JP5031979B2 - Medicinal drug substance containing magnetic particles - Google Patents

Description

  The present invention relates to a drug delivery system (hereinafter referred to as DDS) which is a drug delivery method in the medical technical field, CT (computed tomography) diagnosis and thermotherapy used in X-rays, MRI (magnetic resonance), etc. The present invention relates to a drug substance for use in a magnetic particle-containing medicine for the treatment of.

  More specifically, an object of the present invention is to improve performance such as directivity of delivery of the magnetic particle-containing drug to a diseased tissue or cell, contrast sensitivity at the time of diagnosis by CT, and heat generation at the time of thermotherapy. It is an active pharmaceutical ingredient containing magnetic particles.

  In recent years, magnetic particle-containing pharmaceuticals in which magnetic iron oxide fine particles are used as a magnetic substance and complexed with biocompatible substances such as phospholipids, proteins, and water-soluble polymers have been studied (Patent Documents 1 to 5 and the like).

  Further, in order to prepare a monodispersed aqueous solution of magnetic iron oxide fine particles, a method of coating the particle surface with a surface treatment agent such as a surfactant (Patent Document 6), a method of coating an inorganic substance such as Al and Si (Patent Document) 7) or a method of coating with an organometallic polymer (Patent Document 4) is known.

  However, although these use magnetic iron oxide particles, they mainly have a modification function added to the magnetic particles, and the powder properties such as the particle size and magnetic properties of the magnetic iron oxide fine particles and the magnetic particle-containing pharmaceuticals It is hard to say that the relationship between the characteristics and the characteristic factors has been fully elucidated.

  In particular, it is not easy to uniformly disperse and carry fine magnetic iron oxide particles in a biocompatible substance due to the magnetic aggregation of iron oxide particles. Has been used.

  In addition, magnetic iron oxide particles having a large particle size have a high possibility of iron oxide particles remaining in the body after treatment, and it is difficult to say that safety in use can be sufficiently secured.

  Therefore, magnetic particle-containing pharmaceutical raw materials that have homogeneous functionality, such as reagent delivery properties, contrast sensitivity, heat generation performance, etc., and that can generate magnetic particle-containing pharmaceuticals for diagnosis and treatment that can fully perform their functions with high reproducibility. There is a need for drug development.

Japanese Patent Laid-Open No. 3-128331 JP-A-4-52202 JP 7-122410 A JP-T 8-500700 Publication JP-A-11-106391 JP-A-1-4002 JP-A-5-310429

  As described above, in order to obtain a magnetic substance-containing drug having homogeneous characteristics with good reproducibility, the biocompatible substance and the magnetic iron oxide fine particles are uniformly dispersed and mixed at the time of pharmaceutical preparation of the magnetic particle-containing drug. Therefore, the magnetic iron oxide fine particles in the drug substance must be a monodispersed aqueous colloidal solution composed of fine and uniform magnetic iron oxide fine particles.

  However, when a surface treatment agent such as a surfactant is used to disperse the magnetic iron oxide fine particles, the used surface treatment agent remains, and these surface treatment agents are mixed in the obtained magnetic substance-containing medicine. There are problems such as affecting the safety to the living body and inhibiting mixing with the biocompatible substance. Furthermore, complicated treatment is required to remove the surface treatment agent.

  The present invention has been made in view of the above-mentioned conventional problems, and it is a technical problem to provide a monodispersed colloidal sterile aqueous solution of magnetic iron oxide fine particles having a uniform particle size without using a surface treatment agent. To do.

  As a result of intensive studies to solve the above problems, the present inventor has focused on fine magnetic iron oxide particles as magnetic particles, and found the dispersion stability conditions of a monodispersed colloidal aqueous solution composed of superparamagnetic iron oxide particles.

  That is, the present invention is an active pharmaceutical ingredient containing magnetic particles, which is a sterile colloidal aqueous solution in which magnetic iron oxide fine particles having an average particle diameter of 5 to 30 nm are monodispersed.

The magnetic particle-containing pharmaceutical raw material according to claim 1, wherein the magnetic iron oxide fine particles have a saturation magnetization of 50 to 90 Am ² / kg and a coercive force of 0 to 1.6 kA / m. It is a medicine.

The present invention is also the above-mentioned medicinal drug substance containing magnetic particles, wherein the magnetic iron oxide fine particles are a spinel structure composition MOFe ₂ O ₃ (M is a divalent metal).

Further, in the present invention, M of the composition MOFe ₂ O ₃ (M is a divalent metal) is Fe and / or Mg (provided that the sum of Fe and Mg is 1 mol or less relative to 1 mol of Fe ₂ O ₃ ). The magnetic particle-containing medicinal drug substance characterized by the above.

  The present invention also provides any one of the above-described pharmaceutical ingredients containing magnetic particles, wherein the concentration of magnetic iron oxide fine particles in the colloid sterile aqueous solution is 5 to 50 mg / ml.

Since the magnetic substance-containing drug substance according to the present invention is a monodispersed colloidal sterile aqueous solution of fine magnetic iron oxide particles, it is easy to prepare a medicine comprising a composite in which magnetic particles are homogeneously dispersed in a biocompatible substance. Can be synthesized. Furthermore, since the liquid medium is a drug substance that does not contain a surfactant or the like, the influence on the safety to the living body is as small as possible.
In addition, fine magnetic particles can impart a ferromagnetic function to the granulated particles by adjusting the aggregate state of the fine particles in the pharmaceutical granulation step.
In addition, the ultrafine particles can facilitate excretion from the body after administration.

  The configuration of the present invention will be described in more detail as follows.

  The size of the magnetic iron oxide fine particles in the present invention is 5 nm to 30 nm. When the thickness is 5 nm or less, magnetic aggregation tends to occur. Preferably, it is 5 nm to 20 nm. In addition, when the particle size is 10 nm or less, it is superparamagnetic and does not have a coercive force, which is more preferable.

The magnetic iron oxide fine particles in the present invention are spinel-type ferromagnets MOFe ₂ O ₃ (M is a divalent metal), the composition when M is Fe is FexOFe ₂ O ₃ , and x in this composition formula is 2 Represents the content of valence iron, x = 1 is FeOFe ₂ O ₃ and magnetite, x = 0 is γ-Fe ₂ O ₃ and maghemite, and the intermediate (x = 0 to 1) spinel type iron oxide is also magnetic iron oxide These superparamagnetic iron oxide particles are used.

The reason why Mg other than Fe was selected as M of the composition MOFe ₂ O ₃ (M is a divalent metal) of the magnetic iron oxide fine particles in the present invention is that Mg has biocompatibility, but other 2 A valent metal can be selected and used according to the purpose.

The magnetic iron oxide fine particles in the present invention preferably have a coercive force of 0 to 1.6 kA / m. In the case of a large coercive force of 1.6 kA / m or more, residual magnetization is generated, and magnetic aggregation is likely to occur. More preferably, it is 0.05-1.2 kA / m. The saturation magnetization is 50 to 90 Am ² / kg. The saturation magnetization of 50 Am ² / kg or less is insufficient in magnetism, and 90 Am ² / kg or more is difficult to obtain with spinel iron oxide particles. More preferably, it is 55-85 Am < ² > / kg.

  Here, the sterile aqueous solution is an aqueous solution of a drug substance that is negative in both a toxicity test and an endotoxin test.

  Here, the monodispersed colloid means that the so-called magnetic iron oxide fine particles have a narrow particle size distribution, and specifically, is calculated by multiplying the value obtained by dividing the standard deviation of the particle size distribution by the average particle size by 100. It means that the coefficient of variation is 15% or less. When the coefficient of variation exceeds 15%, it is difficult to say that the particle size distribution is uniform. More preferably, it is 12% or less.

  The concentration of the magnetic iron oxide fine particles of the medicinal drug substance containing magnetic particles according to the present invention is preferably 5 to 50 mg / ml. If it exceeds 50 mg / ml, the effect of van der Waals force acting between the particles becomes large and aggregation is likely to occur, which is not preferable. If it is less than 5 mg / ml, the concentration is too thin to be practical. A preferred concentration is 10-40 mg / ml.

  The pH value of the medicinal drug substance containing magnetic particles according to the present invention is preferably 7.0 or more, more preferably 9.0 to 11.0.

  The electric conductivity of the drug substance containing magnetic particles according to the present invention is preferably 100 μS or more.

  Next, a method for producing a magnetic particle medical drug substance according to the present invention will be described.

  A monodispersed aqueous colloidal solution of magnetic iron oxide fine particles can be produced by the following three steps.

  That is, (1) after producing magnetic iron oxide fine particles, (2) purifying a colloidal aqueous solution of magnetic iron oxide fine particles by removing water-soluble by-product salts by-produced during the reaction from the reaction mother liquor by washing with a conventional method. 3) It can be obtained by replacing the dispersion medium of the purified colloidal aqueous solution with ultrapure water.

  The magnetic iron oxide fine particles in the present invention are obtained by an aqueous solution reaction using an iron salt aqueous solution and an alkali (referred to as a wet method), or a method in which iron oxide powder is heated and reduced in a reducing gas such as hydrogen (referred to as a dry method). Can be synthesized.

  In the method of synthesizing the magnetic iron oxide fine particles, synthesis is generally performed by a wet method called a coprecipitation method or an oxidation reaction of ferrous hydroxide colloid.

  In the coprecipitation method, when an alkaline aqueous solution is added to a mixed aqueous solution of 1 mol of ferrous salt aqueous solution Fe (II) and 2 mol of ferric salt aqueous solution Fe (III) while stirring, Fe (II) and 2Fe ( This is a reaction in which the coprecipitation reaction of III) occurs and magnetite particles, which are black spinel type magnetic iron oxide, are generated. When a divalent metal other than Fe, for example, Mg is added in this reaction, spinel-type magnetic iron oxide particles containing Mg are obtained. In addition, since the size of the generated particles can be controlled by reaction conditions such as iron salt concentration and mixing temperature, magnetic iron oxide fine particles can be synthesized by combining these reaction conditions.

  The ferrous hydroxide colloid oxidation reaction method is that when an aqueous alkali solution is added to a ferrous salt aqueous solution, a ferrous hydroxide colloid is formed, and the aqueous solution containing the ferrous hydroxide colloid is heated and stirred. When oxygen-containing gas such as air is ventilated, magnetite particles, which are black magnetic iron oxide, are generated by oxidation reaction of ferrous hydroxide colloid. When a divalent metal other than Fe is added as in the coprecipitation method, spinel iron oxide particles containing the added metal are obtained. Moreover, magnetic iron oxide fine particles can be synthesized by controlling the reaction conditions in combination.

  The colloidal solution containing magnetic iron oxide fine particles may be washed with water according to a conventional method.

  Moreover, after carrying out solid-liquid separation with a centrifuge, it can implement by the method of adding and redispersing an ultrapure water.

  Then, the concentration of the aqueous colloidal solution is adjusted to 5 to 50 mg / ml with ultrapure water to obtain a magnetic particle-containing medicinal drug substance in which magnetic iron oxide fine particles are monodispersed in sterile water.

  The medical drug substance according to the present invention can be used for various applications, for example, for therapeutics such as DDS, which is a drug delivery method, CT diagnosis and thermotherapy used in X-rays, MRI (magnetic resonance) and the like. Etc.

  The magnetic iron oxide fine particles in the medical drug substance according to the present invention can be uniformly dispersed and supported on a biocompatible substance and used for various applications.

  The biocompatible substance referred to in the present invention includes, for example, phospholipids, proteins, water-soluble polymers, and the like, which are substances that are used in ordinary medicine.

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As a result of extensive research, the present inventor has focused on the superparamagnetism of fine magnetic iron oxide particles as magnetic particles, and found the dispersion stability conditions of a monodispersed colloidal aqueous solution composed of superparamagnetic iron oxide particles.

  Superparamagnets are manifested by ferromagnets with zero coercivity. That is, even if the ferromagnetic particles have a single magnetic domain structure, if the particles are large and magnetized by applying an external magnetic field and then released from the external magnetic field, residual magnetization occurs. It decreases to zero and finally magnetizes when an external magnetic field is applied, but no residual magnetization occurs after release from the external magnetic field. This phenomenon is due to thermal disturbance, and such ferromagnetic fine particles are said to be superparamagnetic.

The medical drug substance according to the present invention is a monodispersed colloidal aqueous solution that does not aggregate even when a permanent magnet having a surface magnetic flux of 100 gauss is brought close thereto and is stable for a long time. This seems to be a phenomenon contradictory to the fact that the saturation magnetization of the magnetic iron oxide particles is a ferromagnetic body of 50 to 90 Am ² / kg. However, the saturation magnetization value is a measurement of the magnetic iron oxide particles in powder form. Since it represents the magnetization value per unit weight of time, when this is converted into the magnetization value per particle, the finer the particle, the greater the total number of particles per unit weight, and the magnetization value per particle Is a small value.
Accordingly, the magnetization value per monodispersed superparamagnetic iron oxide particle is naturally small, and it is difficult to be affected by the magnetic aggregation between the particles and the influence of the external magnetic field, so that a stable dispersed state can be maintained.

  The reason why superparamagnetic iron oxide is used as magnetic particles is that iron oxide has biocompatibility, and excretion from the living body becomes easier as fine particles.

  By the way, the magnetic properties as a drug containing magnetic particles are insufficient just by uniformly dispersing the magnetic iron oxide fine particles as the drug substance in the biocompatible substance. Since the iron fine particles are aggregated to form composite particles when granulated as a drug, they exhibit ferromagnetism. This phenomenon can be explained by the well-known phenomenon that even in superparamagnetic particles, when the particles are connected together in a rosary form, shape magnetic anisotropy occurs, the coercive force increases, and the material becomes ferromagnetic. That is, when superparamagnetic iron oxide particles are uniformly dispersed and mixed with a biocompatible substance to form a composite, and then granulated to a desired size, the granulated particles depend on the number and aggregate form of the magnetic particles in the granulated particles. It has been found that the magnetic properties necessary for a pharmaceutical containing magnetic particles can be adjusted even if superparamagnetic particles are used.

  In the case of using the drug substance as a heating element of a pyrogen in cancer thermotherapy, for example, when the magnetic iron oxide microparticles are used as a core, an aggregate composed of a plurality of magnetic iron oxide microparticles is used as a core, and phospholipids and cationic lipids are used. Liposomal composite particles having a bilayer membrane as a shell can be generated and used.

  Hereinafter, the present invention will be described specifically by way of examples. However, the present invention is not limited to these examples.

  For structural analysis of the product, an X-ray diffractometer was used, and the average particle size was calculated from the half width of the X-ray diffraction line (311) using the Scherrer equation.

The particle size distribution was observed with a transmission electron microscope TEM. Furthermore, the average particle diameter and the standard deviation value were obtained by digitizer analysis, and the coefficient of variation was obtained from these values using the following equation.
Coefficient of variation (%) = (standard deviation) × 100 / (average particle diameter)

The Fe ²⁺ content was measured by chelate titration method.

  The magnetic characteristics were measured using a vibrating sample magnetometer VSM in a magnetic field of 10 k / 4π kA / m.

  The product was subjected to sterility testing and endotoxin testing for the presence of debris.

  The electrical conductivity of the product was measured using an electrical conductivity meter.

  The magnetic drug substance containing magnetic particles is checked for the presence of magnetic aggregation using a permanent magnet with a surface magnetic flux of 100 gauss.

Example 1
A 5000 ml reaction vessel equipped with a stirrer and a heating device was used, the raw iron salt and caustic soda were special grade reagents, and the water was ion-exchanged water.

(1) Step of synthesizing superparamagnetic iron oxide particles 500 ml of an aqueous ferrous chloride solution having a concentration of 0.5 mol and 1000 ml of an aqueous ferric chloride solution having a concentration of 0.5 mol are placed in a reaction vessel, and stirred to After adjusting the mixed aqueous solution of iron and ferric salt, the temperature was raised by heating. When this mixed iron salt aqueous solution was heated to 80 ° C., 2300 ml of a 1.0 mol caustic soda aqueous solution prepared in advance was added to the mixed aqueous solution with stirring. After the addition was completed, the temperature was kept at 80 ° C. and stirring was continued for 60 minutes. The product was a black colloidal solution that was sensitive to magnets.
As a result of analyzing a powder obtained by collecting a part of the colloidal aqueous solution obtained and freeze-drying the paste after washing with water, the particle size of the spinel crystal structure having an average particle size of 10 nm is changed. The coefficient was 7%. The magnetic iron oxide particles had an Fe ²⁺ content of 17.5 mol%, and the magnetic properties were superparamagnetic iron oxide particles with a saturation magnetization σs of 68 Am ² / kg and a coercive force Hc of 0.4 kA / m. .

(2) Purification process of colloidal particles The resulting aqueous solution of black colloid contains soluble salts produced as a by-product of the synthesis reaction of black colloidal particles. Therefore, by-product salt is formed by decantation using ion-exchanged water. The black colloid aqueous solution was purified by washing with water.

(3) Refining process of drug substance containing magnetic substance (substitution with ultrapure water)
100 ml of the remaining black colloid aqueous solution collected in order to evaluate the physical properties of the product was collected with good stirring, and the colloid aqueous solution was subjected to solid-liquid separation using a centrifuge to remove the dispersion medium. Thereafter, the same amount of ultrapure water was injected and redispersed using an ultrasonic disperser. This was repeated as 5 cycles, and the dispersion medium of the colloidal aqueous solution was replaced with ultrapure water. Next, ultrapure water is added to the colloidal aqueous solution to adjust the colloidal particle concentration to 22 mg / ml, and 0.1 Z caustic soda aqueous solution is added while dispersing with an ultrasonic disperser to adjust the zeta potential to -55 mV. did. After 60 minutes, the ultrasonic disperser was stopped and the aqueous colloid solution was allowed to stand, and left for 360 minutes.
It was observed that no precipitation occurred in the obtained colloidal aqueous solution and that the surface magnetic flux was not magnetically aggregated using a 100 gauss permanent magnet. This colloidal aqueous solution was tested for toxicity and endotoxin, and both were confirmed to be negative, and 150 ml of a monodispersed colloidal sterile aqueous solution of superparamagnetic iron oxide particles was produced.
The resulting aqueous colloidal solution had a pH of 9.7 and an electric conductivity of 210 μS.

Example 2
(2) except that in the synthesis step of superparamagnetic iron oxide particles in the above step (1), 300 ml of an aqueous ferrous chloride solution having a concentration of 0.5 mol and 200 ml of an aqueous solution of 0.5 mol of magnesium sulfate were used. And each process of (3) produced | generated the drug substance containing a magnetic particle containing the superparamagnetic iron oxide particle with the density | concentration of 20 mg / ml on the same conditions as Example 1. FIG.

As a result of analyzing a powder obtained by freeze-drying a paste obtained by collecting a portion of the obtained aqueous colloid solution, washing with water and filtering, it was found that the particle size distribution coefficient was a spinel type crystal powder having an average particle size of 8 nm. Was 7%. Further, it is magnetic iron oxide particles having an Fe ²⁺ content of 14 mol% and an Mg ²⁺ content of 5.5 mol%, and the magnetic properties are a saturation magnetization σs of 63 Am ² / kg and a coercive force Hc of 0.2 kA / m. The superparamagnetic iron oxide particles.

Further, in the same manner as in Example 1, the dispersion medium liquid was replaced with ultrapure water, and the concentration of the colloidal dispersion liquid was diluted to 20 mg / ml, and at the same time, a 0.1N aqueous sodium hydroxide solution was added to make the zeta potential −45 mV. It was adjusted. Furthermore, it was observed that no magnetic aggregation occurred using a permanent magnet having a surface magnetic flux density of 100 gauss. The colloidal aqueous solution was endotoxin-checked to confirm that it was negative, and 150 ml of a monodispersed colloidal sterile aqueous solution of superparamagnetic iron oxide particles was produced.
The resulting aqueous colloidal solution had a pH of 9.8 and an electric conductivity of 240 μS.

Since the magnetic substance-containing medicinal drug substance according to the present invention is a monodispersed, sterile aqueous solution of magnetic iron oxide fine particles, it is easy to synthesize a drug comprising a composite in which magnetic fine particles are uniformly dispersed in a biocompatible substance. In addition, in the pharmaceutical granulation step, the function of a ferromagnetic material can be imparted to the granulated particles by adjusting the aggregate state of the fine particles.
In addition, since the liquid medium is a drug substance that does not contain a surfactant or the like, and it is an ultrafine particle, it can be easily excreted from the body after administration, so that safety and metabolism after administration to the human body.・ We can provide drug substance that does not cause any problems with excretion.

Claims (5)

A magnetic drug substance containing magnetic particles, which is a sterile colloidal aqueous solution in which magnetic iron oxide fine particles having an average particle diameter of 5 to 30 nm are monodispersed. The magnetic drug substance according to claim 1, wherein the magnetic iron oxide fine particles have a saturation magnetization of 50 to 90 Am ² / kg and a coercive force of 0 to 1.6 kA / m. Magnetic particles containing pharmaceutical drug according to claim 1 or 2, characterized in that the magnetic iron oxide fine particles is a composition of the spinel structure MOFe 2 O _{3 (M} is a divalent metal). M of the composition MOFe ₂ O ₃ (M is a divalent metal) is Fe and / or Mg (however, the sum of Fe and Mg is 1 mol or less with respect to 1 mol of Fe ₂ O ₃ ) The medicinal drug substance containing magnetic particles according to claim 3. The magnetic drug substance containing the drug substance according to any one of claims 1 to 4, wherein the concentration of the magnetic iron oxide fine particles in the colloid sterile aqueous solution is 5 to 50 mg / ml.