Abstract:
A radiopaque biodegradable vascular embolic microsphere comprises of a biodegradable material and a radiopaque material which can be both delivered to the vascular system, in which, the biodegradable material incorporates the radiopaque material to form granule structure. The embolic microsphere, readily visible under X-ray, can be delivered or drift with blood flow to a peripheral vessel or site, and can be manufactured using a simple process. A radiopaque biodegradable vascular embolic microsphere incorporating therapeutic agent(s) comprises of a biodegradable material, a radiopaque material, and therapeutic agent(s), which can be all delivered to the vascular system, in which, the biodegradable material incorporates the radiopaque material and the therapeutic agent to form granule structure. This embolic microsphere can be delivered to the targeted site under X-ray guidance, and then embolize the site, and release the therapeutic agent directly at the targeted site while degrading in vivo.

Description:
TECHNOLOGY FIELD 
       [0001]    The present invention relates to a vascular embolic material, furtherly relates to a radiopaque biodegradable vascular embolic microsphere, and relates to an embolic vascular microsphere which is biodegradable, and incorporates a therapeutic agent or agents or a drug or drugs. 
       BACKGROUND ART 
       [0002]    Various materials have been proposed for interventional vascular embolization. Commonly used examples include: polyvinyl alcohol (PVA), sodium alginate, gelatin sponge, surgical sutures, stainless steel or platinum coils, detachable balloons, cyanoacrylates, anhydrous ethanol, iodized oil, sodium morrhuate, et al. Positive clinical results have been obtained using stainless steel coils, surgical sutures, and gelatin sponges as embolic agents in vasculars. However, the long term curative effects have been limited due to the establishment of collateral circulation. The embolic agents which are liquid, such as cyanoacrylates, anhydrous ethanol, iodized oil, and sodium morrhuate, may cause non-target embolization and are difficult to control during the procedure. In addition, the embolic agents that are non-radiopaque; such as polyvinyl alcohol, sodium alginate microspheres, gelatin sponges, and surgical sutures, are difficult to assess the proper delivery of these materials to the site. 
       CONTENTS OF THE INVENTION 
       [0003]    The present invention describes a radiopaque, biodegradable, embolic microspheres for use in the vascular system. These microspheres, readily visible under X-ray, can be delivered or drift with blood flow to a peripheral vessel or site, and can be manufactured using a simple process. 
         [0004]    According to the present invention, there is provided a radiopaque biodegradable vascular embolic microsphere comprising of a biodegradable material and a radiopaque material which can be both delivered to the vascular system. The biodegradable material incorporates the radiopaque material to form granule structure. 
         [0005]    The present invention also describes a radiopaque, biodegradable, embolic microsphere which incorporates a therapeutic agent. This microsphere can be delivered to the targeted site under X-ray guidance. The microsphere can then embolize the site, and release the therapeutic agent directly at the targeted site while degrading in vivo. 
         [0006]    According to the present invention, there is also provided a radiopaque biodegradable vascular embolic microsphere incorporating therapeutic agent(s) comprising of a biodegradable material, a radiopaque material, and therapeutic agent(s), which can be all delivered to the vascular system. The biodegradable material incorporates the radiopaque material and the therapeutic agent to form granule structure. 
         [0007]    The preferred therapeutic agent is an antineoplastic agent. These agents can include the following drugs: carboplatin, cisplatin, docetaxel, oxaliplatin, cyclophosphamide, ifosfamide, doxorubicin, pegylated liposomal doxorubicin, epirubicin, topotecan, irinotecan, etoposide, bleomycin, fluorouracil, gemcitabine, vincristine, actinomycin, and paclitaxel, or one of their derivatives, as well as any combination thereof. 
         [0008]    According to further features in preferred embodiments of the invention, the biodegradable material is made from polyesters, including polylactide, poly (lactide-co-glycolide), poly (lactide-ether) copolymer, and the blend of one or more of their derivatives. 
         [0009]    According to further features in preferred embodiments of the invention, the biodegradable material is made from polycaprolactone, including polycaprolactone, poly (caprolactone-ether) block copolymer, polycaprolactone copolymer, poly (caprolactone-ether-lactide) copolymer, poly (glycolide-L-lactide) copolymer, poly (glycolide-L-lactide-caprolactone) copolymer, poly (caprolactone-caprolactone-glycolide) copolymer, poly (fatty acid-caprolactone) copolymer, and the blend of one or more of their derivatives. 
         [0010]    According to further features in preferred embodiments of the invention, the biodegradable material is made from nature polymer, including collagen, chitin, chitosan, gelatin or alginate, and the blend of one or more of their derivatives. 
         [0011]    The radiopaque material may incorporate effective components of vascular contrast agents. These components may incorporate one or more of the following materials: residues of freeze-drying of an ionic contrast agent, such as diatrizoate; and nonionic contrast agent, such as iohexyl, iopromide, iopamidol, and the nonionic dimer iotrolan. 
         [0012]    The density of the embolic microsphere is from 0.8 g/cm 3  to 1.65 g/cm 3 , and preferred specific density of the embolic microsphere is from 1.0 g/cm 3  to 1.35 g/cm 3 . 
         [0013]    The diameter of these microspheres lies in the range of 10 μm to 1500 μm. These can be subdivided into many grades such as: 10 μm˜150 μm, 100 μm˜350 μm, 200 μm˜500 μm, 400 μm˜650 μm, 500 μm˜750 μm, 650 μm˜950 μm, 850 μm˜1100 μm, 1000 μm˜1350 μm and 1250 μm˜1500 μm. 
         [0014]    The above mentioned radiopaque, biodegradable, therapeutic agent incorporating, embolic microspheres have the following advantages:
       Good visibility under X-ray, beneficial for ensuring accurate delivery of the embolic microspheres to the correct site.   Controllable biodegradation rate to prevent unwanted or excessive damage to organs.   Can consist of non-ferrous material to allow MRI examination post embolization.   Selection of the appropriate specific gravity for the microspheres allows them to be suspended in the blood, to be taken to the targeted peripheral vessels for embolization.   The avoidance of back flow allows accurate embolization of the target vessels.   The diameter of the microsphere is controllable for appropriate vessel sizing.   The resultant products are easily prepared.       
 
         [0022]    In summary, an ideal vascular intervention embolic material is described, especially suited for targeting peripheral vascular vessels for embolization and/or delivery of controlled release of antineoplastic agents or anticancer drugs. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Example 1 
     Radiopaque Polylactide (PLA) Vascular Embolic Material 
       [0023]    Vascular contrast agent, such as diatrizoate which is an ionic contrast agent, is purchased from the market. The contrast agent is processed be vacuum freeze-drying, and the residues are used as the imaging material. PLA is used as the biodegradable material, and the radiopaque microsphere can be fabricated by commonly known processes. 
         [0024]    There are many examples of processes to prepare drug-loading microsphere with PLA as the coating materials. YANG Fan, etc., “Study on the Ciprofloxacin acid microspheres” published in the  Journal of China Pharmaceutical University,  2004, 35: 207-210. In the article, YANG discloses a preparation method to prepare ciprofloxacin acid microsheres. ZHAO Rui Ling, “Study on preparation of Adriamycin PLA microspheres and release behavior in vitro” published in the  Chinese Journal of Hospital Pharmacy,  2004, Vol. 24, Issue 2. In the article, ZHAO discloses a preparation method to prepare adriamycin polylactide microspheres. LI Yan, ect., “Study on development of some factors for preparing microspheres” published in  Foreign Medical Sciences  ( Section on Pharmacy ), 2001.6., Vol. 28, Issue 3. In the article, LI introduces some factors for preparing microspheres. 
         [0025]    In this example, a special emulsification and solvent-evaporation method is used to fabricate a developable PLA microsphere-base vascular embolic agent. 
         [0026]    PLA is dissolved in organic solvents (e.g. dichloromethane), and a radiopaque agent is dispersed into the solvent. The above mixture is added to a PVA solution drop by drop while stirring to emulsify. Then, the primary emulsification solution is poured into a large volume of PVA solution under a low concentration to evaporate the organic solvent, centrifuged, filtered, washed, dried, and sterilized. PLA microspheres incorporating radiopaque agents are thus obtained. 
         [0027]    Other contrast agents may be used besides the diatrizoate described in this example. These contrast agents may be selected from nonionic contrast agents, such as iohexyl, iopromide, iopamidol, or the nonionic dimer iotrolan. 
       Example 2 
     Radiopaque poly(lactic-co-glycolic acid) (PLGA) Vascular Embolic Microspheres 
       [0028]    The second embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the first embodiment with the difference that in this example, the biodegradable material is PLGA rather than PLA. 
         [0029]    The radiopaque materials are selected from the residues by freeze-drying of one of the following materials: ionic contrast agent diatrizoate, nonionic contrast agent iohexyl, iopromide and iopamidoi, and non-ionic dimmer iotrolan. 
         [0030]    The developable PLA and PLGA microsphere in present invention are prepared by emulsification and solvent-evaporation method and phase separation-aggregation method. 
         [0031]    In addition, a new method such as supercritical fluid technology can also be adopted. The solution which incorporates biodegradable material and developable material is atomized and injected into the incorporateer incorporating compressed CO 2 . Because of the extraction and diffusion of organic solvents in CO 2 , the polymers precipitate and the radiopaque PLA or PLGA microspheres can be obtained. The resultant microspheres have better mobility and appearance, and the amount of surfactant and residual solvents are reduced. 
       Example 3 
     Radiopaque poly(glycolic acid-co-caprolactone) Copolymer Vascular Embolic Microspheres 
       [0032]    The third embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the first embodiment with the difference that in this example, the biodegradable material is poly(glycolic acid-co-caprolactone) copolymer. 
         [0033]    The radiopaque materials are selected from the residues by freeze-drying of one of the following materials: ionic contrast agent diatrizoate, nonionic contrast agent iohexyl, iopromide and iopamidol, and non-ionic dimmer iotrolan. 
         [0034]    The microspheres are prepared by emulsification and solvent-evaporation method and phase separation-aggregation method, or CO 2  supercritical fluid technology. 
       Example 4 
     Radiopaque Chitosan Vascular Embolic Microspheres 
       [0035]    The fourth embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the first embodiment with the difference that in this example, the biodegrade material is chitosan. 
         [0036]    The radiopaque materials are the residues by freeze-drying of ionic contrast agent diatrizoate. 
         [0037]    The microspheres are prepared by emulsification and solvent-evaporation method, phase separation-aggregation method or CO 2  supercritical fluid technology. 
       Example 5 
     Radiopaque Gluten Vascular Embolic Microspheres 
       [0038]    The fifth embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the first embodiment with the difference that in this example, the biodegrade material is gluten. 
         [0039]    The radiopaque materials are the residues by freeze-drying of ionic contrast agent diatrizoate. The microspheres are prepared by emulsification and solvent-evaporation method and phase separation-aggregation method, or CO 2  supercritical fluid technology. 
         [0040]    In above examples 1-5, the biodegradable material may incorporate the radiopaque material to form granule structure in the following three types: first, the radiopaque material is dispersively distributed in the embolic microsphere which is made of the biodegradable material; second, the radiopaque material is encapsulated by the biodegradable material to form the granular structure; third, the radiopaque material is adsorbed in the embolic microsphere which is made of the biodegradable material. 
       Example 6 
     Radiopaque, Vascular, Embolic PLA Microspheres Incorporating Therapeutic Agent(s) 
       [0041]    Vascular contrast agent is purchased from the market, such as diatrizoate which is a kind of ionic contrast 
         [0042]    Therapeutic agents such as one of the following, or combination of two or more of the antineoplastic drugs are chosen: carboplatin, cisplatin, paclitaxel, docetaxel, oxaliplatin, cyclophosphamide, ifosfamide, doxorubicin, pegylated liposomal doxorubicin, epirubicin, topotecan, irinotecan, etoposide, bleomycin, fluorouracil, gemcitabine, vincristine, actinomycin, and paclitaxel, and their derivatives, as well as any combination thereof. 
         [0043]    PLA is used as the biodegradable material. These PLA microspheres which incorporate radiopaque materials and antineoplastic agents are prepared by commonly known processes. 
         [0044]    In this example, a special emulsification-solvent evaporation method is used to prepare the radiopaque, vascular, embolic PLA microspheres. Additional details are as follows. 
         [0045]    PLA is dissolved in organic solvents (e.g. dichloromethane), and a radiopaque agent is dispersed into the solvent. The mixture is added to a PVA solution drop by drop while stirring to emulsify. Then, the primary emulsification solution is poured into a large volume of PVA solution under a low concentration to evaporate the organic solvent, centrifuged, filtered, washed, dried, and sterilized. PLA microspheres incorporating radiopaque agents are thus obtained. 
         [0046]    In this example, the radiopaque materials also could be selected from the residues, by freeze-drying, of ionic contrast agent diatrizoate, nonionic contrast agent iohexyl, iopromide and iopamidol, and non-ionic dimer iotrolan. 
       Example 7 
     Radiopaque, Vascular, Embolic PLGA Microspheres Incorporating Therapeutic Agent(s) 
       [0047]    The seventh embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the sixth embodiment with the difference that in this example, the biodegradable material is PLGA. 
         [0048]    The radiopaque material is selected from one of the residues, by freeze-drying, of ionic contrast agent diatrizoate, nonionic contrast agent iohexyl, iopromide and iopamidol, and non-ionic dimer iotrolan. 
         [0049]    Therapeutic agents such as one of the following, or combination of two or more of the antineoplastic drugs are chosen: carboplatin, cisplatin, paclitaxel, docetaxel, oxaliplatin, cyclophosphamide, ifosfamide, doxorubicin, pegylated liposomal doxorubicin, epirubicin, topotecan, irinotecan, etoposide, bleomycin, fluorouracil, gemcitabine, vincristine, actinomycin, and paclitaxel, or their derivatives. 
         [0050]    The radiopaque PLGA microspheres in present invention are prepared by emulsification and solvent-evaporation method and phase separation-aggregation method. In addition, a new method such as supercritical fluid technology can also be used. The solution which incorporates biodegradable and radiopaque materials is atomized and injected into the incorporateer incorporating compressed CO 2 . By the extraction and diffusion of organic solvents in CO 2 , the polymers precipitate, and the radiopaque PLGA microspheres are obtained. The resultant microspheres have better mobility and appearance, and the amount of surfactant and residual solvents are reduced. 
       Example 8 
     Radiopaque, Vascular, Embolic poly(caprolactone-glycolide) Microspheres Incorporating Therapeutic Agent(s) 
       [0051]    The eighth embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the sixth embodiment with the difference that in this example, the biodegradable material is poly(caprolactone-caprolactone-glycolide). 
         [0052]    The radiopaque material is selected from one of the residues, by freeze-drying, of ionic contrast agent diatrizoate, nonionic contrast agent iohexyl, iopromide and iopamidol, and non-ionic dimer iotrolan. 
         [0053]    Therapeutic agents such as one of the following, or combination of two or more of the antineoplastic drugs are chosen: carboplatin, cisplatin, paclitaxel, docetaxel, oxaliplatin, cyclophosphamide, ifosfamide, doxorubicin, pegylated liposomal doxorubicin, epirubicin, topotecan, irinotecan, etoposide, bleomycin, fluorouracil, gemcitabine, vincristine, actinomycin, and paclitaxel, or their derivatives. 
         [0054]    The microspheres are prepared by emulsification and solvent-evaporation method and phase separation-aggregation method, or CO 2  supercritical fluid technology. 
       Example 9 
     Radiopaque, Vascular, Embolic Chitosan Microspheres Incorporating Cisplatin 
       [0055]    The ninth embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the sixth embodiment with the difference that in this example, the biodegradable material is chitosan. 
         [0056]    The radiopaque material is the residues by freeze-drying of ionic contrast agent diatrizoate. 
         [0057]    The microspheres are prepared by emulsification and solvent-evaporation method and phase separation-aggregation method or CO 2  supercritical fluid technology. 
       Example 10 
     Radiopaque, Vascular, Embolic Chitosan Microspheres Incorporating Carboplatin 
       [0058]    The tenth embodiment of the radiopaque biodegradable vascular embolic microsphere is generally similar to the sixth embodiment with the difference that in this example, the biodegrade material is carboplatin. The radiopaque material is the residues by freeze-drying of ionic contrast agent diatrizoate. 
         [0059]    The antineoplastic agent is carboplatin. The microspheres are prepared by emulsification and solvent-evaporation method and phase separation-aggregation method, or CO 2  supercritical fluid technology. 
         [0060]    For flexibility and optimizing patient treatment, the degradation rate of these radiopaque microspheres related in the present invention can be controlled. 
         [0061]    In above examples 6-10, the biodegradable material incorporates the radiopaque material and the therapeutic agent to form granule structure in the following three types: first, the radiopaque material and the therapeutic agent are dispersively distributed in the embolic microsphere which is made of the biodegradable material; second, the radiopaque material and the therapeutic agent are encapsulated by the biodegradable material to form the granular structure; third, the radiopaque material and the therapeutic agent are adsorbed in the embolic microsphere which is made of the biodegradable material. 
         [0062]    Additionally, by changing the molecular weights of polymers or their chemical compositions of the microspheres, degradation rates such as 7 days, 15 days, 30 days, 60 days, and 180 days are achievable. 
         [0063]    It should be noted that the structure, described and made public in this text, can be replaced with other structure(s) owning the same function. Meanwhile, the examples introduced by the invention are not the only structure that does carry out the invention. Although this invention has given introduction and elucidation of the implementation example, the technician in this field are clearly know that this is just an illustration with example. The technician in this field can make numerous changes, improvements and replacements. However, it can&#39;t be divorced from this invention. Therefore, we should limit protection ranges of the invention according to the spirit and scope of claims enclosed invention.