Doxorubicin polymer prodrug loading method

Abstract

The invention discloses a doxorubicin polymer prodrug loading method, which adopts linear or T-shaped structure polyethylene glycol as a polymer carrier, when the polymer carrier is the linear structure polyethylene glycol, the volume ratio of the polymer carrier to doxorubicin is (1-5): 1, and the volume concentration of the doxorubicin is 2-10%; when the polymer carrier is polyethylene glycol with a T-shaped structure, the volume ratio of the polymer carrier to the adriamycin is 1: 1, and the volume concentration of the adriamycin is 2-10%. Compared with the prior art, the doxorubicin can be efficiently wrapped, the targeting and controllability of drug release are improved, the immune recognition and rejection of an organism to a drug carrier are reduced, and the safety and tolerance of the drug are improved.

Description

Technical Field

[0001] The present invention belongs to the field of pharmaceutical technology, and in particular, relates to a method for loading doxorubicin polymer prodrug. Background Art

[0002] Doxorubicin (DOX) is an anthracycline anticancer drug widely used in clinical practice. Due to its high anti-cancer activity, it is used in the treatment of various malignant tumors. Currently, all clinically applied doxorubicin is covalently linked with a carrier to form a prodrug delivery system with targeting, controlled release, low toxicity, and high drug loading. At present, the drug loading technology of doxorubicin mainly focuses on the following aspects: 1. Liposome drug loading technology Liposomes are closed vesicles composed of phospholipid bilayers. Doxorubicin can be encapsulated in its internal aqueous phase or phospholipid membrane, which can effectively improve the drug targeting and biocompatibility and reduce cardiotoxicity. However, this technology has a low drug loading capacity, and is easily affected by factors such as plasma proteins and phospholipases in the blood circulation, resulting in membrane structure damage and drug leakage. In addition, although liposomes can achieve tumor targeting by modifying targeting molecules on the liposome surface, the modification process is relatively complex, and the connection of targeting molecules may affect the stability and drug loading performance of liposomes.

[0003] 2. Inorganic nanoparticle drug loading technology By methods such as adsorption and covalent binding, doxorubicin is loaded onto inorganic nanomaterial carriers such as gold nanoparticles, magnetic nanoparticles, and mesoporous silica nanoparticles. Inorganic nanomaterials have a large specific surface area and unique pore structures, and can load a large amount of doxorubicin, improving the drug loading efficiency. However, the long-term metabolism and potential toxicity problems of inorganic nanomaterials in the body have not been fully clarified, and there may be risks such as cumulative toxicity. In addition, inorganic nanomaterials usually have a rigid structure and have a large steric hindrance during blood circulation and tissue penetration in the body.

[0004] 3. Polymer prodrug drug loading technology Polymer prodrug drug loading is a drug delivery system formed by connecting drug molecules to a polymer carrier through chemical bonds. The polymer carrier in the prodrug can change the distribution, metabolism, and excretion behavior of the drug in the body. By selecting a suitable polymer, the circulation time of the drug in the blood can be increased, the distribution of the drug in non-target tissues can be reduced, and the bioavailability of the drug can be improved. The chemical bond between the drug and the polymer gradually breaks under specific conditions in the body (such as specific enzymes, pH values, etc.), thereby realizing the slow release of the drug, maintaining an effective blood drug concentration for a long time, reducing the dosing frequency, and reducing the toxic and side effects of the drug. Although polymer prodrugs can achieve slow drug release, the drug release rate and release extent are affected by various factors, such as the degradation rate of the polymer, the stability of the chemical bond, and changes in the in vivo environment. Precise control of drug release still poses certain challenges. In addition, factors such as the molecular weight, chain segment structure, hydrophilicity and hydrophobicity of the polymer have a significant impact on the drug loading performance, pharmacokinetic properties, and biocompatibility of polymer prodrugs. Some polymers also have poor biocompatibility, triggering immune responses or toxic and side effects in the body. The existing polymer carriers applied to doxorubicin mainly include poly(lactic-co-glycolic acid) (PLGA), polyphosphate esters, cyclodextrins, hyaluronic acid (HA), and polyethylene glycol, etc., and have the following different advantages and disadvantages.

[0005] 3.1 Poly(lactic-co-glycolic acid) (PLGA): PLGA is a commonly used biodegradable polymer. It can be degraded into lactic acid and glycolic acid in the body, and these two substances are normal products of human metabolism and can be metabolized and excreted by the body, effectively reducing the long-term toxicity risk of the carrier in the body. However, the ester bond structure dominates, and its dispersibility in aqueous media is poor, which easily leads to the aggregation of the drug-loaded carrier in the body, affecting drug release and absorption.

[0006] 3.2 Polyphosphate esters: Polyphosphate esters have good biocompatibility and degradability, and the phosphate ester bond has a certain polarity, which can combine with a variety of drugs through physical or chemical interactions, and is easy to load different types of drugs, including hydrophilic drugs, hydrophobic drugs, and biological macromolecules, etc., and has a strong drug loading capacity. However, the solubility and dispersibility of polyphosphate esters in aqueous media are relatively poor, and more surfactants need to be added to improve their dispersibility. Moreover, the molecular chain of polyphosphate esters is relatively rigid and has a large steric hindrance, and is more easily recognized and taken up by phagocytic cells such as macrophages in the blood circulation, resulting in a short circulation time in the body and affecting the targeted delivery effect of the drug.

[0007] 3.3 Cyclodextrin: Cyclodextrin has good encapsulation ability. It has a special ring-shaped cavity structure with hydrophobic interior and hydrophilic exterior, and can form inclusion complexes with various drug molecules through van der Waals forces, hydrogen bonds, hydrophobic interactions, etc., increasing the water solubility and stability of drugs, and reducing the irritation and toxic side effects of drugs. Cyclodextrin and its derivatives generally have good biocompatibility, can be slowly metabolized in vivo, and have low toxicity to the human body, making them suitable as drug carriers for in vivo administration. However, due to the limited cavity size of cyclodextrin, each cyclodextrin molecule can usually only encapsulate one or a few drug molecules, resulting in a relatively low drug loading capacity. For some drugs that require high-dose administration, a relatively large dose of cyclodextrin carrier may be needed to meet the treatment requirements. Moreover, cyclodextrin has a certain selectivity for the encapsulation of drug molecules, and only those drug molecules with appropriate size, shape and polarity can be effectively encapsulated. For some drugs with complex structures or that do not meet the cyclodextrin encapsulation requirements, the encapsulation effect may not be ideal, limiting its application scope.

[0008] 3.4 Hyaluronic acid (HA): HA is a naturally occurring component in human tissues, with excellent biocompatibility. It can be degraded by hyaluronidase, etc. in vivo, and the metabolites are carbon dioxide and water, without toxic side effects and without causing immune reactions. However, HA is easily degraded by factors such as hyaluronidase and free radicals in vivo, resulting in a relatively short half-life in the blood circulation. The drug carrier may be partially degraded before reaching the action site, affecting the effective delivery of drugs. The structural modification of HA is relatively complex. When modifying the carboxyl, hydroxyl and other functional groups on its molecule, the impact on its biological activity and structural integrity needs to be considered, and the requirements for the selectivity and controllability of the reaction are relatively high, and the modification process is relatively cumbersome. In addition, the mechanical strength of drug delivery systems in the form of HA hydrogels is relatively low, and it is easily damaged by external forces during the preparation and use processes, which may affect the drug encapsulation efficiency and release behavior, and often need to be compounded with other materials to enhance its mechanical properties.

[0009] 3.5 Polyethylene Glycol (PEG): PEG is a polymer material widely used in drug delivery systems. Its main chain consists of repeating ethylene glycol units, and the simple repeating unit arrangement provides it with good water solubility and biocompatibility. For example, linear PEG can form relatively regular conformations in aqueous solutions, which is beneficial for drug molecules to be encapsulated around it through molecular interactions. Secondly, the molecular weight of PEG can be precisely regulated by the degree of polymerization, ranging from a few hundred to several hundred thousand. PEGs with different molecular weights have different pharmacokinetic properties in the body, providing the possibility for the long-term release of drugs. In addition, the structure of PEG can be highly designed. By chemically modifying the hydroxyl groups at both ends, various different branched structures can be derived. These branches can be connected to different positions of the PEG main chain through chemical bonds to form various complex topological structures such as star-shaped, comb-shaped, and linear, and the rich branched structure design provides a broad space and diverse binding sites for encapsulating different drugs.

[0010] From the above comparison, it can be seen that the polyethylene glycol drug carrier is the polymer carrier with the best performance. However, due to its complex structure, its drug loading effect is more likely to be limited by steric hindrance at high drug ratios. Therefore, there is an urgent need to develop a drug loading method for doxorubicin polymer prodrugs that can achieve efficient encapsulation of doxorubicin, improve the targeting and controllability of drug release, reduce the immune recognition and rejection of the drug carrier by the body, and improve the safety and tolerance of the drug. Summary of the Invention

[0011] The present invention is to solve the above technical problems existing in the prior art and provides a drug loading method for doxorubicin polymer prodrugs.

[0012] The technical solution of the present invention is: a drug loading method for doxorubicin polymer prodrugs, which is to connect doxorubicin molecules to a polymer carrier through chemical bonds. The polymer carrier is polyethylene glycol with a linear or T-shaped structure. When the polymer carrier is polyethylene glycol with a linear structure, the volume ratio of the polymer carrier to doxorubicin is 1-5:1, and the volume concentration of doxorubicin is 2-10%; when the polymer carrier is polyethylene glycol with a T-shaped structure, the volume ratio of the polymer carrier to doxorubicin is 1:1, and the volume concentration of doxorubicin is 2-10%.

[0013] The present invention uses polyethylene glycol with a linear or T-shaped structure as the polymer carrier. When the polymer carrier is polyethylene glycol with a linear structure, the volume ratio of the polymer carrier to doxorubicin is 1-5:1, and the volume concentration of doxorubicin is 2-10%; when the polymer carrier is polyethylene glycol with a T-shaped structure, the volume ratio of the polymer carrier to doxorubicin is 1:1, and the volume concentration of doxorubicin is 2-10%. Compared with the prior art, it can achieve efficient encapsulation of doxorubicin, improve the targeting and controllability of drug release, reduce the immune recognition and rejection of the drug carrier by the body, and improve the safety and tolerance of the drug. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a comparison diagram of the drug-loading effects of the carriers in the examples and comparative examples of the present invention.

[0015] Figure 2 It is a comparison diagram of the drug-loading effects of the carriers with different drug concentrations in the examples and comparative examples of the present invention.

[0016] Figure 3 It is a comparison diagram of the drug-loading effects of the carriers with different ratios of the carrier to the drug in the examples of the present invention.

[0017] Figure 4 It is a comparison diagram of the drug-loading effects of the carriers with different ratios of the carrier to the drug in the comparative examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION Example 1

[0018] A method for loading doxorubicin polymer prodrug of the present invention is to connect doxorubicin molecules to the polymer carrier through chemical bonds according to the prior art. The difference from the prior art is that the polymer carrier is polyethylene glycol with a linear structure, the volume ratio of the polymer carrier to doxorubicin is 1:1, and the volume concentration of doxorubicin is 5%. Example 2

[0019] A method for loading doxorubicin polymer prodrug of the present invention is to connect doxorubicin molecules to the polymer carrier through chemical bonds according to the prior art. The difference from the prior art is that the polymer carrier is polyethylene glycol with a T-shaped structure, the volume ratio of the polymer carrier to doxorubicin is 1:1, and the volume concentration of doxorubicin is 5%.

[0020] Example 3: It is basically the same as the method of Example 1, except that the drug volume concentration is 2%.

[0021] Example 4: It is basically the same as the method of Example 1, except that the drug volume concentration is 10%.

[0022] Example 5: It is basically the same as the method of Example 2, except that the drug volume concentration is 2%.

[0023] Example 6: It is basically the same as the method of Example 2, except that the volume concentration of the drug is 10%.

[0024] Example 7: It is basically the same as the method of Example 1, except that the volume ratio of the carrier to the drug is 2:1.

[0025] Example 8: It is basically the same as the method of Example 1, except that the volume ratio of the carrier to the drug is 5:1.

[0026] Experiment: Comparative Example 1: It is basically the same as the method of Example 1, except that the polymer carrier is polyethylene glycol with a symmetric structure.

[0027] Comparative Example 2: It is basically the same as the method of Example 1, except that the polymer carrier is polyethylene glycol with a cross-shaped structure.

[0028] Comparative Example 3: It is basically the same as the method of Comparative Example 1, except that the volume concentration of the drug is 2%.

[0029] Comparative Example 4: It is basically the same as the method of Comparative Example 1, except that the volume concentration of the drug is 10%.

[0030] Comparative Example 5: It is basically the same as the method of Example 2, except that the volume ratio of the carrier to the drug is 2:1.

[0031] Comparative Example 6: It is basically the same as the method of Example 2, except that the volume ratio of the carrier to the drug is 5:1.

[0032] Comparative Example 7: It is basically the same as the method of Comparative Example 1, except that the volume ratio of the carrier to the drug is 2:1.

[0033] Comparative Example 8: It is basically the same as the method of Comparative Example 1, except that the volume ratio of the carrier to the drug is 5:1.

[0034] The drug-loading effects of the carriers in Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention are as Figure 1 shown. Figure 1 Among them, (a) Example 1; (b) Example 2; (c) Comparative Example 1; (d) Comparative Example 2. Figure 1 In it, the red particles are hydrophilic and drug-phobic A, the blue particles are hydrophobic and drug-philic B, and the yellow particles are drug D.

[0035] Figure 1The results show that in Examples 1 and 2 of the present invention, the drug is dispersed and encapsulated in multiple small aggregates with relatively uniform sizes, indicating that the carriers with linear and T-shaped structures in Examples 1 and 2 both have high flexibility and adjustability. The hydrophobic chain B can freely interact with drug molecules, thus adapting to different numbers of drug molecules and forming multiple stable small drug-loaded aggregates. Such multi-aggregates help improve the dispersibility of the drug, reduce the exposure of the drug in the solvent, and thereby enhance the stability and bioavailability of the drug. In contrast, the geometric configuration of the symmetric structure carrier in Comparative Example 1 is relatively complex, and the symmetry of its main chain limits the flexibility of the carrier, resulting in the drug molecules being mainly concentrated in one area of the carrier. Therefore, in the symmetric structure carrier system, although the drug can also be encapsulated by the carrier, only one large aggregate can be formed. For the grid-shaped structure carrier in Comparative Example 2, due to the distribution of the grid-shaped hydrophilic and drug-repellent particles A on the periphery, the steric hindrance is large, seriously hindering the effective binding of the drug to the hydrophobic and drug-affinitive particles B and unable to encapsulate the drug in the carrier. In order to reduce the system energy, the drug in the grid-shaped system of Comparative Example 2 can only aggregate and precipitate by itself, and the drug-loading effect of the carrier is very poor.

[0036] The drug-loading effects of the carriers in Examples 1, 2, 3, 4, 5, 6 and Comparative Examples 1, 3, 4 of the present invention are as Figure 2 shown. Figure 2 in (a) Example 3; (b) Example 1; (c) Example 4; (d) Example 5; (e) Example 2; (f) Example 6; (g) Comparative Example 3; (h) Comparative Example 1; (i) Comparative Example 4. Figure 2 In which, the red particles are hydrophilic and drug-repellent A, the blue particles are hydrophobic and drug-affinitive B, and the yellow particles are drug D.

[0037] Figure 2 The results show that the experimental results at drug volume concentrations of 2% and 10% are basically the same as those at a drug volume concentration of 5%, indicating that within the concentration range of the examples of the present invention, the change in concentration does not significantly change the drug-loading ability of the carrier. This may be because the main interactions between the polymer carrier and drug molecules, such as hydrophobic interaction and van der Waals force, are relatively stable within this drug concentration range and do not change fundamentally due to small fluctuations in drug concentration.

[0038] The drug-loading effects of the carriers in Examples 1, 7, 8, 2 and Comparative Examples 5, 6 of the present invention are as Figure 3 shown. Figure 3 in (a) Example 1; (b) Example 7; (c) Example 8; (d) Example 2; (e) Comparative Example 5; (f) Comparative Example 6. Figure 3 In which, the red particles are hydrophilic and drug-repellent A, the blue particles are hydrophobic and drug-affinitive B, and the yellow particles are drug D.

[0039] Figure 3The results show that: on the premise that the drug concentration is 5%, with the increase of the drug ratio, the encapsulation effect of the T-shaped structure carrier in Example 1 has changed significantly. In the system with a ratio of 1:2, the linear structure carrier can still encapsulate the drug well and the aggregate size is uniform, while the T-shaped structure carrier no longer forms multiple uniform small aggregates, but large aggregates similar to the symmetric structure system in Comparative Example 1 appear. This is because compared with the linear structure carrier, the geometric configuration of the T-shaped carrier is more complex. When the drug concentration in the system is relatively high, the drug is more likely to contact the hydrophilic chain. At this time, the hydrophilic chain will generate a large steric hindrance to the diffusion of the drug, and the branched chain B chain is difficult to effectively disperse the drug molecules, resulting in the drug being concentrated at the hydrophobic end to form a large aggregate. When the drug ratio is further increased to 1:5, the drug molecules show a connectivity phenomenon in the system. This indicates that when the drug concentration is too high and exceeds the loading capacity of the carrier, the interaction between drug molecules far exceeds the interaction between the carrier and the drug, and the drug D molecules are difficult to be effectively dispersed, resulting in the self-aggregation and precipitation of drug D.

[0040] The drug-loading effects of the carriers in Comparative Examples 1, 7, and 8 of the present invention are as Figure 4 shown. Figure 4 Among them, (a) is Comparative Example 1; (b) is Comparative Example 7; (c) is Comparative Example 8. Figure 4 In the figure, the red particles are hydrophilic and drug-phobic A, the blue particles are hydrophobic and drug-philic B, and the yellow particles are drug D.

[0041] Figure 4 The results show that: under the three ratios of the carrier to the drug, the symmetric structure carrier in the comparative example can always form only one aggregate, indicating that the geometric configuration of the symmetric carrier limits its encapsulation ability, and changing the carrier ratio alone cannot significantly improve the drug-loading effect.

Claims

1. A method for loading doxorubicin polymer prodrug, which is to connect doxorubicin molecules to a polymer carrier through chemical bonds, is characterized in that: The polymer carrier is polyethylene glycol with a linear or T-shaped structure. When the polymer carrier is polyethylene glycol with a linear structure, the volume ratio of the polymer carrier to doxorubicin is 1-5:1, and the volume concentration of doxorubicin is 2-10%; when the polymer carrier is polyethylene glycol with a T-shaped structure, the volume ratio of the polymer carrier to doxorubicin is 1:1, and the volume concentration of doxorubicin is 2-10%.

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