JPWO2018168643A1 - Method for producing ioflupan - Google Patents

Abstract

Provided is a method capable of producing large amounts of [ ¹²³ I] ioflupane without deteriorating quality. The method comprises the steps of: (a) reacting a labeled precursor compound with a radioactive iodide ion to obtain a radioactive iodine-labeled compound; and (b) subjecting the radioactive iodine-labeled compound obtained in step (a) to high-performance liquid chromatography. Purifying by radiographic (HPLC) method, wherein the radioactive iodide ion used in step (a) has a radioactivity of at least 200 GBq at the start of step (a), Step (b) is performed using a reversed-phase column having a diameter of 7 mm or more, and using an aqueous ethanol solution as an eluent.

Description

  The present invention relates to a method for producing ioflupan.

[ ¹²³ I] ioflupan ( ¹²³ I) has a high affinity for the dopamine transporter (DAT) at the synapse of striatal dopaminergic neurons, so that the line of ataxia disease in which nigrostriatal dopamine neurons degenerate. The density of DAT distribution in the striatum can be visualized by single photon emission tomography (SPECT), and has been used for diagnosis of the ataxia disease Parkinson's disease and other Parkinson's syndromes and Lewy body dementia.

As a method for producing [ ¹²³ I] ioflupane, for example, a trimethyltin compound, which is a radiolabeled precursor of [ ¹²³ I] ioflupane, is reacted with a radioactive iodide, and then eluted using a 4.6 mm × 300 mm C18 column. It is conventionally known to use a mixed solution of methanol / water / triethylamine as a liquid and to purify the obtained reaction solution by HPLC with a retention time of 10 minutes to obtain a labeled compound [ ¹²³ I] ioflupane (Non-patent Document 1 and 2).

On the other hand, a tropane compound similar to [ ¹²³ I] ioflupane described in Patent Document 1 is known. For example, for [ ¹²³ I] β-CIT, the synthesis time is shortened and the prescription time is simplified. It has been reported that after the radioactive iodine labeling reaction, the reaction solution is purified by HPLC using a compact column and an aqueous ethanol solution with a retention time of 5 to 6 minutes (Non-Patent Document 3).

International Publication WO95 / 01184

Baldwin R. M. et al. , Nucl. Med. Biol. , Vol. 22, no. 2, pp. 211-219, 1995 Neumeyer J .; L. , J. et al. Med. Chem. , 1994, 37, 1558-1581. Katsifis A. et al. , Applied Radiation and Isotopes 64, (2008), 27-31.

  However, the methods described in Non-Patent Documents 1 and 2 have a problem in that use of methanol with low safety is considered in consideration of application to humans. Therefore, by adopting a safer method using ethanol as an eluent, it has been approved as a pharmaceutical in 34 countries or regions (as of July 2013) and filed in Japan in 2014. Sold by people.

However, it is clear from the findings of the present inventors that if the amount of radioactivity used for production is increased in order to improve productivity, the stability of [ ^123I ] ioflupane may be reduced and the product may not meet the regulatory approval standards. became. The above-mentioned Non-Patent Document 3 and Patent Document 1 do not disclose or suggest any problems relating to the mass production of [ ^123I ] ioflupane.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method capable of producing a large amount of [ ¹²³ I] ioflupane without lowering the quality.

The present inventors have conducted intensive studies in order to solve the above-mentioned problems. As a result, the reaction solution obtained by the radiolabeling reaction was subjected to high-performance liquid chromatography (HPLC) using a column having a large diameter to obtain [ ¹²³ I] ioflupane. By purifying, it was found that the concentration of radioactivity in the column was suppressed, and even when radioactivity of 200 GBq or more was used at the start of production, the radiochemical purity standard of [ ¹²³ I] ioflupane could be secured. The present invention has been completed.

Thus, according to one aspect of the present invention,
(A) reacting a labeled precursor compound represented by the following general formula (1) with a radioactive iodide ion to obtain a radioactive iodine-labeled compound represented by the following general formula (2);
(B) purifying the radioactive iodine-labeled compound obtained in the step (a) by a high performance liquid chromatography (HPLC) method,
The amount of radioactivity of the radioactive iodide ion used in the step (a) is 200 GBq or more at the start of the step (a);
The step (b) provides a method for producing radioactive iodine-labeled ioflupane, which is performed using a reversed-phase column having a diameter of 7 mm or more and using an aqueous ethanol solution as an eluent.

(In the above general formula (1), R is a trialkylstannyl substituent having 1 to 6 carbon atoms in the alkyl chain or a triphenylstannyl substituent.)

(In the above general formula (2), X is a radioisotope of iodine.)

  According to the present invention, the reaction solution obtained by the radiolabeling reaction is subjected to HPLC purification using a column having a large diameter, so that concentration of radioactivity in the column is suppressed and productivity is improved. Can be.

  As used herein, the term "ioflupane" refers to the IUPAC designation methyl (1R, 2S, 3S, 5S) -8- (3-fluorophenyl) -3- (4-iodophenyl) -8-azabicyclo [3. 2.1] Refers to a compound called octane-2-carboxylate or N-ω-fluoropropyl-2β-carbomethixix-3β- (4-iodophenyl) nortropane.

[(A) Radioiodination step]
In the radioiodination step (a) of the present invention, the labeled precursor compound represented by the above general formula (1) is reacted with a radioiodide ion to carry out a radioiodination reaction, whereby the above general formula (2) To obtain a radioactive iodine-labeled compound represented by the formula:

  In the labeled precursor compound represented by the general formula (1), R is preferably a trialkylstannyl substituent having an alkyl chain having 1 to 6 carbon atoms, and is preferably a trimethylstannyl substituent or a triethylstannyl substituent. Groups, tripropylstannyl and tributylstannyl groups are more preferred.

  The labeled precursor compound can be synthesized, for example, using the methods described in Non-Patent Documents 1 and 2.

The reaction between the labeled precursor compound and the radioactive iodide ion is preferably performed in a suitable solvent in the presence of an oxidizing agent. Examples of the radioactive iodide ion include ions such as ¹²³ I, ¹²⁴ I, ¹²⁵ I, and ¹³¹ I. Of these, ¹²³ I is preferable. The amount of radioactivity of the radioiodide ion is 200 GBq or more at the start of the radioiodination step (a). However, the method of the present invention can achieve high yield even at 400 GBq or more at the start of the radioiodination step (a). Radioiodine labeled ioflupan can be produced at a high rate. The upper limit of the radioactivity of the radioactive iodide ion is not particularly limited, but is, for example, 3500 GBq or less, and 2000 GBq or less is practical.

Further, the radioactive iodide ion may be a salt having a counter ion. Examples of the counter ion include an alkali metal ion and an alkaline earth metal, and examples of the salt containing an iodide ion include sodium iodide (NaI), potassium iodide (KI), and ammonium iodide (NH ₄ I). ), Iodates of amines such as cesium iodide (CsI), lithium iodide (LiI), triethylamine hydroiodide (Et ₃ N HI), and quaternary such as tetrabutylammonium iodide (Bu ₄ NI). Examples thereof include ammonium salts, and among them, radioactive sodium iodide is preferable.

  As the solvent, those conventionally used in radioactive iodination reactions may be used, and acidic solutions such as hydrochloric acid, trifluoroacetic acid, sulfuric acid, and acetic acid; alcohol solvents such as ethanol; ether solvents such as tetrahydrofuran (THF); Examples include a polar solvent selected from acetonitrile and the like, a halogen-based solvent such as methylene chloride, and a non-polar solvent selected from toluene and the like. These acidic liquids, polar solvents and non-polar solvents can be used alone or in combination of two or more. When a polar solvent and a non-polar solvent are used, it is preferable to add the above-mentioned acidic solution, phosphoric acid, or an acidic buffer solution of phosphoric acid.

  Examples of the oxidizing agent include N-chlorosuccinimide, hydrogen peroxide and the like.

  The concentration of the labeled precursor compound in the solvent is not particularly limited, but is preferably 0.3 mg / mL or more, and 0.3 to 0.8 mg / mL, from the viewpoint of improving the yield of radioactive iodine-labeled ioflupane. Is more preferable.

  The reaction between the labeled precursor compound and a radioactive iodide ion is preferably performed in the presence of a non-radioactive iodide ion. In this case, the concentration of the non-radioactive iodide ion is not limited, but is preferably 0.015 mg / mL or more, and 0.015 to 0.04 mg / mL, from the viewpoint of improving the yield of radioactive iodine-labeled ioflupane. Is more preferable.

  The amount of the reaction solution in the radioiodination reaction is not particularly limited, but is, for example, 1 to 5 mL.

  The temperature at the time of the reaction between the labeled precursor compound and the iodide ion is not particularly limited, but is preferably from 10 to 120 ° C, and more preferably from 15 to 40 ° C.

  The reaction time between the labeled precursor compound and the radioactive iodide ion is not particularly limited, but is preferably 5 to 30 minutes.

  A glass container or a plastic container resistant to a solvent can be used as a reaction container for performing the radioactive iodine labeling reaction. The heater is not particularly limited, but, for example, a block heater or an air heater is used.

[Purification step (b)]
The purification step (b) of the present invention is a step of purifying the radioactive iodine-labeled compound represented by the general formula (2) from the reaction solution obtained in the step (a) by HPLC (high performance liquid chromatography). However, specifically, after packing the above reaction solution into a reverse phase column together with an appropriate eluent, eluting from the reverse phase column, and collecting the eluate having a retention time at which the radioactive iodine-labeled compound elutes, And isolating the radioactive iodine-labeled compound.

  According to the present invention, in the purification step (b), a radioactive iodine-labeled compound is eluted within a retention time of 12 minutes or less by using a reverse phase column having a diameter of 7 mm or more as the column and using an aqueous ethanol solution as the eluent. The feature is that it has made it possible. The column temperature during the execution of HPLC is preferably from 10 to 30 ° C.

  In the present invention, from the viewpoint of suppressing concentration of radioactivity in the column, a reverse phase column having an inner diameter of 7 mm or more is used as the reverse phase column, and a reverse phase column having an inner diameter of 7 to 30 mm is more preferably used. . In addition, the length of the reversed-phase column is preferably from 50 to 200 mm, more preferably from 60 to 170 mm, from the viewpoint of shortening the retention time and reducing the pressure loss. As a specific example of the reversed phase column, the silyl group is selected from n-ethyl group, n-butyl group, n-octyl group, n-octadecylsilyl group, phenyl group, cyanopropyl group, trimethylsilyl group, and triacontyl group. And those using a filler modified with a functional group selected from the group consisting of n-octyl group, n-octadecylsilyl group and phenyl group. Such reversed-phase columns can be obtained commercially, for example, from Waters, Phenomenex, Nomura Chemical, Tosoh, Shiseido, YMC. The above columns may be used alone or in combination of two or more. For example, when two or more columns are used in combination, the first column must be shorter than the subsequent columns, and after removing non-radioactive inorganic substances from the reaction solution and concentrating, elute and purify It may function as a pretreatment column for introduction into the column. The length of the pretreatment column is preferably from 10 to 50 mm, more preferably from 10 to 20 mm, from the viewpoint of increasing the efficiency of concentration. The second column functions as a purification column, and it is preferable to use a column longer than the pretreatment column. The length of the purification column is preferably from 50 to 150 mm, more preferably from 100 to 150 mm.

  The eluent used in the present invention contains ethanol and water, and is preferably a mixture of ethanol and a buffered aqueous solution or an aqueous solution of a weak acid alkali metal salt. As the buffer aqueous solution, a phosphate buffer, an acetate buffer, a citrate buffer, a tartrate buffer, a borate buffer, and the like can be used, and among them, an acetate buffer is preferable. These buffers can be prepared from a conjugate acid and a conjugate base. For example, an acetate buffer can be prepared from an aqueous solution obtained by mixing acetic acid and sodium acetate. As the aqueous solution of the alkali metal salt of a weak acid, an aqueous solution of an alkali metal salt of a weak acid such as phosphoric acid, acetic acid, citric acid, tartaric acid, boric acid (for example, a sodium salt or a potassium salt) is used. An aqueous sodium acetate solution is preferred. Further, the pH of the buffered aqueous solution or the aqueous solution of the alkali metal salt of a weak acid is preferably set so as to shorten the elution peak of radioactive iodine-labeled ioflupan and to improve the reproducibility. It is more preferable because the degree of separation between iodine-labeled ioflupane and impurities is improved. Further, by setting the pH to 12 or less, damage to the reversed-phase column can be reduced, which is more preferable. More preferably, the pH is between 4.5 and 8.6. Further, the concentration of ethanol in the eluent is preferably 30 to 75% by volume, more preferably 50 to 70% by volume, based on 100% by volume of the total of ethanol and the buffer aqueous solution.

  Regarding the preparation of a sample of radioactive iodine-labeled ioflupane during HPLC, it is preferable to prepare a solution containing ethanol from the viewpoint of further reducing the radiolysis of radioactive iodine-labeled ioflupane. More preferably, by preparing the ethanol concentration to be 20% by volume or less and performing HPLC, the radiolysis of radioactive iodine-labeled ioflupane can be suppressed without affecting the separation conditions.

  Since the eluate eluted in the step (b) is usually in a high concentration as it is, from the viewpoint of further reducing the radiolysis of radioactive iodine-labeled ioflupane, an appropriate concentration of the eluate in an appropriate diluent at the time of collection into a collection container is used. , And more preferably at the time of elution, to a concentration of 10 GBq / mL or less. The diluent includes a diluent containing ethanol and / or a buffered aqueous solution. As the buffer aqueous solution, those described above as usable for the eluent can be used. The diluent is preferably a mixture of ethanol and acetate buffer, and more preferably the same as the eluent. The dilution may be performed by directly storing the eluate containing the iodine-labeled compound eluted from the reverse phase column in a collection container in which the diluent has been stored in advance.

  The radioiodine-labeled ioflupane obtained in the present invention is finally prepared in various dosage forms such as injections and provided as a preparation. Such a preparation is generally provided in the form of an aqueous solution containing the radioactive iodine-labeled compound of the general formula (2), and the aqueous solution diluted with the diluent may be further diluted, if necessary, for physiological, pharmaceutical, or pharmaceutical purposes. It is prepared by adding various or chemically acceptable additives. For example, in the case of preparing an injection, the additives that can be included include a stabilizer, a pH adjuster, a physiological saline, a solubilizer, and the like. Such an additive may be previously added to the diluent.

  When the radioactive iodine-labeled ioflupane obtained in the present invention is prepared as an injection, a generally used pH range is from pH 2 to 10, preferably from pH 4 to 8, and particularly preferably from pH 4 to 6.

  When the radioactive iodine-labeled ioflupane obtained in the present invention is prepared as an injection, it can be used as an imaging agent used for various diagnoses in the brain, and specifically, in ataxia disease in which striatal striatal dopamine neurons are degenerated. It can be suitably used as an imaging agent for SPECT diagnosis of certain Parkinson's disease and other Parkinson's syndrome and dementia with Lewy bodies.

  Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these contents.

(Examples 1 to 6, Comparative Example 1)
(A) Labeling step
^A 0.1 mol / L aqueous sodium hydroxide solution was added to ¹²³ I obtained by the ¹²⁴ Xe (p, 2p) ¹²³ I reaction to prepare a [ ¹²³ I] sodium iodide solution. To the obtained [ ¹²³ I] sodium iodide solution, an aqueous solution of non-radioactive sodium iodide (NaI in Table 1 shown later) was added. In Examples 1 to 3 and Comparative Example 1, before adding the non-radioactive sodium iodide aqueous solution, and in Examples 4 to 6, after adding the non-radioactive sodium iodide aqueous solution, the solution was concentrated at 120 ° C to adjust the liquid volume. did. Subsequently, an anhydrous ethanol solution of N-ω-fluoropropyl-2β-carbomethoxy-3β- (4-trimethylstannylphenyl) nortropane (hereinafter, SnFP-CT), 50 μL of 30% hydrogen peroxide, 40 μL of 25% sulfuric acid, and After adding 50 μL of a 0.2 mol / L aqueous sodium acetate solution and stirring at room temperature for 10 minutes or more, the reaction was quenched by adding 150 μL of a 30% aqueous sodium pyrosulfite solution and 250 μL of a 0.2 mol / L aqueous sodium acetate solution. In Examples 4 to 6, ethanol was added so that the ethanol concentration became 18% by volume.

(B) Purification Step Examples 1 to 6 were subjected to high-performance liquid chromatography under the following conditions A and Comparative Example 1 under the following conditions B to separate and purify ioflupane ( ¹²³ I). And in Comparative Example 1, a recovery container containing 5 mL of an acetic acid / sodium acetate buffer solution, and in Examples 4 to 6, 75 mL of an acetic acid / sodium acetate buffer solution and 5 mL of ethanol so as to be maintained at 10 GBq / mL or less during elution. Was eluted into a collection container containing the, to obtain a fractionated solution of ioflupane ( ¹²³ I).
<Condition A>
Precolumn: XBridge BEH Prep C18 (manufactured by Waters), 5 μm, φ10 × 10 mm
Column: XBridge BEH Prep C18 (manufactured by Waters), 5 μm, φ10 × 100 mm
Mobile phase: 0.2 mol / L aqueous sodium acetate solution (pH 8.2) / ethanol = 33: 67
Flow rate: 2.0 mL / min Detector: UV 230 nm
Column temperature: 25 ° C
Retention time: 9-11 minutes <Condition B>
Precolumn: Spherisorb ODS2 (manufactured by Waters), 5 μm, φ4.6 × 30 mm
Column: Spherisorb ODS2 (manufactured by Waters), 5 μm, φ4.6 × 250 mm
Mobile phase: 0.2 mol / L aqueous sodium acetate solution (pH 8.2) / ethanol = 33: 67
Flow rate: 0.6 mL / min Detector: UV 230 nm
Column temperature: 25 ° C
Retention time: 14-17 minutes

(C) Formulation step To the aliquot obtained in the above step (b), anhydrous ethanol and acetic acid / sodium acetate buffer were added, and the radioactivity concentration of ioflupane ( ¹²³ I) was determined at the time of the assay (from the start of production). After 27 hours), the mixture was adjusted to be 74 MBq / mL and 5.0% by volume of absolute ethanol, and then filtered through a 0.22 μm-pore-size membrane filter made of polyethersulfone to obtain a washed and sterilized colorless glass syringe-type vial ( (2 mL in volume) and stoppered with a cleaned and sterilized rubber gasket.

[Purity test and radiochemical foreign substance evaluation]
2.3 mL of 99.5% ethanol, 7.3 mL of 0.1 mol / L acetic acid / sodium acetate aqueous solution and 0.4 mL of sodium iodide aqueous solution (1 g of sodium iodide dissolved in water to 100 mL) were added to 40 mg of ioflupane. In addition, the mixture was dissolved to prepare an ioflupan standard solution. Then, Iofurupan ^{(123 I)} and Iofurupan standard solution 1: Take appropriate amount of mixed sample solution in 1, ethyl acetate / acetone / triethylamine mixture (57: 43: 1) as the developing solvent, to about the lower end of the thin layer plate In addition to using the height of 30 mm as the base line, a test was performed by thin-layer chromatography, and the radioactivity on the thin layer was measured using a chromatogram scanner. It was measured. From the result of measuring the radioactivity on the thin layer, the ratio (%) of the radioactivity of ioflupane ( ¹²³ I) (Rf = 0.5 to 0.7) to the total radioactivity on the thin layer was determined. The thin plate was prepared using silica gel for thin layer chromatography (containing a fluorescent agent).

Table 1 shows the results. In Table 1, SOS is the production start time of Iofurupan ⁽¹²³ I). In this example, the production start time is the time at which the preparation of [ ¹²³ I] iodide ion was completed in the above-mentioned (a) labeling step and the concentration was started at 120 ° C. Further, the yield is a value corrected for attenuation. Immediately after the production is immediately after the completion of the (c) formulation step, and the expiration date is 34 to 35 hours after the start of the production. ND indicates that no data has been acquired.

From Table 1, when the radioactivity of [ ¹²³ I] iodide ion used is 200 GBq or more at the production start time, in the case of Comparative Example 1 using a column having a diameter of less than 7 mm, the radiation of the obtained ioflupane ( ¹²³ I). While the chemical purity may not satisfy the specifications before the expiration date, in Examples 1 to 6 using a column having a diameter of 7 mm or more, the purity of the obtained ioflupane ( ¹²³ I) is 95% or more. Could be maintained. Also, from the results of Examples 3 to 6, when the labeled precursor compound of 0.3 mg / mL or more is used, the radioactivity of [ ¹²³ I] iodide ion used is 400 GBq or more at the production start time. In this case, the yield of ioflupane ( ¹²³ I) could be increased to about 50% or more. Therefore, it was shown that the method of the present invention enables large-scale production of high-purity ioflupane.

  This application claims priority based on Japanese Patent Application No. 2017-052700 filed on Mar. 17, 2017, the disclosure of which is incorporated herein in its entirety.

Claims (9)

(A) reacting a labeled precursor compound represented by the following general formula (1) with a radioactive iodide ion to obtain a radioactive iodine-labeled compound represented by the following general formula (2);
(B) purifying the radioactive iodine-labeled compound obtained in the step (a) by high performance liquid chromatography.
The amount of radioactivity of the radioactive iodide ion used in the step (a) is 200 GBq or more at the start of the step (a);
The process (b) is a method for producing radioactive iodine-labeled ioflupane, which is performed using a reversed-phase column having a diameter of 7 mm or more and using an aqueous ethanol solution as an eluent.

(In the above general formula (1), R is a trialkylstannyl substituent having 1 to 6 carbon atoms in the alkyl chain or a triphenylstannyl substituent.)

(In the above general formula (2), X is a radioisotope of iodine.)   The method for producing radioactive iodine-labeled ioflupane according to claim 1, wherein the eluent is a mixture of ethanol and an aqueous solution containing sodium acetate. The eluent in the step (b) is a mixture of ethanol and a buffered aqueous solution or an aqueous solution containing an alkaline salt of a weak acid, and the pH of the aqueous buffer solution or the aqueous solution containing the alkaline salt of a weak acid is 4 to 12. Item 3. The method according to Item 1 or 2. 4. The method according to claim 1, wherein, in the step (a), 0.3 mg / mL or more of the labeled precursor compound is reacted with the radioactive iodide ion in the presence of a solvent. 5. . The production method according to claim 4, wherein in the step (a), the labeled precursor compound is reacted with the radioactive iodide ion in the presence of 0.015 mg / mL or more of non-radioactive iodide ion. The production method according to claim 4 or 5, wherein the radioactivity of the radioactive iodide ion used in the step (a) is 400 GBq or more at the start of the step (a). The eluate containing the radioactive iodine-labeled compound eluted in the step (b) is received in a collection container, and the radioactive iodine-labeled compound is diluted to a concentration of 10 GBq / mL or less. The production method according to the paragraph. The recovery container contains a diluent for diluting the radioactive iodine-labeled compound in advance, and receiving the eluate eluted from the reverse-phase column in the recovery container, the radioiodine-labeled compound Is diluted to a concentration of 10 GBq / mL or less. In the step (b), after the radioactive iodine-labeled compound obtained in the step (a) is prepared so that the ethanol concentration is 20% by volume or less, the purification by the high performance liquid chromatography method is performed. 9. The production method according to any one of 1 to 8.