JP2006347949A - Drug substance for magnetic particle-containing medicine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drug substance for magnetic particle-containing medicine which can produce with good reproducibility a magnetic particle-containing medicine for diagnosis and medical treatment capable of exhibiting homogenous functional property. <P>SOLUTION: The drug substance for magnetic particle-containing medicine is a frozen body or a dried powder body consisting of a magnetic iron oxide fine particle of which the average particle size is 5-30 nm, the saturation magnetization is 35-90 Am<SP>2</SP>/kg, the coercive force is 0-6.0 kA/m and the coefficient of variation of particle size is 10% or lower; and it can be obtained by producing fine magnetic iron oxide particles, then purifying a colloidal water solution of the magnetic iron oxide fine particles by washing and removing water-soluble salts by-produced from the reaction solution at the time of reaction, with water by the usual method, and freezing it. Furthermore, a dried drug substance for the magnetic particle-containing medicine can be obtained by drying under reduced pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

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.
Furthermore, the present invention relates to a magnetic particle-containing pharmaceutical comprising a complex of the magnetic iron oxide particles and a polysaccharide, protein or dextran.

  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. Magnetic drug substance containing magnetic particles and drug 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 utilize 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 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 fine particles in the drug substance must be 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.

  Usually, magnetic iron oxide fine particles are not once taken out as a drug substance, but following the production of magnetic iron oxide fine particles, a complex with phospholipid, polysaccharide, protein or dextran is prepared. However, in the manufacturing process, it may be unavoidably held in the state of an aqueous dispersion containing magnetic iron oxide fine particles. However, in the state of an aqueous dispersion (colloid aqueous solution) containing magnetic iron oxide fine particles, the growth of bacteria becomes a problem, and it is very difficult to maintain and maintain a sterile state. Furthermore, when transporting in the state of an aqueous dispersion, it is very difficult to guarantee a sterile condition during transport.

  This invention is made | formed in view of the said conventional problem, and makes it a technical subject to provide the magnetic iron oxide microparticles | fine-particles which have a uniform particle size, without using a surface treating agent.

  As a result of intensive studies to solve the above problems, the present inventor has found a condition for adjusting a drug substance containing a magnetic particle that is composed of fine magnetic iron oxide fine particles as a magnetic particle and whose form is a frozen body. .

  That is, the present invention is an active pharmaceutical ingredient containing magnetic particles comprising magnetic iron oxide fine particles having an average particle diameter of 5 to 30 nm and having a frozen form (Invention 1).

The present invention is also the above-mentioned medicinal drug substance containing magnetic particles, wherein the magnetic iron oxide fine particles have a saturation magnetization of 35 to 90 Am ² / kg and a coercive force of 0 to 6.0 kA / m (this book) Invention 2).

  The present invention is also the above-mentioned medicinal drug substance containing magnetic particles, wherein the coefficient of variation of the particle size distribution of the magnetic iron oxide fine particles is 10% or less (Invention 3).

The present invention is also the above-mentioned drug substance containing magnetic particles, wherein the magnetic iron oxide fine particles are a composition MOFe ₂ O ₃ (M is a divalent metal) having a spinel structure (Invention 4).

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 drug substance containing the magnetic particles according to the present invention (Invention 5).

  Further, the present invention is the above-mentioned medicinal drug substance containing magnetic particles comprising the magnetic iron oxide fine particles having an average particle diameter of 5 to 30 nm, the form of which is a dry powder (this book) Invention 6).

  In addition, the present invention is a drug substance containing magnetic particles characterized by being a complex of the magnetic iron oxide particles described above and a phospholipid, polysaccharide, protein or dextran (Invention 7). ).

Since the medicinal drug substance containing magnetic particles according to the present invention is a frozen or lyophilized body of fine magnetic iron oxide particles that can be redispersed in water, the magnetic particles are homogeneously dispersed in a biocompatible substance. A pharmaceutical comprising a composite can be easily synthesized. Furthermore, since the drug substance does not contain a surfactant or the like, its influence on the safety to the living body is extremely small.
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 average particle diameter of the magnetic iron oxide fine particles in the present invention is 5 to 30 nm. If it is less than 5 nm, it is amorphous, and if it exceeds 30 nm, magnetic aggregation tends to occur. Preferably it is 5-20 nm. In addition, when the particle size is 10 nm or less, superparamagnetism is obtained and the coercive force is not preferable.

The magnetic iron oxide fine particles in the present invention are spinel-type ferromagnets MOFe ₂ O ₃ (M is a divalent metal), and the composition when M is Fe is xFeO · Fe ₂ O _3. Represents the content of divalent iron, x = 1 is magnetite with FeO.Fe ₂ O ₃ , x = 0 is maghemite with γ-Fe ₂ O ₃ , and intermediate (x = 0 to 1) spinel iron oxide Is also magnetic iron oxide, and these superparamagnetic iron oxide particles are used.

  In the particle size distribution of the magnetic iron oxide fine particles in the present invention, the value of the coefficient of variation obtained by dividing the standard deviation value by the average particle size is preferably 10% or less, more preferably 8% or less. When it exceeds 10%, a problem occurs in the dispersibility in water, and the problem that the magnetic particles settle over time occurs.

The reason why Mg other than Fe was selected as M in 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. A valent metal can be selected and used according to the purpose.

The magnetic iron oxide fine particles in the present invention are preferably a superparamagnetic material, but the coercive force is preferably 0 to 6.0 kA / m. In the case of a large coercive force exceeding 6.0 kA / m, remanent magnetization occurs and magnetic aggregation is likely to occur. Preferably it is 0.05-4.0 kA / m. The saturation magnetization is preferably 35 to 90 Am ² / kg. When the saturation magnetization is less than 35 Am ² / kg, the magnetism is insufficient, and with spinel iron oxide particles, it is difficult to obtain a magnetization value exceeding 90 Am ² / kg. More preferably, it is 50-85 Am < ² > / kg.

The aseptic condition in the present invention is a drug substance that is negative in both a toxicity test and an endotoxin test. Specifically, the viable cell count is less than 1 × 10 ⁻⁶ / UNIT, and the endotoxin is 5.0 EU / kg or less.

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

  A frozen body 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 freezing the dispersion medium of the purified aqueous colloidal solution.

  The magnetic iron oxide fine particles in the present invention are synthesized by an aqueous solution reaction using an iron salt aqueous solution and an alkali (referred to as a wet method) or a method of heating and reducing iron oxide powder in a reducing gas such as hydrogen (referred to as a dry method). can do.

  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 aqueous dispersion containing magnetic iron oxide fine particles may be washed according to a conventional method. For example, there are a method of washing with ultrapure water by a decantation method, and a method of washing with ultrapure water after solid-liquid separation with a centrifuge.

Next, ultrapure water is added to the aqueous dispersion containing the magnetic iron oxide fine particles and redispersed using an ultrasonic disperser. At this time, it is important to adjust by adding caustic soda or a buffer so that the pH of the aqueous dispersion is 9 or more and less than 12.
When the pH of the aqueous dispersion is less than 9, there is a problem in the dispersion state of the magnetic iron oxide fine particles, and there is a problem in the redispersibility after drying. On the other hand, a pH of 12 or more is not preferable because the amount of dissolved salts is excessive.

Next, the aqueous drug dispersion containing magnetic iron oxide fine particles can be frozen to obtain a sterile drug substance containing magnetic particles. The concentration of the magnetic iron oxide fine particles in the aqueous dispersion before freezing is preferably adjusted to about 5 to 50 mg / ml. When it exceeds 50 mg / ml, the effect of van der Waals force acting between the particles becomes large and aggregation tends 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 freezing condition is preferably left in a freezer at -20 ° C or lower for 5 hours or longer.

  On the other hand, as a method for further drying the frozen body, drying under reduced pressure, in other words freeze drying, is preferable in view of preventing the oxidation of the magnetic particles and redispersibility of the dry powder in water.

  The medicinal drug substance according to the present invention is obtained by adding a frozen body of magnetic iron oxide fine particles to water whose pH is adjusted to 9 or more with caustic soda or a buffer, and dispersing the mixture with an ultrasonic disperser or a homomixer. It is possible to return to the colloidal state (aqueous dispersion) before freezing. The obtained aqueous dispersion containing magnetic iron oxide fine particles preferably has a pH value of 9.0 or more, and preferably has an electric conductivity of 50 to 400 μS.

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

  The magnetic iron oxide fine particles in the medicinal 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 is, for example, a phospholipid, polysaccharide, protein, dextran, or the like, which is a substance used in ordinary medicine.

<Action>
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 adjustment conditions for a frozen or lyophilized body made of superparamagnetic iron oxide particles.

  The medicinal drug substance according to the present invention can be easily redispersed in water and can be stored while maintaining sterility.

  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.

  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 complex, 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. Even if superparamagnetic particles are used, the magnetic properties necessary as a magnetic particle-containing drug can be adjusted.

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

  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 specific surface area value was measured by the BET method.

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 drug substance containing magnetic particles was subjected to sterility testing by membrane filter method and endotoxin testing for the presence of bacterial debris.

  The electrical conductivity of the drug substance containing magnetic particles was measured using an electrical conductivity meter.

  The zeta potential was measured by ELS-6000 (manufactured by Otsuka Electronics).

  The magnetic drug substance containing magnetic particles confirms the occurrence of magnetic aggregation using a permanent magnet having a surface magnetic flux of 10 mT (100 gauss).

Example 1
A 500-ml reaction vessel equipped with a stirrer and a heating device was used, the raw iron salt and caustic soda were special reagent grades, and the water was ion-exchanged water.

(1) Step of synthesizing magnetic iron oxide fine particles 75 ml of an aqueous ferrous chloride solution having a concentration of 1.5 mol and 225 ml of an aqueous ferric chloride solution having a concentration of 1.0 mol are charged into a reaction vessel and stirred to ferrous iron. And a mixed aqueous solution of iron and ferric salt was prepared, and then the temperature was increased by heating. When this mixed iron salt aqueous solution was heated to 60 ° C., it was added to the prepared mixed aqueous solution of 189 ml of caustic soda solution having a concentration of 6.0 mol and 11 ml of pure water while stirring. After the addition was complete, the temperature was maintained at 60 ° C. and stirring was continued for 60 minutes. The product was a black colloidal solution that was sensitive to magnets.
A part of the aqueous colloid solution obtained here was collected, and the powder obtained by freeze-drying the paste obtained by washing and filtering was analyzed. As a result, a spinel type having a BET specific surface area of 92.0 m ² / g and an average particle size of 11 nm The coefficient of variation of the particle size distribution of the primary particles was 7% with the particle powder having a crystal structure. The magnetic iron oxide fine particles had an Fe ²⁺ content of 13.8 mol%, and the magnetic properties were magnetic iron oxide fine particles having a saturation magnetization σs of 64 Am ² / kg and a coercive force Hc of 2.0 kA / m. The aggregate particle diameter was 85 nm.

(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 the black colloidal particles, so the by-product salt is washed with pure water using a decantation method. Then, a 0.1 N aqueous sodium hydroxide solution was added to purify an aqueous black colloid solution having a zeta potential of −55 mV, pH 9.7, and electric conductivity of 210 μS.

(3) Preparation process for drug substance containing magnetic substance (freezing)
The colloidal aqueous solution was filtered under reduced pressure with Nutsche to separate the paste-like magnetic iron oxide fine particles, and then a frozen body was obtained with a prefreezer PFM-1000 (manufactured by Tokyo Rika Kikai Co., Ltd.).
The magnetic properties of the obtained dry powder of magnetic iron oxide fine particles were a BET specific surface area of 92.0 m ² / g, a saturation magnetization σs of 64 Am ² / kg, and a coercive force Hc of 2.0 kA / m.

Example 2
In the step of synthesizing magnetic iron oxide fine particles in the above step (1), 100 ml of an aqueous ferrous chloride solution having a concentration of 1.5 mol, 200 ml of an aqueous solution of 0.5 mol of magnesium sulfate, and a chloride of 1.0 mol Except for using 225 mL of ferric aqueous solution, each of the steps (2) and (3) produced a magnetic particle-containing pharmaceutical drug substance composed of magnetic iron oxide fine particles under the same conditions as in Example 1.

As a result of analyzing the powder thus obtained, it was a particle powder having a spinel crystal structure with an average particle diameter of 10 nm, and the variation coefficient of the particle size distribution was 7%. Further, it is a magnetic iron oxide particle having an Fe ²⁺ content of 8 mol% and an Mg ²⁺ content of 5.5 mol%, a BET specific surface area of 132 m ² / g, and a magnetic property having a saturation magnetization σs of 55 Am ² / kg, The magnetic iron oxide fine particles had a coercive force Hc of 0.8 kA / m.

Example of Use By adding the frozen body of magnetic iron oxide fine particles obtained in Example 1 to water with a pH of 10.0 to which 0.1 N sodium hydroxide aqueous solution is added, and performing a dispersion treatment for about 20 minutes with a homomixer, A colloidal state in which magnetic iron oxide fine particles are dispersed in water can be obtained.
The resulting aqueous colloidal solution had a pH of 9.7 and an electric conductivity of 210 μS.
Furthermore, it was confirmed to be sterile by a membrane filter method. Specifically, the viable cell count was less than 1 × 10 ⁻⁶ / UNIT.

The magnetic substance-containing medicinal drug substance according to the present invention is a monodispersed sterile frozen body or dry powder of magnetic iron oxide fine particles, so that there is no growth of bacteria during storage and it is relatively easy to maintain and manage the sterile state. become. Furthermore, it is possible to easily synthesize a pharmaceutical comprising a composite in which magnetic fine particles are uniformly dispersed in a biocompatible substance, and in the pharmaceutical granulation step, the granulated particles are adjusted by adjusting the aggregate state of the fine particles. The function of a ferromagnet can be imparted to.
In addition, it is a drug substance that does not contain a surfactant or the like on the surface of the magnetic particle, and since it is an ultrafine particle, it can be easily excreted from the body after administration. In addition, it is possible to provide a drug substance that does not cause any problems regarding metabolism and excretion.

Claims (7)

A magnetic particle-containing drug substance comprising magnetic iron oxide fine particles having an average particle diameter of 5 to 30 nm and having a frozen form. Magnetic drug-containing drug substance according to claim 1, wherein the magnetic iron oxide fine particles have a saturation magnetization of 35 to 90 Am ² / kg and a coercive force of 0 to 6.0 kA / m. The magnetic particle-containing medicinal drug substance according to claim 1 or 2, wherein the coefficient of variation of the particle size distribution of the magnetic iron oxide fine particles is 10% or less. Magnetic drug-containing drug substance according to any one of claims 1 to 3, wherein the magnetic iron oxide fine particles are a spinel-structured composition 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 4. The magnetic drug substance containing the drug substance according to any one of claims 1 to 5, wherein the drug substance comprises magnetic iron oxide fine particles having an average particle diameter of 5 to 30 nm, and the form thereof is a dry powder. A magnetic drug substance containing a magnetic particle, which is a complex of the magnetic iron oxide particle according to any one of claims 1 to 6 and a phospholipid, polysaccharide, protein, or dextran.