JP3414894B2 - Ultrasound contrast agent and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic contrast agent and a method for producing the same, and more particularly to an ultrasonic contrast agent having long-life and uniformly stable bubbles and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, the field of medical diagnostic imaging has made rapid progress. Especially radionuclide images (Radio-nuclide im
aging), ultrasound, and imaging techniques that form images based on information obtained by MRI have begun to develop around 1960, and are most widely used today in medical clinical diagnosis. In addition, CT scanning using X-rays is most popular and used today, and the skeleton and internal tissues of human bodies and animals can be visualized by the action of X-rays.

However, there are some problems in irradiating a human body with X-rays. The first problem is that the internal tissues of the human body are exposed to radiation. Particularly, a sick person is exposed to radiation each time the examination is performed, and thus there is a risk that the patient is exposed to a radiation dose that affects the human body. The second problem is that the irradiated X-rays are accumulated in the human body. Therefore, the exposure dose of X-rays to the human body must be limited to a certain limit. The third problem is that the X-ray examination alone does not always provide satisfactory imaging of organs or organs and blood vessels.

Therefore, the above radionuclide (Radio-nuclide)
) In imaging technology, radioactive materials (eg thallium (T
l)) is injected into a blood vessel as a contrast agent, and the blood vessel is photographed. Therefore, an effective image of the heart can be obtained. However, a high-precision and expensive device is indispensable for imaging the above-mentioned blood vessels, and there is a problem of lacking versatility. Further, an image superior to other medical diagnostic imaging techniques cannot be obtained, and this technique also has a problem that radioactive substances are accumulated in the human body.

On the other hand, ultrasonic waves are currently widely used in the field of medical diagnostic imaging. A medical diagnostic image using ultrasonic waves is that ultrasonic waves are transmitted from the ultrasonic probe to the human body, reflected waves from the human body tissue, that is, ultrasonic echoes are received, and the received ultrasonic echoes are received. An image visualized based on the above. A typical ultrasonic diagnostic apparatus uses one ultrasonic probe. Then, this ultrasonic probe transmits and receives ultrasonic waves. Then, the information of the ultrasonic echo obtained from the ultrasonic probe is sent to the ultrasonic diagnostic apparatus, the ultrasonic diagnostic apparatus performs image creation processing, and the image is output to the monitor. This image allows a doctor or the like to observe the inside of the human body.

The human body has different acoustic characteristics because the basic characteristics, that is, the density, hardness, etc., differ depending on each tissue. Acoustic properties are sound velocity, attenuation, and scattering. The ultrasonic echoes received by the ultrasonic probe are caused by the backscattering properties of human body tissue. Therefore, the image output to the monitor displays the basic characteristics of the human body tissue being measured. On the other hand, abnormal tissue can be easily detected from the image displayed on the monitor because of its different acoustic characteristics. Furthermore, the ultrasonic diagnostic apparatus has the advantages of being inexpensive and safe for the human body.

However, the early ultrasonic diagnostic techniques were
The diagnostic image was unclear. Therefore, due to intensive studies and improvements, ultrasonic diagnostic apparatuses with clear images have become popular in recent years. Furthermore, in recent years, it has become possible to obtain a clearer image by introducing a contrast agent for ultrasonic waves into the bloodstream.

The above-mentioned acoustic characteristics of ultrasonic waves change most greatly at the boundary surfaces of different substances (for example, the interface between solid and liquid, the interface between liquid and gas, etc.). That is, when ultrasonic waves are transmitted to various media, the acoustic characteristics of ultrasonic waves change significantly at the interfaces between different substances. Therefore, the ultrasonic echo from the interface is significantly different from the ultrasonic echoes of other parts, and the image becomes clearer based on the ultrasonic echo from the boundary surface.

Therefore, in order to utilize the above-mentioned ultrasonic characteristics, a contrast agent for ultrasonic waves has recently been used. As the contrast agent for ultrasonic waves, a liquid containing air bubbles in a liquid having excellent ultrasonic reflection characteristics is preferable. Such a contrast agent has an excellent backscattering property and is injected and / or sprayed into a microscopic conduit such as an animal or a human body. As a result, the boundary surface between the tissues becomes clearer and the ultrasonic diagnostic image itself of the tissue (for example, myocardial tissue) becomes clearer than in the case where the contrast agent is not used.

[0010]

However, with regard to the bubble type contrast agent containing bubbles in the liquid as described above, the stability and durability of the bubble diameter and the uniformity of the bubbles, and the toxicity of the bubble embolism are high. Little research has been done on the problem.

According to the literature, when forming bubbles in a liquid,
Bubble diameters of 1-80 μm can be produced (Yasuo Matsuda:
“Present and Future Prospects of Contrast Echo” New Medicine, p.36 ・ 41,
May 1994, Kiyomitsu Ikeoka, et al .: “Effects of contrast bubbles on resistance vascular endothelium” JpnJ Med Ultrasonics Vol.21.
・ 1, p.37 ・ 44,1994).

However, even if bubbles having a diameter of 25 to 80 μm are injected into blood vessels and carried to the lungs by the blood flow, they cannot pass through the minute blood vessels in the lungs. Therefore,
When a bubble-containing contrast agent having a diameter of 25 to 80 μm is used, there is no choice but to observe an ultrasonic echo by in vitro injection.

Further, the micro bubbles having a diameter of 25 to 80 μm are
It can damage microvessels (eg, capillaries).

Therefore, the diameter of the microbubbles of the contrast medium, which remain stable and have a long life in the human body even after passing through the lungs, is 1 to 10 μm.
It is preferably m. In recent years, "ALBUNEX" (Molecu
SanDiego, CA USA manufactured by larBiosystems, Inc.) and lipid coated microbubbles (LIPID-COATED-MACROBUBBLE (LCM))
, Etc. have been developed, but a contrast medium that has been required as a body-injection type contrast medium has not yet been developed. In addition, "AL
"BUNEX" is a 5% human serum albumin membrane with air bubbles enclosing microbubbles having an average particle size of 4 μm.

The present invention has been made in view of the above problems, and an object thereof is to provide a long-lived microbubble-containing ultrasound contrast agent that stably exists in the human body even after passing through the lungs, and a method for producing the same. Is to provide.

[0016]

In order to solve the above problems, an ultrasonic contrast agent and a method for producing the same according to the present invention have the following features.

[0017]

( 1 ) Consists of microbubbles coated with sodium stearate and saponin.

[0019]

( 2 ) Consists of microbubbles having a diameter of 10 μm or less covered with sodium stearate and saponin.

( 3 ) Sodium stearate and saponin
A contrast agent for ultrasound, which comprises microbubbles coated with a mixture of the following and (a) or (b) below.
Ri, (a) stearic acid (b) sodium laurate.

( 4 ) Sodium stearate and saponin
And a mixture of either (a) or (b) below with a hardening agent consisting of calcium chloride or magnesium chloride, and having a diameter of 10 μm coated with the mixture.
an adult Ru ultrasound contrast agents from the microbubbles m, (a) stearic acid (b) sodium laurate.

[0023]

( 5 ) Sodium stearate or stearate
Mixture or steer of sodium formate and saponin
Mixture of sodium phosphate, saponin and stearic acid
Or sodium stearate, saponin and lauric acid
There is a step agitation step of agitating water and gas containing a surfactant composed of any of a mixture with sodium with an agitation device, and a buoyancy separation step of separating bubbles of a minute diameter by a buoyancy difference after agitation. And sodium stearate
Or a mixture of sodium stearate and saponi
Is sodium stearate, saponin and stearic acid
Or a mixture of sodium stearate, saponin and soup
Any of the mixture with sodium laurate latearate
Contrast agent for producing microbubbles coated by
Is a manufacturing method .

( 6 ) In the method for producing an ultrasonic contrast agent according to the above ( 5 ), in the step stirring step, the aqueous solution containing the surfactant is stirred at low power, and then the aqueous solution is left to stand and then again lowered. It includes a low stirring step of repeating stirring with power and a high stirring step of stirring the aqueous solution with high power.

( 7 ) In the method for producing an ultrasonic contrast medium according to ( 5 ) or ( 6 ), the stirring device is a homogenizer or a vibration stirring device.

( 8 ) In the method for producing an ultrasonic contrast agent according to the above ( 5 ), the buoyancy separation step includes a step of leaving the emulsion containing microbubbles produced in the step agitation step, and a step of leaving the emulsion after leaving it in a minute state. The method includes a collecting step of collecting bubbles floating on the liquid surface of the bubble-containing emulsion and a sorting step of sorting the collected bubbles according to bubble size.

( 9 ) In the method for producing an ultrasonic contrast medium according to the above ( 5 ), the bubbles having a minute diameter are bubbles having a diameter of 10 μm or less.

( 10 ) In the method for producing an ultrasonic contrast agent according to the above ( 5 ), the curing agent may be calcium chloride.
Or magnesium chloride is added .

( 11 ) The method for producing a contrast agent for ultrasonic waves according to ( 5 ) above further includes a storage step of refrigerating the microbubbles obtained by buoyancy separation.

The ultrasonic contrast agent of the present invention having the above-described structure is a coating agent for air bubbles, that is, a surfactant as an agent that is oriented and adsorbed at the interface between air bubbles and water, particularly sodium stearate or sodium stearate. By using a mixture of saccharine and saponin, long-term stable microbubbles can be obtained. Furthermore, when calcium chloride or magnesium chloride is added to these, the stability of bubbles is improved.

Further, by setting the diameter of the microbubbles to 10 μm or less, even if the bubbles are carried to the lungs by venous blood flow,
It can pass through the fine blood vessels in the lungs. Therefore,
By injecting into the body and forming an image based on ultrasonic echoes from a heart disease such as myocardial infarction, turbulent blood flow in the heart or tumor blood vessels in the liver, doctors etc. Further, it is possible to more accurately observe human body tissue or heart disease, for example, myocardial infarction, a site where turbulent blood flow in the heart occurs, or a site of tumor disease in the liver. In particular, since minute bubbles can enter the capillaries, early cancer can be detected.

Further, in the method for producing a contrast agent for ultrasonic waves of the present invention, a large amount of micro bubbles can be generated by the step stirring step of stirring the water and the gas containing the surfactant with the stirring device. In addition, in the buoyancy separation step of separating bubbles having a minute diameter by a difference in buoyancy after stirring, bubbles having a desired diameter, that is, 10 μm or less can be separated.

Further, by using the stepwise stirring step as two steps of the low stirring step and the high stirring step, it is possible to efficiently produce the microbubble-containing emulsion containing a large amount of a desired diameter (1 to 10 μm). .

The buoyancy separation step is a step of leaving the emulsion containing the microbubbles generated in the step agitation step, and a collection step of collecting bubbles floating on the liquid surface of the emulsion containing the microbubbles after leaving. By adopting a separation step of separating bubbles according to bubble size, it is possible to separately collect bubbles of a desired size by utilizing the difference in specific gravity between bubbles and water and the difference in specific gravity due to bubble size. That is, it is possible to separately collect bubbles of a desired size by utilizing the difference in floating speed between large bubbles and small bubbles, that is, the difference in buoyancy.

Further, in the method for producing a contrast agent for ultrasonic waves, by using sodium stearate or a mixture of sodium stearate and saponin as the surfactant, it is possible to obtain long-term stable microbubbles. further,
Addition of calcium chloride or magnesium chloride as a hardening agent strengthens the coverage of the bubbles and improves the long-term stability of the bubbles.

In addition, in the method of producing a contrast agent for ultrasonic waves, the storage stability of bubbles is improved by providing a storage step of refrigerating the fine bubbles obtained by buoyancy separation. Further, storage stability is better when storing only air bubbles than when storing air bubbles in the liquid.

In particular, by using sodium stearate and using a homogenizer as a stirrer, it is possible to increase the desired production rate of bubbles of 1 to 10 μm.
Further, by the buoyancy separation, it is possible to remove bubbles having a large diameter, which have a fast floating time, and obtain bubbles having a desired diameter (1 to 10 μm).

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings.

Method for Manufacturing Ultrasonic Contrast Agent The method for manufacturing an ultrasonic contrast agent is roughly divided into two steps as shown in FIG. That is, it has a step stirring step of stirring water to which sodium stearate has been added and a gas such as air by a homogenizer 40 to generate bubbles, and a buoyancy separation step of separating bubbles having a desired diameter after stirring. . Further, the step agitation step has two steps of a low agitation step and a high agitation step.

Stepwise Stirring Process First, the stepwise stirring process will be described.

In the low stirring step, the stirring shaft of the homogenizer 40 is put into an aqueous solution to which a predetermined amount of sodium stearate is added, and the aqueous solution is fed with low power (for example, 10,
(000 rpm) for a predetermined time. After leaving this emulsion for a predetermined time (for example, after several minutes), the above operation is repeated again.

In the high stirring step after the low stirring step, the solution is stirred using a homogenizer 40 with a large power (for example, 20,000 rpm) for a predetermined time, and a large amount of air is separately injected into the solution. .

Note that air may be additionally enclosed in the solution during stirring.

As a result, a white emulsion containing fine bubbles can be obtained by the two-step stirring process.

Although sodium stearate was used in the method of producing the contrast agent for ultrasonic waves, stearates, saponins, alginic acid or salts thereof can be used as other surfactants. Examples of stearates include alkali metal salts such as sodium stearate and potassium stearate, alkaline earth metal salts such as calcium stearate, and ammonium stearate. Further, examples of the alginate include sodium alginate and potassium alginate.

Particularly preferred is sodium stearate or a mixture of sodium stearate and saponin. When sodium stearate is used with a mixture of sodium stearate and saponin,
The stability of bubbles is significantly improved. Note that saponin is a glycoside distributed in the plant kingdom and is a substance whose aqueous solution becomes a foaming liquid. Steroids and triterpene glycosides, and the sugars are generally D-glucose, D-galactose, L-arabinose, and D-xylose.

In addition, any one or a combination of stearic acid, phloxine, crystal violet, polyvinyl alcohol, and sodium laurate may be added to the ultrasonic contrast agent.

Calcium chloride (Ca
When Cl ₂ ) and / or magnesium chloride (MgCl ₂ ) are added to the contrast agent for ultrasound, the long-term stability is excellent. Therefore, control of the disappearance time of the contrast agent in the body,
To improve product retention stability, use CaCl ₂ , MgC
It is effective to add l ₂ .

The gas in the bubbles in the solution is not limited to air, and any gas that is harmless to the human body (for example, nitrogen, oxygen, carbon dioxide) may be used.

Buoyancy Separation Step Next, the buoyancy separation step will be described.

After the high stirring step of the above two-step stirring step, the white emulsion containing fine bubbles is left to stand. Since bubbles have a lower specific gravity than water, they float to the surface of the emulsion. Therefore, the tip of a suction device such as the buret 50 is attached to the liquid surface of the emulsified liquid to collect bubbles on the liquid surface. At that time, some water is sucked into the buret 50 together with the bubbles.

Next, inside the buret 50, the bubbles having a larger diameter have a smaller specific gravity, and thus float up above the buret 50, that is, in the upper layer on the opposite side of the tip, in a short time through a small amount of water. On the other hand, since bubbles having a small diameter have a larger specific gravity than bubbles having a large diameter, it takes time to float and stays near the tip of the buret 50 for a while.

Utilizing the above phenomenon, after the bubbles have been sucked from the emulsion by the buret 50, only the bubbles near the tip of the buret 50 suction port are sucked after a lapse of a predetermined time.
If it is released from the tip of the
10 μm) is obtained. That is, the diameter of the bubbles can be freely controlled by the time for which the bubble-containing emulsion is left in the buret 50 and the release rate of the bubble-containing emulsion from the buret 50.

Storage Bubbles having a desired diameter collected by the buoyancy separation process are stored in a temperature-controlled room. The temperature of the temperature-controlled room during storage is 2
4 ° C is preferred. It can be stored even at room temperature.

[0056]

EXAMPLES Next, specific examples of the ultrasonic contrast agent and the method for producing the same will be shown below. Experimental Example 1 50 mg of dry powdery sodium stearate 50 mg
1 of distilled water was added. Then, this aqueous solution was low-stirred for 30 seconds using a homogenizer (HG30 type manufactured by Hitachi, Ltd.). The stirring power level of the homogenizer at this time is "1" (5,000 rpm). Then, after stirring for 30 seconds, stirring was stopped for 2 minutes and the aqueous solution was allowed to stand. Then, the above stirring is repeated again, that is, 3
Agitation power level "1" (5,000 rpm) for 0 seconds
Then, the aqueous solution was stirred. Next, the stirring power level of the homogenizer was raised to "5" (15,000 rpm), and the aqueous solution was stirred for another 3 minutes. During this high stirring, a large amount of gas was injected into the aqueous solution by a gas injection means separately provided. The stirring power level of the homogenizer is 1 to 10 steps.

After leaving the air bubble-containing emulsion obtained by the above production method (stable gas-in-liquid emulsion) for 45 minutes, the air bubbles were collected using the buret 50 according to the above-mentioned buoyancy separation step, and after leaving it Only the microbubbles having a diameter of 1 to 10 μm at the tip of the buret 50 were discharged and desired microbubbles were collected. The size distribution of the obtained microbubbles is "TM
D350 microscope (manufactured by Nikon Corporation). The obtained microbubble-containing emulsion is a stable gas-in-liquid emulsion that has excellent long-term stability.
lsion). Furthermore, the bubble-containing emulsion was good as a contrast agent for ultrasonic diagnosis.

Experimental Example 2 80 mg of sodium stearate was added to 80 ml of distilled water. Then, this aqueous solution was stirred low for 30 seconds using a homogenizer. The stirring power level of the homogenizer at this time is "2" (7,500 rpm). Then, after stirring for 30 seconds, stirring was stopped for 2 minutes and the aqueous solution was allowed to stand. Then, the aqueous solution was stirred again at the stirring power level "2" (7,500 rpm) for 30 seconds. Next, the stirring power level of the homogenizer was raised to "5" (15,000 rpm), and the aqueous solution was stirred for another 3 minutes. The stirring power level of the homogenizer is 1 to 10 steps.

The bubble-containing emulsion obtained by the above production method was placed in two 50 ml burettes and left at 24 ° C. for 1 hour. Then, bubbles having different diameters were separately collected according to the buoyancy separation step described above. Then, the bubbles collected separately were observed with a microscope. All bubble sizes are 20 μm
It was below.

The amount of distilled water is not limited to 80 ml, and the volume of the aqueous solution may be appropriately increased depending on the foaming state.

Next, the stability of bubbles in the emulsion containing microbubbles will be described. Here, the microbubble-containing emulsion is
It was manufactured according to the above manufacturing method. Below, an experimental example is shown.

Experimental Example 3 The emulsified liquid containing microbubbles obtained according to the above Experimental Example 2 was used.
It was stored under different conditions of 0 ° C and 24 ° C. The bubbles were observed under a microscope and the size distribution was measured by taking a photograph. Four photographs were taken for each sample, and the photographs were taken on a 10 μm scale when photographing the bubble size. The size of the scale was measured with a caliper. 10 μm
The length of the scale corresponds to 6 mm of the picture taken. Therefore, the bubble size was measured in consideration of the bubble size and the scale size.

The bubble size was measured every 1, 2, 3, 4, 6 hours, and the number of bubbles photographed was measured.
The number of bubbles was measured every 1, 2, 3, 4, and 6 hours. The results are shown below. FIG. 1 shows the bubble size distribution after 1 hour has passed since the production of the emulsion containing microbubbles. 2 to 7 are graphs showing the results of Table 1.

[0064]

[Table 1] As is clear from Table 1 and FIGS. 2 to 7, the bubble diameter was 10 μm or less after 6 hours. Also, the number of bubbles and the size of bubbles contained in one photograph differed depending on different storage conditions. The bubble size at 4 ° C was smaller than that at 24 ° C. Moreover, as shown in FIG. 1, the distribution of bubbles was mainly 2 to 3 μm. And, bubbles of 10 μm or more were not included. Also, air bubbles were present for 10 days.

Experimental Example 4 Mixture 3 of powdered sodium stearate and saponin
0 mg was added to 30 ml of distilled water. Here, the weight ratio of sodium stearate and saponin is 1: 1. Then, this aqueous solution was stirred for 1 minute with a homogenizer. The stirring power level of the homogenizer at this time is "3" (10,000 rpm). After stirring for 1 minute, stirring was stopped for 2 minutes and the aqueous solution was left to stand. Then, the aqueous solution was stirred again at the stirring, that is, at the stirring power level "3" (10,000 rpm) for 1 minute. Next, the stirring power level of the homogenizer was raised to "5" (15,000 rpm), and the aqueous solution was stirred for another 2 minutes. The stirring power level of the homogenizer is 1 to 10 steps.

The bubble-containing emulsion obtained by the above production method was yellow. It is derived from saponin.

Next, the bubble-containing emulsion obtained by the above-mentioned production method was placed in a 25 ml buret and kept at 4 ° C. for 1 hour.
It was left refrigerated for 5 minutes. After refrigeration for 1 hour 15 minutes, collect only the bottom 10 ml of the burette. At this point, a micrograph was taken. After that, 10 ml of burette lower layer
The microbubble-containing emulsion of was dispensed into a plurality of test tubes and refrigerated at 4 ° C. Only bubbles were collected and liquid was removed from some microbubble-containing emulsions refrigerated at 4 ° C for 3 hours.
Here, a micrograph of bubbles was taken.

Further, only the fine bubbles from which the liquid has been removed are placed at 4 ° C.
It was refrigerated for another 4 hours. The bubble size distribution was measured after refrigeration for 4 hours. The bubble size was measured using an image processing device manufactured by Fujitsu Limited. The image processing device manufactured by Fujitsu Limited can measure up to 0.4 μm.

Experimental Example 5 Mixture 5 of powdered sodium stearate and saponin
0 mg was added to 50 ml of distilled water, and according to Experimental Example 4, desired microbubbles refrigerated at 4 ° C. for a total of 7 hours were produced. The result is shown in FIG. As is clear from FIG. 8, the size of the bubbles was 0.5 to 5.5 μm, and extremely minute bubbles could be obtained. Further, in the present invention, by refrigerating at 4 ° C., bubbles can exist stably for a long time. The bubbles produced in Experimental Example 4 were stably present for 16 hours when refrigerated at 4 ° C. Also, air bubbles are more likely to exist in the liquid than to be refrigerated and stored.
As described in Experimental Examples 4 and 5, the storage stability of the bubbles is improved by refrigerating and storing only the bubbles.

Experimental Example 6 Mixture of powdered sodium stearate and saponin 5
0 mg is added to 50 ml distilled water. Add 2 ml of 2.5% to 15% CaCl ₂ to the aqueous solution of bubbles.
The aqueous solution (or MgCl ₂ aqueous solution) was added to produce the desired microbubbles. As a result, as is clear from FIG.
The size of the bubbles was 1 μm to 4 μm, the average size was 1.5 μm, and extremely fine bubbles could be obtained (measured with a Coulter Counter). Further, in the present invention, by storing at 24 ° C., it was still stable for up to 9 months. Usually, a holding time from manufacturing and sales to the time of being subjected to an experiment is required, so that it is sufficient if the microbubbles can be stabilized for 60 days or more.

Experimental Example 7 A microbubble dispersion was prepared by the method disclosed in any of Experimental Examples 1 to 6. 18 animals, 30
The prepared 3dose microbubble dispersion liquid was administered to 0 to 400 g of Wistar rats. The 3 dose microbubbles were administered by the following three methods.

(I) 1 ml of iclobubble dispersion was administered per 250 g of rat body weight (ii) 0.5 ml of icrobubble dispersion was administered per 250 g of rat body weight (iii) 0.2 ml of iclobubble per 250 g body weight of rat The dispersion was administered.

Three doses were administered once daily to 18 rats for 14 days, but none of the rats died after 14 days. Furthermore, no obvious abnormality occurred in all rats. These results indicate that the microbubble contrast agent according to the present invention has no fatal harm.

It was found that none of the microbubble dispersions prepared in the above Experimental Examples 1 to 6 was harmful.

Further, in the step stirring step of the above-mentioned manufacturing method, a vibration stirrer may be used instead of the homogenizer. The stepwise stirring method using the vibration stirring device will be described below.

As shown in FIG. 11, tanks 200a, 200
In b, distilled water to which a small amount of the above-mentioned sodium stearate is added and air or a gas such as nitrogen, oxygen, carbon dioxide, etc. are stored, and valves 70a, 7 are provided, respectively.
Vibration agitator 100 (for example, "Vibromixer" manufactured by Cryogenic Industry Co., Ltd.) by pumps 71a and 71b via 0b
Is supplied to. Then, the inflow port 1 of the vibration stirrer 100
A sodium stearate-containing aqueous solution and a gas such as air are sucked from 2a and 12b, and are agitated by the agitator 20 in the conduit 10 by the vibration of the vibration source 30 of the vibration agitator 100. The bubble-containing emulsion obtained by the vibration stirring is discharged from the outlet 14. In addition, the outlet 14
The inlet 12c and the inlet 12c are connected by a pipe, and the outlet 1
The bubble-containing emulsion discharged from No. 4 is sent to the inflow port 12c by the pump 71c, returned to the vibration stirring device 100 again, and stirred again.

When performing stepwise stirring, first, the sodium stearate-containing aqueous phase and the gas such as air are stirred for a predetermined time with low vibration, and then the pumps 71a and 71b are stopped,
The supply of the aqueous solution containing sodium stearate and the gas such as air from the tanks 200a and 200b is stopped, and the bubble-containing emulsion is left for a predetermined time (for example, after several minutes). Then, stirring is performed again with low vibration while the pumps 71a and 71b are stopped. After that, the vibrating agitator is vibrated with high agitation for a predetermined time. As a result, an emulsion containing microbubbles is obtained. The desired microbubbles may be collected separately from the obtained microbubble-containing emulsion by the above-mentioned buoyancy separation method.

In this embodiment, the homogenizer and the vibration stirrer were used in the step stirring step of the above-mentioned manufacturing method. However, the present invention is not limited to this, and as long as bubbles with a diameter of 10 μm or less can be generated, a perforated plate type A sonic atomizer, a squeeze film type ultrasonic atomizer, a water filter, etc. may be used. Also, if you select the optimum frequency of the vibration stirrer,
The microbubble-containing emulsion can be obtained by one-step stirring.

[0079]

INDUSTRIAL APPLICABILITY As described above, the contrast agent for ultrasound of the present invention comprises a mixture of sodium stearate or sodium stearate and saponin, and CaCl ₂ or MgCl ₂ as a curing agent, as a foam coating agent. By using it, long-term stable microbubbles can be obtained.

Further, by setting the diameter of the fine bubbles to be 10 μm or less, even if the bubbles are carried to the lungs by the blood flow, they can pass through the fine blood vessels in the lungs. Therefore, by injecting into the body and forming an image based on ultrasonic echoes from blood vessels or the like, a doctor or the like can more accurately observe a human body tissue (for example, a tumor at an early stage of the liver).

Further, in the method for producing a contrast agent for ultrasonic waves of the present invention, a large amount of fine bubbles can be generated by the step stirring step of stirring the water containing sodium stearate and the gas with the stirring device. In addition, in the buoyancy separation step of separating bubbles having a minute diameter by a difference in buoyancy after stirring, bubbles having a desired diameter, that is, 10 μm or less can be separated.

Further, since the step agitation process is composed of the low agitation process and the high agitation process, the microbubble-containing emulsion containing a large amount of the desired diameter (1 to 10 μm) can be efficiently produced. .

The buoyancy separation step is a step of leaving the emulsion containing microbubbles generated in the step stirring step, and a step of collecting bubbles floating on the surface of the emulsion containing microbubbles after the step of collecting. By adopting a separation step of separating bubbles according to bubble size, it is possible to separately collect bubbles of a desired size by utilizing the difference in specific gravity between bubbles and water and the difference in specific gravity due to bubble size. That is, it is possible to separately collect bubbles of a desired size by utilizing the difference in floating speed between large bubbles and small bubbles, that is, the difference in buoyancy.

Further, in the method for producing an ultrasonic contrast medium, the surfactant is sodium stearate or a mixture of sodium stearate and saponin, whereby long-term stable microbubbles can be obtained. further,
The long-term stability is further improved by adding CaCl ₂ or MgCl ₂ of the above mixture.

Further, in the method for producing an ultrasonic contrast medium, the storage stability of the bubbles is improved by providing the storage step of refrigerating the fine bubbles obtained by the buoyancy separation. Further, storage stability is better when storing only air bubbles than when storing air bubbles in the liquid.

In particular, by using sodium stearate, saponin and CaCl ₂ and using a homogenizer as a stirrer, the desired production rate of bubbles of 1 to 10 μm can be increased. In addition, buoyancy separation removes large-diameter bubbles with a fast ascent time,
It is possible to obtain air bubbles of 10 μm).

Therefore, a clearer image can be obtained by injecting the ultrasound contrast agent of the present invention into a blood vessel or an organ and collecting ultrasound echo information. That is, by using the contrast agent for ultrasonic waves of the present invention containing a bubble in a liquid having excellent ultrasonic wave reflection characteristics, for example, water, etc., the backscattering characteristics are excellent, and it is injected and / or sprayed into a fine conduit of an animal or a human body. As compared with the case where the contrast agent is not used, the boundary surface between the tissues becomes clearer, and the ultrasonic diagnostic image itself of the tissues (for example, hepatocellular carcinoma, colon cancer liver metastasis, etc.) becomes clearer.

[Brief description of drawings]

FIG. 1 is a distribution diagram of bubble sizes 1 hour after the production of a microbubble-containing emulsion produced by the method for producing an ultrasonic contrast agent according to the present invention.

FIG. 2 is a graph showing the relationship between the elapsed time and the number of bubbles when stored at 24 ° C.

FIG. 3 is a graph showing the relationship between the elapsed time and the number of bubbles when stored at 4 ° C.

FIG. 4 is a graph showing the relationship between the elapsed time and the number of bubbles when stored at 24 ° C. and when stored at 4 ° C.

FIG. 5 is a graph showing the relationship between the elapsed time and the size of bubbles when stored at 24 ° C.

FIG. 6 is a graph showing the relationship between the elapsed time and the size of bubbles when stored at 4 ° C.

FIG. 7 is a graph showing the relationship between the elapsed time and the size of bubbles when stored at 24 ° C. and when stored at 4 ° C.

FIG. 8 is a distribution diagram of bubble sizes after the microbubble-containing emulsion produced by the method for producing an ultrasound contrast agent according to the present invention was refrigerated for further 7 hours.

FIG. 9 is a distribution diagram of bubble sizes after the microbubble-containing emulsion produced by the method for producing a contrast agent for ultrasonic waves according to the present invention is further refrigerated after being produced.

FIG. 10 is a process diagram in the case where a homogenizer is used in the step stirring process in the method for producing an ultrasonic contrast agent according to the present invention.

FIG. 11 is a diagram showing an apparatus configuration in the case where vibration stirring is performed in a step stirring step in the method for producing an ultrasonic contrast agent according to the present invention.

[Explanation of symbols]

10 conduits 12a, 12b, 12c Inlet 14 Outlet 20 Stirrer 30 vibration sources 40 homogenizer 50 bullets 70a, 70b, 70c valves 71a, 71b, 71c, 80d Pump 100 Vibration Stirrer 200a, 200b tank

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) A61K 49/00 A61K 47/12 A61K 47/26 B01J 13/02 BIOSIS (STN) CAPLUS (STN) MEDLINE (STN) EMBASE ( STN)

Claims (11)

(57) [Claims] 1. A contrast agent for ultrasonic waves, which comprises microbubbles coated with sodium stearate and saponin. 2. An ultrasonic contrast agent comprising microbubbles having a diameter of 10 μm or less and coated with sodium stearate and saponin. 3. A contrast agent for ultrasonic waves, comprising microbubbles coated with a mixture of sodium stearate, saponin, and either (a) or (b) below. (A) Stearic acid (b) Sodium laurate 4. A mixture of sodium stearate, saponin, and either (a) or (b) below is mixed with a hardening agent composed of calcium chloride or magnesium chloride, and the mixture is coated with a diameter of 10 μm. An ultrasound contrast agent comprising the following micro bubbles. (A) Stearic acid (b) Sodium laurate 5. A surfactant comprising either sodium stearate or a mixture of sodium stearate and saponin, or a mixture of sodium stearate, saponin and stearic acid or a mixture of sodium stearate, saponin and sodium laurate. And a buoyancy separation step of separating bubbles having a minute diameter by a buoyancy difference after stirring, and a step of stirring water and gas containing water with a stirring device, and sodium stearate or sodium stearate and saponi. Ultrasound imaging characterized in that it produces microbubbles coated with either a mixture of sodium stearate, saponin and stearic acid or a mixture of sodium stearate, saponin and sodium laurate stearate. Made of agent Method. 6. The method for producing a contrast agent for ultrasonic waves according to claim 5, wherein in the step stirring step, an aqueous solution containing a surfactant is stirred with low power, and then the aqueous solution is left to stand, and again with low power. A method for producing a contrast agent for ultrasonic waves, comprising: a low stirring step of repeating stirring, and a high stirring step of stirring the aqueous solution with high power. 7. The method for producing an ultrasonic contrast agent according to claim 5, wherein the stirring device is a homogenizer or a vibration stirring device. 8. The method for producing a contrast agent for ultrasonic waves according to claim 5, wherein the buoyancy separation step includes a step of leaving the emulsion containing microbubbles generated in the step agitation step, and a step of containing microbubbles after leaving. A method for producing an ultrasonic contrast agent, comprising: a collecting step of collecting bubbles floating on a liquid surface of an emulsified liquid; and a separating step of separating the collected bubbles according to bubble size. 9. The method for producing an ultrasound contrast agent according to claim 5, wherein the bubbles having a minute diameter are bubbles having a diameter of 10 μm or less. 10. The method for producing an ultrasonic contrast agent according to claim 5, wherein calcium chloride or magnesium chloride is added as the curing agent. 11. The method for producing an ultrasonic contrast agent according to claim 5, further comprising a storage step of refrigerating microbubbles obtained by buoyancy separation. .