JPH10286453A - Water-in-oil microemulsion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare a water-in-oil microemulsion having high safety to a living body by using the ester compd. of a lower alcohol and a higher fatty acid as an oil component and bile acid or its salt as a surfactant and further using an auxiliary activator. SOLUTION: The ester compd. of a 2-6C, preferably 3-4C lower straight chain or branched chain mono- or polyhydric alcohol and a 10-20C, preferably 14-18C straight chain or branched chain satd. or unsatd. fatty acid is, e.g. used as an oil component. Bile acid having >=2 OH groups such as cholic acid, chenodeoxycholic acid or deoxycholic acid or its alkali metallic salt, e.g. used as a surfactant. The ester of a 10-20C, preferably 12-18C fatty aid and sorbitol or glycerol is, e.g. used as an auxiliary activator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-in-oil type (W / O type).
The present invention relates to a microemulsion, and more specifically, in forming a microemulsion, using a bile acid or a salt thereof as a surfactant, using a co-activator in combination, and further using a higher fatty acid ester of a lower alcohol as an oil component. The present invention relates to a water-in-oil microemulsion characterized by being used.

[0002]

2. Description of the Related Art Water-in-oil (W / O) microemulsions have nanometer-sized dispersed particles shorter than the wavelength of light and are extremely fine particles, so that they are used for drug delivery (DDS). Has recently been scattered (see references 1, 2, 3, and 4).

In 1943, it was reported that the addition of a medium-chain alcohol to an ordinary emulsion resulted in a colloidal solution which was almost clear but retained the properties of an emulsion. This is called a microemulsion because it is a finer emulsion than an ordinary emulsion (see Reference 6).

At first, it was thought that this microemulsion was formed when the surface energy was reduced to almost zero by the surfactant and the medium-chain alcohol, but then the micelle swelled and the dispersion medium was encapsulated. Came to be considered.

[0005] Microemulsions differ depending on the water (salt concentration and pH), oil (degree of polarity and chemical structure) and surfactant (HLB and chemical structure) used, but the ratio of water: oil: surfactant is used. Alternatively, it can be formed by appropriately selecting the combination of the properties of the surfactant and the oil to be used.

Conventionally, medium-chain alcohols such as butanol, heptanol, octanol and the like have been used to form microemulsions, but they have drawbacks such as unpleasant odor.

Further, microemulsions have been attempted to be used in drug delivery systems for physiologically active substances which are hardly absorbed transdermally / transmucosally, such as high molecular weight physiologically active peptides and poorly absorbable low molecular weight compounds. . Most of these high-molecular-weight peptides are water-soluble, and many of the poorly-absorbable low-molecular-weight compounds are also water-soluble, and attempts to improve the absorbability by formulating them as W / O-type microemulsions Has been done. Conventional W / O-type microemulsions require the use of a large amount of a surfactant, and thus a microemulsion preparation technique using a surfactant with higher safety is required.

Among the nonionic surfactants, those having an ester bond (such as sorbitan fatty acid esters and glycerin fatty acid esters) as highly safe surfactants
Further, compounds in which polyoxyethylene is ether-bonded to these ester compounds are also known.

[0009] On the other hand, bile salts are present in bile and are important components involved in digestion in the digestive tract of a living body, and their surface activity is already known. Since bile salts are components of in-vivo digestive fluid, they are highly safe when administered to humans, and are expected as components of DDS. However, bile salts have a strong lipophilic moiety due to having a steroid skeleton, and it has a hydroxyl group and a carboxyl group apart from its side chain, so that part has hydrophilicity.
It has a special structure and special properties as a surfactant.

Heretofore, there have been no reports of practically successful preparation of W / O type microemulsions using bile salts. This is thought to be due to the fact that bile salts differ greatly in properties from general surfactant components. Although there is a literature generally describing that bile salts are contained as a component of the W / O type microemulsion (Japanese Patent Application Laid-Open No. 8-505367), there is no specific description and examples are also described. It has not been. Thus, this document merely states the availability of bile salts in microemulsions.

In the case where a microemulsion is formed by using a bile salt as a surfactant and a fatty acid triglyceride or the like as an oil component, according to studies by the present inventors, the bile salt is dissolved in the oil component. Reduces emulsion formation by acting as if a cosurfactant (co-surfactant or co-surfactant), which helps form liquid crystals or dissolves in oil to form reverse micelles, is pulled from the water / oil interface. Or For this reason, it is difficult to prepare a microemulsion using bile salts with fatty acid triglycerides, etc., whose polarity is slightly maintained. Here, if the bile salt is an oil component in which the bile salt is slightly dissolved, the ratio of the enclosed water to the whole system of the microsystem is about 0.01 to 0.1% by properly selecting the co-activator. Preparation of the emulsion is possible. However, the drug needs to be dissolved in water, and therefore, if the proportion of water in the whole system is less than 0.5%, the amount of the drug that can be dissolved becomes extremely small. Even if incorporated, the amount of formulation to be administered will necessarily increase, exceeding the practical range.

[0012]

SUMMARY OF THE INVENTION In the case where a microemulsion is formed by using a bile acid or a salt thereof, which is highly safe for a living body, as a surfactant, the above-mentioned disadvantages have been solved. There is a demand for the development of a microemulsion that is high and has a high ratio of water in which the drug can be dissolved.

[0013]

Means for Solving the Problems In order to prepare a W / O-type microemulsion using bile salts which are highly safe for application to a living body, the present inventors have studied the properties of bile salts and the properties thereof. Focusing on the relationship with the physical properties of the oil, which is the continuous phase of the W / O type microemulsion, as a result of various studies, the use of a specific ester compound as an oil component, and the use of a specific surfactant It has been found that the intended purpose can be achieved by using the active adjuvant in combination, and the present invention has been completed.

That is, the gist of the present invention is to provide a water-in-oil type (W
/ O-type) microemulsions, wherein in forming the microemulsions, an ester compound of a lower alcohol and a higher fatty acid is used as an oil component, a bile acid or a salt thereof is used as a surfactant, and an auxiliary activity is used. A water-in-oil type microemulsion characterized by using an agent in combination.

Hereinafter, the present invention will be described. In the present invention, an ester compound of a lower alcohol and a higher fatty acid is used as the oil component. For example, C2 to C6, preferably C3 to C4 lower linear or branched, monohydric or polyhydric alcohols, and C10 to C20, preferably C14 to C18 linear or branched, saturated or unsaturated fatty acids. And the like. Specific examples include isopropyl myristate, isopropyl palmitate, ethyl linoleate, isopropyl isostearate, butyl stearate and the like. Other low-polarity fatty acid triglycerides, for example, triglycerides composed of C8 to C16 fatty acids can also be used. Since the oil component of the present invention is an ester compound, it is preferable because it has high safety.

In the present invention, bile acids or salts thereof are used as the surfactant. For example, bile acids having two or more hydroxyl groups, specifically, cholic acid, chenodeoxycholic acid, deoxycholic acid, taurocholic acid, taurodeoxycholic acid or glycocholic acid, and alkali metal salts thereof, specifically Sodium salts, potassium salts and the like can be mentioned.

In the present invention, when a bile acid is used, the desired microemulsion can be prepared by emulsification in a buffer containing the above salt under neutral or alkaline conditions.

The co-activator used in the present invention is not particularly limited as long as it can be appropriately dissolved in the above-mentioned oil component, does not form a liquid crystal, and can form a reverse micelle. Examples include esters of C10 to C20, preferably C12 to C18 fatty acids with sorbitol, glycerol, or propylene glycol. Specific examples include mono-fatty acid sorbitan ester, mono-fatty acid mono- or diglycerin ester, mono-fatty acid mono- or dipropylene glycol ester, polyoxyethylene hydrogenated castor oil, and polyoxyethylene alkyl ether. When used, these co-activators may be used alone or in combination.
More than one species can be combined.

The microemulsion of the present invention is a W / O type microparticle containing a drug by adding a bile acid or a salt thereof and a drug to a mixed solution or a solution of an oil component and a co-activator under stirring. An emulsion can be formed.

The proportions of bile acids or salts thereof, co-activators, and water components are as follows. The bile acid (or salt thereof) is selected from the range of 0.1% to 10%, preferably 1.0 to 7%, based on the total amount of bile acid (salt) and co-activator. The ratio of the surfactant to the whole system is 1 to 3
0%, preferably in the range of 5 to 15%. The use ratio of the water component to the whole system is selected from the range of 0.5 to 20%.

The drug content varies depending on the water solubility, ionic strength, and therapeutically necessary amount of the drug, but is 0.001 to 10%, preferably 0.01 to 5%, based on the whole system.
%.

The drug which can be incorporated in the microemulsion of the present invention is particularly preferably a transmucosal poorly absorbable drug, but is not limited thereto. For example, parathyroid hormone, calcitonin, progestin-releasing hormone, insulin, erythropoietin, colony-forming stimulating factor (CS
F), peptidic compounds such as interleukins, interferons, vasopressin; and theophylline, propranolol, methotrexate, cytarabine, diclofenac, isosorbide dinitrate, diltiazem, oxyprenolol, dopamine, flourouracil,
Water-soluble low-molecular compounds such as meclofenoxate, dihydroergotoxine mesylate, bleomycin hydrochloride, neocarzinostatin and the like can be mentioned.

The use of such co-activators in combination with bile salts results in very good physical properties, with dispersed water particles of nanometer size and up to 6% of the total weight of the system. As described above, it is possible to prepare a stable W / O type microemulsion in which a large amount of water, which has not been seen conventionally, is dispersed.

In the present invention, by using a bile acid or a salt thereof as a surfactant in combination with an active aid, the surfactant and the active aid are appropriately dissolved in both water and oil components. And oil, the surfactants contained therein form micelles that easily encapsulate water, and water is sequentially introduced into the micelles by continuing stirring, and the desired W
It is considered that a / O type microemulsion is formed.

In the present invention, when a specific ester compound is used as an oil component, when a microemulsion is prepared using bile salts, triglyceride which has been conventionally used mainly as an oil component is used. The present inventors have succeeded in solving various problems, that is, poor microemulsion formation due to liquid crystal formation, insufficient formation of reverse micelles, extraction of the co-activator from the oil phase by bile salts, and the like.

[0026]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

Example 1 Na Taurocholate (hereinafter NaTC) 0.35% Sorbitan monolaurate (hereinafter SL-10) 9.65% Isotonic phosphate buffer (PBS) 4.5% G-CSF 0.01% Isopropyl myristate (hereinafter referred to as IPM) 100% in total amount First, the entire amount of sodium taurocholate (NaTC) and G-CSF was added to an aqueous isotonic phosphate buffer solution (PBS), followed by stirring to dissolve. Separately, co-activator SL-10 was dissolved and dispersed in IPM. Next, the water component and the oil component in which the respective components were dissolved were mixed, and stirring was continued (10 to 30 minutes) to obtain a clear oily colloid solution. As a result of observing the Tyndall phenomenon, it was confirmed that the optical path glowed blue-white and was a colloidal solution. The particle size is measured using a laser light scattering automatic particle measuring device (Otsuka Electronics: Ar laser output 75 mW,
DLS-7000), 43n
It was confirmed that m microemulsions were formed. Breaking the emulsification, ultra high-speed centrifuge (Beckman Co., Ltd.)
Ultra-high-speed centrifugation at 50,000 rpm or more for 1 hour or more at 50,000 rpm or more, the oil / activator component was separated, the aqueous phase was recovered, and the G-CSF content was measured by RIA. As a result, 75% was recovered. Was.

Example 2 Na Taurocholate (hereinafter NaTC) 0.35% Sorbitan Monolaurate (hereinafter SL-10) 9.65% Isotonic Phosphate Buffer (PBS) 4.0% G-CSF 0.01% Isopropyl myristate (hereinafter referred to as IPM) 100% in total amount First, NaTC and G-CSF were added in PBS to all amounts, and stirred to dissolve. Separately, co-activator SL-10 was dissolved and dispersed in IPM. A water component and an oil component in which the respective components were dissolved were mixed, and stirring was continued (10 to 30 minutes) to obtain a clear oily colloid solution. As a result of observing the Tyndall phenomenon, it was confirmed that the optical path glowed blue-white and was a colloidal solution. As a result of measuring the particle diameter with a laser light scattering automatic particle measuring apparatus (DLS-7000 type), 39
The peak of the particle size distribution was observed at nm and 5100 nm. Since the peak at 39 nm, which occupies most of the distribution, is considered to be a microemulsion and the portion at the peak at 5000 nm is considered to be a normal emulsion portion, the peak is 0.2 μm.
And the filtrate was recovered. When the Tyndall phenomenon of the filtrate was observed, it was observed that the light path glowed blue-white, and the particle size distribution was only a peak at 39 nm, confirming that a microemulsion was formed. The emulsification of the filtrate was destroyed, and ultra-high speed centrifugation was performed in the same manner as in Example 1 to collect G-CSF. As a result, 55% was recovered.

[Example 3] Na cholate (hereinafter NaC) 0.42% Sorbitan monolaurate (hereinafter SL-10) 9.58% Physiological saline solution (hereinafter saline solution) 3.0% Isopropyl myristate ( Hereinafter, IPM) 100% in total amount First, the entire amount of NaC is added to the saline solution, and stirred to dissolve.
Separately, co-activator SL-10 was dissolved and dispersed in IPM. A water component and an oil component in which the respective components were dissolved were mixed, and stirring was continued (10 to 30 minutes) to obtain a clear oily colloid solution. As a result of observing the Tyndall phenomenon, the light path glowed white and it was confirmed that the colloidal solution was used. The particle diameter is measured using a laser light scattering automatic particle measuring device (DLS-7000).
5), 158 nm, 5
Four peaks of 80 nm and 8000 nm in particle size distribution were observed. The peak at 150 nm occupying about 1/4 of the distribution was considered to be a microemulsion, the portion at 5 nm was considered to be micelles, and the portion at 8000 nm was considered to be a normal emulsion portion. A 0.2 μm membrane filtration was performed to recover the filtrate. When the Tyndall phenomenon of the filtrate was observed, it was observed that the light path glowed blue-white, and it was confirmed that a microemulsion was formed.

Example 4 Na Taurocholate (hereinafter NaTC) 0.35% Sorbitan Monolaurate (hereinafter SL-10) 9.65% Isotonic Phosphate Buffer (PBS) 4.5% Erythropoietin 03% Isopropyl myristate (hereinafter IPM) 100% in total amount First, NaTC and erythropoietin were added in total amount to PBS as a water component, and stirred to dissolve. Separately, co-activator SL-
10 was dissolved and dispersed in IPM. A water component and an oil component in which the respective components were dissolved were mixed, and stirring was continued (10 to 30 minutes) to obtain a clear oily colloid solution. As a result of observing the Tyndall phenomenon, it was confirmed that the optical path glowed blue-white and was a colloidal solution. As a result of measuring the particle size with a laser light scattering automatic particle measuring device (DLS-7000 type), a 52 nm microemulsion was formed. Break the emulsification, and use an ultra high-speed centrifuge (Beckman, L8
After ultra-high-speed centrifugation at 50,000 rpm or more at 50,000 rpm or more for 1 hour or more, the oil / activator component was separated, the aqueous phase was recovered, and the content of erythropoietin was measured by RIA. As a result, 105% was recovered. Almost 100% is recovered, and 5% of the excess is R
It is considered to be a quantification error of IA.

Example 5 Na Taurocholate (hereinafter NaTC) 0.3% Polyoxyethylene (10 mol) hydrogenated castor oil (hereinafter HCO-10) 9.7% Isotonic phosphate buffer (hereinafter PBS) 3 0.0% Isopropyl myristate (hereinafter IPM) 100% in total amount First, the whole amount of NaTC was added to the saline solution and stirred to dissolve. Separately, the co-activator HCO-10 is dissolved in IPM,
Dispersed. When a water component and an oil component in which the respective components were dissolved were mixed and stirring was continued (10 to 30 minutes), a clear oily colloid solution was obtained. As a result of observing the Tyndall phenomenon, it was confirmed that the optical path was bluish white and was a colloidal solution. As a result of measuring the particle size with a laser light scattering automatic particle measuring device (DLS-7000 type), 5
nm, 68 nm, 660 nm, and 7000 nm, and four peaks of the particle size distribution were observed. The peak at 71 nm occupying about 1/5 of the distribution is considered to be a microemulsion,
It is considered that the portion at 5 nm is a micelle and the portion at the peak of 660 to 7000 nm is a normal emulsion portion. 0.2
The membrane was filtered through a μm membrane, and the filtrate was collected. When the Tyndall phenomenon of the filtrate was observed, it was observed that the light path glowed blue-white, and it was confirmed that a microemulsion was formed. As a result of particle size measurement using DLS-7000, 5n
Two peaks at m and 60 nm were observed.

Example 6 Na Glycocholate (hereinafter NaGC) 0.42% Sorbitan monolaurate (hereinafter SL-10) 9.58% Physiological saline solution (hereinafter saline) 3.0% Isopropyl myristate (Hereinafter referred to as IPM) 100% in total amount First, the entire amount of NaC was added to the saline solution, followed by stirring to dissolve.
Separately, co-activator SL-10 was dissolved or dispersed in IPM. When a water component and an oil component in which the respective components are dissolved are mixed and stirring is continued (10 to 30 minutes), a clear oily colloid liquid is obtained. As a result of observing the Tyndall phenomenon, the light path glowed white and it was confirmed that the colloidal solution was used. The particle size is measured using a laser light scattering automatic particle measuring device (DLS-70).
As a result of the measurement of the particle size using the “00 type”, 3.6 nm and 65 n
m, 7850 nm, and three peaks of the particle size distribution were observed. The peak at 65 nm occupying about 1/4 of the distribution is considered to be a microemulsion, the 3.6 nm portion is considered to be a micelle, and the 7850 nm peak portion is considered to be a normal emulsion portion. A 0.2 μm membrane filtration was performed to recover the filtrate. When the Tyndall phenomenon of the filtrate was observed, it was observed that the light path glowed blue-white, and it was confirmed that a microemulsion was formed.

Example 7 Na Taurocholate (hereinafter NaTC) 0.2% Polyoxyethylene (10 mol) hydrogenated castor oil (hereinafter HCO-10) 9.8% Physiological saline solution (hereinafter saline solution) 1. 5% Ethylhexyl triglyceride (hereinafter referred to as TEH) 100% in total amount First, the whole amount of NaTC was added to the saline solution and stirred to dissolve. Separately, the co-activator HCO-10 was dissolved and dispersed in TEH. Mix the water component and oil component in which each component is dissolved,
When stirring was continued (10 to 30 minutes), a clear oily colloid liquid was obtained. As a result of observing the Tyndall phenomenon, the light path glowed white and it was confirmed that the colloidal solution was used. The particle size is measured using a laser light scattering automatic particle analyzer (DLS-7).
000 type), the result was 150 nm, 85
Two peaks of 00 nm and a particle size distribution were observed. 0.
A 4 μm membrane filtration was performed to recover the filtrate. When the Tyndall phenomenon of the filtrate was observed, it was observed that the optical path glowed white, and it was confirmed that a microemulsion was formed. As a result of measuring the particle size by DLS-7000, 145
nm peak was observed.

Example 8 Na Glycocholate (hereinafter referred to as NaGC) 0.42% Sorbitan monolaurate (hereinafter referred to as SL-10) 9.58% Physiological saline solution (hereinafter referred to as saline) 3.0% Isopropyl palmitate (Hereinafter referred to as IPP) 100% in total amount First, the entire amount of NaGC was added to the saline solution, followed by stirring to dissolve. Separately, co-activator SL-10 was dissolved and dispersed in IPP. Mix the water component and oil component in which each component is dissolved,
When stirring was continued (10 to 30 minutes), a clear oily colloid liquid was obtained. As a result of observing the Tyndall phenomenon, the light path glowed white and it was confirmed that the colloidal solution was used. The particle size is measured using a laser light scattering automatic particle analyzer (DLS-7).
As a result of measuring the particle size by using
nm, 1200 nm, and 8120 nm, and four or more peaks in the particle size distribution were observed. A 0.45 μm membrane filtration was performed and the filtrate was recovered. When the Tyndall phenomenon of the filtrate was observed, it was observed that the light path glowed blue-white, and it was confirmed that a microemulsion was formed.

[0035]

[Literature]

(1) Ritschel WA; Meth Find Exp Clin Pharmacol, 13
(3) 205-220,1991 (2) PPConstantinides, JP.Scalart, etc.; Proceed Inter
n Symp Control Rel BioactMater, 20 (1993) 184-185, Con
trolled Release Society Inc. (3) Luisi PL et al; Topics in Pharmaceutical Sciences
1983; Elsevier Science Publisher B.V., (1983) (4) Japanese Patent Application No. 6-80598 (5) PCT / US93 / 09916 (WO94 / 086)
10) (6) Hoar TP & Shulman JH; Nature, 152 (102), 1943

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B01J 13/04 B01J 13/02 A (72) Inventor Hironobu Kunieda 4-28-601 Wakabadai, Asahi-ku, Yokohama-shi, Kanagawa Prefecture

Claims (12)

[Claims] 1. A water-in-oil (W / O type) microemulsion, wherein an ester compound of a lower alcohol and a higher fatty acid is used as an oil component when forming the microemulsion, and bile is used as a surfactant. A water-in-oil microemulsion comprising an acid or a salt thereof and a co-activator. 2. The co-activator is selected from the group consisting of mono fatty acid sorbitan esters, mono fatty acid mono or diglycerin esters, mono fatty acid mono or dipropylene glycol esters, polyoxyethylene hydrogenated castor oil and polyoxyethylene alkyl ether. 1
2. The water-in-oil microemulsion according to claim 1, which is at least one species. 3. The bile acid or a salt thereof, wherein the bile acid or a salt thereof is a bile acid having two or more hydroxyl groups or a salt thereof.
The water-in-oil microemulsion described. 4. The water-in-oil microemulsion according to claim 3, wherein the bile acid is cholic acid, chenodeoxycholic acid, deoxycholic acid, taurocholic acid, taurodeoxycholic acid or glycocholic acid. 5. The water-in-oil microemulsion according to claim 1, wherein the bile acid salt is an alkali metal salt. 6. The water-in-oil microemulsion according to claim 5, wherein the alkali metal salt is a sodium salt or a potassium salt. 7. The co-activator is a monofatty acid sorbitan ester whose fatty acid is C10 to C16, or a monofatty acid (mono or di) glycerin ester whose fatty acid is C8.
And mono-fatty acid (mono or di) propylene glycol esters wherein the fatty acid is C8-C1
8, polyoxyethylene hydrogenated castor oil having a polyoxyethylene addition mole number of 5 to 60, and polyoxyethylene alkyl ether having a polyoxyethylene addition mole number of 2 to 40 and an alkyl group of C10 to C10.
The water-in-oil microemulsion according to claim 2, which is one or more co-activators selected from the group consisting of C18. 8. The water-in-oil microemulsion according to claim 1, wherein the lower alcohol constituting the oil component is a C2 to C4 alcohol. 9. The higher fatty acid constituting the oil component is C
The water-in-oil microemulsion according to any one of claims 1 to 8, which is a 14 to C16 fatty acid. 10. The method according to claim 1, wherein the amount of water contained in the water-in-oil microemulsion is 0.5% or more based on the whole system. Water-in-oil microemulsion. 11. The water-in-oil microemulsion according to any one of claims 1 to 10, wherein the water-in-oil microemulsion contains a drug. 12. The water-in-oil microemulsion according to claim 11, wherein the drug is a peptide or a protein physiologically active substance.