Preparation method of rapamycin drug balloon and rapamycin drug balloon
阅读说明：本技术 一种雷帕霉素药物球囊的制备方法及雷帕霉素药物球囊 (Preparation method of rapamycin drug balloon and rapamycin drug balloon ) 是由 成松明 王法磊 于 2021-08-27 设计创作，主要内容包括：本发明涉及一种雷帕霉素药物球囊的制备方法,其能够制备可有效递送雷帕霉素的药物球囊。所述药物球囊有效解决了雷帕霉素药物涂层在喷涂于药物球囊后容易脱落的问题,大幅提高了药物球囊扩张后雷帕霉素向血管内皮细胞的转移率。同时,转移到血管的雷帕霉素胶束粒子有着良好的药代动力学性质,作用时间长。本发明的雷帕霉素药物球囊构成材料安全无毒,雷帕霉素利用率高、作用时间长,因此特别适合在PTCA中应用。(The invention relates to a preparation method of a rapamycin drug balloon, which can be used for preparing a drug balloon capable of effectively delivering rapamycin. The medicine balloon effectively solves the problem that the rapamycin medicine coating is easy to fall off after being sprayed on the medicine balloon, and greatly improves the transfer rate of rapamycin to vascular endothelial cells after the medicine balloon is expanded. Meanwhile, the rapamycin micelle particles transferred to blood vessels have good pharmacokinetic properties and long action time. The rapamycin medicinal balloon is made of safe and nontoxic rapamycin medicinal materials, has high rapamycin utilization rate and long action time, and is particularly suitable for being applied to PTCA.)
1. A method of making a rapamycin drug balloon, comprising:
1) dissolving rapamycin or its derivatives, poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer, and phospholipid in solvent, and mixing to obtain rapamycin medicinal solution; the phospholipid is selected from at least one of Dioleoylphosphatidylethanolamine (DOPE) or Dioleoylphosphatidylcholine (DOPC); the weight ratio of the poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer to the phospholipid is 1.5-3.2: 1;
2) adding an emulsifier and glucan into deionized water, and stirring to dissolve the emulsifier and the glucan to prepare an emulsified solution;
3) under high-speed stirring, adding the rapamycin medicinal solution into the emulsified solution drop by drop, and emulsifying by using an ultrasonic probe emulsifying instrument after the addition is finished to prepare a medicine-carrying micelle solution;
4) centrifuging the obtained drug-loaded micelle solution by using a high-speed centrifuge, washing by using deionized water, and freeze-drying to prepare drug-loaded micelles;
5) dispersing the drug-loaded micelle with an organic solvent, adding chitosan, and dispersing to prepare a spraying solution;
6) washing the naked saccule by deionized water, and carrying out surface plasma pretreatment after drying;
7) spraying the spraying solution on the surface of the naked balloon by using an ultrasonic spraying process until the drug loading on the surface of the balloon reaches 0.1-10 mu g/mm2；
8) Drying and folding to obtain the rapamycin medicinal balloon.
2. The preparation method according to claim 1, wherein the molecular weight of the polydioxanone-polyethylene glycol-polydioxanone (PPDO-PEG-PPDO) triblock copolymer in the step 1) is 2000-8000 g/mol, wherein the mass ratio of PPDO block to PEG block is 1-5: 1.
3. the method of claim 1, wherein the polydioxanone-polyethylene glycol-polydioxanone (PPDO-PEG-PPDO) triblock copolymer is prepared by a method comprising:
under the protection of inert gas, putting p-dioxanone, polyethylene glycol and a catalyst into a reaction device, heating to 60-100 ℃, stirring, keeping the temperature, performing polymerization reaction, and purifying to obtain the poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer.
4. The method according to claim 1, wherein the weight ratio of the polydioxanone-polyethylene glycol-polydioxanone (PPDO-PEG-PPDO) triblock copolymer to the phospholipid in step 1) is 1.8-2.6: 1.
5. the method according to claim 1, wherein the emulsifier in step 2) is selected from a complex system of tween series and sodium dodecyl sulfate, sodium dodecyl sulfate or sodium dodecyl benzene sulfonate.
6. The preparation method according to claim 1, wherein the amount of the emulsifier is 6 to 14 times of the total mass of the polydioxanone-polyethylene glycol-polydioxanone (PPDO-PEG-PPDO) triblock copolymer and the phospholipid.
7. The preparation method of claim 1, wherein the amount of the glucan used in the step 2) is 5-15% by mass of the emulsifier.
8. The preparation method of claim 1, wherein the amount of chitosan used in step 5) is 4-16% of the mass of the drug-loaded micelle.
9. A rapamycin drug balloon made according to the method of making of any one of claims 1-8.
10. Use of a rapamycin drug balloon according to claim 9 in Percutaneous Transluminal Coronary Angioplasty (PTCA).
Technical Field
The invention relates to the field of medical instruments, in particular to a preparation method of a rapamycin drug balloon, and the rapamycin drug balloon prepared by the method.
Background
Coronary atherosclerotic heart disease is a big killer to harm human health. In 1977, Gruentzig performed the first Percutaneous coronary angioplasty (PTCA), which began the precedent of interventional coronary heart disease treatment. The PTCA technology is rapidly popularized due to small wound and good effect. In 1986, pulol and Sigmart first placed a metallic bare coronary stent into the coronary artery, completing a coronary stenting procedure that significantly reduced PTCA induced acute coronary dissection and occlusion, and significantly reduced the rate of advanced restenosis. In 2003, Drug Eluting Stents (DES) were beginning to be used clinically, further reducing the rate of restenosis.
Drug-Coated Balloons (DCB) are an emerging means for treating in-stent restenosis that has emerged in recent years. Different from a drug eluting stent, the drug balloon is coated with an antiproliferative drug on the surface of the balloon, and the antiproliferative drug is transferred to the wall of a target lesion blood vessel when the drug balloon is expanded so as to play a role in resisting endothelial cell proliferation. The drug balloon has the following advantages: (1) the blood vessel stent has the advantages that the metal stent is not used, the original anatomical structure of the blood vessel is saved, the physiological characteristics of self-relaxation and self-contraction of the blood vessel are also realized, and the influence on the blood flow mode is avoided; (2) the medicine is uniformly distributed in a specific area at high concentration for a short time, and does not cause long-term inflammatory reaction and systemic adverse reaction; (3) the treatment course of the antiplatelet therapy is shortened, the treatment cost is reduced, and bleeding complications are reduced. Therefore, the drug balloon has good application prospect theoretically.
The current commercialized drug balloon Sequent polymerase is developed by the Branson company, paclitaxel is used as an active drug, iopromide is used as a carrier, and the preparation is sprayed on the surface of the balloon to prepare the drug balloon Sequent polymerase. Subsequently, invitec corporation developed an additral Xtreme drug balloon with urea as the carrier and paclitaxel as the active drug; lutonix corporation developed Lutonix035 drug balloons that use polysorbate as the carrier and paclitaxel as the active drug; and so on. Almost all commercial drug balloons at present use paclitaxel as an active drug, with the exception of carrier technology. This is because paclitaxel is effective in inhibiting rapid cell proliferation, and also in inhibiting smooth muscle cell migration and phenotypic changes, inhibiting the intimal proliferative inflammatory response. Meanwhile, paclitaxel has high lipophilicity and adsorbability, and can be rapidly absorbed by the inner membrane when the saccule is released, so that irreversible influence is generated on the cytoskeleton structure. However, the drug toxicity of paclitaxel is drawing increasing attention, and particularly the fact that paclitaxel drug-coated balloons and stents may increase the risk of patient death during treatment of femoral artery disease has been reminded by the FDA.
Rapamycin is a natural macrolide drug, is a potent immunosuppressant, can prolong graft survival, and is effective for tissue transplantation, bone marrow transplantation, and islet cell transplantation. Rapamycin binds to a specific transducin, called TOR (rapamycin target), and acts in the mitotic G1 phase of the cell and inhibits its activity, returning the cell to the resting phase, thereby inhibiting cell growth. Rapamycin is less toxic than other immunosuppressive agents due to its unique mechanism of action. In addition, rapamycin inhibits inflammatory responses and smooth muscle cell hyperproliferation following arterial injury and stent implantation. Thus, rapamycin has been used in drug eluting stents.
Furthermore, the drug utilization of drug balloons is mainly affected by four aspects: (1) how to realize effective bonding between the drug coating and the surface of the balloon and avoid drug loss in the process of folding the balloon; (2) how to avoid the scouring and dissolving effect of blood flow on the drug balloon coating and avoid the drug loss in the process of delivering the balloon to the focus part; (3) how to maximize drug transfer to vascular endothelial cells after the drug balloon is expanded to make temporary contact with the vessel wall; (4) how to ensure that the rapamycin transporter transferred to the blood vessel has good pharmacokinetics.
Therefore, there is a need to develop a method for making a drug balloon that can effectively deliver rapamycin.
Disclosure of Invention
The invention aims to provide a preparation method of a rapamycin drug balloon, which can prepare the drug balloon capable of effectively delivering rapamycin.
The preparation method comprises the following steps:
1) dissolving rapamycin or its derivatives, poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer, and phospholipid in solvent, and mixing to obtain rapamycin medicinal solution; the phospholipid is selected from at least one of Dioleoylphosphatidylethanolamine (DOPE) or Dioleoylphosphatidylcholine (DOPC); the weight ratio of the poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer to the phospholipid is 1.5-3.2: 1;
2) adding an emulsifier and glucan into deionized water, and stirring to dissolve the emulsifier and the glucan to prepare an emulsified solution;
3) under high-speed stirring, adding the rapamycin medicinal solution into the emulsified solution drop by drop, and emulsifying by using an ultrasonic probe emulsifying instrument after the addition is finished to prepare a medicine-carrying micelle solution;
4) centrifuging the obtained drug-loaded micelle solution by using a high-speed centrifuge, washing by using deionized water, and freeze-drying to prepare drug-loaded micelles;
5) dispersing the drug-loaded micelle with an organic solvent, adding chitosan, and dispersing to prepare a spraying solution;
6) washing the naked saccule by deionized water, and carrying out surface plasma pretreatment after drying;
7) spraying the spraying solution on the surface of the naked balloon by using an ultrasonic spraying process until the drug loading on the surface of the balloon reaches 0.1-10 mu g/mm2；
8) Drying and folding to obtain the rapamycin medicinal balloon.
In one embodiment of the invention, the molecular weight of the poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer in the step 1) is 2000-8000 g/mol, wherein the mass ratio of PPDO block to PEG block is 1-5: 1. preferably, the molecular weight of the poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer is 2800-5000 g/mol, wherein the mass ratio of PPDO block to PEG block is 2-3: 1.
the preparation method of the poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer comprises the following steps:
under the protection of inert gas, putting p-dioxanone, polyethylene glycol and a catalyst into a reaction device, heating to 60-100 ℃, stirring, keeping the temperature, performing polymerization reaction, and purifying to obtain the poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer.
Preferably, the mass ratio of the p-dioxanone to the polyethylene glycol is 1-5: 1, preferably 2 to 3: 1.
preferably, the catalyst is at least one selected from stannous octoate, stannous lactate, butylstannoic acid, dibutyltin oxide and tetra-n-butyl titanate. The amount of the catalyst is 0.01-1 wt% of the p-dioxanone, preferably 0.05-0.5 wt%, and more preferably 0.1-0.3 wt%.
Preferably, the temperature of the polymerization reaction is 70-80 ℃. If the polymerization temperature is too low, the polymerization reaction is difficult to proceed; if the polymerization temperature is too high, the polymerization rate is high and the degree of polymerization is deep, and the molecular weight of the copolymer becomes too high.
Preferably, the purification comprises dissolving the polymerization reaction product in dimethyl sulfoxide or N, N-dimethylformamide, then dropping the obtained solution into water under stirring, soaking the precipitated solid particles in acetone or anhydrous ethanol, filtering and drying to obtain the purified poly (p-dioxanone) -polyethylene glycol-poly (p-dioxanone) (PPDO-PEG-PPDO) triblock copolymer. Through purification, impurities in the PPDO-PEG-PPDO triblock copolymer can be removed, and the purity of the PPDO-PEG-PPDO triblock copolymer is greatly improved.
Preferably, the weight ratio of the polydioxanone-polyethylene glycol-polydioxanone (PPDO-PEG-PPDO) triblock copolymer to the phospholipid in the step 1) is 1.8-2.6: 1, more preferably 2.0 to 2.5: 1. the ratio of PPDO-PEG-PPDO triblock copolymer to phospholipid may affect various properties of the micelle.
In one embodiment of the invention, the emulsifier in step 2) is selected from a complex system of tween series and sodium dodecyl sulfate, sodium dodecyl sulfate or sodium dodecyl benzene sulfonate. Preferably, the tween series is selected from tween 20, tween 40, tween 60, tween 80 and tween 85. Preferably, the mass ratio of the tween series to the sodium dodecyl sulfate, the sodium dodecyl sulfate or the sodium dodecyl benzene sulfonate is 1: 2-6, and preferably 1: 3-4.
Preferably, the amount of the emulsifier is 6 to 14 times, preferably 8 to 12 times of the total mass of the polydioxanone-polyethylene glycol-polydioxanone (PPDO-PEG-PPDO) triblock copolymer and the phospholipid.
Preferably, the dosage of the glucan in the step 2) is 5-15% of the mass of the emulsifier, and preferably 7-12%. The addition of a small amount of dextran in the present invention helps to increase the stability of the micelle, thereby prolonging the duration of action of rapamycin.
In one embodiment of the present invention, the high speed stirring in step 3) means that the rotation speed of the stirring is preferably 6000 to 15000rpm, more preferably 8000 to 12000 rpm.
Preferably, the particle size of the drug-loaded micelle is not more than 350nm, preferably not more than 300 nm. Preferably, the particle size of the drug-loaded micelle is not less than 50nm, preferably not less than 100 nm. The drug-loaded micelle with the particle size is particularly suitable for the transportation of rapamycin.
Preferably, the drug-loaded micelle has a drug loading of not less than 5%, preferably not less than 10%, more preferably not less than 15%. Preferably, the drug-loaded micelle has a drug loading of no greater than 50%, preferably no greater than 40%, more preferably no greater than 35%.
In one embodiment of the present invention, the organic solvent in step 5) is at least one selected from ketone solvents such as acetone, alcohol solvents such as methanol and ethanol, and alkane solvents such as n-hexane, n-heptane and cyclohexane. Preferably, the organic solvent is selected from the combination of acetone and methanol or ethanol, wherein the volume ratio of acetone to methanol or ethanol is 1-5: 1, preferably 2 to 3: 1.
preferably, the dosage of the chitosan in the step 5) is 4-16%, preferably 7-12% of the mass of the drug-loaded micelle. The chitosan plays a role in auxiliary bonding, and the introduction of the chitosan can increase the adhesive force among micelles, between the micelles and the surface of the pretreatment balloon and between the micelles and the vascular endothelial cells, so that the coating is prevented from falling off, and the transfer rate of the coating is improved. However, the use of chitosan in large amounts does not lead to a further improvement of this effect.
In one embodiment of the invention, the conditions of the plasma pre-treatment in step 6) comprise the use of a volume ratio of 1: 2-4 of mixed gas of nitrogen and oxygen, the plasma treatment power is 50-150W, the frequency is 30-80 MHz, and the air pressure is 40-80 Pa. Plasma treatment on the surface of the drug balloon can increase the roughness of the balloon surface, increase the adhesive strength of the coating to the balloon, and reduce the scouring of the drug coating on the balloon surface by blood flow during the process of delivering the drug balloon to the lesion part, thereby reducing the loss of the drug.
In one embodiment of the invention, the conditions of the ultrasonic spraying process in the step 7) are that the ultrasonic power is set to be 3-5W, the flow rate of the micro-injection pump is 1.5-3 ml/h, and the moving speed of the spray head is 4-6 mm/s
Preferably, the drug-loaded capacity of the surface of the drug balloon prepared by the invention is 1-8 mug/mm2Preferably 1.5 to 5. mu.g/mm2More preferably 3 to 4. mu.g/mm2。
The invention also aims to provide a rapamycin medicine balloon prepared by the preparation method.
It is another object of the present invention to provide the use of the rapamycin drug balloon in Percutaneous Transluminal Coronary Angioplasty (PTCA).
In conclusion, the invention provides a preparation method of a rapamycin drug balloon, which is simple to operate and can easily prepare the drug balloon capable of effectively delivering rapamycin. The medicine balloon effectively solves the problem that the rapamycin medicine coating is easy to fall off after being sprayed on the medicine balloon, greatly improves the transfer rate of rapamycin to vascular endothelial cells after the medicine balloon is expanded, and improves the initial tissue medicine concentration. Meanwhile, the rapamycin micelle particles transferred to blood vessels have good pharmacokinetic properties, and the effective treatment concentration of rapamycin in tissues can still be detected within 90 days. The rapamycin medicinal balloon is made of safe and nontoxic rapamycin medicinal materials, has high rapamycin utilization rate and long action time, and is particularly suitable for being applied to PTCA.
Detailed Description
Hereinafter, preferred examples of the invention will be described in detail. The examples are given for the purpose of better understanding the inventive content and are not intended to be limiting. Insubstantial modifications and adaptations of the embodiments in accordance with the present disclosure remain within the scope of the invention.
Synthesis example 1:
under the protection of argon, 20.4g of p-dioxanone, 6.8g of PEG800 and 0.04g of stannous octoate catalyst are placed in a reaction device, the temperature is raised to 80 ℃, and the reaction is carried out for 48 hours under stirring and heat preservation; mixing the reaction product with a proper amount of dimethyl sulfoxide according to the proportion that 1g of the product is prepared into 0.1L of solvent, heating to 120 ℃, and stirring for dissolving; then, the mixture is dripped into deionized water with 5 times of volume under stirring to precipitate solid particles, the solid particles are soaked in acetone for 2 hours, the solid particles are separated by filtration, and 25g of purified PPDO-PEG-PPDO triblock copolymer is obtained after vacuum drying. The mass ratio of PPDO to PEG blocks was analyzed to be about 3: 1; the number average molecular weight is about 3150 g/mol.
Example 1:
1) dissolving 75mg of rapamycin in 25ml of acetone, adding 180mg of PPDO-PEG-PPDO triblock copolymer synthesized in synthesis example 1 and 80mg of dioleoyl phosphatidylethanolamine, stirring to dissolve, and fully and uniformly mixing to prepare rapamycin medicinal solution;
2) adding 0.6g of Tween 80, 1.8g of sodium dodecyl sulfate and 0.2g of glucan into 200ml of deionized water, and stirring to dissolve to prepare an emulsified solution;
3) dropwise adding the rapamycin medicinal solution into the emulsified solution at the rotating speed of 2000rpm, wherein the dropping speed is 1ml/min, and emulsifying for 5 minutes by using an ultrasonic probe emulsifying instrument after the dropping is finished to prepare a drug-loaded micelle solution;
4) centrifuging the prepared drug-loaded micelle solution by using a high-speed centrifuge, washing by using deionized water, and freeze-drying to prepare 320mg of drug-loaded micelle; a small amount of micelle was taken and the drug loading was found to be about 22%. Dispersing in deionized water, and analyzing particle size with laser scattering particle size analyzer (Mastersizer 3000, Malverpa department) to obtain average particle size of 247 nm;
5) dispersing the drug-loaded micelle by using 30ml of solvent with the volume ratio of acetone to ethanol being 3:1, then further adding chitosan accounting for 10 percent of the weight of the drug-loaded micelle, and fully dispersing to prepare a spraying solution;
6) the nylon naked balloon with the diameter of 4mm and the length of 40mm is washed by deionized water, and after drying, the surface plasma pretreatment is carried out on the naked balloon by a plasma machine in a ten thousand-level clean environment, wherein the volume ratio of pretreatment gas is 1:2, the plasma treatment power is 100W, the frequency is 50MHz, the treatment time is 30min, and the gas pressure is 50 Pa; after the treatment is finished, fixing the ultrasonic spraying device on an automatic ultrasonic spraying instrument;
7) setting the ultrasonic power at 3.5W, the flow rate of a micro-injection pump at 2ml/h and the movement rate of a nozzle at 5.4mm/s, and uniformly spraying the spraying solution on the surface of a bare balloon by adopting an ultrasonic spraying process for 7 times until the drug loading on the surface of the balloon is 3 mu g/mm 2;
8) drying and folding to obtain the rapamycin medicinal balloon.
Example 2:
the same as in example 1 except that dioleoylphosphatidylcholine was used in the same amount in place of dioleoylphosphatidylethanolamine. Wherein, the obtained drug-loaded micelle is 318mg, and the particle size is 231 nm. The same was applied until the drug loading on the balloon surface was 3 μ g/mm 2.
Example 3:
same as example 1 except that the amount of chitosan in step 5) was 15% of the weight of the drug-loaded micelle. The same was applied until the drug loading on the balloon surface was 3 μ g/mm 2.
Example 4
Same as in example 1, except that acetone was replaced with 30ml of dichloromethane in step 1). Wherein, the obtained drug-loaded micelle is 326mg, and the particle size is 264 nm. The same was applied until the drug loading on the balloon surface was 3 μ g/mm 2.
Comparative example 1:
the same as example 1, except that 260mg of the PPDO-PEG-PPDO triblock copolymer synthesized in Synthesis example 1 was used instead of 180mg of the PPDO-PEG-PPDO triblock copolymer synthesized in Synthesis example 1 and 80mg of dioleoylphosphatidylethanolamine. Wherein the obtained drug-loaded micelle is 324mg and has a particle size of 413 nm. The same was applied until the drug loading on the balloon surface was 3 μ g/mm 2.
Comparative example 2:
same as example 1, except that no dextran was added in step 2). Wherein the obtained drug-loaded micelle is 304mg and the particle size is 308 nm. The same was applied until the drug loading on the balloon surface was 3 μ g/mm 2.
Comparative example 3:
same as example 1, except that no chitosan was added in step 5). Wherein, the drug loading on the surface of the balloon is 3 mug/mm 2 by spraying.
And (3) testing properties:
test 1, balloon-folded drug loss test:
the rapamycin content was measured by HPLC after taking the unfolded drug balloon and completely dissolving the coating of the drug loaded portion with methanol, 5 of each sample were tested and the average was taken and recorded as the initial drug load M0. The folded drug balloon was then removed, the coating of the drug loaded portion was also completely dissolved with solvent and rapamycin content was measured by HPLC, 5 of each sample were tested and the average was taken and recorded as balloon drug loading M1. The folded drug loss rate was calculated according to the following formula:
the folding drug loss rate is (M0-M1)/M0 multiplied by 100%
Wherein M0 is the initial drug loading; m1 is balloon drug loading.
Test 2, balloon delivery loss test:
the folded drug saccule is inserted into an in-vitro simulation flushing device without expansion, PBS is adopted to simulate blood, the flow rate is 35ml/min, the temperature is 37 ℃, and the flushing time is 3 min. After removal, the drug coating was completely dissolved in methanol and the rapamycin content was measured by HPLC, 5 of each sample were tested and the average was taken as the drug loading M2 without balloon dilation withdrawal. The delivered drug loss rate was calculated according to the following formula:
the loss rate of the delivered drug is (M1-M2)/M1 multiplied by 100%
Where M1 is balloon drug loading (as measured in test 1); m2 is the drug load for the non-expanded retrieval balloon.
Experiment 3, simulated transfer rate test:
taking an isolated porcine artery vascular section, keeping the constant temperature of 37 ℃, taking a sterilized bare balloon to dilate the blood vessel for 1min at 6atm, and then decompressing and taking out the bare balloon. The folded drug balloon is placed into the dilated blood vessel, dilated for 1min at 6atm, and then decompressed to take out the drug balloon. After complete dissolution of the coating with methanol, the rapamycin content was measured by HPLC, 5 of each sample were tested, and the mean value was recorded as the simulated residual drug loading M3. The transfer rate was calculated according to the following formula:
the rate of analog transfer was (M1-M3)/M1X 100%
Where M1 is balloon drug loading (as measured in test 1); m3 is a simulated residual drug load.
The above results are reported in table 1:
table 1:
from the above results, it can be seen that the rapamycin drug balloon made according to the method of the present invention has little loss during the folding process as well as during delivery of the balloon, and is capable of transferring a substantial portion of the drug coating to the vascular endothelial cells after balloon expansion. The drug balloon of the comparative example 1 has poor adhesion of the drug coating on the balloon and poor ability of transferring to vascular endothelial cells because of no phospholipid; the drug balloon of comparative example 3 also suffers from insufficient adhesion on the balloon due to the lack of chitosan. Test 4, actual transfer rate and pharmacokinetic evaluation:
the 20 pigs were divided into 4 groups of 5 pigs each, each group of pigs administered the same drug balloon. The folded drug balloons are respectively arranged on the Left Anterior Descending (LAD), the Right Coronary Artery (RCA) and the Circumflex (CX) parts of the coronary artery of the same domestic pig, the expansion is carried out for 1min under 6atm, then the pressure is released, the balloons are withdrawn, after the coating is completely dissolved by methanol, the content of the rapamycin is measured by HPLC, and the average value of the residual drug loading of 15 (3 multiplied by 5) drug balloons in each group is taken as the actual residual drug loading M4 of the test sample. The actual residual rate was calculated according to the following formula and the actual transfer rate was investigated in combination with the rate of loss of the delivered drug in test 3:
the actual residue rate was M4/M1X 100%
Where M1 is balloon drug loading (as measured in test 1); m4 is the actual residual drug loading.
Thereafter, the pig was sacrificed and dissected at 10 minutes, 7 days, 28 days, 60 days and 90 days, respectively, the dilated blood vessels were removed, the drug in the tissues was extracted with methanol, the rapamycin concentration in the tissues was measured by HPLC, and the average value of the residual rapamycin in the tissues of 3 sites was taken as the tissue drug residual concentration thereof. The results are reported in table 2:
table 2:
"-" indicates no detection.
From the above results, it can be seen that the rapamycin drug balloon prepared according to the method of the present invention has high initial tissue drug concentration and long drug action time, and still has effective rapamycin concentration after 90 days. The drug balloon of comparative example 1 had a low initial tissue drug concentration with the same rapamycin concentration in the coating due to the low transfer rate, resulting in an insufficient rapamycin duration of action. The drug balloon of comparative example 2 was prepared without introducing dextran, and the stability of the micelle was decreased, resulting in insufficient duration of action of rapamycin. Furthermore, the results of the test on the domestic pig were consistent with those obtained by the simulation test in terms of the residual rate, indicating that the simulation test was sufficiently accurate.
Finally, it is noted that the above-mentioned preferred embodiments illustrate rather than limit the invention, and that, although the invention has been described in detail with reference to the above-mentioned preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the scope of the invention as defined by the appended claims.