KR20070050195A - Heparin coated liposomes to prolong circulation time in bloodstream and preparation method thereof - Google Patents

Abstract

The present invention is to prepare a liposome in which a hydrophilic polymer is bound by binding a negatively charged polymer such as heparin to the surface of a liposome having a positive charge by electrostatic bonding, and more specifically, the structural stability of the liposome in blood. In order to increase the circulation time in the body, negatively charged heparin is bound to the surface of the liposome to increase the body circulation time of the liposome, while reducing the body's toxicity of the anticancer agent and effectively delivering the drug into the tumor tissue. It is about.

Stability, Cycle Time, Liposomes, Heparin, Hydrophilic Polymers

Description

Heparin-coated liposomes to prolong circulation time in bloodstream and preparation method

1 is a graph for observing the particle size change of liposomes in plasma as a result for predicting the stability of liposomes. Comparative Example 1, Comparative Example 2, Example 2;

Figure 2 is a graph showing the distribution of drugs and liposomes in the body after injection of pure drug and liposome formulations in the rat rat via the tail vein.

The present invention relates to a circulating sustained liposome in which a negatively charged hydrophilic polymer such as heparin is bound to the surface of a cationic liposome, and a method for preparing the same, and more particularly, to a liposome that is unstable by adsorption of plasma proteins in blood. Structural stability and liposome formulations improve circulation time in the body by reducing the uptake by reticuloendothelial system as they circulate in the blood (liver and spleen) and improve the circulation time and safely formulate drugs to the heart. The present invention relates to a method for preparing stabilized-internally purified heparin-binding liposomes for reducing the intrinsic toxicity of drugs, and to producing liposomes incorporating anionic polymers for realizing increased pharmacokinetic half-life and increased drug migration into tumor tissues. .

Since liposomes use phospholipids present in the body as main components, they have been widely applied as drug carriers that can carry out efficient drug transfer with excellent biocompatibility [AD Bangham, M. Standish, JC Watkis, J. Mol. Biol. , 13 , 238 (1965). In addition, as a highly toxic anticancer drug, it has the advantage of reducing the inherent toxicity of the drug and preventing serious side effects accompanying it [D. Needham, MW Dewhirst, Adv. Drug Deliver. Rev. , 53 , 285 (2001). In particular, anti-cancer drugs of the anthracycline series have strong toxic effects on the heart and have serious side effects that affect the normal cells outside the heart. Using liposomes to efficiently transport these drugs to cancerous tissues has been reported to reduce the toxicity of drugs and increase the circulation time in the body [DJA Crommelin, L. van Bloois, Int. J. Pharm. , 17 , 135 (1983). However, such liposomes are currently inadequately applied as drug carriers because of structural instability of liposomes due to adsorption of plasma proteins and degradation of lipids by enzymes. Therefore, various methods for improving the stability of liposomes have been introduced. In particular, negatively charged polymers are combined on the surface of liposomes to prevent plasma proteins and adsorption, and the stability and retention time of liposomes in the blood are improved. Research is ongoing to increase [H. Takeuchi, H. Kojima, H. Yamamoto, Y. Kawashima, J. Control. Release , 75 , 83 (2001).

Among the anionic polymers, heparin is a water-soluble substance mainly composed of hydrophilic structures such as sulfone groups, carboxy groups, and hydroxyl groups, and shows biocompatibility with stability against interaction with cells and tissues [ML Walfrom, WH Mcneely , J. AM. Chem. Soc. , 67 , 748 (1945). In addition, strong anti-thrombin Ⅲ binds strongly to prevent the formation of fibrin clot, a clotting substance in the blood, and studies on drug carriers using it as an antithrombogenic drug have been actively conducted. Wirsen, M. Ohrlander, AC Albertsson, Biomaterials , 17 , 1881 (1996), A. Sahli, M. Cansell, J. Tapon-Bretaudiere, D. Letourneur, J. Jozefonvicz, AM Fischer, Colloid Surf. B-Biointerfaces , 10 , 205 (1998), XH Wang, DP Li, WJ Wang, QL Feng, FZ Cui, YX Song, Int. J. Biol. Macromol. , 33 , 95 (2003).

1,2-Disteroyl- sn -glycero-3-phosphoethanolamine-N- [methoxy- (polyethyleneglycol) -2000, in which polyethylene glycol is bound to lipids, in recent cases of liposome development to improve stability in the body Research on the production of structurally stable liposomes from (DSPE-mPEG2000) has been published. [B. Ceh, M. Winterhalter, PM Frederik, JJ Vallner, DD Lasic, Adv. Drug Deliv. Rev. , 24 , 3356 (1997). The preparation of liposomes using methoxy polyethylene glycol 2000 according to the prior arts has been a suitable method for improving formulation stability and circulation time [B. Ceh, M. Winterhalter, PM Frederik, JJ Vallner, DD Lasic, Adv. Drug Deliv. Rev. , 24 , 3356 (1997). However, the current medical treatment is still a problem about the toxicity of the drug caused by liposomes, there is an active discussion about how to improve the stability and circulation time of liposomes.

Therefore, it is urgent to develop a formulation for lowering the biodistribution of the drug to tissues other than tumor tissues, which greatly improves stability and reduces body residence time and toxicity compared to liposomes currently used medically. It is urgent to develop a formulation that is independent of the drug and improves the circulation half-life of the drug to continuously maintain the effective therapeutic concentration of the drug in the body and to concentrate the drug only on the target tumor tissue.

In this regard, the present inventors studied to develop liposomes that can improve liposome stability in the body and concentrate on tumor tissues while continuously circulating to induce release of drugs. As a result, heparin was ion-bonded to the surface of the cationic liposome, resulting in a strong negative charge on the surface of the liposome, which reduced plasma protein and adsorption, resulting in increased stability and circulation time in the body. It became.

Therefore, the present invention modifies heparin, a polymer having a strong anion on the surface of the lipid membrane of liposomes to increase the stability and circulation time in the blood, and stabilizes the plasma protein and adsorption-internal circulation liposomes with low adsorption and a method of preparing the same. The purpose is to provide.

The present invention is characterized by liposomes characterized in that heparin or a derivative thereof having a weight average molecular weight of 1000 to 300,000 is modified on a liposome surface.

In addition, the present invention has another feature of an injection drug in which any hydrophobic drug selected from anthracycline-based drugs, alkaloid-based drugs, paclitaxel-based drugs and derivatives thereof is encapsulated in the liposomes.

Hereinafter, the present invention will be described in detail.

In the present invention, heparin can be separated and extracted from various animal tissues or recombinant heparin (recombinant heparin) can be used. Most of the heparin presently used for this purpose is separated from porcine mesangial membranes, and the separation process includes hydrolysis of the mucosa and extraction of heparin. In particular, the heparin molecular weight of the present invention is in the range of 1000 to 300,000. Therefore, low molecular weight heparin (molecular weight heparin) having a molecular weight of 1,000 to 6,000 or high molecular weight heparin (molecular weight heparin) having a molecular weight of 6,000 to 100,000 can be used. If the molecular weight is less than the above range, there is a problem that heparin is not bonded to the liposome surface, and if the molecular weight exceeds the above range, there is a problem that the stability of the liposome structure is inferior. Also preferably, heparin having a weight average molecular weight of 3,000 to 100,000 is used. As used herein, "heparin" is meant to include the heparin, fragments of the heparin, salts of the heparin or derivatives of the heparin.

In the present invention, by modifying the surface of the liposomes with heparin provides a circulating sustained liposomes showing anionic properties improved blood stability and circulation time. As used herein, "surface modification" means that the surface is coated with ionic bonds on the surface with strong anionic heparin. In addition, the "in vivo circulation sustained-type" liposome as used herein is a liposome modified by the heparin as a modified liposome on the surface of the liposome. Means liposomes. The heparin is 1 to 60 parts by weight, preferably 30 to 60 parts by weight, based on 100 parts by weight of the lipid forming liposome. If heparin is present below the above range, the anionicity of the surface of the liposome is not sufficient, so there is concern about the adsorption of plasma proteins in the blood, and the effect of improving stability and circulation time is not great, and the surface area of the liposome is limited even if it exceeds the above range. As a result, the anionic enhancement effect of liposomes no longer occurs. In addition, the average particle diameter of the liposome is 30 to 200 nm, preferably 90 to 150 nm. If the mean particle size of the liposome exceeds the above range, uptake occurs by the reticuloendothelial system in the organ, ie, the liver or spleen during circulation, and if the liposome is below the above range, the amount of drug delivered to the target site ( drug payload) is insufficient.

The lipid constituting the liposome of the present invention as the lipid for forming the liposome is not particularly limited, and may be a known lipid. Examples of the lipid include phospholipids, glycolipids, fatty acids, dialkyl dimethylammnonium, polyglycerol alkyl ethers, polyoxyethylene alkyl ethers, alkylglycosides, alkylmethylglucamides, alkyl sucrose esters, Long-chain alkylamines or long-chain fatty acid hydrazides such as amphiphilic block copolymers such as dioxypolyoxyethylene ether and dialkyl polyglycerol ether, and polyoxyethylene-polylactic acid.

As the phospholipid, for example, phosphatidylcholine (soy phosphatidylcholine, egg yolk phosphatidylcholine, bovine phosphatidylcholine, dilauroylphosphatidylcholine, dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine or distearoylphosphatidylcholine, etc.), phosphatidylethanolamine Lauroyl phosphatidyl ethanolamine, dimyristoyl phosphatidyl ethanol amine, dipalmitoyl phosphatidyl ethanol amine or distearoyl phosphatidyl ethanol amine, dioleoyl phosphatidyl ethanol amine, etc.), phosphatidylserine (dilauroyl phosphatidyl serine, di Myristoylphosphatidylserine, dipalmitoylphosphatidylserine or distearoylphosphatidylserine, etc.), phosphatidic acid, phosphatidylglycerol (dilauroylphosphatidylglycerol, dimyristoylphosphatidylglycerol, dipalmitoylphosphatidylglycerol or distea in Ylphosphatidylglycerol, etc.), phosphatidyl inositol (dilauroylphosphatidyl inositol, dimyristoyl phosphatidylinositol, dipalmitoyl phosphatidylinositol or distearoylphosphatidyl inositol, etc.), risphophosphidylcholine, sphingomyelin, yolk lecithin, soybean lecithin Or natural or synthetic phospholipids such as hydrogenated phospholipids.

As said glycolipid, glycerol glycolipid, sphingolipid glycolipid, etc. are mentioned, for example. Examples of the glycerol glycolipids include digalactosyldiglycerides (digalactosyldilauroylglycerides, digalactosyldimyristoylglycerides, digalactosyldipalmitoylglycerides or digalactosyldistearoylglycerides, and the like) or galactosyldi Glycerides (galactosyl dilauroyl glyceride, galactosyl dimyristoyl glyceride, galactosyl dipalmitoyl glyceride, galactosyl distearoyl glyceride, etc.) etc. are mentioned. Examples of the sphingoglycolipids include galactosyl selecbroside, lactosyl selecbroside, and gangloside.

Examples of the sterols include cholesterol, cholesterol hexasuccinate, 3β- [N- (N '(N', N'-dimethylaminoethane) carbamoyl] cholesterol, ergosterol or lanosterol, and the like. It is preferable to contain 20-45 mol% in forming lipids. If the ratio of sterol is out of the above range, the stability of the liposome is lowered and there is a problem in the encapsulation of the drug.

Moreover, as said dialkyl dimethyl ammonium, dioctadecyl dimethyl ammonium (bromide salt), dialkyl dimethyl ammonium propane, dialkyl trimethyl ammonium propane, etc. are mentioned, for example.

The liposome forming lipids can be used alone or in combination of two or more thereof.

In addition, although the charge of the liposomes bound to heparin is not necessarily limited, cationic liposomes capable of increasing the ionic binding force between the heparin and the liposomes are preferable. For this purpose, the liposome-forming lipid preferably contains 10 to 30 mol% of a dialkyldimethylammonium, dioleoylphosphatidylethanolamine, dioleoyldialkyltrimethylammoniumpropane, or dioleoyldialkyldimethylammonium propane as a cationic lipid. . If the cationic lipid is out of this range, stability problems such as precipitation of liposomes occur.

In addition, one of the preferred embodiments of the present invention is to use a liposome composition composed of phosphatidylcholine, which is effective for the formation and stability of liposomes, dimethyldioctadecylammonium (bromide salt) having cholesterol and cationicity.

The preparation method of liposomes before modifying heparin of the present invention can be prepared by various known techniques. One of the preferred methods for preparing liposomes before modifying the heparin of the present invention is not limited to the reversed phase evaporation method described below.

First, the lipid components capable of forming liposomes are mixed. The liposome-forming lipid preferably contains cationic lipids as described above. After dissolving the mixed lipid component in a solvent capable of dissolving lipids such as chloroform, the chloroform is distilled off using an evaporative condenser to form a thin lipid film. Thereafter, a solution such as ammonium sulfate (Ammonium Sulfate), which may play a role of drug loading due to the difference in concentration, is added to hydrate the lipid membrane to form liposomes. The liposome is subjected to reduced pressure extrusion to prepare liposomes having an average particle diameter of 30 to 200 nm.

Next, the drug is encapsulated in liposomes. “Entrapping” herein means that the compound is encapsulated in the central aqueous compartment of the liposome, in an aqueous space between the liposome lipid bilayers or within the bilayer itself. The circulating sustained liposome of the present invention is an anthracycline-based drug (doxorubicin, epirubicin, hirubicin, daunorubicin, esorubicin, idarubicin, etc.) which is generally used as an anti-cancer drug for hydrophobic injection. Drugs, paclitaxel-based drugs, and pharmacologically acceptable salts and acids thereof are advantageous for encapsulation, but are not particularly limited thereto. Anthracycline-based drugs such as doxorubicin have the characteristic of encapsulating drugs by forming a precipitate with ammonium sulfate in liposomes. The efficiency of encapsulation in liposomes of the drug ranges from 80 to 100%.

The drug-encapsulated liposome, preferably the drug-encapsulated cationic liposome and heparin of the present invention is mixed with 1 to 60 parts by weight with respect to 100 parts by weight of liposome-forming lipid, and stirred at 4 ° C. for 24 hours. The reason for stirring at 4 ° C is to maximize the stability of liposomes and to bind heparin. Heparin not bound with the liposomes is removed using gel permeation chromatography.

The liposomes are used alone or in combination with conventional carriers in the pharmaceutical field as injections, for example subcutaneous injection, intravenous injection, intramuscular injection or thoracic injection. Injections prepared using the circulating sustained liposomes of the present invention may exhibit pharmacological activity equivalent to or better than that of the pure drug, even if less than 30% of the pure drug is used.

Hereinafter, the present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Preparation Example 1 Preparation of Cationic Liposomes

L-a-phosphatidylcholine (HSPC), cholesterol (CHOL), and dimethyldioctadecylammonium (DDAB) were mixed at a molar ratio of 70:30:20 as liposome-forming lipid components. Thereafter, chloroform was used to dissolve L-a-phosphatidylcholine, cholesterol, and dimethyldioctadecylammonium, and then the solvent was distilled off using an evaporative condenser to form a thin lipid membrane. Next, 50 ml of a 250 mM ammonium sulfate solution was added to hydrate the formed lipid membrane to prepare a liposome. After completion of the hydration process, the size of the liposome was formed to about 100 nm using a pressure extruder, and residual lipids and ammonium sulfate were removed by membrane permeation.

Production Example  2: heparin Combined  Preparation of Biocirculation Sustained Liposomes

Heparin (HEP) 5 mg / ㎖ H ₂ O was mixed on the surface of the liposome prepared in Preparation Example 1 and stirred at 4 ° C for 24 hours. The heparin used had a characteristic of having a molecular weight of 3000 or less, and the mixed amount of heparin was stirred by mixing 30 parts by weight based on 100 parts by weight of the total liposome-forming lipid. Gel permeation chromatography was then used to remove uncoated heparin on the liposome surface.

Comparative Example 1

A liposome was prepared in the same manner as in Preparation Example 1, using La-phosphatidylcholine (HSPC) and cholesterol (CHOL) at a 70:30 molar ratio, without using dimethyldioctadecylammonium (DDAB) as a liposome lipid component. It was.

Comparative Example 2

In the same manner as in Preparation Example 1, except 1,2-disteroyl-sn-glycero-3-phosphoethanolamine-N- [methoxy-polyethyleneglycol)-instead of dimethyldioctadecylammonium (DDAB)- La-Phosphatidylcholine, Cholesterol, 1,2-Disteroyl-sn-glycero-3-phosphoethanolamine-N- [methoxy-polyethyleneglycol) -2000] (DSPE-mPEG) -mPEG) liposomes were prepared in a mass ratio of 3: 1: 1.

Experimental Example 1

Particle sizes and surface charges of Preparation Examples 1 and 2 and Comparative Examples 1 and 2 were measured using a particle size analyzer (ELS-8000, Otus-ka, Japan) (L. Zhu, RA Seburg, EW Tsai, J. Pharm). Biomed.Anal. , 8 (2005)). Particle sizes in the range of 90 to 120 nm are shown in all preparation and comparative examples. In addition, Preparation Example 1 exhibited a cationic property, it was confirmed that the circulating sustained liposome of Preparation Example 2 in which heparin was modified to the liposome of Preparation Example 1 shows a strong anionicity compared to Comparative Examples 1 and 2.

division ingredient Particle size (nm) Z-potential (mV) Comparative Example 1 HSPC: CHOL 98.8 -3.88 Comparative Example 2 HSPC: CHOL: DSPE-mPEG 96.3 0.13 Preparation Example 1 HSPC: CHOL: DDAB 91.2 14.02 Preparation Example 2 HSPC: CHOL: DDAB + HEP 101.2 -42.12

Experimental Example 2

In order to measure the amount of heparin coated on the liposome surface, 2 ml of toluidine blue solution was added to 1 ml of the circulating continuous liposome solution prepared in Preparation Example 2, and the amount of toluidine blue solution and adsorbed heparin was measured by an ultraviolet spectrophotometer. (Wavelength 673 nm). The amount of heparin adsorbed on the liposome surface was 2.8 mg / ml, and the adsorption efficiency was 92%.

Experimental Example 3

In order to measure the liposome particle stability in the blood, the bovine serum solution and the liposomes prepared in Preparation Example 2 and Comparative Examples 1 and 2 were mixed at a volume ratio of 1: 1 and maintained at 37 ° C., followed by liposome particles over time. The change in size is measured and the results are shown in FIG. 1. As shown in Figure 1, heparin-coated liposomes according to the present invention of Preparation Example 2 compared to Comparative Example 1 was confirmed that does not show a change in particle size in bovine serum. However, the PEG-bound liposome of Comparative Example 2 did not show a significant difference from the heparin-bound liposome of Preparation Example 2. Thus, PEG and heparin both prevent the adsorption of plasma proteins in the blood. However, this is only an in vitro experiment, and since the heparin-bound liposome of Preparation Example 2 reduced the adsorption of plasma proteins than the PEG-bound liposome of Comparative Example 2, these in vivo experiment results are shown in Experimental Example 4 below. .

Preparation Example 3 Preparation of Liposomal Injection

The liposome prepared in Preparation Example 2 and a doxorubicin mixed solution of doxorubicin dissolved at 2 mg / ml in sucrose (10% w / v) were mixed at a volume ratio of 1: 1, and reacted at 60 ° C. for 2 hours. Doxorubicin not contained in liposomes in the mixed solution was removed by membrane dialysis to prepare a heparin-coated liposome injection (HSPC: CHOL: DDAB + HEP).

In addition, an injection using a liposome of Comparative Example 1 (HSPC: CHOL) and an injection using a liposome of Comparative Example 2 (HSPC: CHOL: DSPE-mPEG) were prepared using a doxorubicin mixed solution in the same manner as the above method.

Experimental Example 4: Pharmacokinetic Experiment

In order to observe the circulating time of liposomes, pure drug and liposome solution were administered to the C57BL / 6 experimental rats through the tail vein, and blood was collected by time to measure the concentration of drug encapsulated in liposomes. Pharmacokinetic results were calculated as. The pharmacokinetic results were used to confirm the circulation time of the drug. The concentration of drug in the liposome was measured by diluting the blood sampled with saline, and centrifuging the supernatant. The supernatant was diluted with 60 mM ethylenediaminetetraacetic acid (EDTA) solution and 50 mM N-2-hydroxyethylpiperazine-N'-. The hop light intensity of the drug was measured by dilution with 2-ethanesulfonic acid (HEPES) solution. The fluorescence intensity was measured using an ultraviolet spectrophotometer and measured at a wavelength of 490 nm of the drug. The pharmacokinetic results calculated in the above experiments are shown in Table 2.

Pure doxorubicin Injection using liposome of Comparative Example 1 (HSPC: CHOL) Injection using liposome of Comparative Example 2 (HSPC: CHOL: DSPE-mPEG) Injection using liposome of Preparation Example 2 (HSPC: CHOL: DDAB + HEP) AUC (µg / h / ml) 12.00 25.59 201.24 319.59 t _1/2 (h) 1.68 2.37 12.80 19.80 CL (ml / h) 17.40 4.62 0.60 0.38 MRT (h) 1.95 4.82 17.78 28.42

Table 2 a (area under the curve) AUC is area for retention levels, t _1/2 is the half-life, CL is the instability (clearance), (mean residence time ) MRT represents the drug residence time.

As shown in Table 2, the injection using the heparin binding liposome of Preparation Example 2 according to the present invention (HSPC: CHOL: DDAB + HEP) has a half-life of 19.80 hours, the drug residence time (MRT, mean residence time ) Was 28.42 hours, area under the curve (AUC, area under the curve) was 319 μg · h / mL, and CL (clearance) was 0.38 mL / h. However, the injection using the PEG-bound liposome of Comparative Example 2 had a half-life of 12.80 hours, the injection using the liposome of Comparative Example 1 had a half-life of 2.37 hours, and the pure doxorubicin had a half-life of 1.68 hours. The fact that the half-life is increased suggests that 50% or more of the drug dwells in the body to maintain the effective concentration of the drug, and that the heparin-bound liposomes are superior to other comparative examples. Could confirm. In addition, the residence time of the drug was 17.78 hours for the injection using the PEG-bound liposome of Comparative Example 2, 4.82 hours for the injection using the liposome of Comparative Example 1, 1.95 hours for the pure doxorubicin, and the retention time was 1.95 hours using the heparin-bound liposome of Preparation 2. It can be observed that it is smaller than the injection. As a result, the injection using heparin-bound liposome of Preparation Example 2 had the least instability of liposomes in the body (see CL results in Table 1), and the area of drug residence time, half-life and retention concentration was the best. The binding of heparin to the surface of liposomes suggests that liposome stability and body cycle time can be increased compared to conventional PEG liposomes.

Experimental Example 4: Biodistribution Diagram of Drug

Preparation using the heparin-coupled liposomes of Preparation Example 2 prepared in the same manner as in Preparation Example 3 (Heparin-coated liposomes), Comparative Example 1 liposomes (Conventional liposomes), Comparative Example 2 using the liposomes (PEG-liposomes) Injectables and pure doxorubicin were injected into the rat tail vein at 6 mg drug / kg of mouse body weight, and then biodistribution of the drug was observed in the rats.

To examine the biodistribution of the liposomes, pure drug and liposome solution were administered to the C57BL / 6 experimental rats transplanted with B16F10 skin cancer cell line (melanoma) through the tail vein, and the tumor, heart, liver, and spleen of the rats were collected over time. The distribution of drugs was confirmed (FIG. 2). The method for measuring the concentration of the drug was in Experiment 4.

As shown in FIG. 2, the heparin-bound liposomes of Preparation Example 2 were found to be more concentrated in tumor tissues than the PEG-bound liposomes of Comparative Example 2 (FIG. 2A). This result confirms that the heparin-binding liposome of Preparation Example 2 is highly concentrated in the tumor tissue, which increases the circulation time and increases the stability of the liposome compared to the PEG liposome of Comparative Example 2, which may be transferred to the tumor tissue. Enhanced permeability and retention effect "(EPR effect) is expected to be due to the results of this experiment, the therapeutic effect of the tumor is also expected to be synergistic. On the other hand, in the heart (Fig. 2B), a lot of pure doxorubicin is detected because of the cardiac toxicity inherent in pure drugs. Therefore, when only pure doxorubicin is injected, serious toxicity is expected. Therefore, it is preferable to transport the drug effectively by using a drug carrier. In this case, it is possible to reduce the toxicity of the drug by preparing a liposome using a polymer such as PEG or heparin. Confirmed. In addition, in the case of liver and spleen (FIGS. 2C and 2D), in the case of liposome of Comparative Example 1, in which the polymer was not bound, it was confirmed that the trapped by the reticuloendothelial system in liver and spleen, thus circulating the liposomes effectively In order to ensure that the binding of the polymer was confirmed that the preferred method.

As described above, according to the present invention, heparin-modified biocyclic sustained liposomes have improved surface circulation sustainability compared to conventional liposomes, and thus, liposomes containing drugs when the drug delivery system is administered to the body using the same. The effect of prolonging the retention rate that can circulate in the blood for a long time is shown, and the efficiency of delivering the drug to the target site in the body is improved, thereby reducing the side effects.

Claims (6)

A liposome characterized in that a heparin or a derivative thereof having a weight average molecular weight of 1000 to 300,000 is modified on a liposome surface. The liposome according to claim 1, wherein the heparin is contained in an amount of 1 to 60 parts by weight based on 100 parts by weight of the lipid forming the liposome. The liposome according to claim 1, wherein the liposome has an average particle diameter in the range of 30 to 200 nm. The liposome according to claim 1, wherein the liposome comprises 10 to 30 mol% of cationic lipids. The method according to claim 4, wherein the cationic lipid is any one or a mixture of two or more selected from dialkyl dimethylammonium, dioleoylphosphatidylethanolamine, dioleoyldialkyltrimethylammonium propane and dioleoyldialkyl dimethylammoniumpropane. Liposomes characterized. In the injection in which any one hydrophobic drug selected from an anthracycline-based drug, an alkaloid-based drug, a paclitaxel-based drug and derivatives thereof is encapsulated in liposomes, The liposome is an injection, characterized in that any one of the liposomes selected from claim 1 to claim 5.

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