RU2315624C2 - Method for production of nanocolloid for producing of radiopharmaceutical agents - Google Patents

Abstract

FIELD: pharmaceutical chemistry, radioactive nuclide diagnosis and therapy.

SUBSTANCE: claimed method includes sequential mixing under cooling solutions of sodium perrhenate, gelatin, sodium thiosulfate, and hydrochloric acid at sodium thiosulfate and sodium perrhenate molar ratio of 1.5-3.4. Obtained mixture is heated on boiling water bath under continuous stirring for 10 min, cooled, conditioned for 2-3 h, passed through chromatography column filled with anion exchange resin and containing sterilizing filter. Filtrate is collected up to acidic fraction breakthrough, pre-packed at aseptic conditions into sterile bottles for drugs and stored in refrigerator. Said nanocolloid has 80 % or more particles with size of 2-100 nm; 5 % or less particles with size of <20 nm; nanocolloid solution has storage stability of 6 months or more; radioactive preparation obtained on the base of such nanocolloid has radiochemical purity of 90 % or more wherein said radiochemical purity is kept for not less than 4 hours.

EFFECT: new radiopharmaceutical agents useful in lymphoscintigraphy.

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Description

The invention relates to the field of pharmaceutical chemistry, and in particular to methods for producing colloids for the preparation of radiopharmaceuticals, and can be used as part of the latter in radionuclide diagnostics and therapy.

Hydrosols (nanocolloids), labeled with radionuclides, have found their application in the diagnostic and therapeutic procedures of nuclear medicine, and the decisive factor for success is not the chemical composition of the radiopharmaceutical, but the size of the nanoparticles. It is known, for example, that the optimal contrasting substance for lymphoscintigraphy should have a particle diameter of 20 ÷ 100 nm. Such particles are removed from the tissues at a speed that does not allow them to penetrate into the bloodstream, since getting the drug into the bloodstream makes it impossible to visualize the lymphatic vessels [1]. Therefore, finally, the quality of the nanocolloid is established after the standard procedure for labeling with a radionuclide, for example, technetium-99 m, according to the determination of the radiochemical purity of the radiopharmaceutical and its biological distribution.

A known method of producing antimony sulfide nacloid is as follows: gaseous hydrogen sulfide is bubbled through 100 ml of distilled water (cooled to 0 ° C), then 5 ml of a 3.5% solution of polyvinylpyrrolidone (PVP-mv 40,000) is added to this solution and mixed for 5 minutes, 10 ml of a 1% potassium antimonyl tartrate solution and mix for another 10 minutes. To remove excess hydrogen sulfide, nitrogen is passed through the solution while monitoring the absence of hydrogen sulfide using indicator paper saturated with lead acetate. Next, the solution is sterilized by membrane filtration (0.22 μm) and stored at 0 ° C. The disadvantage of this method is the complexity of the sol preparation technology and the need to use gaseous hydrogen sulfide, as well as the polydispersity of the resulting nanocolloid, which can be found in up to 90% of particles with a diameter of <0.02 μm (20 nm), which has been established by many authors, which leads to significant accumulation of the corresponding drug in the blood and, therefore, makes it impossible to visualize the lymphatic vessels [1].

There is also a method for producing antimony sulfide nacloid described in [3] by preliminary mixing 60 ml of 0.1 mol of a solution of thioacetamide with 10 ml of a 1% potassium antimonyl tartrate solution, followed by the addition of 10 ml of nacolloid solution obtained by the method described in 1]. Next, the mixture is neutralized to a pH of 5-6 0.1 mol. HCl and heated in a water bath under reflux for 6 hours, then cooled to room temperature (25 ° C), Packed in sterile flasks through a membrane filter (0.22 μm) and stored at 0 ° C. The particle size of the obtained nanocolloid is 45 ± 14 nm. The standard procedure for labeling such a colloid with technetium-99 m is also described there, which consists in adding 1.5 ml of sodium pertechnetate solution ( ^99m Tc) to 0.1 ml of 0.1 mol. HCl, heating the resulting mixture in a boiling water bath for 30 minutes, cooling to room temperature (25 ° C) and adding 0.5 ml of acetate or phosphate buffer solution until neutral. The disadvantages of this method: the complexity of the preparation technology of the nanocolloid and the need to use gaseous hydrogen sulfide and subsequently the complexity of the preparation of the radioactive drug in the clinic. In addition, back in the 60s of the last century it was found that antimony is the most toxic element for the body compared to sulfur or rhenium.

A known method of preparing a radiopharmaceutical ^99m TC-sulfide of rhenium colloid described in [4]. 0.5 ml of sodium pertechnetate solution ( ^99m Tc), 0.5 ml of 1.0 M HCl and 0.5 ml of a mixture of sodium thiosulfate and potassium perrenate (19.2 mg KReO ₄ and 80.0 mg Na ₂ S ₂ O ₃ dissolved in 8.0 ml of water for injection) is injected sequentially into a vial containing 1 ml of a 10% gelatin solution. The vial is kept in a boiling water bath for 3-5 minutes, cooled to room temperature and 0.5 ml of phosphate buffered saline is added to obtain a pH of 5.0-6.5. This method involves the precipitation of ^99m Tc in the form of sulfide with rhenium sulfide in the presence of hydrochloric acid, however, in the solution of the preparation obtained by this method, the presence of colloidal sulfur particles was observed on the surface of which the reduced forms of rhenium and technetium-99 m were adsorbed and which had dimensions that were not coinciding with the particle sizes of rhenium sulfide. According to [4], in the preparation obtained as described above, along with the fraction of particles having an average diameter value of 40.3 ± 9.6 nm, the presence of fractions with a particle diameter of 438.6 ± 14.5 nm, as well as larger particles in the range of 650-2200 nm. Moreover, 72.1 ± 5.6% of the ^99m Tc activity is adsorbed by particles whose diameter is> 200 nm, and only 20% of the radioactive particles are suitable for lymphoscintigraphy. Thus, the simultaneous preparation of a nanocolloid and the corresponding radiopharmaceutical leads to a significant scatter in the diameters of the resulting particles, which does not provide the possibility of high-quality scintigraphic studies.

We have not found any methods for producing rhenium heptasulfide nanocolloids in the literature. These circumstances set the authors the task of developing a method for producing a nanocolloid, which provides the possibility of preparing a radiopharmaceutical that is acceptable for lymphoscintigraphy and meets the following requirements:

- at least 80% of the particles must have a size in the range of 20-100 nm;

- the relative content of particles with sizes <20 nm should not exceed 5%;

- the solution of nanocolloid should remain stable during storage for at least 6 months;

- a radioactive preparation obtained on the basis of this nanocolloid should have a radiochemical purity of at least 90%; the indicated level of radiochemical purity must be maintained for at least 3 hours.

The problem is solved in that a method for producing a rhenium heptasulfide nanocolloid by mixing under cooling (5 ° C.) and continuous mixing of solutions of sodium perrenate, gelatin, sodium thiosulfate and hydrochloric acid is proposed. Without stopping stirring, the reaction vessel was placed in a water bath and incubated for 10 minutes, after which it was cooled in a mixture of water with ice or running cold water. Next, the resulting mixture was passed through a chromatographic column containing anion exchange resin and a sterilizing filter (0.22 μm). The resulting solution of nanocolloid is Packed under aseptic conditions in sterile bottles for medical preparations and stored in a refrigerator (2-10 ° C).

The technical result when using the invention is to obtain a nanocolloid, which provides the ability to prepare a radiopharmaceutical acceptable for lymphoscintigraphy, and meets the following requirements:

- at least 80% of the particles have a size in the range of 20-100 nm;

- the relative content of particles with sizes <20 nm does not exceed 5%;

- the solution of nanocolloid remains stable during storage for at least 6 months;

- a radioactive preparation obtained on the basis of this nanocolloid has a radiochemical purity of at least 90%; the indicated level of radiochemical purity is maintained for at least 4 hours.

The invention is illustrated by the following examples:

Example 1. The reaction vessel is placed in a crystallizer with a mixture of water and ice and, with continuous stirring, 12.5 ml of NaReO ₄ solution (2 g / l by Re), 10 ml of gelatin solution (10 wt.%) And 12, are sequentially introduced into the vessel. 5 ml of a solution of Na ₂ S ₂ O ₃ (9.0 g / l Na ₂ S ₂ O ₃ · 5H ₂ O), continue mixing the mixture until it reaches 5 ° C and add 15.0 ml of 1.2 M HCl ( the molar ratio of sodium thiosulfate to sodium perrenate in the reaction mixture is 3.4); the vessel is transferred to a boiling water bath and the mixture is heated with stirring for 10 minutes, then cooled, stirring is stopped and incubated for 2-3 hours; the contents of the reaction vessel are transferred to a chromatographic column filled with anion exchange resin AB-17 in the OH form containing a sterilizing filter (0.22 cm); the filtrate is collected until an acid fraction breakthrough (pH ~ 2), which is controlled by indicator paper. The resulting solution of nanocolloid is Packed under aseptic conditions in sterile bottles for medical preparations and stored in a refrigerator (2-10 ° C). The resulting nanocolloid was analyzed on a Unicor SP setup using dynamic light scattering. The particle size of the nanocolloid was 75 ± 10 nm immediately after preparation and after 6.5 months. The radiochemical purity of the corresponding preparation with technetium-99 m was 93% at the time of preparation and 94.5% 4 hours after preparation. The content of the fraction of particles with sizes <20 nm did not exceed 5%, which was controlled according to the accumulation of ^99m Tc in the blood 1 hour after drug administration to experimental animals.

Example 2. The reaction vessel is placed in a crystallizer with a mixture of water and ice, and with continuous stirring, 25 ml of NaReO ₄ solution (2 g / L by Re), 20 ml of gelatin solution (10 wt.%) And 25 ml of Na solution are successively added to the vessel. ₂ S ₂ O ₃ (4 g / L Na ₂ S ₂ O ₃ · 5H ₂ O), continue to mix the mixture until it reaches 5 ° C and add 30 ml of 1.2 M HCl (molar ratio of sodium thiosulfate to sodium perrenate in the reaction mixture is 1.5); the vessel is transferred to a boiling water bath and the mixture is heated with stirring for 10 minutes, then cooled, stirring is stopped and incubated for 2-3 hours; the contents of the reaction vessel are transferred to a chromatographic column filled with anion exchange resin AB-17 in the OH form containing a sterilizing filter (0.22 μm); the filtrate is collected until an acid fraction breakthrough (pH ~ 2), which is controlled by indicator paper. The resulting solution of nanocolloid is Packed under aseptic conditions in sterile bottles for medical preparations and stored in a refrigerator (2-10 ° C). The resulting nanocolloid was analyzed on a Unicor SP setup using dynamic light scattering. The particle size was 60 ± 10 nm and did not change for 7 months. The radiochemical purity of the corresponding preparation with technetium-99 m was 96% at the time of preparation and 4 hours after preparation. The content of the fraction of particles with sizes <20 nm did not exceed 5%, which was controlled according to the accumulation of ^99m Tc in the blood 1 hour after drug administration to experimental animals.

Example 3. The reaction vessel is placed in a crystallizer with a mixture of water and ice, and with continuous stirring, 30 ml of NaReO ₄ solution (1.5 g / L by Re), 15 ml of gelatin solution (10 wt.%) And 16, are sequentially introduced into the vessel. 5 ml of a solution of Na ₂ S ₂ O ₃ (6.1 g / l Na ₂ S ₂ O ₃ · 5H ₂ O), continue to mix the mixture until it reaches 5 ° C and add 13.5 ml of 2 M HCl (molar ratio the amount of sodium thiosulfate and sodium perrenate in the reaction mixture is 1.7); the vessel is transferred to a boiling water bath and the mixture is heated with stirring for 10 minutes, then cooled, stirring is stopped and incubated for 2-3 hours; the contents of the reaction vessel are transferred to a chromatographic column filled with anion exchange resin AB-17 in the OH form containing a sterilizing filter (0.22 μm); the filtrate is collected until an acid fraction breakthrough (pH ~ 2), which is controlled by indicator paper. The resulting solution of nanocolloid is Packed under aseptic conditions in sterile bottles for medical preparations and stored in a refrigerator (2-10 ° C). The resulting nanocolloid was analyzed on a Unicor SP setup using dynamic light scattering. The particle size was 55 ± 10 nm and did not change after 6 months. The radiochemical purity of the corresponding preparation with technetium-99 m was 95% at the time of preparation and 5 hours after preparation. The content of the fraction of particles with sizes <20 nm did not exceed 5%, which was controlled according to the accumulation of ^99m Tc in the blood 1 hour after drug administration to experimental animals.

Literature

1. Sampson C.V. Textbook of Radiopharmacy Theory and Practice. Vol 3, 2 ^nd ed. London, United Kingdom: Gordon and Breach; 1994: 196.

2. Garzon O.L., Palcos M.C., Radicella R. Int. J. Appl. Radiat. Isot. 16 (1965), 613.

3. Lin Y, Zhang X., Li J. et al. Appl. Radiat. Isot., 58 (2003), 347-352.

4. Tsopelas C.J. Nucl. Med., 42 (2001), 3, 460-466.

Claims (1)

A method for producing rhenium heptasulfide nanocolloid for the preparation of radiopharmaceuticals, characterized in that solutions of sodium perrenate, gelatin, sodium thiosulfate and hydrochloric acid are mixed sequentially with cooling at a molar ratio of sodium thiosulfate and sodium perrenate of 1.5-3.4, then the resulting mixture is heated to boiling water bath with continuous stirring for 10 min, cooled, incubated for 2-3 hours, passed through a chromatographic column filled with anion exchange resin and containing ste the filter, collect the filtrate until the acid fraction is broken through, packaged in aseptic conditions in sterile bottles for medicines and stored in the refrigerator.