Balloon catheter

Abstract

Provided is a balloon catheter with which a drug transferred from a balloon to a blood vessel wall does not easily separate from the blood vessel wall.　This balloon catheter has a balloon (20). The balloon (20) has a balloon body part (30) having a longitudinal direction x and a radial direction y, and a drug layer (40) that is disposed outward of the balloon body part (30) in the radial direction y and contains a drug. The drug layer (40) has a radial crystal group (42) including a plurality of columnar crystals (41) of the drug arranged radially. In a cross section in the longitudinal direction x, the radial crystal group (42) has a fan shape, and the central angle θ of the fan shape exceeds 180°.

Description

Balloon catheter

[0007] ,

[0006] ,

[0001] The present invention relates to a balloon catheter having a balloon with a drug retained on its surface.

[0002] Stenosis occurs in blood vessels, which are channels for blood circulation in the body, and various diseases are caused by the stagnation of blood circulation. As one method of treating such diseases, there is angioplasty in which a balloon catheter is used to expand the stenosis.

[0003] Among balloon catheters, there is a drug-coated balloon catheter (DCB) in which a drug is retained on the surface of the balloon, and after the balloon is delivered into the blood vessel, the drug is released to administer the drug to the target tissue (for example, Patent Documents 1 to 4). For example, after the expansion of the stenosis, the neointima of the blood vessel may proliferate excessively and restenosis may occur, but restenosis can be prevented by administering the drug to the blood vessel wall with a drug-coated balloon.

[0004] Japanese Patent Publication No. 2012-533338, Japanese Patent Publication No. 2017-515598, International Publication No. 2019 / 059347, International Publication No. 2017 / 164281

[0005] In a conventional balloon catheter, there is room for improvement in stably administering a drug to the blood vessel wall so that the drug that has migrated from the balloon to the blood vessel wall does not detach from the blood vessel wall. Therefore, an object of the present invention is to provide a balloon catheter in which a drug that has migrated from the balloon to the blood vessel wall is difficult to detach from the blood vessel wall.

[0006] The balloon catheter according to an embodiment of the present invention that has solved the above problems is as follows. [1] A balloon catheter having a balloon, wherein the balloon has a balloon main body portion having a longitudinal direction and a radial direction, and a drug layer disposed outside the balloon main body portion in the radial direction and containing a drug, the drug layer has a radially crystalline group including a plurality of columnar crystals of the drug arranged radially, and in a cross section in the longitudinal direction, the radially crystalline group has a fan shape and the central angle of the fan shape is more than 180° balloon catheter.

[0007] The drug layer in the balloon of the balloon catheter described above has a radial crystal group containing multiple columnar crystals of the drug arranged radially. In a longitudinal cross-section, this radial crystal group has a fan shape, and the central angle of the fan shape is greater than 180°. When the balloon is expanded after being delivered to the treatment site, the radial crystal group migrates from the outer surface of the balloon body to the blood vessel wall. However, because the central angle of the fan shape of the radial crystal group is greater than 180°, columnar crystals can exist that extend radially inward into the blood vessel. These columnar crystals extending radially inward into the blood vessel cause turbulence in the blood, making thrombus formation more likely. Thus, the formation of a thrombus in the part where the radial crystal group has migrated to the blood vessel wall prevents the radial crystal group from detaching from the blood vessel wall. As a result, a balloon catheter that can effectively deliver the drug to the target tissue can be provided.

[0008] The balloon catheter described above is preferably any of the following [2] to

[11] . [2] The balloon catheter according to [1], wherein the central angle of the fan shape is 270° or less. [3] The balloon catheter according to [1] or [2], wherein in the longitudinal cross-section, the radius of the fan shape is 5 μm or more and 30 μm or less. [4] The balloon catheter according to any of [1] to [3], wherein in a plan view from the outside of the radial direction of the balloon, the major axis of the radial crystal group is 10 μm or more and 80 μm or less. [5] The balloon catheter according to any of [1] to [4], wherein the drug is paclitaxel. [6] The balloon catheter according to any of [1] to [5], wherein the balloon has a gap in which the radial crystal group is separated from the outer surface of the balloon body. [7] The balloon catheter according to [6], wherein a swelling substance is disposed in the gap. [8] The balloon catheter according to [7], wherein the swelling substance remains on the balloon after expansion. [9] The balloon catheter according to any one of [1] to [8], wherein the radial crystal group is a plurality of radial crystal groups having a fan shape, and the plurality of radial crystal groups includes radial crystal groups in which each of the plurality of radial crystal groups overlaps with each other radially outside the center of the fan shape.

[10] The balloon catheter according to any one of [1] to [9], wherein the radial crystal group is a plurality of radial crystal groups having a fan shape, and the plurality of radial crystal groups includes radial crystal groups in which each of the plurality of radial crystal groups is joined with each other radially outside the center of the fan shape.

[11] The balloon catheter according to any one of [1] to

[10] , further comprising a protective agent layer on the radially outside of the drug layer.

[0009] The balloon catheter described above makes it difficult for the drug that has moved from the balloon to the blood vessel wall to detach from the vessel wall. This makes it possible to provide a balloon catheter that can effectively deliver drugs to target tissues.

[0010] This is a side view of a balloon catheter according to one embodiment of the present invention. The drug layer is omitted in this drawing. This is a partially enlarged view of the longitudinal cross-section of the balloon of a balloon catheter according to one embodiment of the present invention. This is a diagram illustrating the fan shape of a radial crystal group according to one embodiment of the present invention. This is an SEM image of the longitudinal cross-section of the balloon of a balloon catheter according to one embodiment of the present invention. This is a perspective view of a columnar crystal according to one embodiment of the present invention. This is a schematic diagram of a radial crystal group according to one embodiment of the present invention in a plan view from the radial outside. This is an SEM image of the balloon of a balloon catheter according to one embodiment of the present invention observed from the radial outside. This is a partially enlarged view of the longitudinal cross-section of the balloon of a balloon catheter according to another embodiment of the present invention. This is a partially enlarged view of the longitudinal cross-section of the balloon of a balloon catheter according to yet another embodiment of the present invention. This is a partially enlarged view of the longitudinal cross-section of the balloon of a balloon catheter according to yet another embodiment of the present invention. This is a partially enlarged cross-sectional view showing the state when a water-soluble additive is applied to the outer surface of the balloon body during the manufacturing process of a balloon catheter according to one embodiment of the present invention. This is an SEM image of the balloon body observed from the radial outside when a water-soluble additive is applied to the outer surface of the balloon body during the manufacturing process of a balloon catheter according to one embodiment of the present invention. Figure 11 is a partially enlarged cross-sectional view showing the state after a solution containing the drug has been applied to the outer surface of the balloon body. Figure 13 is a partially enlarged cross-sectional view showing the state after the nucleus of the water-soluble additive has been removed from the state shown in Figure 13.

[0011] The present invention will be described below based on embodiments, but the present invention is not limited to the embodiments described below, and it is certainly possible to implement it with appropriate modifications within the scope that is consistent with the spirit of the preceding and following descriptions, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component reference numerals may be omitted in the drawings for convenience, in which case please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority has been given to helping to understand the features of the present invention.

[0012] An example of the configuration of a balloon catheter according to an embodiment of the present invention will be described with reference to the drawings. Figure 1 is a side view of a balloon catheter according to one embodiment of the present invention. Figure 1 is a diagram for understanding the overall configuration of the balloon catheter, and the drug layer is omitted. Figure 2 is a partially enlarged view of the longitudinal cross-section of the balloon of the balloon catheter according to one embodiment of the present invention, showing the configuration of the balloon membrane. Figure 3 is a diagram illustrating the fan shape of the radial crystal group according to one embodiment of the present invention. Figure 4 is an SEM image of the longitudinal cross-section of the balloon according to one embodiment of the present invention. Figure 4 was obtained by SEM observation of the surface of the balloon membrane after exposing the cross-section of the drug layer by irradiating it with a focused ion beam. Figure 5 is a perspective view of a columnar crystal according to one embodiment of the present invention. In Figure 5, one columnar crystal extending radially outward from the nucleus of the radial crystal group and one columnar crystal extending radially inward from the nucleus of the radial crystal group are shown, and other columnar crystals are omitted. Figure 6 is a schematic diagram of the radial crystal group according to one embodiment of the present invention in a plan view from the radial outside. Figure 7 is an SEM image of the balloon of a balloon catheter according to one embodiment of the present invention, observed from the radial outside. Figure 8 is a partially enlarged view of the longitudinal cross-section of the balloon of a balloon catheter according to another embodiment of the present invention. Figure 9 is a partially enlarged view of the longitudinal cross-section of the balloon of a balloon catheter according to yet another embodiment of the present invention. Figure 10 is a partially enlarged view of the longitudinal cross-section of the balloon of a balloon catheter according to yet another embodiment of the present invention. Figure 11 is a partially enlarged cross-sectional view showing the state when a water-soluble additive is applied to the outer surface of the balloon body during the manufacturing process of a balloon catheter according to an embodiment of the present invention. Figure 12 is an SEM image of the balloon body observed from the radial outside when a water-soluble additive is applied to the outer surface of the balloon body during the manufacturing process of a balloon catheter according to an embodiment of the present invention. Figure 13 is a partially enlarged cross-sectional view showing the state when a solution containing a drug is further applied to the outer surface of the balloon body of Figure 11. Figure 14 is a partially enlarged cross-sectional view showing the state when the nucleus of the water-soluble additive is removed from the state of Figure 13.

[0013] As shown in Figure 1, the balloon catheter 100 has a shaft 10 and a balloon 20 provided on the outside of the shaft 10. The balloon catheter 100 has a proximal end and a distal end, with the balloon 20 provided at the distal end of the shaft 10. The proximal end of the balloon catheter 100 refers to the direction toward the user's proximal end in the direction of extension of the balloon catheter 100 from the proximal end to the distal end, and the distal end refers to the opposite direction from the proximal end, i.e., the direction toward the treatment target. Each component or part of the balloon catheter 100 similarly has a proximal end and a distal end.

[0014] The balloon 20 has a balloon body 30. Preferably, the balloon body 30 is formed in a bag shape with openings on the proximal and distal sides. The balloon body 30 is the part that expands and contracts when fluid is supplied to or discharged from inside through the shaft 10, and is formed from a resin film to constitute the basic shape of the balloon 20. Fluid can be supplied or discharged using an indeflerator (a pressure regulator for balloons). The fluid may be a pressurized fluid pressurized by a pump or the like.

[0015] The resin film forming the balloon body 30 and the drug layer 40, which will be described later and is placed on the resin film, are sometimes collectively referred to as the balloon membrane.

[0016] The balloon body 30 has a longitudinal direction x, a radial direction y, and a circumferential direction z. The longitudinal direction x of the balloon body 30 refers to the direction extending from the proximal side to the distal side of the balloon body 30. The radial direction y of the balloon body 30 refers to the direction from the centroid of the outer edge of the balloon body 30 toward the outer edge in a plane perpendicular to the longitudinal direction x. The inner side of the radial direction y refers to the direction from the outer edge toward the centroid, and the outer side of the radial direction y refers to the direction from the outer edge toward the opposite side of the centroid. The circumferential direction z of the balloon body 30 refers to the direction along the outer edge of the balloon body 30 in a plane perpendicular to the longitudinal direction x.

[0017] The balloon catheter 100 and the other components and parts of the balloon catheter 100 besides the balloon body 30 each have a longitudinal direction, a radial direction, and a circumferential direction. The longitudinal direction, radial direction, and circumferential direction of these components and parts may coincide with the longitudinal direction x, radial direction y, and circumferential direction z of the balloon body 30, or they may be different. For the sake of clarity, in this specification, it will be explained that the longitudinal direction, radial direction, and circumferential direction of all components and parts coincide with the longitudinal direction x, radial direction y, and circumferential direction z of the balloon body 30, respectively.

[0018] When each member or part is divided into two equal parts along its longitudinal direction x, the distal portion is called the distal part of the member or part, and the proximal portion is called the proximal part of the member or part. The distal end of each member or part is the end located furthest distal to the member or part. The proximal end of each member or part is the end located furthest proximal to the member or part. The end of each member or part refers to the end of the member or part and its surrounding area. That is, the distal end of each member or part refers to the distal end of the member or part and its surrounding area, and the proximal end of each member or part refers to the proximal end of the member or part and its surrounding area.

[0019] As shown in Figure 1, it is preferable that the balloon body portion 30 has, in the longitudinal direction x, an expandable portion 32, a proximal sleeve portion 31 located proximal to the expandable portion 32, and a distal sleeve portion 33 located distal to the expandable portion 32. It is preferable that the expandable portion 32 expands and contracts with the supply and discharge of fluid, while the proximal sleeve portion 31 and the distal sleeve portion 33 do not expand or contract with the supply and discharge of fluid. This makes it easier to fix the proximal sleeve portion 31 and the distal sleeve portion 33 to the shaft 10.

[0020] Although not shown in the figures, it is preferable that the expansion portion 32 of the balloon body 30 has, in the longitudinal direction x, a straight tube portion, a proximal tapered portion located proximal to the straight tube portion, and a distal tapered portion located distal to the straight tube portion. The straight tube portion is formed in a substantially cylindrical shape extending in the longitudinal direction x, and the length in the radial direction y, i.e., the outer diameter, is formed to be the largest. This makes it easier for the straight tube portion, which has the largest outer diameter, to come into contact with the blood vessel wall. It is preferable that the proximal tapered portion and the distal tapered portion are formed so that the outer diameter decreases as they move away from the straight tube portion. Because the proximal tapered portion and the distal tapered portion are reduced in diameter, when the balloon body 30 is deflated, the outer diameter of the proximal and distal ends of the balloon body 30 can be reduced, thereby reducing the step between the shaft 10 and the balloon body 30, making it easier to insert the balloon 20 into a body cavity, into the forceps channel of an endoscope, or into a delivery catheter such as a guiding catheter.

[0021] The size of the balloon body 30 is not particularly limited. For example, the length x in the longitudinal direction can be set to 4 mm to 400 mm, and the outer diameter of the expansion portion 32 can be set to 1 mm to 30 mm as appropriate.

[0022] The thickness of the balloon body 30 can be set appropriately according to the application, required expansion pressure, flexibility, etc. For example, the thickness of the balloon body 30 can be 5 μm or more, 10 μm or more, 15 μm or more, or 100 μm or less, 50 μm or less, or 30 μm or less.

[0023] The balloon body 30 is preferably made of a resin, and more preferably a thermoplastic resin. This makes it easy to manufacture the balloon body 30 by molding. Examples of resins that make up the balloon body 30 include polyolefin resins such as polyethylene, polypropylene, and ethylene-propylene copolymer; polyester resins such as polyethylene terephthalate and polyester elastomer; polyurethane resins such as polyurethane and polyurethane elastomer; polyamide resins such as polyphenylene sulfide resin, polyamide, and polyamide elastomer; fluororesin, silicone resin, and natural rubber such as latex rubber. These may be used alone or in combination of two or more. Among these, polyamide resins, polyester resins, and polyurethane resins are preferably used. In particular, it is preferable to use an elastomer resin from the viewpoint of thinning the balloon body 30 and its flexibility. For example, among polyamide resins, nylon 12 and nylon 11 are suitable materials, and nylon 12 is preferably used because it can be molded relatively easily when blow molding. Furthermore, from the viewpoint of thinning the balloon body 30 and improving its flexibility, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferably used. Among these, polyether ester amide elastomers are preferably used because they have high yield strength and good dimensional stability of the balloon body 30.

[0024] As shown in Figure 2, the balloon 20 is positioned radially outward from the balloon body 30 and has a drug layer 40 containing the drug.

[0025] The drug layer 40 is preferably located on the outer surface of the expansion portion 32 within the balloon body 30, and more preferably located on the straight tube portion. This facilitates the administration of the drug to the target tissue by the expansion of the balloon body 30.

[0026] The drug contained in the drug layer 40 is not particularly limited as long as it is a pharmacologically active substance, and examples include gene therapy drugs, non-gene therapy drugs, small molecules, cells, and other drugs that are accepted as pharmaceuticals. In particular, when the balloon catheter 100 is used to suppress restenosis of blood vessels after treatment in angioplasty, anti-restenotic agents such as antiproliferative agents and immunosuppressants can be preferably used as the drug, and specifically, drugs such as paclitaxel, sirolimus (rapamycin), everolimus, and zotarolimus can be used. These drugs may be used individually or in combination of two or more. Among these, paclitaxel is preferred as the drug contained in the drug layer 40. The drug layer 40 may contain, along with the pharmacologically active substance, auxiliary agents to improve the dispersibility of the drug, its transfer to the blood vessel wall, and its storage stability. Examples of auxiliary agents include stabilizers, binders, disintegrants, moisture-proofing agents, and preservatives.

[0027] As shown in Figures 2, 4, and 7, the drug layer 40 has a radial crystal group 42 which includes a plurality of columnar crystals 41 of the drug arranged radially.

[0028] As shown in Figure 5, the columnar crystal 41 has a longitudinal axis 41L, and preferably has a first end 41a and a second end 41b in the direction of the longitudinal axis 41L. The columnar crystal 41 is preferably a polygonal prism, and the cross-sectional shape perpendicular to the longitudinal axis 41L is preferably a polygon such as a triangle, quadrilateral, pentagon, or hexagon. However, the cross-sectional shape perpendicular to the longitudinal axis 41L of the columnar crystal 41 does not necessarily have to be a polygon; the corners of the polygon may be flattened, the sides of the polygon may be distorted, or it may be irregular in shape. The shape and size of the cross-sectional shape on the first end 41a side and the second end 41b side of the columnar crystal 41 may differ, and the sides of the polygonal prism do not have to be straight lines. The longitudinal axis 41L of the columnar crystal 41 can be a straight line connecting the centroid 41C of the base surface at the first end 41a and the centroid 41C of the base surface at the second end 41b. Alternatively, the longitudinal axis 41L of the columnar crystal 41 can be a straight line parallel to the longitudinal axis, passing through the centroid of the cross-section at the midpoint of the longitudinal axis direction of the columnar crystal 41. The columnar crystal 41 may be solid or hollow.

[0029] The outer diameter of the cross-section perpendicular to the longitudinal axis 41L of the columnar crystal 41 is, for example, 0.01 μm or more, 0.1 μm or more, 0.5 μm or more, and 5 μm or less, 3 μm or less, and 1 μm or less. Here, the outer diameter corresponds to the diameter of the circle circumscribed by the shape of the cross-section perpendicular to the longitudinal axis 41L of the columnar crystal 41.

[0030] The length of the columnar crystal 41 in the direction of its longitudinal axis 41L is, for example, 3 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 40 μm or less, 30 μm or less, 25 μm or less, or 20 μm or less. Preferably, the length of the columnar crystal 41 in the direction of its longitudinal axis 41L is longer than the outer diameter of the cross section perpendicular to the longitudinal axis 41L of the columnar crystal 41. For example, the length in the direction of its longitudinal axis 41L may be 2 times or more, 3 times or more, 5 times or more, 10 times or more, or 200 times or less, 150 times or less, 100 times or less, or 50 times or less of the outer diameter of the cross section perpendicular to the longitudinal axis 41L.

[0031] As shown in Figures 2 to 4, in a cross-section along the longitudinal direction x, the radial crystal group 42 has a fan shape F, and the central angle θ of the fan shape F is greater than 180°. When the balloon 20 is delivered to the treatment site and then expanded, the portion of the radial crystal group 42 located on the outer side in the radial direction y comes into contact with the blood vessel wall and migrates to the blood vessel wall. At this time, because the central angle θ of the fan shape F of the radial crystal group 42 is greater than 180°, columnar crystals 41 can exist that extend from the blood vessel wall to the radially inward side of the blood vessel. These columnar crystals 41 extending radially inward cause turbulence in the blood, making it easier for thrombi to form. In this way, the formation of thrombi in the portion of the radial crystal group 42 that has migrated to the blood vessel wall prevents the radial crystal group 42 from detaching from the blood vessel wall. As a result, a balloon catheter 100 that can effectively deliver drugs to target tissue can be provided.

[0032] The fan shape F is formed by arranging a plurality of columnar crystals 41 radially. As shown in Figure 5, it is preferable that the first ends 41a of each of the plurality of columnar crystals 41 are joined together to form a nucleus 42J of the radial crystal group 42, and as shown in Figure 2, the fan shape F is formed by the columnar crystals 41 extending radially from the nucleus 42J.

[0033] Preferably, the radial crystal group 42 has a plurality of columnar crystals 41o extending outward from the nucleus 42J in the radial direction y and a plurality of columnar crystals 41i extending inward from the nucleus 42J in the radial direction y. The columnar crystals 41o extending outward from the nucleus 42J in the radial direction y make it easier for the radial crystal group 42 to come into contact with the blood vessel wall. In addition, the columnar crystals 41i extending inward from the nucleus 42J in the radial direction y can function as columnar crystals 41 extending radially inward from the blood vessel when the radial crystal group 42 migrates to the blood vessel wall, and can contribute to the formation of a thrombus.

[0034] It is preferable that the multiple columnar crystals 41o extending radially y outward from the nucleus 42J include columnar crystals 41o whose longitudinal axis length 41L is longer than the longitudinal axis length 41L of the columnar crystals 41i extending radially y inward from the nucleus 42J. The columnar crystals 41o extending radially y outward from the nucleus 42J are more likely to come into contact with the blood vessel wall when the balloon 20 is expanded at the lesion site, and in some cases, they may even penetrate the wall. Therefore, a longer longitudinal axis length 41L allows for effective delivery of the drug to the target tissue.

[0035] Preferably, each of the multiple columnar crystals 41o extending radially y outward from the nucleus 42J includes some that are separated from each other at their second end 41b. The second end 41b of the columnar crystal 41o is the part that first contacts the blood vessel wall when the radial crystal group 42 migrates to the blood vessel wall. By separating these parts from each other, the second end 41b of the columnar crystal 41o can more easily contact the blood vessel wall, making it easier to effectively deliver the drug to the target tissue.

[0036] Multiple columnar crystals 41i extending inward in the radial direction y from the nucleus 42J may include columnar crystals 41i having a longitudinal axis 41L shorter than the radius r of the fan shape F, which will be described later. This prevents the length of the columnar crystals 41 extending radially inward from the blood vessel wall from the blood vessel wall from becoming too long when the radial crystal group 42 migrates to the blood vessel wall, thereby preventing unnecessary obstruction of blood flow.

[0037] It is preferable that each of the multiple columnar crystals 41i extending radially y inward from the nucleus 42J includes some that are separated from each other at the second end 41b. The second end 41b of the columnar crystal 41i is the part that contributes to thrombus formation when the radial crystal group 42 migrates to the blood vessel wall, and the separation of these parts from each other can promote thrombus formation.

[0038] As shown in Figure 6, in a plan view from the outside in the radial direction y, the radial crystal group 42 has a position P in the circumferential direction z that has its maximum width in the longitudinal direction x. The shape of the contour of the radial crystal group 42 when viewed from the outside in the radial direction y is not particularly limited, but may be circular, elliptical, polygonal, rounded polygonal, etc., or it may be irregular in shape.

[0039] The fan shape F can be confirmed by SEM observation as shown in Figure 4. Preferably, the fan shape F is observed in the cross-section of the radial crystal group 42 in the longitudinal direction x at position P.

[0040] Although not shown in the diagram, in order to give the balloon catheter 100 a scoring function, the balloon body 30 may have a projection that protrudes radially y outward and extends longitudinally x. The drug layer 40 may also be placed on the surface of the projection. That is, the drug layer 40 may be placed on both the outer surface of the balloon body 30 in the portion where the projection is not formed and the outer surface of the projection. When the balloon body 30 has a projection and the drug layer 40 is also placed on the surface of the projection, it is preferable to perform microscopic observation, such as with a SEM, on the drug layer 40 placed on the outer surface of the balloon body 30 in the portion where the projection is not formed. This makes it easier to observe the radial crystal group 42 at position P.

[0041] As shown in Figure 6, in a plan view from the outside in the radial direction y, when L is the length from the centroid of the outer edge 42E of the radial crystal group 42 to the outer edge 42E, the area of ​​a circle with radius L / 2 centered on the centroid of the outer edge 42E is defined as the central part 42c of the radial crystal group 42, and the area of ​​a circle with radius L centered on the centroid of the outer edge 42E, excluding the central part 42c, is defined as the peripheral part 42p. As shown in Figure 2, it is preferable that the length in the radial direction y of the radial crystal group 42 at the central part 42c is longer than the length in the radial direction y of the radial crystal group 42 at the peripheral part 42p. This makes it possible to form irregularities in the drug layer 40 based on the size of the radial crystal group 42. Since the blood vessel wall to which the drug is administered has irregularities, the presence of irregularities in the drug layer 40 makes it easier to bring the drug layer 40 into contact with the blood vessel wall.

[0042] As shown in Figures 2 to 4, it is preferable that the balloon 20 has a gap 42a in which the radial crystal group 42 is separated from the outer surface of the balloon body 30, provided that the central angle θ of the sector shape F is greater than 180°. It is preferable that the radial crystal group 42 has a bottom surface facing the outer surface of the balloon body 30 formed by columnar crystals 41i extending inward in the radial direction y from the nucleus 42J, and it is preferable that a gap 42a is formed between this bottom surface and the outer surface of the balloon body 30. This makes it easier for the radial crystal group 42 to detach from the outer surface of the balloon body 30 when the balloon 20 is expanded after being delivered to the treatment site, and makes it easier to transfer the drug to the blood vessel wall as a mass of radial crystal group 42. As a result, more effective drug administration becomes possible.

[0043] As shown in Figure 3, the radius r of the sector shape F is preferably half the maximum width of the radial crystal group 42 in a cross-section in the longitudinal direction x at position P. That is, the center C of the sector shape F is preferably located on a straight line L1 parallel to the radial direction y, passing through the midpoint of the line segment connecting the ends of the radial crystal group 42 in the longitudinal direction x, in a cross-section in the longitudinal direction x at position P. Furthermore, the center C is preferably located on a straight line L2 parallel to the longitudinal direction x, passing through the outer end in the radial direction y of the void 42a, in a cross-section in the longitudinal direction x at position P. That is, the center C of the sector shape F is preferably at the intersection of the straight line L1 and the straight line L2.

[0044] It can be said that the core 42J of the radial crystal group 42 is the center C of the fan shape F. It is preferable that the portions of the respective first ends 41a of the plurality of columnar crystals 41 are joined to each other at the center C to form the core 42J of the radial crystal group 42. Alternatively, the portions of the respective first ends 41a of the plurality of columnar crystals 41 may be joined in the vicinity of the center C. Or, among the plurality of columnar crystals 41, there may be those in which the portions of the respective first ends 41a are joined at positions other than the center C.

[0045] The larger the central angle θ of the fan shape F, the longer the length from the outer surface of the balloon main body 30 in the radial direction y to the core 42 of the radial crystal group 42, and thus the length of the void 42a in the radial direction y may be formed longer.

[0046] The central angle θ of the fan shape F is preferably 270° or less. Thereby, the length of the radial crystal group 42 extending outward in the radial direction y from the center C of the fan shape F, that is, the length of the columnar crystal 41o, can be made longer than the length of the radial crystal group 42 extending inward in the radial direction y from the center C of the fan shape F, that is, the length of the columnar crystal 41i. Therefore, the columnar crystal 41o can easily contact the target tissue and the drug can be more effectively administered to the blood vessel wall. Also, since the central angle θ is 270° or less, the length of the void 42a in the radial direction y does not become unnecessarily long, and thus the radial crystal group 42 can be prevented from dropping off from the outer surface of the balloon main body 30 during delivery.

[0047] The central angle θ of the fan shape F is more than 180°, preferably 200° or more, more preferably 220° or more, and preferably 270° or less, more preferably 240° or less.

[0048] In the cross section in the longitudinal direction x, the radius r of the fan shape F is preferably 5 μm or more and 30 μm or less. The radius r of the fan shape F in the cross section in the longitudinal direction x is more preferably 7 μm or more, further preferably 10 μm or more, more preferably 25 μm or less, and further preferably 20 μm or less. The radius r of the fan shape F is preferably the one in the cross section in the longitudinal direction x at the position P in the circumferential direction z where the radial crystal group 42 has the maximum width in the longitudinal direction x in a plan view from the outer side in the radial direction y.

[0049] As shown in Fig. 7, in a plan view from the outside in the radial direction y of the balloon 20, it is preferable that the major axis of the radial crystal group 42 is 10 μm or more and 80 μm or less. The major axis of the radial crystal group 42 is more preferably 15 μm or more and 70 μm or less, and even more preferably 20 μm or more and 60 μm or less. There are minute irregularities on the body cavity wall such as blood vessels, which are the target tissues, and the sizes of these irregularities are often of the same degree as described above. Therefore, when the major axis of the radial crystal group 42 is within the above range, the radial crystal group 42 can easily fit into the irregularities of the body cavity wall, and the radial crystal group 42 after administration to the body cavity wall is difficult to fall off from the body cavity wall, so that the drug can be effectively imparted to the target tissue.

[0050] In Fig. 7, although there are portions where the radial crystal groups 42 are in contact with each other, a lump in which the columnar crystals 41 are radially arranged starting from one nucleus 42J can be regarded as one radial crystal group 42.

[0051] Since the radius r of the fan shape F is preferably the one in the cross section in the longitudinal direction x at the position P, even if twice the radius r of the fan shape F does not necessarily coincide with the major axis of the radial crystal group 42 in a plan view from the outside in the radial direction y, it may be acceptable.

[0052] In the radial direction y of the cross section in the longitudinal direction x at the position P, the length from the nucleus 42J of the radial crystal group 42 to the outer end of the radial crystal group 42 is preferably longer than the length from the nucleus 42J to the inner end of the radial crystal group 42, that is, the length to the outer surface of the balloon main body 30. In the radial direction y of the cross section in the longitudinal direction x at the position P, the length from the nucleus 42J of the radial crystal group 42 to the outer end of the radial crystal group 42 can be, for example, 3 times or more, 5 times or more, 10 times or more, and also 50 times or less, 40 times or less, 30 times or less, etc. of the length from the nucleus 42J to the inner end of the radial crystal group 42, that is, the length to the outer surface of the balloon main body 30.

[0053] In the portion where the void 42a exists, it is preferable that the balloon main body 30, the void 42a, and the radial crystal group 42 are arranged in this order from the inside to the outside in the radial direction y. By arranging in this way, the release of the radial crystal group 42 from the outer surface of the balloon main body 30 becomes easy.

[0054] Preferably, the void 42a is formed in a cross-section along the longitudinal direction x by being surrounded by the outer surface of the balloon body 30 and the radial crystal group 42. This allows the contact area between the balloon body 30 and the radial crystal group 42 to be larger than a certain area, thereby preventing the radial crystal group 42 from falling off during delivery of the balloon body 30. Furthermore, if there is a portion of the void 42a that is not surrounded by the outer surface of the balloon body 30 and the radial crystal group 42, it is preferable that 60% or more of the void 42a is surrounded by the radial crystal group 42, more preferably 70% or more of the void 42a is surrounded by the radial crystal group 42, and even more preferably 80% or more of the void 42a is surrounded by the radial crystal group 42.

[0055] The void 42a is preferably located in the central part 42c of the radial crystal cluster 42. Furthermore, it is preferable that at least a portion of the peripheral edge 42p of the bottom surface of the radial crystal cluster 42 is in contact with or fixed to the outer surface of the balloon body 30. This facilitates the retention of the radial crystal cluster 42 on the outer surface of the balloon body 30, preventing the radial crystal cluster 42 from falling off during the transport of the balloon 20, while facilitating the release of the radial crystal cluster 42 from the outer surface of the balloon body 30 when the radial crystal cluster 42 comes into contact with the target tissue.

[0056] As shown in Figure 4, columnar crystals 41i extending radially y inward from the nucleus 42J may be arranged in the void 42a. The arrangement of columnar crystals 41i in the void 42a may divide the void 42a into multiple spaces. The number of columnar crystals 41i extending radially y inward from the nucleus 42J in one radial crystal group 42 may be, for example, 1 or more, 2 or more, 3 or more, 5 or more, or 20 or less, 15 or less, or 10 or less. These columnar crystals 41i can also contribute to the formation of thrombi.

[0057] As shown in Figure 4, columnar crystals 41i may be arranged radially y-inward from the sector shape F determined by the center C, radius r, and central angle θ. The number of columnar crystals 41i arranged radially y-inward from the sector shape F in one radial crystal group 42 may be, for example, 1 or more, 2 or more, 3 or more, 5 or more, or 20 or less, 15 or less, or 10 or less. These columnar crystals 41i can also contribute to the formation of thrombi.

[0058] It is preferable that the void 42a is maintained as a space. This makes it easier for the radial crystal clusters 42 to detach from the outer surface of the balloon body 30 when the balloon body 30 is expanded after the balloon 20 has been delivered to the treatment site, and as a result, the drug can be delivered to the target tissue more easily.

[0059] Alternatively, a swelling substance may be placed in the void 42a. By including a swelling substance in the void 42a that swells upon contact with blood, the balloon body 30 expands after the balloon 20 is delivered to the treatment site, allowing blood to enter the void 42a and come into contact with the swelling substance, thereby increasing the volume of the swelling substance. This causes an outward force in the radial direction y to act on the radial crystal group 42, making it easier for the radial crystal group 42 to detach from the outer surface of the balloon body 30. As a result, it becomes easier to obtain a balloon catheter 100 in which the radial crystal group 42 can effectively migrate to the target tissue.

[0060] The swelling substance preferably contains a hydrophilic swelling component that swells upon contact with blood. The hydrophilic swelling component is preferably a component insoluble in water that absorbs water, such as hydrophilic polymers like polyvinylpyrrolidone, sodium poly(meth)acrylate, polyvinyl alcohol, cellulose polymers, gelatin, and hyaluronic acid. Methods for making the hydrophilic polymer insoluble in water include using a high molecular weight polymer or crosslinking the polymers together.

[0061] The volume of the swellable material placed in the void 42a is preferably 10% or more of the volume of the void 42a, more preferably 20% or more, even more preferably 30% or more, and preferably 95% or less, more preferably 90% or less, and even more preferably 80% or less. The presence of voids 42a without the swellable material allows bodily fluids to enter these voids, making it easier for the bodily fluids to come into contact with the swellable material and promoting its swelling. As the swellable material swells, its volume may occupy 100% of the volume of the void 42a. When the amount of the swellable material is within the above range, the swellable material promotes the release of the radial crystal group 42.

[0062] It is preferable that a swelling substance remains on the balloon 20 after expansion. The remaining rate of the swelling substance on the balloon 20 after expansion, that is, the ratio of the remaining swelling substance to the amount of swelling substance added, is preferably 50% or more, more preferably 70% or more, and even more preferably 80% or more. The remaining rate of the swelling substance may also be 100% or less, 95% or less, or 90% or less. Although the drug layer 40 needs to be released from the balloon body 30 after expansion at the treatment site, if the swelling substance also detaches and falls into the bloodstream, there is a risk that the swelling substance will obstruct blood flow. If the remaining rate of the swelling substance is within the above range, adverse effects such as obstruction of blood flow by the swelling substance can be prevented.

[0063] It is preferable that no non-swelling or poorly swelling material is placed in the void 42a. That is, it is preferable that the void 42a is maintained as an empty space, or if material is placed in the void 42a, that material is a swelling material. The effects of space and swelling material on the release of the radial crystal group 42 are as described above. If a non-swelling or poorly swelling material is placed in the void 42a, the release of the radial crystal group 42 may be inhibited by that material, but the absence of such material facilitates the release of the radial crystal group 42.

[0064] As shown in Figure 8, the radial crystal group 42 is a plurality of radial crystal groups 42 having a fan shape F, and it is preferable that each of the plurality of radial crystal groups 42 includes radial crystal groups 42 that overlap each other outside the center C of the fan shape F in the radial direction y. Because the radial crystal groups 42 overlap each other outside the center C of the fan shape F in the radial direction y, the drug layer 40 can be stably positioned on the outer surface of the balloon body 30. As a result, it is possible to prevent the drug layer 40 from falling off the outer surface of the balloon body 30 during delivery of the balloon 20 to the treatment site.

[0065] In each of the multiple radial crystal groups 42, the columnar crystals 41 contained within each group may overlap if the second ends 41b of the columnar crystals 41o extending radially outward from the nucleus 42J in the radial direction y overlap. In this case, it is preferable that the second ends 41b of the columnar crystals 41i contained in separate radial crystal groups 42 that extend radially inward from the nucleus 42J in the radial direction y do not overlap. As a result, the second ends 41b of the columnar crystals 41o overlap and contribute to the stable arrangement of the drug layer 40, while the second ends 41b of the columnar crystals 41i can exist separately from each other, thereby promoting thrombus formation. Consequently, it becomes easier to create a balloon catheter 100 in which the drug layer 40 is less likely to fall off during delivery to the treatment site and the drug is less likely to detach from the blood vessel wall.

[0066] All of the multiple radial crystal groups 42 may overlap each other outside the radial y direction beyond the center C of the sector shape F. Alternatively, some of the multiple radial crystal groups 42 may overlap each other outside the radial y direction beyond the center C of the sector shape F, while the other radial crystal groups 42 do not need to overlap each other.

[0067] As shown in Figure 9, the radial crystal group 42 is a plurality of radial crystal groups 42 having a fan shape F, and it is preferable that the plurality of radial crystal groups 42 include radial crystal groups 42 in which each radial crystal group 42 is bonded to one another outside the center C of the fan shape F in the radial direction y. Because the plurality of radial crystal groups 42 are not only overlapping but also bonded to one another, the radial crystal groups 42 can be more stably arranged on the outer surface of the balloon body 30. As a result, it is easier to prevent the drug layer 40 from falling off the outer surface of the balloon body 30 during delivery to the treatment site.

[0068] In each of the multiple radial crystal groups 42, the columnar crystals 41 contained within each group may be bonded together by the second end 41b portion of the columnar crystals 41o extending radially outward from the nucleus 42J in the y direction, thereby bonding the radial crystal groups 42 together. In this case, it is preferable that the second end 41b portions of the columnar crystals 41i contained in separate radial crystal groups 42, which extend radially inward from the nucleus 42J in the y direction, are not bonded to each other. As a result, the second end 41b portions of the columnar crystals 41o are bonded to each other, contributing to the stable arrangement of the drug layer 40, while the second end 41b portions of the columnar crystals 41i can exist separately from each other, thereby promoting thrombus formation. Consequently, it becomes easier to create a balloon catheter 100 in which the drug layer 40 is less likely to detach during delivery to the treatment site, and in which the drug is less likely to detach from the blood vessel wall.

[0069] All of the multiple radial crystal groups 42 may be bonded to each other outside the radial y direction from the center C of the sector shape F. Alternatively, some of the multiple radial crystal groups 42 may be bonded to each other outside the radial y direction from the center C of the sector shape F, while the other radial crystal groups 42 may not be bonded to each other but merely overlapping or separated from each other.

[0070] As shown in Figure 10, the balloon catheter 100 may further have a protective layer 60 outside the drug layer 40 in the radial direction y. The protective layer 60 prevents the drug layer 40 from unintentionally falling off or the drug from leaching out of the drug layer 40.

[0071] The protective layer 60 may be positioned outside the outer edge of the drug layer 40 in the radial y direction, or it may be positioned from the outside to the inside of the outer edge of the drug layer 40 in the radial y direction. In particular, it is preferable that the protective layer 60 covers the radial crystal groups 42 so as to span across adjacent radial crystal groups 42. This prevents the radial crystal groups 42 from unintentionally falling off or the drug from leaching out from the radial crystal groups 42.

[0072] The protective layer 60 is preferably composed of hydrophobic components. When delivering the balloon 20 into a body cavity containing body fluids with a high water content, such as blood vessels, if the protective layer 60 composed of hydrophobic components is provided on the outer surface of the drug layer 40, the dissolution of the protective layer 60 when it comes into contact with body fluids such as blood is suppressed, and the protective layer 60 can exert its protective function for the drug layer 40. Examples of hydrophobic compounds include lipid compounds such as lecithin, propylene glycol stearate, cholesterol, and terpenes; hydrocarbon compounds such as petrolatum; hydrophobic (meth)acrylic polymers such as ethyl polyacrylate and polymethyl methacrylate; hydrophobic polyester polymers such as polylactic acid and polyglycolic acid; and silicone oil.

[0073] Furthermore, it is also preferable that the protective layer 60 be composed of hydrophilic components, particularly hydrophilic polymers with high molecular weight, as described later. When a hydrophilic polymer with high molecular weight is used as the protective layer 60, it is possible to prevent the protective layer 60 from dissolving due to the moisture in body fluids and to maintain the protective function of the drug layer 40.

[0074] Examples of hydrophilic components include hydrophilic polymers such as carboxymethylcellulose, hydroxypropylcellulose, methylcellulose, hydroxyethylcellulose, polyvinyl alcohol, alginic acid, pectin, gum arabic, gellan gum, guar gum, xanthan gum, carrageenan, gelatin, polyethylene glycol, hyaluronic acid, and sodium polyacrylate; salts such as potassium chloride and ammonium acetate; amino acids such as glycine and glutamic acid; sugars such as glucose and fructose; and urea.

[0075] The protective layer 60 is preferably amorphous. This enhances the protective function of the protective layer 60. Examples of components of the amorphous protective layer 60 include hydrophilic polymers such as hyaluronic acid and sodium poly(meth)acrylate, hydrophobic polyester polymers such as D,L-polylactic acid and lactic acid-glycolic acid copolymers, and lipid compounds such as lecithin.

[0076] It is preferable that the protective layer 60 is positioned up to the void 42a formed between the bottom surface of the radial crystal group 42 and the outer surface of the balloon body portion 30. In this case, the protective layer 60 and the above-mentioned swelling substance may have different components, but if the protective layer 60 is composed of a component that swells with bodily fluids, it is also preferable that the protective layer 60 functions as the above-mentioned swelling substance.

[0077] Furthermore, it is also preferable that the protective layer 60 is not placed in the void 42a formed between the bottom surface of the radial crystal group 42 and the outer surface of the balloon body 30. If the protective layer 60 is placed in the void 42a, the protective layer 60 may hinder the release of the radial crystal group 42 from the balloon body 30, but the absence of the protective layer 60 in the void 42a facilitates the release of the radial crystal group 42.

[0078] The radial crystal group 42 can be formed by applying a solution containing the drug to the outer surface of the balloon body 30. Since the drug suitable for the embodiments of the present invention, such as paclitaxel, is poorly soluble in water, it is preferable to use an organic solvent. The organic solvent is not particularly limited, but examples include tetrahydrofuran, methanol, ethanol, glycerin, acetone, dichloromethane, hexane, and ethyl acetate. The concentration of the drug in the solution is preferably 0.1 to 20% by mass.

[0079] The application of the drug-containing solution can be carried out by known methods such as brush coating, dip coating, or spray coating, with spray coating being preferred. By spraying the drug-containing solution onto the outer surface of the balloon body 30, it becomes easy to grow columnar crystals 41 of the drug and form radial crystal groups 42.

[0080] As an example of a method for forming a radial crystal group 42 having a fan shape F and a central angle θ of the fan shape F greater than 180°, the following method can be used. First, prior to applying a solution containing the drug to the outer surface of the balloon body 30, a water-soluble additive is applied to the outer surface of the balloon body 30 to form nuclei 42b of the water-soluble additive, as shown in Figure 11. At this time, as shown in Figures 11 and 12, it is preferable to scatter the nuclei 42b of the water-soluble additive on the outer surface of the balloon body 30 so that the outer surface of the balloon body 30 is exposed. Examples of water-soluble additives include sugars such as glucose, salts such as potassium chloride and sodium acetate, and amino acids such as glycine. As the aqueous solvent, water or a mixed solvent of water and an organic solvent such as ethanol can be used. Note that the nuclei 42b of the water-soluble additive do not need to be aligned along the cross section in the longitudinal direction x, i.e., at the same position in the circumferential direction z, as shown in Figure 11. In Figure 11, for clarity, the nuclei 42b of the water-soluble additive are shown as being arranged at the same position in the circumferential direction z.

[0081] Next, as shown in Figure 13, a solution containing the above-described agent is applied to the outer surface of the balloon body 30 on which the nuclei 42b of the water-soluble additive are located to form a radial crystal group 42. Subsequently, by removing the nuclei 42b of the water-soluble additive with an aqueous solvent, a radial crystal group 42 having a fan shape F and a central angle θ of the fan shape F greater than 180° is formed, as shown in Figure 14.

[0082] The water-soluble additive is preferably applied by spray coating. This makes it easy to distribute the nuclei 42b of the water-soluble additive on the outer surface of the balloon body 30.

[0083] The removal of the nuclei 42b of the water-soluble additive can be carried out, for example, by immersing the outer surface of the balloon body 30 on which the radial crystal group 42 is formed in water. To increase the solubility of the water-soluble additive in water and promote the removal of the nuclei 42b of the water-soluble additive, it is also preferable to heat the water to 40°C or higher when removing the nuclei 42b of the water-soluble additive.

[0084] Figure 1 shows a so-called rapid exchange type balloon catheter 100, which has a guidewire port 72 located midway from the distal to the proximal end of the shaft 10, and an inner shaft 10a that functions as a guidewire insertion passage from the guidewire port 72 to the distal end of the shaft 10.

[0085] It is preferable that the shaft 10 has a fluid channel and a guide wire insertion passage inside. To configure the shaft 10 to have a fluid channel and a guide wire insertion passage inside, for example, the shaft 10 may have an inner shaft 10a and an outer shaft 10b positioned outside the inner shaft 10a, with the inner shaft 10a functioning as a guide wire insertion passage and the space between the outer shaft 10b and the inner shaft 10a functioning as a fluid channel. In such a configuration, it is preferable that the inner shaft 10a extends distally so as to penetrate the balloon 20, with the distal side of the balloon 20 connected to the inner shaft 10a and the proximal side of the balloon 20 connected to the outer shaft 10b.

[0086] The balloon catheter 100 preferably has a distal outer shaft 12 and a proximal outer shaft 11, and the distal outer shaft 12 and the proximal outer shaft 11 may be separate components, and the proximal end of the distal outer shaft 12 may be connected to the distal end of the proximal outer shaft 11 to form an outer shaft 10b that extends from the balloon 20 to the proximal end of the balloon catheter 100. Alternatively, one outer shaft 10b may extend from the balloon 20 to the proximal end of the balloon catheter 100, and the distal outer shaft 12 and the proximal outer shaft 11 may be further composed of multiple tubular members.

[0087] The shaft 10 is preferably made of resin, metal, or a combination of resin and metal. Using resin as a constituent material for the shaft 10 makes it easier to impart flexibility and elasticity to the shaft 10. Using metal as a constituent material for the shaft 10 can improve the insertion of the balloon catheter 100.

[0088] Examples of resins that make up the shaft 10 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, fluororesins, vinyl chloride resins, silicone resins, natural rubber, synthetic rubber, etc. These may be used individually or in combination of two or more. Examples of metals that make up the shaft 10 include stainless steel such as SUS304 and SUS316, platinum, nickel, cobalt, chromium, titanium, tungsten, gold, Ni-Ti alloy, Co-Cr alloy, or combinations thereof. If the shaft 10 includes a distal outer shaft 12 and a proximal outer shaft 11, for example, the distal outer shaft 12 may be formed from resin and the proximal outer shaft 11 from metal. Furthermore, the shaft 10 may have a laminated structure made of different or the same materials.

[0089] The balloon 20 and the shaft 10 can be joined by adhesive bonding, welding, or by attaching a ring-shaped member to the overlapping portion of the balloon 20 and the shaft 10 and crimping it. In particular, it is preferable that the balloon 20 and the shaft 10 are joined by welding. By welding the balloon 20 and the shaft 10, the joint between the balloon 20 and the shaft 10 is less likely to come undone even when the balloon 20 is repeatedly expanded or contracted, thus improving the joint strength.

[0090] Preferably, a tip member 80 is provided at the distal end of the balloon catheter 100. The tip member 80 may be provided at the distal end of the balloon catheter 100 by being connected to the distal end of the balloon 20 as a separate component from the inner shaft 10a, or the inner shaft 10a, which extends distal to the distal end of the balloon 20, may function as the tip member 80.

[0091] The shaft 10 may have radiopaque markers 90 positioned in the longitudinal direction x where the balloon 20 is located, in order to allow confirmation of the balloon 20's position under X-ray fluoroscopy. The radiopaque markers 90 can be positioned, for example, on the inner shaft 10a located inside the balloon 20, preferably at positions corresponding to both ends of the balloon 20's expansion portion 32, or at a position corresponding to the center of the balloon 20's expansion portion 32.

[0092] A hub 70 may be provided on the proximal side of the shaft 10, and it is preferable that the hub 70 is provided with a fluid injection section 71 that communicates with the fluid passage for the fluid supplied to the inside of the balloon 20.

[0093] The shaft 10 and the hub 70 can be joined by, for example, adhesive bonding or welding. In particular, it is preferable that the shaft 10 and the hub 70 are joined by adhesive bonding. By bonding the shaft 10 and the hub 70, the bonding strength between the shaft 10 and the hub 70 can be increased, improving the durability of the balloon catheter 100, especially when the materials constituting the shaft 10 and the hub 70 are different, for example, when the shaft 10 is made of a highly flexible material and the hub 70 is made of a highly rigid material.

[0094] Although not shown in the figures, the present invention can also be applied to so-called over-the-wire type balloon catheters, which have a guidewire insertion passage extending from the distal to the proximal end of the shaft. In the case of the over-the-wire type, it is preferable that the inflation lumen and guidewire lumen extend to a hub located on the proximal end, and that the proximal opening of each lumen is provided in a bifurcated hub.

[0095] In the case of a rapid exchange type catheter, it is preferable that the outer walls of the distal outer shaft 12 and / or the proximal outer shaft 11 are appropriately coated, and it is more preferable that both the distal outer shaft 12 and the proximal outer shaft 11 are coated. In the case of an over-the-wire type catheter, it is preferable that the outer wall of the outer shaft is appropriately coated.

[0096] The coating can be hydrophilic or hydrophobic depending on the purpose, and can be applied by immersing the shaft 10 in a hydrophilic or hydrophobic coating agent, applying a hydrophilic or hydrophobic coating agent to the outer wall of the shaft 10, or covering the outer wall of the shaft 10 with a hydrophilic or hydrophobic coating agent. The coating agent may contain chemicals or additives.

[0097] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether maleic anhydride copolymer, or hydrophilic coating agents made from any combination thereof.

[0098] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluoroethylene propylene (FEP), perfluoroalkoxyalkanes (PFA), silicone oil, hydrophobic urethane resins, carbon coatings, diamond coatings, diamond-like carbon (DLC) coatings, ceramic coatings, and substances with low surface free energy terminated with alkyl groups or perfluoroalkyl groups.

[0099] This application claims the benefit of priority based on Japanese Patent Application No. 2024-232079, filed on 27 December 2024. The entire specification of Japanese Patent Application No. 2024-232079, filed on 27 December 2024, is incorporated herein by reference.

[0100] 10: Shaft 10a: Inner shaft 10b: Outer shaft 11: Proximal outer shaft 12: Distal outer shaft 20: Balloon 30: Balloon body 31: Proximal sleeve 32: Expanding part 33: Distal sleeve 40: Drug layer 41: Columnar crystal 41a: First end 41b: Second end 41C: Centroid 41L: Longitudinal axis 42: Radial crystal group 42a: Void 42b: Nucleus of water-soluble additive 42E: Outer edge of radial crystal group 42J: Nucleus of radial crystal group 60: Protective layer 70: Hub 71: Fluid injection part 72: Guidewire port 80: Tip component 90: Radiopaque marker 100: Balloon catheter

Claims

1. A balloon catheter having a balloon, wherein the balloon has a balloon body having a longitudinal direction and a radial direction, and a drug layer containing a drug disposed radially outward of the balloon body, the drug layer having a radial crystal group containing a plurality of columnar crystals of the drug arranged radially, and in the longitudinal cross-section, the radial crystal group has a fan shape, and the central angle of the fan shape is greater than 180°.

2. The balloon catheter according to claim 1, wherein the central angle of the sector shape is 270° or less.

3. The balloon catheter according to claim 1 or 2, wherein the radius of the fan shape in the longitudinal cross-section is 5 μm or more and 30 μm or less.

4. The balloon catheter according to claim 1 or 2, wherein, in a plan view from the radially outer side of the balloon, the major axis of the radial crystal group is 10 μm or more and 80 μm or less.

5. The balloon catheter according to claim 1 or 2, wherein the drug is paclitaxel.

6. The balloon catheter according to claim 1 or 2, wherein the balloon has a gap between the radial crystal group and the outer surface of the balloon body.

7. The balloon catheter according to claim 6, wherein a swellable substance is disposed in the void.

8. The balloon catheter according to claim 7, wherein the swelling substance remains on the balloon after expansion.

9. The balloon catheter according to claim 1 or 2, wherein the radial crystal group comprises a plurality of radial crystal groups having a fan shape, and each of the plurality of radial crystal groups includes a radial crystal group in which each of the plurality of radial crystal groups overlaps with the others radially outside the center of the fan shape.

10. The balloon catheter according to claim 1 or 2, wherein the radial crystal group comprises a plurality of radial crystal groups having a fan shape, and each of the plurality of radial crystal groups comprises a radial crystal group in which each of the plurality of radial crystal groups is bonded to one another radially outside the center of the fan shape.

11. The balloon catheter according to claim 1 or 2, further comprising a protective layer on the radially outer side of the drug layer.

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