Liposome composition and method for preparing same

Abstract

The present invention provides a method for preparing a liposome composition. The method includes the steps of providing a liposome precursor encapsulating a platinum-based drug precursor and incubating the liposome precursor in a salt solution to convert the platinum-based drug precursor into a platinum-based drug, thereby obtaining a liposome composition. The liposome precursor is prepared by hydrating the platinum-based drug to obtain a platinum-based drug precursor and adding the platinum-based drug precursor to a lipid bilayer carrier to obtain a liposome precursor. The liposome composition prepared by this method has good coverage and strong drug loading capacity.

Description

[Technical Field]

[0001] This patent application claims priority to U.S. provisional application Ser. No. 62 / 987366, filed March 10, 2020, the entire contents of which are incorporated by reference into this patent application. The present invention relates to a liposome composition, and more particularly to a liposome composition encapsulating a platinum-based drug precursor and a method for preparing the same. [Background technology]

[0002] Cis-diaminedichloroplatinum (II) (CDDP, also known as cisplatin) is a well-known and commonly used chemotherapy drug. However, this drug has drawbacks such as poor water solubility and high toxicity, which causes various side effects. Summary of the Invention

[0003] To improve the solubility of cis-diamminedichloroplatinum and reduce its toxicity, some embodiments of the present invention provide a method for preparing a liposome composition, comprising the steps of providing a liposome precursor encapsulating a platinum-based drug precursor, and incubating the liposome precursor in a salt solution to convert the platinum-based drug precursor into a platinum-based drug to form a liposome composition. Another embodiment of the present invention provides a method for preparing a liposome composition, including the steps of providing salt liposomes encapsulating a salt; and mixing the salt liposomes with a platinum-based drug precursor, allowing the platinum-based drug precursor to enter the salt liposomes and react with the salt, thereby converting the platinum-based drug precursor into a platinum-based drug to form a liposome composition. Another embodiment of the present invention provides a method for preparing a liposome composition, comprising the steps of providing a liposome precursor encapsulating a platinum-based drug precursor and providing a salt liposome encapsulating a salt; and mixing the liposome precursor and the salt liposome to convert the platinum-based drug precursor into a platinum-based drug to form a liposome composition. Another embodiment of the present invention further provides a method for preparing a liposome composition, including the steps of providing a precursor core encapsulating a platinum-based drug precursor and providing a salt core encapsulating a salt; mixing the precursor core and the salt core to convert the platinum-based drug precursor into a platinum-based drug to form a liposome core; and mixing the liposome core and a first lipid formulation to form a liposome composition. Another embodiment of the present invention further provides a liposome composition prepared by any one of the above preparation methods, wherein the liposome composition has a drug loading rate (%) of at least 10%. The liposome composition according to any of the embodiments of the present invention provides an effective solution for improving the solubility of platinum-based drugs and the coverage of liposome particles. According to the preparation methods of the embodiments of the present invention, liposome precursors are converted into platinum-based drugs encapsulated in liposomes by a convenient and low-cost preparation method. Furthermore, these preparation methods provide an effective means for improving the drug loading rate (%) of liposome compositions. [Brief explanation of the drawings]

[0004] [Figure 1] FIG. 1 is a chemical reaction diagram for preparing a liposome composition according to an exemplary embodiment of the present invention. [Figure 2] FIG. 1 is a chemical reaction diagram for the preparation of a cis-diamminedichloroplatinum precursor (CDDP precursor) of a liposome composition according to an exemplary embodiment of the present invention. [Figure 3] FIG. 2 is a chemical reaction scheme for the preparation of a liposome composition according to another exemplary embodiment of the present invention. [Figure 4] FIG. 2 is a chemical reaction scheme for the preparation of a liposome composition according to another exemplary embodiment of the present invention. [Figure 5] FIG. 2 is a chemical reaction scheme for the preparation of a liposome composition according to another exemplary embodiment of the present invention. [Figure 6] 1 is a cryogenic electron microscopy (Cryo-EM) image of a liposome composition according to an exemplary embodiment of the present invention. [Figure 7] FIG. 1 is a graph showing the size distribution results of a liposome composition according to an exemplary embodiment of the present invention. [Figure 8] FIG. 1 is a diagram showing the results of pharmacokinetic analysis of a liposome composition according to an exemplary embodiment of the present invention in an animal model. [Figure 9] FIG. 1 shows the results of tumor growth rate and tumor volume changes in a mouse xenograft model of human non-small-cell lung cancer (NSCLC) adenocarcinoma H1975 cells, in which a treatment experiment with phosphate buffered saline (PBS), a treatment experiment with cis-diamminedichloroplatinum, and a treatment experiment with a liposome composition using a lipid bilayer as a carrier and encapsulating cis-diamminedichloroplatinum as a platinum drug (hereinafter referred to as LipoCis) were performed. [Figure 10] FIG. 1 shows graphs of the results of tumor growth rate, tumor volume, and changes in body weight in A549 cell xenograft mouse models treated with phosphate buffered saline and LipoCis, respectively. [Figure 11] FIG. 1 shows the results of tumor volume, body weight, tumor growth rate, and body weight change at different effective doses in a H460 cell xenograft mouse model in which a phosphate buffered saline treatment experiment and a LipoCis treatment experiment were performed, respectively. [Figure 12] FIG. 1 shows the results of tumor volume changes in mouse models xenografted with human oral squamous cell carcinoma (HOSCC) SAS cells, after treatment with phosphate buffered saline, cis-diamminedichloroplatinum, and LipoCis. [Figure 13] FIG. 10 is a graph showing the tumor-reducing effect of metastasizing SAS cells in a mouse model of human oral squamous cell carcinoma according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0005] The present invention will be more fully understood from the following detailed description, which is intended to illustrate but not limit the invention. Referring to Figure 1, a first embodiment of the present invention provides a method for preparing a liposome composition. The method may include providing a liposome precursor encapsulating a platinum-based drug precursor and incubating the liposome precursor in a salt solution to convert the platinum-based drug precursor into a platinum-based drug to form a liposome composition. Specifically, the liposome precursor can be prepared by hydrating the platinum-based drug to form a platinum-based drug precursor and adding the platinum-based drug precursor to a lipid bilayer carrier to form the liposome precursor.

[0006] Platinum-based drugs can be hydrated by incubating them with silver nitrate (AgNO3), silver sulfate (Ag2SO4), silver phosphate (Ag3PO4), calcium nitrate (Ca(NO3)2), calcium sulfate (CaSO4), calcium phosphate (Ca3(PO4)2), magnesium nitrate (Mg(NO3)2), magnesium sulfate (MgSO4), and / or magnesium phosphate (Mg2PO4)2).

[0007] In some examples, the platinum-based drug may include at least one platinum-halides bond (e.g., a platinum-fluorine bond, a platinum-chlorine bond, a platinum-bromine bond, or a platinum-iodine bond). In some examples, the platinum-based drug may include cisplatin, triplatin, phenanthriplatin, picoplatin, satraplatin, cis-diamminediiodoplatinum(II), cis-diamminedifluoroplatinum(II), and cis-diamminedibromoplatinum(II).

[0008] Referring to FIG. 2, the platinum-based drug precursor may be a monoaqua and / or diaqua platinum-based drug, for example, cis-[Pt(NH3)2(H2O)2](NO3)2 or cis-[Pt(NH3)2(H2O)2] 2+Because platinum-based drug precursors are water-soluble, they can be encapsulated in lipid bilayer carriers (e.g., liposome nanoparticles).

[0009] The lipid bilayer carrier can be prepared by mixing the lipid formulation with an organic solution such as, for example, chloroform, cyclohexane, methanol, ethanol, or any combination thereof. The lipid formulation may comprise a composition consisting of phosphatidylcholine, cholesterol, and a polyethylene glycol (PEG-based)-containing compound. Preferably, the phosphatidylcholine may comprise a neutral lipid, such as distearoylphosphatidylcholine (1,2-distearoyl-sn-glycero-3-phosphocholine, DSPC), 1,2-dioleoyl-sn-glycero-3-phosphocholine (1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DOPC), or 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (1,2-dipalmitoyl-sn-glycero-3-phosphocholine). 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), hexadecyl phosphorylcholine (HePC), 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine (SOPC), 1,2-diphytanoyl-sn-glycero-3-phosphocholine (diPhyPC), or any combination thereof. The polyethylene glycol-containing compound may be a distearoylphosphatidyl ethanolamine (DSPE)-PEG compound, such as N-(carbonyl-methoxypolyethylene glycol-200)-1,2-distearoyl-tin-glycero-3-phosphoethanolamine (N-(carbonyl-methoxypolyethylene glycol-200)-1,2-distearoyl-sn-glycero-3-phosphoethanolamine), polyethylene glycol 200-distearoylphosphatidylethanolamine (DSPE-PEG-200 or DSPE-mPEG-200), polyethylene glycol 400-distearoylphosphatidylethanolamine (DSPE-PEG-400 or DSPE-mPEG-400), polyethylene glycol 800-distearoylphosphatidylethanolamine amine (DSPE-PEG-800 or DSPE-mPEG-800), polyethylene glycol 1000-distearoylphosphatidylethanolamine (DSPE-PEG-1000 or DSPE-mPEG-1000), polyethylene glycol 2000-distearoylphosphatidylethanolamine (DSPE-PEG-2000 or DSPE-mPEG-2000), polyethylene glycol 2500-distearoylphosphatidylethanolamine (DSPE-PEG-2500 or DSP E-mPEG-2500), polyethylene glycol 3000-distearoylphosphatidylethanolamine (DSPE-PEG-3000 or DSPE-mPEG-3000), polyethylene glycol 4000-distearoylphosphatidylethanolamine (DSPE-PEG-4000 or DSPE-mPEG-4000), polyethylene glycol 5000-distearoylphosphatidylethanolamine (DSPE-PEG-5000 or DSPE-mPEG-5000), polyethylene In some embodiments, the polyethylene glycol (PEG)-containing compound is DSPE-PEG-aminoethyl anisamide (DSPE-PEG-aminoethyl anisamide), or any combination thereof.The ligand moiety may be selected from DSPE-PEG-AEAA), DSPE-PEG-monoclonal antibody (DSPE-PEG-mAb), and DSPE-PEG with other ligand moieties.

[0010] The lipid formulations can self-assemble into lipid bilayer carriers in an aqueous environment through hydrophobic interactions and / or van der Waals interactions. In one or more preferred embodiments, the neutral nature of the lipid formulations provides minimal energy for binding with the encapsulated active pharmaceutical ingredient (API) or its precursor, facilitating in vivo drug release. Additionally, the neutral lipid bilayer carriers do not interact with charged precursors, thereby not affecting or inhibiting drug conversion occurring therein.

[0011] In some embodiments, the volume ratio of the lipid bilayer carrier to the cis-diamminedichloroplatinum precursor in the liposome composition is 1:1 to 20:1. The molar ratio of the cis-diamminedichloroplatinum precursor to the lipid bilayer carrier is 0.1:1 to 1:1. The cis-diamminedichloroplatinum precursor is added to the lipid bilayer carrier, and the volume ratio of the lipid bilayer carrier (i.e., the ratio of oil to water) is 1:0.01 to 1:0.8. The molar concentration of the platinum-based drug precursor in the lipid bilayer carrier or liposome precursor is 25 mM to 600 mM, preferably 1.5 mM to 5 mM.

[0012] To convert a platinum-based drug precursor to a platinum-based drug, liposome precursors can be incubated in a salt solution to incorporate salt into the liposome precursor. In this embodiment, the salt solution can contain fluoride, chloride, bromide, iodide, or other salts containing a halogen group. The salt solution has a molar concentration of 0.2 M to 4 M. Specifically, when sodium chloride is used as the salt in the conversion, the molar concentration of sodium chloride can be 0.4 M to 3.9 M. When potassium chloride is used as the salt in the conversion, the molar concentration of potassium chloride can be 0.4 M to 3.0 M. In some embodiments, liposome precursors can be incubated in the salt solution at 4 to 65°C for 1 to 24 hours to incorporate salt into the liposome precursor and convert the diaqua-form cis-diamminedichloroplatinum precursor into cis-diamminedichloroplatinum. For example, to stabilize the structure of the liposome composition, the liposome precursor may be incubated overnight in a salt solution at 4-7°C, or may be incubated in a salt solution at 10-50°C for 2-15 hours and then cooled.

[0013] In one or more embodiments, a highly concentrated salt solution generates osmotic pressure that irreversibly pushes halogen ions through the lipid bilayer carrier, retaining them within the liposome precursor without affecting the stability of the liposome structure. As halogen ions within the liposome precursor are consumed for the conversion of the active ingredient drug, more halogen ions continuously diffuse into the liposome precursor. Such an osmotic method provides an approach to promote drug conversion within the liposome precursor, and is cost-effective and time-efficient.

[0014] In the first example, to prepare a liposome composition (hereinafter abbreviated as LipoCis) using a lipid bilayer composed of distearoylphosphatidylcholine, cholesterol, and polyethylene glycol 2000-distearoylphosphatidylethanolamine as a carrier and encapsulating cis-diaminedichloroplatinum as a platinum-based drug, the cis-diaminedichloroplatinum precursor was prepared by dissolving 0.2 to 0.4 mmol of cis-diaminedichloroplatinum in 0.3 to 0.4 mmol of an aqueous silver nitrate solution (AgNO3(aq) The lipid bilayer carrier may be prepared by culturing the mixture in a 25°C (25°C) for 16-18 hours or at 60°C for 3-4 hours. Subsequently, distearoylphosphatidylcholine, cholesterol, and polyethylene glycol 2000-distearoylphosphatidylethanolamine are mixed at a weight ratio of 40-50:25-50:10-30 w / w% for 10-60 minutes at 30-60°C and 100-400 rpm to form a lipid bilayer carrier. Then, cis-diamminedichloroplatinum precursor is added to the lipid bilayer carrier, and the volume ratio of oil to water in the lipid bilayer carrier is 1:0.01 to 1:0.8. This addition process may be carried out at a rate of 1 mL / min using a micropipette to form liposome precursors, or by manual shaking or a large-volume mixing method using a stirrer for 15-30 minutes to achieve uniform mixing. The liposomes encapsulating the cis-diamminedichloroplatinum precursor are then homogenized 1 to 10 times to obtain liposomes with a size of 60 to 250 nm. Finally, the homogenized liposome precursor is incubated in a 0.2 to 3.9 M potassium chloride or sodium chloride solution at 25 to 50°C for 2 to 24 hours with uniform stirring to convert the cis-diamminedichloroplatinum precursor within the liposomes to cis-diamminedichloroplatinum. The product, LipoCis, is then purified by removing excess salts using a tangential flow filtration (TFF) system to obtain the product. This product is then stored in a buffer solution containing 10 mM HEPE and 5% glucose (pH 6.5 to 7.6), a buffer solution containing 10 mM HEPE and 0.9% saline (pH 6.5 to 7.6), a solution containing 0.9% saline and 5% glucose, or secondary pure water. The drug-to-lipid (D / L) ratio of the resulting product LipoCis can reach 0.05-0.8 per mole.

[0015] Referring to Figure 3, Example 2 provides another method for preparing a liposome composition. The method includes the steps of providing salt liposomes encapsulating a salt; and incubating the salt liposomes with a platinum-based drug precursor, allowing the platinum-based drug precursor to enter the salt liposomes and react with the salt, thereby converting the platinum-based drug precursor into the platinum-based drug to form a liposome composition. Specifically, the salt liposomes may be prepared by adding a salt to a lipid bilayer carrier to form the salt liposomes. Details of the components and steps used in the preparation method of Example 2 are similar to those described in Example 1, and reference is made to the relevant description above.

[0016] Referring to FIG. 4 , Example 3 provides another method for preparing a liposome composition. The method includes the steps of providing a liposome precursor encapsulating a platinum-based drug precursor and providing salt liposomes encapsulating a salt, and mixing the liposome precursor with the salt liposomes to convert the platinum-based drug precursor into a platinum-based drug to form a liposome composition. Specifically, the liposome precursor can be prepared by hydrating the platinum-based drug to form a platinum-based drug precursor and adding the platinum-based drug precursor to a lipid bilayer carrier to form a liposome precursor. Similarly, the salt liposome can be prepared by adding a salt to a lipid bilayer carrier to form a salt liposome. Details of the components and steps used in the preparation method of Example 3 are the same as those described in Example 1, and please refer to the relevant description above.

[0017] Referring to Figure 5, Example 4 provides another method for preparing a liposome composition. The method includes the steps of providing a precursor core encapsulating a platinum-based drug precursor and a salt core encapsulating a salt; mixing the precursor core and the salt core to convert the platinum-based drug precursor into a platinum-based drug to form a liposome core; and mixing the liposome core and a first lipid formulation to form a liposome composition. Specifically, the precursor core can be prepared by hydrating the platinum-based drug to form a platinum-based drug precursor and adding the platinum-based drug precursor to a lipid bilayer carrier to form the precursor core. Similarly, the salt core can be prepared by adding a salt to a lipid monolayer carrier to form the salt core. Details of the components and steps used in the preparation method of Example 4 are the same as those described in Example 1, and please refer to the related description above.

[0018] In some embodiments, the first lipid formulation may include cholesterol and a polyethylene glycol-containing compound. The first lipid formulation may be dissolved in an organic solution (e.g., chloroform, ethanol) and then mixed with the liposome cores at 25-45°C for 25-60 minutes. For example, as shown in Figure 5, after the lipid formulation is added, cholesterol stabilizes the single-layer liposome core, and polyethylene glycol 2000-distearoylphosphatidylethanolamine coats the outside of the liposome core to form a bilayer liposome composition.

[0019] The lipid monolayer carrier may be prepared by mixing a second lipid formulation dissolved in an organic solution (e.g., chloroform, ethanol). This second lipid formulation may contain distearoylphosphatidylcholine and / or other phosphatidylcholines. When using chloroform or other oil solutions, the lipid monolayer carrier can be formed immediately in the solution. In water-miscible systems (e.g., ethanol), heating to 45-60°C and acting for 15-30 minutes may be necessary to form the lipid monolayer carrier. As is evident from the high conversion rate and drug loading rate (%) demonstrated in Table 1, the preparation method according to the embodiment of the present invention described above can effectively coat platinum-based drug precursors and convert them into platinum-based drugs. As a result, the liposome composition prepared by the preparation method according to the embodiment of the present invention can achieve a calculated drug loading rate (%) of as high as 62%.

[0020] Table 1. Drug loading rate (DL) (%) of LipoCis in the examples

[0021] [Table 1]

[0022] Referring to Figures 6 and 7, in one example, cis-diamminedichloroplatinum is encapsulated and precipitated within a lipid bilayer composed of distearoylphosphatidylcholine, cholesterol, and polyethylene glycol 2000-distearoylphosphatidylethanolamine to form LipoCis nanoparticles (NPs). These LipoCis nanoparticles can be characterized using a variety of methods. In the example shown in Figures 6 and 7, the size and zeta potential of LipoCis nanoparticles are measured using a nanoparticle size and potential analyzer (Malvern Zetasizer Nano series). The morphology of LipoCis nanoparticles is observed using a cryo-electron microscope. The number of cis-diamminedichloroplatinum molecules is measured using high-performance liquid chromatography (HPLC). The platinum content of LipoCis nanoparticles was measured using inductively coupled plasma-atomic emission spectroscopy (ICP-AES) or inductively coupled plasma-optical emission spectroscopy (ICP-OES). The excipient concentrations were measured using HPLC evaporative light scattering detectors (ELSD). As shown in Figure 6, images of LipoCis nanoparticles taken with a cryo-electron microscope showed a perfect, uniform, monodisperse morphology with an estimated particle size of 80-150 nm. This result is consistent with the results measured by dynamic light scattering (DLS). All interaction polymer chromatography (IPC) values ​​of LipoCis nanoparticles were measured, as shown in Figure 7.

[0023] Referring to Figure 8, a pharmacokinetic analysis of LipoCis prepared in Example 1 of the present invention was performed in a rat animal model. As shown in Table 2, LipoCis exhibited low clearance (CL), a high area under the curve (AUC), and a long circulation time in vivo (i.e., the volume of distribution (Vz) and volume of distribution at steady state (Vss) of LipoCis were lower than those of the active ingredient drug). Measurements of drug half-life and mean residence time (MRT) showed no statistically significant differences between LipoCis and the active ingredient drug. These pharmacokinetic results indicate that LipoCis has sustained release properties in vivo.

[0024] [Table 2]

[0025] To evaluate the inhibitory ability of LipoCis on tumor growth, xenograft experiments were conducted for 21 days, with daily observation of the xenografted animals. 6 100 cells / 200 μL of a 1:1 solution of phosphate buffered saline-Martigel were subcutaneously injected into the right hind leg of Balb / c nude mice. After tumors of a significant size developed, the tumor size was measured daily or every other day and calculated using the formula (length × width × height) / 2. When the tumor size reached a predetermined size (e.g., 100-210 mm), the tumor size was measured. 3 ), experimental mice in the LipoCis group will receive an intravenous injection of the drug once a week for three weeks.

[0026] Referring to Figures 9-11, experiments were conducted using three lung cancer cell lines (including human non-small cell lung cancer H1975 and A549 cells, and human large cell carcinoma H460 cells) to assess the in vivo efficacy of LipoCis nanoparticles. As shown in Figure 9, treatment with LipoCis prepared in accordance with the present invention in a mouse xenograft of lung adenocarcinoma H1975 cells demonstrated significant cell apoptosis (based on immunohistochemistry). Compared with treatment with cis-diamminedichloroplatinum, treatment with LipoCis demonstrated a significant tumor inhibitory effect. As shown in Figures 10-11, similar results were observed in both the mouse xenograft of lung adenocarcinoma A549 cells and the mouse xenograft of lung large cell carcinoma H460 cells.

[0027] 12 and 13, a human oral squamous cell carcinoma (HOSCC) xenograft animal model was constructed. 5 × 10 cells were cultured in 200 μL of Martigel (Martigel Cell Culture Medium, Corning Life Sciences, USA). 6 160 μL of human oral cancer SAS cells containing 1000 cells were taken and injected into 7-9 week-old male nude mice (product name: BALB / cAnN.Cg-Foxn1) using a 28-gauge needle. nu The mice (purchased from the National Laboratory Animal Center, Taipei, Taiwan) were injected subcutaneously into the right lower dorsal region of the SAS cell xenograft experiment. Mice were randomly divided into three groups and treated with the following drugs: (i) phosphate buffered saline, (ii) cis-diamminedichloroplatinum, and (iii) LipoCis nanoparticles. All drug treatments were administered intravenously. Both the drug cis-diamminedichloroplatinum and the drug LipoCis nanoparticles were administered at a drug dose of 3.0 mg / kg. The drugs were administered to mice with tumors measuring 200.1 mm. 3 ±3.5 (or 195-210mm 3) and administered after tumor size reached 100 mg / kg. Tumor size was calculated using the formula: length x width x height x 0.5. Experimental mice from each group were sacrificed on day 12 for data collection. The excised tumors and organs were sectioned and fixed in 10% formalin for subsequent experiments. All of the above experimental studies were conducted in accordance with the guidelines set forth by the Laboratory Animal Care and Use Committee of Chung Yuan University, Taiwan.

[0028] To verify the efficacy of LipoCis nanoparticles in vivo, tumors with a volume of 200.1 ± 3.5 mm were treated. 3 In the SAS cell xenograft experiment, mice were randomly divided into three groups: (i) a phosphate-buffered saline-treated group, (ii) a cis-diamminedichloroplatinum-treated group, and (iii) a LipoCis nanoparticle group. Each group received two drug treatments, each treatment six days apart. As shown in Figures 9 and 10, LipoCis also exhibited tumor growth inhibition against SAS cells.

[0029] According to the above embodiments of the present invention, LipoCis provides an effective solution for improving the solubility of platinum-based drugs and the coverage of liposome particles. According to the preparation methods of the embodiments of the present invention, liposome precursors are converted into platinum-based drugs encapsulated in liposomes through a convenient and low-cost preparation method. These preparation methods also provide an effective means for improving the drug loading rate (%) of liposome compositions.

[0030] The technical contents of the present invention have been disclosed above by preferred embodiments, but they are not intended to limit the present invention. In comparison, any slight modifications and similar modifications made without departing from the scope and spirit of the appended claims are intended to be included within the scope of the present invention. The said scope should be given the broadest interpretation so as to include such modifications and similar modifications.

Claims

1. providing a liposome precursor encapsulating a platinum-based drug precursor; and incubating the liposome precursor in a salt solution to convert the platinum-based drug precursor into a platinum-based drug to form a liposome composition; The liposome precursor is hydrating the platinum-based drug to form the platinum-based drug precursor; mixing the lipid formulations to form a lipid bilayer carrier; adding the platinum-based drug precursor to the lipid bilayer carrier to form the liposome precursor; The method for preparing a liposome composition, wherein the lipid formulation comprises distearoylphosphatidylcholine, cholesterol, and one selected from the group consisting of polyethylene glycol 2000-distearoylphosphatidylethanolamine, polyethylene glycol 3000-distearoylphosphatidylethanolamine, polyethylene glycol 4000-distearoylphosphatidylethanolamine, polyethylene glycol 5000-distearoylphosphatidylethanolamine, and polyethylene glycol 10000-distearoylphosphatidylethanolamine.

2. 2. The method of claim 1, wherein the step of hydrating the platinum-based drug comprises incubating the platinum-based drug with at least one compound selected from the group consisting of silver nitrate, silver sulfate, silver phosphate, calcium nitrate, calcium sulfate, calcium phosphate, magnesium nitrate, magnesium sulfate, and magnesium phosphate.

3. 10. The method of claim 1, wherein the lipid formulation is mixed in an organic solution comprising chloroform or ethanol.

4. 2. The method of claim 1, wherein the volume ratio of the lipid bilayer carrier to the platinum-based drug precursor is 1:1 to 20:

1.

5. 2. The method of claim 1, wherein the molar ratio of the platinum-based drug to the lipid bilayer carrier is 0.1:1 to 1:

1.

6. 2. The method of claim 1, wherein in the step of adding the platinum-based drug precursor to the lipid bilayer carrier, the ratio of oil to water in the lipid bilayer carrier is 1:0.01 to 1:0.

8.

7. The method of claim 1, wherein the platinum-based drug comprises at least one platinum-halogen bond.

8. 2. The method of claim 1, wherein the platinum-based drug is selected from the group consisting of cisplatin, triplatin, phenanthriplatin, picoplatin, and satraplatin.

9. The method of claim 1 , wherein the platinum-based drug precursor is at least one of a monoaqua form of the platinum-based drug and a diaqua form of the platinum-based drug.

10. The method of claim 1 , wherein the salt solution comprises chloride or bromide.

11. 2. The method of claim 1, wherein the platinum-based drug precursor has a volume molar concentration of 25 mM to 600 mM in the liposome precursor.

12. 2. The method of claim 1, wherein the salt solution for incubating the liposome precursor has a volume molarity of 0.2M to 4M.

13. 2. The method of claim 1, wherein the liposome precursors are incubated in the salt solution at 4 to 65°C for 1 to 24 hours.

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