituted with 0.9-1.0 mL  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc, and heated in a boiling water bath for ten minutes. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 10.  
                           TABLE 10                                      HPLC RCP (%)                                     Preparation   0.5 hr   3 hr   6 hr   9 hr                                         Control   94.1   92.4   85.9   80.0       L-Methionine (4 mg)   98.4   97.2   95.5   92.8                          
 
     EXAMPLE 7  
     Stabilization of a  99m Tc Bisamine Bisthiol Chelator by  L -Methionine  
     [0295] L -methionine was tested for its ability to stabilize a  99 )Tc-labelled non-peptide chelator (4-(butanoic acid)-2,2,9,9 tetramethyl-4,7-diaza-1,10-decanedithiol) having the structure.  
                   
     [0296] The non-peptide chelator was radiolabelled with  99m Tc in the presence and absence of  L -methionine using the placebo vial heated preparation procedure as described in Example 6. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 11.  
                           TABLE 11                                      HPLC RCP (%)                                             Preparation   0.5 hr   3 hr   6 hr   9 hr                                                     Control   48.5   56.5   54.0   52.9           Methionine (4 mg)   66.7   70.0   70.8   70.4                      
 
     [0297] These results show that  L -methionine increases the radiolabelling yield and the stability of a  99m Tc-labelled non-peptide chelator.  
     EXAMPLE 8  
     Stabilization of a  99m Tc-Labelled Peptide by Methionine Derivatives  
     [0298] 2-(Ethylthio)ethylamine, methioninol, and 3-methylthio-1,2-propanediol are hydrophilic thioethers having the structures.  
                 
 
     [0299] These compounds and  L -methionine were tested for their ability to stabilize  99m Tc-labelled depreotide.  
     [0300] Each hydrophilic thioether was dissolved in water made up at 40 mg/mL and adjusted to pH 7 with HCl or NaOH. Each hydrophilic thioether (4 mg in 100 μL) was added to a formulated kit vial containing the peptide (“control” formulation in Table 1). To the control vials were added 100 μL water. The vials were reconstituted with 1.0 mL  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and heated in a boiling water bath for ten minutes. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 12.  
                           TABLE 12                       Additive   Initial RCP   3.5 hr RCP   6.5 hr RCP                                                Day 1:                   None (Control 1)   89.8   82.9   79.4       Methionine   95.0   90.4   89.3       2-(Ethylthio)ethylamine   92.8   94.2   93.3       Day 2:       None (Control 2)   89.9   78.0   74.4       Methioninol   94.1   93.9   90.7       3-Methylthio-1,2-propanediol   89.1   84.0   80.9                  
 
     [0301] These results show that the hydrophilic thioethers 2-(ethylthio)ethylamine, methioninol, and 3-methylthio-1,2-propanediol increase the radiolabelling yield and the stability of a  99m Tc-labelled peptide. Methionine sulfoxide, methionine sulfone, and 3-(methylthio)propionaldehyde had no effect on  99m Tc-labelled peptide radiolabelling yield or stability.  
     EXAMPLE 9  
     Stabilization of  99m Tc-Labelled Depreotide by Trolox® 
     [0302] Lyophilized kit vials were prepared containing depreotide, Trolox®, and other components as described in Table 13. All formulations were adjusted to pH 7.4 prior to lyophilization.  
                                   TABLE 13                                   Trolox   Trolox   Trolox       Component   Control   Trolox I   II   III   IV                  Depreotide   50 μg     50 μg    50 μg    50 μg    50 μg       Sodium Glucoheptonate    5 mg     5 mg    5 mg    5 mg    5 mg       Dihydrate       Edetate Disodium   100 μg    100 μg   100 μg   100 μg   100 μg       Dihydrate       Stannous Chloride    50 μg     50 μg    50 μg    50 μg    50 μg       Dihydrate       Trolox   —    0.6 mg    1 mg    2 mg    5 mg                  
 
     [0303] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and incubation at room temperature for 30 minutes following reconstitution. Some of the formulations were also radiolabelled in a heated preparation (heat in a boiling water bath for 10 minutes). Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 14.  
                       TABLE 14                                      HPLC RCP (%)                                 Formulation   Prep Type   0.5 hr   3.5 hr   6.5 hr               Control   Heated   92.0   85.9   84.5           Heated   91.4   85.3   78.3       (Average):       (91.7)   (85.6)   (81.5)           Rm Temp   92.0   85.0   84.2           Rm Temp   92.6   85.2   80.7           Rm Temp   92.0   81.4   79.5           Rm Temp   89.5   82.8   —       (Average ± 1SD):       (91.5 ± 1.4)   (83.6 ± 1.8)   (81.5 ± 2.4)       Trolox I (600 μg)   Rm Temp   94.3   93.2   92.0           Rm Temp   91.8   88.6   89.1       (Average):       (93.1)   (90.9)   (90.6)       Trolox II (1 mg)   Rm Temp   91.3   89.6   91.0           Rm Temp   92.9   91.8   92.5           Rm Temp   94.1   93.2   91.1       (Average ± 1SD):       (92.8 ± 1.4)   (91.5 ± 1.8)   (91.5 ± 0.8)       Trolox III (2 mg)   Heated   94.9   91.1   85.6           Heated   95.3   92.9   88.7       (Average):       (95.1)   (92.0)   (87.2)           Rm Temp   95.4   94.8   95.4           Rm Temp   94.5   93.7   93.8           Rm Temp   95.5   —   92.2           Rm Temp   93.8   91.7   92.4           Rm Temp   94.8   92.4   93.0           Rm Temp   —   94.6   93.5       (Average ± 1SD):       (94.8 ± 0.7)   (93.4 ± 1.4)   (93.4 ± 1.2)       Trolox IV (5 mg)   Rm Temp   93.3   92.0   —           Rm Temp   92.1   94.8   93.8       (Average):       (92.7)   (93.4)   (93.8)                          
 
     EXAMPLE 10  
     Stabilization of 99 m Tc Depreotide by Trolox® in Lyophilized Kit Preparations; Accelerated Temperature (40° C.) Storage  
     [0304] Lyophilized kits were prepared containing depreotide, Trolox®, and other components as described in Table 15. All formulations were adjusted to pH 7.4 prior to lyophilization. The kits were stored for one week at 40° C. Some kits were also stored at −10° C. as controls.  
                               TABLE 15                                   Component   Control   Trolox                          Depreotide    50 μg    50 μg           Sodium Glucoheptonate    5 mg    5 mg           Dihydrate           Edetate Disodium Dihydrate   100 μg   100 μg           Stannous Chloride Dihydrate    50 μg    50 μg           Trolox ®   —    2 mg                      
 
     [0305] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and incubation either at room temperature (30 minutes) or in a boiling water bath (10 min). Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 16.  
                       TABLE 16                                      HPLC RCP (%)                                     Formulation   Storage Temp   Prep Type   0.5 hr   3.5 hr   6.5 hr               Control   −10° C.   Heated   —   82.6   77.8             40° C.   Heated   —   82.6   79.0       Trolox ®   −10° C.   Rm Temp   94.4   92.9   92.3             40° C.   Rm Temp   86.6   89.2   88.6                  
 
     [0306] These results indicate that the Trolox® stabilizes  99m Tc-depreotide prepared from lyophilized kits which had been thermally stressed under conditions of accelerated temperature storage.  
     EXAMPLE 11  
     Stabilization of a  99m Tc-Labelled Peptide by Trolox  
     [0307] Trolox® was tested for its ability to stabilize a  99m Tc-labelled glycoprotein IIb/IIIa receptor-binding peptide having the structure.  
                 
 
     [0308] This peptide is represented as:  
     [0309] (   CH   2   CO .Y D .Amp.GDC .KGCG.amide) 2 ( CH   2   CO ) 2 K(ε-K)GC.amide  
     [0310] in the listing set forth above.  
     [0311] Lyophilized kit vials were prepared containing the peptide (50 μg), sodium glucoheptonate dihydrate (10 mg), stannous chloride dihydrate (50 μg), and edetate disodium dihydrate (100 μg). The formulation was adjusted to pH 7.4 prior to lyophilization.  
     [0312] The lyophilized kits were radiolabelled with  99m Tc in the presence and absence of Trolox®. To the Trolox® preparation was added 2 mg Trolox® in 100 μL ethanol and 100 μL saline. The ethanol was necessary to aid in the dissolution of the Trolox®. To the control preparation was added 100 μL ethanol and 100 μL saline to account for the additional saline or ethanol added with the Trolox. Both vials were then reconstituted with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and allowed to incubate for 30 minutes at room temperature. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 17.  
                       TABLE 17                                      HPLC RCP (%)                                     Preparation   0.5 hr   3.5 hr   6.5 hr                       Control   91.8   80.4   76.2           Trolox ® (2 mg)   89.5   91.9   92.9                      
 
     [0313] These results show that Trolox® increases the radiolabelling yield and the stability of  99m Tc-peptide.  
     EXAMPLE 12  
     Stabilization of  99m Tc-Labelled Peptide Chelator by Trolox® 
     [0314] Trolox® was tested for its ability to stabilize a  99m Tc-labelled monoamine, diamide, single thiol peptide chelator having the structure.  
                 
 
     [0315] N-3-benzoyl-2,3-(S)-diaminopropionyl- L -lysinyl- L -cysteinyl- L -lysinyl Amide  
     [0316] Lyophilized kit “placebo” vials were prepared containing sodium glucoheptonate dihydrate, edetate disodium dihydrate, and stannous chloride dihydrate at the concentrations set forth in Table 1 (control formulation).  
     [0317] The peptide chelator was radiolabelled with  99m Tc in the presence and absence of Trolox®. The peptide chelator was dissolved in water at a concentration of 1 mg/mL, and 50 μg (50 mL) of the peptide was added to each of three placebo vials. Ethanol and Trolox® were added to the control and Trolox®, preparations as described in Example 11. In addition, 100 μL phosphate buffered saline (PBS) was added to each preparation. The vials were reconstituted with 0.9-1.0 mL  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc, and heated in a boiling water bath for ten minutes. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 18.  
                           TABLE 18                                      HPLC RCP (%)                                             Preparation   0.5 hr   3 hr   6 hr   9 hr                       Control   94.1   92.4   85.9   80.0           Trolox ® (2 mg)   95.3   95.4   91.5   86.4                                  
 
     EXAMPLE 13  
     [0318] Stabilization of a  99m Tc Bisamide Bisthiol Chelator by Trolox® 
     [0319] Trolox® was tested for its ability to stabilize a  99m Tc-labelled non-peptide chelator (4-(butanoic acid)-2,2,9,9 tetramethyl-4,7-diaza-1,10-decanedithiol) having the structure.  
                 
 
     [0320] The non-peptide chelator was radiolabelled with  99m Tc in the presence and absence of Trolox® using the placebo vial heated preparation procedure as described in Example 11. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 19.  
                           TABLE 19                                      HPLC RCP (%)                                             Preparation   0.5 hr   3 hr   6 hr   9 hr                       Control   48.5   56.5   54.0   52.9           Trolox ® (2 mg)   88.6   79.1   78.3   77.0                                  
 
     EXAMPLE 14  
     Stabilization of  99m Tc-Labelled Depreotide by  L -Methionine and Trolox® 
     [0321] Lyophilized kit vials were prepared containing depreotide,  L -methionine (Met), Trolox®, and other components as described in Table 20. All formulations were adjusted to pH 7.4 prior to lyophilization.  
                               TABLE 20                                   Component   Control   Trolox + Met                          Depreotide    50 μg    50 μg           Sodium Glucoheptonate    5 mg    5 mg           Dihydrate           Edetate Disodium   100 μg   100 μg           Dihydrate           Stannous Chloride    50 μg    50 μg           Dihydrate           Trolox   —    2 mg           L-Methionine   —    5 mg                      
 
     [0322] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and incubation at room temperature for 30 minutes following reconstitution. Some of the formulations were also radiolabelled in a heated preparation (heat in a boiling water bath for 10 minutes). Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 21.  
                       TABLE 21                                      HPLC RCP (%)                                 Formulation   Prep Type   0.5 hr   3.5 hr   6.5 hr               Control   Heated   91.9   85.0   80.7           Rm Temp   94.8   87.6   78.2           RmTemp   90.7   88.7   83.4       (Average):       (92.8)   (88.2)   (80.8)       Trolox (2 mg) +   Heated   92.0   93.4   94.1       Met (5 mg)   Heated   92.9   93.3   93.2           Heated   93.6   90.7   91.5       (Average ± 1SD):       (92.8 ± 0.8)   (92.5 ± 1.5)   (92.9 ± 1.3)           Rm Temp   85.1   78.6   83.2                  
 
     [0323] These results indicate that the combination of  L -methionine and Trolox® increases the radiolabelling yield and the stability of  99m Tc depreotide prepared from formulated kits.  
     EXAMPLE 15  
     Stabilization of  99m Tc Depreotide by  L -Methionine and Trolox® in Lyophilized Kit Preparations; Accelerated Temperature (40° C.) Storage  
     [0324] Lyophilized kits were prepared containing depreotide,  L -methionine (Met) Trolox®, and other components as described in Table 20. All formulations were adjusted to pH 7.4 prior to lyophilization. The kits were stored for one week at 40° C. Some kits were also stored at −10° C. as controls. The lyophilized kits were radiolabelled with  99m Tc in heated preparations as set forth above. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 22.  
                       TABLE 22                                      HPLC RCP (%) 1                                       Formulation   Storage Temp   Prep Type   0.5 hr   3.5 hr   6.5 hr               Control   −10° C.   Heated   —   82.6   77.8             40° C.   Heated   —   82.6   79.0       Trolox + Met     40° C.   Heated   86.1   86.5   87.0                  
 
     [0325] These results indicate that the combination of L-methionine and Trolox® stabilizes  99m Tc-depreotide prepared from lyophilized k-its which have been thermally stressed under conditions of accelerated temperature storage.  
     EXAMPLE 16  
     Stabilization of a  99m Tc Benzodiazepinedione Derivative by L-Methionine and Trolox in Lyophilized Kit Preparations  
     [0326] L -methionine and Trolox® were tested for their ability to stabilize a glycoprotein IIb/IIIa receptor-binding benzodiazepinedione derivative 1-[(carboxyglycyl-glycyl-glycyl-cysteinamide)methyl]-4-(2-carboxyethyl)-7-[(4-amidinophenyl)methyl]-3,4-dihydro-1H-1,4-benzodiazepine-2,5-dione trifluoroacetate, having the structure.  
                 
 
     [0327] Lyophilized kit vials were prepared containing the benzodiazepinedione derivative and components as described in Table 23. All formulations were adjusted to pH 7.4 prior to lyophilization.  
                               TABLE 23                                   Component   Control   Trolox + Met                          Derivative    40 μg    40 μg           Sodium    25 mg    25 mg           Glucoheptonate           Dihydrate           Edetate Disodium   100 μg   100 μg           Dihydrate           Stannous Chloride    50 μg    50 μg           Dihydrate           Trolox   —    2 mg           L-Methionine   —    5 mg                      
 
     [0328] The lyophilized kits were radiolabelled with  99m Tc by reconstitution with 1.0 mL technetium  99m Tc sodium pertechnetate (Technelite®) containing approximately 50 mCi  99m Tc and heating in a boiling water bath for 10 minutes. Radiolabelling yield (RCP) results as measured by reversed phase HPLC are given in Table 24.  
                       TABLE 24                                      HPLC RCP (%)                             Formulation   0.5 hr   3.5 hr   6.5 hr               Control   93.2   90.1   88.0           93.6   94.5   88.8           92.4   89.2   88.1           85.0   86.1   82.3       (Average ± 1SD):   (91.0 ± 4.1)   (90.0 ± 3.5)   (86.8 ± 3.0)       Trolox (2 mg) + Met (5 mg)   92.5   92.9   90.3           93.9   93.9   93.0           94.1   93.6   90.9       (Average ± 1SD):   (93.5 ± 0.9)   (93.5 ± 0.5)   (91.4 ± 1.4)                  
 
     [0329] These results indicate that the combination of L-methionine and Trolox® increases the radiolabelling yield and the stability of the  99m Tc-labelled benzodiazepinedione derivative prepared from formulated kits.  
     [0330] It should be understood that the foregoing disclosure emphasizes certain specific embodiments of the invention and that all modifications or equivalents thereto are within the spirit and scope of the invention as set forth in the appended claims.  
    
     
       
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Gly Gly Cys Ser Ile Pro Pro Glu Val Lys Phe Asn Lys Pro Phe Val 
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Tyr Leu Ile 

 
           
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Gly Gly Cys Ser Ile Pro Pro Glu Val Lys Phe Asn Lys Pro Phe Val 
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Tyr Leu Ile 

 
           
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Gly Gly Cys Gly Leu Phe 
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Arg Gly Cys Ser Ile Pro Pro Glu Val Lys Phe Asn Lys Pro Phe Val 
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Tyr Leu Ile 

 
           
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Arg Gly Cys Gly His Arg Pro Leu Asp Lys Lys Arg Glu Glu Ala Pro 
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Ser Leu Arg Pro Ala Pro Pro Pro Ile Ser Gly Gly Tyr Arg 
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Gly Gly Cys Arg Pro Lys Pro Gln Gln Phe Phe Gly Leu Met 
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Gly Gly Cys Phe Val Tyr Leu Ile 
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Arg Gly Cys Gln Ala Pro Leu Tyr Lys Lys Ile Ile Lys Lys Leu Leu 
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Glu Ser 

 
           
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His Ser Asp Ala Val Phe Thr Asp Asn Tyr Thr Arg Leu Arg Lys Gln 
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Met Ala Val Lys Lys Tyr Leu Asn Ser Ile Leu Asn Gly Gly Cys 
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Ala Gly Cys His Ser Asp Ala Val Phe Thr Asp Asn Tyr Thr Arg Leu 
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Arg Lys Gln Met Ala Val Lys Lys Tyr Leu Asn Ser Ile Leu Asn 
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His Ser Asp Ala Val Phe Thr Asp Asn Tyr Thr Arg Leu Arg Lys Gln 
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Met Ala Val Lys Lys Tyr Leu Asn Ser Ile Leu Asn Cys 
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Glu Leu His 
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Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser Gly Thr Pro 
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Thr Lys Pro Arg Gly Gly Thr Lys Pro Arg Gly Gly Lys Xaa Gly Cys 
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Lys Lys Xaa Gly Cys Gly Cys Gly Gly Pro Leu Tyr Lys Lys Ile Ile 
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Lys Lys Leu Leu Glu Ser 
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Lys Lys Lys Lys Lys Lys Xaa Gly Cys Gly Gly Pro Leu Tyr Lys Lys 
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Ile Ile Lys Lys Leu Leu Glu Ser 
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His Ser Asp Ala Val Phe Thr Asp Asn Tyr Thr Arg Leu Arg Lys Gln 
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Met Ala Val Lys Lys Tyr Leu Asn Ser Ile Leu Asn Xaa Gly Cys 
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Gln Glu Leu His 
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Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser Gly Thr Pro Xaa 
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Gly Cys 

 
           
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Gly Gly Cys 
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Lys Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser 
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Gly Thr Pro 
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Lys Cys Lys 
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Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser Gly 
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Thr Pro 

 
           
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Xaa Gly Cys 
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Glu Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser 
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Gly Thr Pro 
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Gly Gly Cys 
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Lys Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser 
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Gly Thr Pro 
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Lys Cys Lys 
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Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser Gly 
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Thr Pro 

 
           
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Xaa Gly Cys 
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Glu Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser 
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Gly Thr Pro 
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Ser Asn Leu Ser Thr Cys Val Leu Gly Lys Leu Ser Cys Gly Gly Cys 
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Lys Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser 
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Gly Thr Pro 
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Ser Asn Leu Ser Thr Cys Val Leu Gly Lys Leu Ser Cys Lys Cys Lys 
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Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser Gly 
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Thr Pro 

 
           
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Ser Asn Leu Ser Thr Cys Val Leu Gly Lys Leu Ser Cys Xaa Gly Cys 
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Glu Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser 
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Gly Thr Pro 
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Lys Cys Lys 
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Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asn Thr Gly Ser Gly 
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Thr Pro 

 
           
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Ser Asn Leu Ser Thr Xaa Val Leu Gly Lys Leu Ser Cys Lys Cys Lys 
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Glu Leu His Lys Leu Gln Thr Tyr Pro Arg Thr Asp Val Gly Ala Gly 
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Thr Pro 

 
           
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Cys Asn Pro Arg Gly Asp Cys 
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