JP2018068724A - Balloon catheter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a balloon catheter which can transfer a medicine to a blood vessel wall of lesion in a uniform state.SOLUTION: There is provided a balloon catheter 1 comprising a shaft 2 and a balloon 10 which can be expanded and provided on outside of the shaft 2. At least a part of an outside surface of the balloon 10 has a medicine layer 12, and at least parts of the outside surface of the balloon 10 and/or the medicine layer 12 have a coating part which is covered with a protection cover 20. The protection cover 20 is provided to be peeled from the outside surface of the balloon 10 and/or the medicine layer 12 when the balloon 10 is expanded, and expose at least a part of the medicine layer to outside in the coating part. The coating part has a contact part where the outside surface of the balloon 10 and/or the medicine layer 12 and the protection cover 20 contact, and a non-contact part where they do not contact.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a balloon catheter including a drug layer and a protective cover that covers at least a part of the outer surface of the balloon and / or the drug layer.

  It is known that various diseases occur when a stenosis occurs in a blood vessel, which is a flow path for circulating blood in the body, and the circulation of blood is delayed. In particular, when a stenosis occurs in a coronary artery that supplies blood to the heart, there is a risk of causing serious diseases such as angina pectoris and myocardial infarction. One method for treating such a stenosis of a blood vessel is an angioplasty (PTA, PTCA, etc.) that expands the stenosis using a balloon catheter. Angioplasty is widely performed because it is a minimally invasive therapy that does not require thoracotomy such as bypass surgery.

  By the way, in the case of angioplasty, restenosis may occur in an expanded stenosis, and drug elution with a drug layer on the surface is a treatment method that reduces the frequency of such restenosis (restenosis rate). Treatment using a stent is performed. Recently, treatment using a drug-eluting balloon catheter that does not leave a foreign substance such as a stent in the body and can treat a small blood vessel into which the stent cannot be inserted is also performed. If a drug-eluting balloon catheter is used, the drug can be transferred to the lumen wall by expanding the balloon at the lesion, and it can be expected to suppress the occurrence of restenosis. The drug is held on the outer surface of the balloon of the drug-eluting balloon catheter. In order to prevent the drug from being washed away until the balloon is delivered to the lesion (hereinafter also referred to as delivery). A catheter provided with a cover for protecting a drug has been proposed (for example, Patent Documents 1 and 2). Advantages of the protective cover that covers the drug include suppressing side effects caused by the transfer of the drug to other than the lesion, and obtaining an effect of suppressing the occurrence of restenosis by transferring a sufficient amount of the drug to the lesion. Is mentioned.

Special table 2011-513005 gazette Japanese Patent Laid-Open No. 8-33720

  However, the conventional drug holding balloon catheter provided with the protective cover is a process in which the protective cover is peeled off from the drug layer provided on the outer surface of the balloon when the balloon is expanded, and the drug layer is exposed to body fluid such as blood. As a result, the drug layer is biased to a part due to the drug layer eluting from or falling into the blood, etc., and as a result, the drug cannot be evenly transferred to the diseased blood vessel wall, and the anti-restenosis action is fully exhibited There was a problem that it was not possible.

  This invention is made | formed in view of the said subject, The objective is to provide the balloon catheter which can transfer a chemical | medical agent equally with respect to the blood vessel wall of a lesion.

  As a result of intensive studies for solving the aforementioned problems, the present inventors have completed the present invention. That is, the present invention provides the following balloon catheters [1] to [11].

[1] A balloon catheter having a shaft and an expandable balloon provided outside the shaft,
A drug layer is provided on at least a part of the outer surface of the balloon,
At least a part of the outer surface of the balloon and / or the drug layer has a covering portion covered with a protective cover,
The protective cover is provided in the covering portion so as to peel from the outer surface of the balloon and / or the drug layer when the balloon is expanded, and to expose at least a part of the drug layer to the outside.
The said covering part has a non-contact part which does not contact the contact part which the outer surface and / or the said medicine layer of the said balloon, and the said protective cover contact, and contacts.
[2] The balloon catheter according to [1], wherein an area of the contact portion is 80% or less of an area of the covering portion.
[3] The balloon catheter according to [1] or [2], wherein in the cross section of the balloon, the circumferential length of the contact portion is 80% or less of the circumferential length of the protective cover.
[4] The balloon catheter according to any one of [1] to [3], wherein the drug layer has an intermediate layer between the drug cover and the protective cover.
[5] The balloon catheter according to any one of [1] to [4], wherein the balloon or the drug layer has a protruding portion protruding radially outward on at least one outer surface.
[6] The protrusion is formed so that a line formed by the protrusion is substantially parallel to a vector in a direction in which the protective cover is peeled from the drug layer when the balloon is expanded. The balloon catheter according to [5].
[7] The balloon catheter according to any one of [1] to [6], wherein the protective cover is broken at least partially when the balloon is expanded.
[8]
The balloon catheter according to any one of [1] to [7], wherein a part of the protective cover has a fragile portion whose strength is weaker than that of the surrounding area.
[9] The protective cover is disposed so as to cover at least a part of the outer surface of the balloon and / or the drug layer when the balloon is in a contracted state or a folded state. ] The balloon catheter in any one of [8].
[10]
The balloon catheter according to any one of [1] to [9], wherein the protective cover is formed with pleats.
[11]
The balloon catheter according to any one of [1] to [10], wherein the protective cover is folded when the balloon is in a deflated state or a folded state.

  Since the balloon catheter of the present invention has a drug layer and a protective cover that covers the outer surface of the balloon and / or the drug layer, the drug is eluted into a body fluid such as blood during delivery of the balloon to the lesion. When the balloon is expanded, the contact area between the protective cover and the drug layer is smaller than that of the conventional balloon catheter, so the protective cover can be smoothly peeled off from the drug layer and turned into body fluid such as drug blood. Can be prevented from falling off.

The top view of the balloon catheter of this invention is represented. (A)-(c) is (a) AA sectional drawing, (b) BB sectional drawing, and (c) CC sectional drawing of the balloon catheter shown in FIG. The top view of an example of the balloon in the balloon catheter of this invention is represented. The perspective view of an example of the protective cover before the attachment to a catheter in the balloon catheter of this invention is represented. The top view of an example of the protective cover which has a weak part in an axial direction is represented. The top view of an example of the balloon provided with the protective cover of FIG. 5 is represented. FIG. 7A is a plan view of the example of the balloon in FIG. 6 and FIG. 7B is a side view of the distal side. The top view of an example of the protective cover which has a weak part in the circumferential direction is represented. The top view of an example of the balloon provided with the protective cover of FIG. 8 is represented. The top view of an example at the time of balloon contraction of Drawing 9 is expressed. The top view of an example at the time of balloon expansion is shown in the balloon catheter of this invention shown in FIG. The (a) sectional view in CC section of an example of the balloon of Drawing 1 and (c) a partial enlarged view of a section are expressed. The (a) sectional view in CC section of other examples of the balloon of Drawing 1 and the (c) partial enlarged view of a section are expressed. Sectional drawing in CC cross section of the other example of the balloon of FIG. 1 is represented. The other example of the balloon in the balloon catheter of this invention is represented. The other example of the balloon in the balloon catheter of this invention is represented. The other example of the balloon in the balloon catheter of this invention is represented. The other example of the balloon in the balloon catheter of this invention is represented. The other example of the balloon in the balloon catheter of this invention is represented. The other example of the balloon in the balloon catheter of this invention is represented. The other example of the balloon in the balloon catheter of this invention is represented.

  Hereinafter, the present invention will be described in more detail based on the following embodiments, but the present invention is not limited by the following embodiments as a matter of course, and appropriate modifications are made within a range that can meet the purpose described above and below. In addition, it is of course possible to carry out them, all of which are included in the technical scope of the present invention. In addition, in each drawing, although hatching, a member code | symbol, etc. may be abbreviate | omitted for convenience, in this case, a description and another drawing shall be referred. In addition, the dimensions of the various members in the drawings are given priority to contribute to the understanding of the characteristics of the present invention, and may be different from the actual dimensions.

  The balloon catheter of the present invention has a drug layer provided on at least a part of the outer surface of the balloon, and a covering part in which at least a part of the outer surface of the balloon and / or the drug layer is covered with a protective cover, The covering portion includes an outer surface of the balloon and / or a drug layer and a non-contact portion that is not in contact with the contact portion that is in contact with the protective cover.

  According to the balloon catheter of the present invention, during delivery of the balloon to the lesion, the protective cover prevents the drug layer from being lost due to elution or dropping of the drug layer into body fluid such as blood. Since the area of the contact portion where the protective cover and the drug layer are in contact is smaller than that of a conventional balloon catheter, the drug layer is securely attached to the diseased blood vessel wall without damaging the drug layer when the balloon is expanded. Moreover, it can suppress that a chemical | medical agent falls off from the balloon outer surface at the time of cover peeling. Thereby, a higher restenosis suppressing effect can be expected than a drug holding balloon catheter having a conventional protective cover.

(Balloon catheter)
With reference to FIG. 1 and FIG. 2, the whole structure of the balloon catheter of this invention which has a chemical | medical agent layer and a protective cover is demonstrated. FIG. 1 shows a plan view of a balloon catheter having a protective cover 20, and FIG. 2 shows (a) AA sectional view, (b) BB sectional view, and (c) of the balloon catheter shown in FIG. CC sectional drawing is shown.
FIG. 1 shows a configuration example of a rapid exchange type balloon catheter in which a wire is inserted partway from the distal side to the proximal side of the shaft.
The balloon catheter 1 of the present invention has a shaft 2 and a balloon 10 provided on the outer side of the shaft 2, and further has a drug layer 12 containing a drug on the outer surface of the balloon 10. The balloon catheter 1 is provided with a protective cover 20 so as to cover at least a part of the side surface and / or the drug layer 12.

The balloon catheter 1 of the present invention has a proximal side and a distal side, a balloon 10 is provided on the distal side of the shaft 2, and a hub 5 is provided on the proximal side of the shaft 2. In the present invention, the proximal side of the balloon catheter refers to the direction of the proximal side of the user (operator) with respect to the extending direction of the balloon catheter (particularly the shaft), and the distal side is opposite to the proximal side. The direction (namely, direction on the treatment target side) is indicated. Further, the direction from the proximal side to the distal side of the balloon is referred to as the axial direction, and the outer peripheral direction in the cross section intersecting the axial direction is referred to as the circumferential direction.
The balloon catheter 1 of the present invention is configured such that a pressure fluid is supplied from the hub 5 to the inside of the balloon 10 through the shaft 2, and expansion and contraction of the balloon 10 can be controlled using an indeflator.

The shaft 2 is generally provided with a pressure lumen for allowing the pressure fluid to flow into the balloon 10 and a guide wire lumen for inserting a guide wire for guiding the delivery of the balloon 10 to the lesioned part.
On the distal side of the shaft 2, the inner tube 3 extends from the distal end of the outer tube 4 and penetrates the balloon 10 in the axial direction. The distal side of the balloon 10 is joined to the inner tube 3, and The distal side is configured to be joined to the distal side of the outer tube 4. For example, the shaft 2 includes an inner tube 3 and an outer tube 4 on the distal side, and includes an outer tube 4 on the proximal side. The inner tube 3 defines a guide wire lumen and the outer tube 4 defines a pressurizing lumen. In this case, the guide wire lumen is provided halfway from the distal side to the proximal side of the shaft 2 and has a guide wire port 7 communicated therewith. A pressure lumen is provided from the distal side to the proximal side of the shaft 2 and the hub 5 is configured to have a pressure lumen port 6 in communication with the pressure lumen.

  The balloon 10, the shaft 2 (the inner tube 3, the outer tube 4), and the hub 5 can be joined using a conventionally known joining means such as an adhesive or heat welding. Further, a radiopaque marker may be arranged at the portion of the shaft 2 where the balloon 10 is located in order to make it possible to confirm the position of the balloon 10 under radioscopy.

  The shaft 2 (the inner tube 3 and the outer tube 4) is preferably manufactured, for example, by molding a resin. For example, a resin tube, which is the original shape of a shaft, is manufactured by an extrusion molding method in which a resin is extruded from a mold, and a shaft is manufactured by joining means such as an adhesive or heat welding. be able to. Moreover, it is preferable to manufacture the shaft of the balloon catheter by a known molding method such as dip molding, injection molding or compression molding.

  Examples of the resin constituting the shaft 2 include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, vinyl chloride resins, silicone resins, and natural rubber. These may use only 1 type and may use 2 or more types together. Of these, polyamide resins, polyester resins, and polyurethane resins are preferably used.

  The balloon catheter of the present invention may be an over-the-wire type in which a wire is inserted from the distal side to the proximal side of the shaft. In this case, a guide wire lumen and a pressure lumen are provided from the distal side to the proximal side of the shaft. The guide wire port that communicates with the guide wire lumen may be provided on the hub. In addition to inserting the guide wire, the guide wire port can function as an injection port for drugs and the like, and a suction port for fluids in the body cavity.

  1 and 2 show a balloon catheter in which body fluid such as blood does not pass (does not flow) inside the shaft, the balloon catheter of the present invention is held in the balloon by expanding the balloon for a long time. In order to facilitate the transfer of the applied drug to the inner wall of the blood vessel or the like, it may be a perfusion type balloon catheter having a perfusion lumen that can pass through the balloon and move blood between the proximal side and the distal side of the balloon. .

(balloon)
FIG. 3 is a plan view of a balloon provided in the balloon catheter shown in FIG. The balloon provided in the balloon catheter is not limited to the balloon shown in FIG.

  The balloon 10 is formed in a bag shape having openings on the proximal side and the distal side, respectively. As shown in FIG. 3, the balloon 10 has a cylindrical straight tube portion 14, a proximal taper portion 15 connected to the proximal side thereof, and a distal taper portion 16 connected to the distal side. Preferably, the proximal taper portion 15 and the distal taper portion 16 are formed so as to be reduced in diameter as they move away from the straight tube portion 14. A cylindrical proximal sleeve 17 is connected to the proximal side of the proximal tapered portion 15, and a cylindrical distal sleeve 18 is connected to the distal side of the distal tapered portion 16. In the catheter shown in FIG. 1, the proximal sleeve 17 is joined to the outer tube 4 of the shaft 2, and the distal sleeve 18 is joined to the inner tube 3 of the shaft 2. What is necessary is just to set suitably the outer diameter of the straight pipe part 14, the length of an axial direction, the taper angle of the taper parts 15 and 16, and the length of an axial direction according to the desired function of the balloon 10. FIG. Moreover, the taper angle of the taper parts 15 and 16 can be set to 90 degrees with respect to the axial direction, and the balloon 10 can also be formed in a substantially cylindrical shape. The balloon 10 is configured such that the distal tapered portion 16 swells from the proximal tapered portion 15 through the straight tube portion 14 when a pressure fluid is supplied, and in the present invention, the inflatable portion. Is considered a balloon.

  The balloon is preferably manufactured by molding a resin. For example, the base balloon is preferably manufactured by placing a resin tube extruded by extrusion molding in a mold and blow molding. The base balloon is preferably formed in an arbitrary shape depending on the shape of the mold. In addition, it is preferable to manufacture the balloon by a known molding method such as dip molding, injection molding or compression molding.

  Examples of the resin constituting the balloon include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, vinyl chloride resins, silicone resins, and natural rubber. These may use only 1 type and may use 2 or more types together. Of these, polyamide resins, polyester resins, and polyurethane resins are preferably used. For these resins, it is preferable to use an elastomer resin from the viewpoint of thinning the balloon and flexibility. For example, nylon 12 and nylon 11 are suitable materials for the balloon among polyamide resins, and nylon 12 is preferably used because it can be molded relatively easily during blow molding.

  Further, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferably used from the viewpoint of thinning the balloon and flexibility. Of these, polyether ester amide elastomers are preferably used because they have high yield strength and good dimensional stability of the balloon.

The dimensions of the balloon can be appropriately set according to the size of the treatment site.
In the expanded state of the balloon, for example, when the treatment site is a blood vessel, the axial length is preferably 5 mm or more and 300 mm or less, the outer diameter is preferably 0.5 mm or more and 20 mm or less, and the treatment site is the duodenal papilla. In the case of a digestive tract such as the above, it is preferable that the axial length is 10 mm or more and 100 mm or less, and the outer diameter is 3 mm or more and 30 mm or less.
When the balloon is in a deflated state, for example, the axial length is preferably 5 mm or more and 300 mm or less, and the outer diameter is preferably 0.1 mm or more and 10 mm or less. When the treatment site is a digestive tract such as a duodenal papilla, The axial length is preferably 10 mm or more and 100 mm or less, and the outer diameter is preferably 0.5 mm or more and 20 mm or less.

(Drug layer)
The balloon holds a drug layer on at least a part of the balloon outer surface. In addition, the outer surface of the balloon in the present invention indicates a radially outer surface of the balloon extending from the balloon distal end portion including the sleeve portion to the proximal end portion.

  The drug layer held by the balloon contains at least one drug. The drug layer 12 may be held in a layer shape, or may be held in the form of a microcapsule or the like. The drug suitably used in the present invention is not particularly limited as long as it is a pharmacologically active substance, and examples thereof include pharmaceutically acceptable drugs such as gene therapy drugs, non-gene therapy drugs, small molecules, and cells.

  In particular, when using a balloon catheter for the purpose of suppressing vascular restenosis after treatment in angioplasty, anti-proliferative agents, anti-neoplastic agents, anti-inflammatory agents, immunosuppressive agents, anti-restenosis agents, Vasodilators and the like are preferable, and specifically, drugs such as paclitaxel, sirolimus, rapamycin, everolimus, zotarolimus, tacrolimus and the like can be used. These drugs may be used alone or in combination of two or more.

  The drug layer may contain, together with the pharmacologically active substance, an auxiliary agent for improving the dispersibility, solubility, migration to the blood vessel wall, and storage stability of the drug. As auxiliary agents, stabilizers, binders, disintegrating agents, moisture-proofing agents, preservatives, dissolution aids and the like are used, and specifically, lactose, sucrose, maltose, dextrin, xylitol, erythritol, mannitol, sucralose, Geraniol, dextran, dextrin, cyclodextrin, ethylenediamine, potassium iodide, popidone, urea, polysorbate, dibutylhydroxytoluene, sodium pyrosulfite, ascorbic acid, tocopherol, retinol, benzoic acid, paraoxybenzoates, polyethylene glycol, glycerin, Cholesterol, pepsin, phospholipid, lecithin, hydrogenated phospholipid, myristylic acid, stearic acid, palmitic acid, oleic acid, fatty acids, glycyrrhizic acid, boric acid, carboxymethyl ethyl cellulose , Carmellose, croscarmellose, oxidized cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, glucosamine, hyaluronic acid, dermatan sulfate, that out of the chondroitin sulfate containing at least one preferred.

The balloon catheter of the present invention has a covering portion in which at least a part of the outer surface of the balloon or the drug layer is covered with a protective cover, and the covering portion protects the outer surface of the balloon and / or the drug layer. It has a non-contact part which is not in contact with the contact part which the cover is contacting. Since the balloon catheter of the present invention has a non-contact portion, it is possible to suppress the drop of the drug layer to body fluid such as blood due to peeling of the protective cover when the balloon is expanded.
In addition, the coating | coated part in this invention does not include the part to which the balloon or the shaft and the protective cover are fixed by welding or adhesion | attachment.

  The drug layer of the present invention may have an intermediate layer between the protective covers. As a result, the contact between the protective layer and the drug layer that occurs when the protective cover peels can be further prevented, and the amount of the drug that migrates to the blood vessel wall can be increased by suppressing the dissolution and dropping of the drug into the blood. There is a tendency to be able to.

  The intermediate layer contains a water-soluble polymer from the viewpoint of preventing elution and dropping (hereinafter referred to as initial burst) into blood that occurs when the drug layer suddenly touches blood immediately after the protective cover is peeled off. It is preferable. The water-soluble polymer used in the intermediate layer is not particularly limited, but is, for example, carboxyl methyl cellulose, hydroxymethyl cellulose, hydroxypropyl cellulose, methyl cellulose, oxidized cellulose, polyvinyl alcohol, alginic acid, pectin, gum arabic in terms of excellent lubricity. , Gellan gum, guar gum, xanthan gum, carrageenan, gelatin, hydrophilic petrolatum, polyethylene glycol, hyaluronic acid, dermatan sulfate, chondroitin sulfate, heparin, glycosaminoglycan, dextran, dextrin, cyclodextrin, polylactic acid, polydioxane, polycaprolactone, polyvinyl It is preferable that at least one of alcohols and the like is included.

  In addition, the intermediate layer preferably contains a fat-soluble substance and a surfactant from the viewpoint of transferring more drug in the drug layer into the blood vessel wall and blood vessel tissue. Lipid, fatty acid, phospholipid, bile acid, fatty acid, Preferably, at least one of cholesterol, sphingophospholipid, glycyrrhizic acid and the like is included.

  When the intermediate layer is disposed, it is more preferable to provide a protruding portion protruding radially outward on the outer surface of the balloon or the outer surface of the drug layer. Thereby, damage to the drug layer including the intermediate layer due to peeling of the protective cover at the time of balloon expansion can be suppressed, and the drug can be efficiently transferred to the lesioned portion, and a higher restenosis suppressing effect tends to be obtained.

  As a method for forming the drug layer, for example, a method of applying a solid or liquid drug on the outer surface of the balloon can be preferably used. From the viewpoint of ease of layer formation, it is preferable to apply a drug solution in a state of being dissolved or dispersed in a particulate or colloidal form on the outer surface of the balloon. It is preferable that the balloon for applying the medicine is in an expanded state before the protective cover is disposed. Moreover, the chemical | medical agent at the time of apply | coating may be in the state disperse | distributed in viscous materials, such as a gel form and a sol form.

  As a coating method, a general coating method can be used. For example, coating methods such as brush coating, roll coater coating, dip coating, spray coating, comma coating, knife coating and the like can be mentioned. In particular, from the viewpoint of easy coating, a method of applying by dip coating or spray coating is preferable. Application | coating may be performed only once and may be performed twice or more.

  The type of solvent that can be used for drug application is not particularly limited as long as the drug can dissolve or disperse the drug, but availability, biocompatibility, safety, drug solubility, drug dispersibility, and volatilization after application. It is preferable to have characteristics such as high adhesion on the outer surface of the balloon and drug, and specifically, ethanol, methanol, acetone, ketone, ethyl acetate, methyl acetate, aniline, diethylamine, dimethylamine , Nitromethane, acetonitrile, pyridine, N, N-dimethylacetamide, propanol, isopropanol, ethylene glycol, chloroform, benzyl alcohol, chloroform, dimethyl sulfoxide, tetrahydrofuran, acetic acid, formic acid, pentane, cyclopentane, toluene, hexane, cyclohexane, xylene, It preferably contains at least one of benzene, ethyl ether, methylene chloride, ammonium acetate, ammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and water, and more preferably water, ethanol, and acetone.

  In addition, in order to control the adhesion between the drug layer and the balloon outer surface, the drug layer including the drug layer or the intermediate layer, and the protective cover lumen surface, the balloon surface or the protective cover lumen surface is subjected to surface treatment. As the surface treatment, plasma treatment, laser treatment, ion treatment, ozone treatment, discharge treatment, primer treatment and the like can be preferably used.

  The lumen surface of the protective cover in the present invention refers to the surface of the protective cover that faces the outer surface of the balloon and / or the surface of the drug layer.

(Protective cover)
The shape and material of the protective cover 20 are not particularly limited as long as they cover at least a part of the balloon outer surface and / or the drug layer 12 and can be peeled off from the drug layer when the balloon is expanded.

  The shape of the protective cover 20 is not particularly limited as long as it can cover at least a part of the outer surface of the balloon and the drug layer, and may be formed of one component continuous from the distal side to the proximal side. It may be formed of two or more parts cut. For example, the bag may have a bag-like shape or a shape cut between the distal end and the proximal end of the cover, but the circumferential length of the protective cover is longer than the balloon. It is preferable.

  The protective cover 20 is formed into a cylindrical body 21 formed by rolling a film as shown in FIG. 4 into a cylindrical shape or a cylindrical body formed into a tube shape. Or it can obtain by methods, such as shape | molding in the bag shape or half bag shape which reduced the diameter of the both ends or one end as shown in FIG.

  The protective cover 20 is preferably arranged so as to cover at least a part of the drug layer 12 or the balloon 10 before the balloon is expanded, that is, in a contracted state or a folded state. Thereby, there is a tendency that elution or dropping of a drug into a body fluid such as blood during delivery of a balloon to a lesioned part can be suppressed.

  The protective cover 20 is preferably formed with pleats (folds), and the protective cover 20 is preferably folded before the balloon is expanded, that is, when the balloon is in a deflated state or a folded state. Thereby, it tends to be able to deliver the balloon into the narrow blood vessels.

  Examples of the resin constituting the protective cover include polyamide resins, polyester resins, polyurethane resins, polyolefin resins, vinyl chloride resins, silicone resins, natural rubber and the like, as in the case of balloons. These may use only 1 type and may use 2 or more types together. Of these, polyamide resins, polyester resins, and polyurethane resins are preferably used.

  In particular, nylon 12 and nylon 11 are examples of materials suitable for the balloon among polyamide-based resins, and nylon 12 is preferably used because it can be molded relatively easily when blow molding. Also, polyamide elastomers such as polyether ester amide elastomers and polyamide ether elastomers are preferably used from the viewpoint of thinning the protective cover and flexibility. Of these, polyether ester amide elastomers are preferably used because they have high yield strength and good dimensional stability of the balloon.

  The protective cover 20 may be provided with a radiopaque material or may be kneaded into the protective cover to enable confirmation under radioscopy.

  The radiopaque substance is a substance that can suppress the transmission of radiation, and is more preferably a metal, specifically platinum, gold, barium, calcium, strontium, magnesium, radium, iron, titanium, cobalt, chromium, It is preferable that at least one of aluminum, gallium, and the like is included, and for non-metals, it is preferable that at least one of compounds including iodine and fluorine is included. These can also be used as raw materials for radiopaque markers placed at the position of the balloon 10 on the shaft 2.

  To prevent the protective cover 20 from falling off the balloon catheter, one or all of the protective cover members can be attached directly to the shaft 2 or the proximal or distal sleeve 18 of the balloon, proximal It is preferable that the shaft 2 is fixed to at least one portion of the side or distal tapered portion 16. The fixing method is preferably heat welding, and may be bonded using an adhesive.

  The protective cover 20 is preferably peeled off so that at least a part of the drug layer or the outer surface of the balloon is exposed to body fluid such as blood as the balloon is expanded in the treatment section. A specific method is not particularly limited as long as a part of the drug layer can be exposed to a body fluid such as blood when the balloon is expanded. For example, a method in which at least a part of the protective cover is opened or at least a part when the balloon is expanded. It is more preferable that at least a part of the protective cover is broken at the time of balloon expansion in that the method can be used to break the balloon and the drug layer can be exposed to body fluids such as blood.

  It is preferable that the protective cover 20 has at least a fragile portion 23 whose strength is weaker than that of the surrounding area. The protective cover having a fragile portion expands the balloon by flowing a pressure fluid into the inside of the balloon, breaks at the fragile portion 23 of the protective cover due to the stress generated in the radial direction of the balloon due to the expansion, and peels from the drug layer. , At least a portion of the drug layer can be exposed to body fluids such as blood.

  The method of forming the fragile portion is not particularly limited as long as a portion that can be broken at the time of balloon expansion is formed. For example, a method of forming a discontinuous line such as a perforation that cuts the protective cover in the axial direction or the circumferential direction. , A method of forming a portion thinner than the surroundings, a method of forming a resin having a lower strength than the surroundings, a method of degrading a part of the resin by thermal or chemical treatment, etc. In terms of easy formation, a method of forming a discontinuous line such as a perforation can be preferably used.

  FIG. 5 shows an example of the protective cover 22 having the fragile portion 23 in the axial direction of the balloon catheter, and FIG. 8 shows an example of the protective cover 22 having the fragile portion 23 in the circumferential direction of the balloon catheter.

  FIG. 5 shows an example of the form of the protective cover 22 having the fragile portion 23 in the axial direction of the balloon catheter. For example, the cylindrical body 21 wound with a film-like resin shown in FIG. It can be manufactured by molding a cylindrical body. The fragile portion 23 may be provided in the form of a crease line, a sewing machine line, or the like, and may be provided by bonding by an adhesive or heat welding, or may not necessarily be fixed.

  FIG. 6 shows another example of the embodiment of the protective cover 22 having the fragile portion 23 in the axial direction of the balloon catheter, which is mounted so as to cover the drug layer of the balloon catheter or the balloon, for example, the sleeve 24 of the protective cover. And balloon catheter sleeves 17 and 18. At this time, the balloon may be in an expanded state or a contracted state. At this time, if the balloon is in a deflated state, the balloon may be folded to form a pleat called a pleat, or a pleat may be folded and wrapped to provide a protective cover. Good. When the balloon is in an expanded state, a protective cover may be provided so as to follow the outer shape of the balloon or the drug layer, and the protective cover may be pleated or wrapped and folded together with the balloon or the drug layer.

  FIG. 7A is a plan view of the balloon when the balloon equipped with the protective cover 22 (20) having the fragile portion 23 in the axial direction is expanded, and FIG. 7B is a distal side when the balloon is expanded. The side view of is shown. At the time of balloon expansion, the protective cover 22 (20) is peeled and moved from the drug layer or the balloon outer surface so that the protective cover 22 (20) is broken starting from the weakened portion 23 provided in the axial direction and pushed away in the peeling direction 28 shown in FIG. And converge to a part on the outer surface of the balloon. At this time, the drug layer disposed on the outer surface of the balloon is exposed to body fluid such as blood in a portion other than the range where the protective cover is converged.

  8 and 9 show a protective cover 22 having a fragile portion 23 in the circumferential direction of the balloon catheter. For example, as shown in FIG. 4, a cylindrical body 21 wound with a film-like resin, or a cylindrical cylinder formed into a tube shape. Each of the two bodies is molded, and a method of separately molding the proximal protective cover 22a or the distal protective cover 22b as shown in FIG. 8 and a cylindrical body 21 are molded. It can be obtained by a method of cutting in the circumferential direction to obtain the proximal protective cover 22a or the distal protective cover 22b as shown in FIG. The protective cover 22 having the fragile portion in the circumferential direction can be manufactured by joining the proximal protective cover 22a and the distal protective cover 22b thus obtained so as to form the fragile portion 23.

  The fragile portion 23 can be provided in the form of a crease line, a sewing machine line, or the like, or can be provided by adhering by an adhesive or thermal welding, or not necessarily fixed.

Protective covers 22a, 22b having a fragile portion 23 in the circumferential direction of the balloon catheter
As shown in FIG. 10, it is mounted so as to cover the drug layer of the balloon catheter or the balloon, and is fixed by, for example, a sleeve 24 of the protective cover and sleeves 17 and 18 of the balloon catheter. At this time, the balloon may be in an expanded state or a contracted state. At this time, when the balloon is in a deflated state, the balloon may be provided with a protective cover arranged in a pleated or wrapped state, and when the balloon is in an expanded state, the outer shape of the balloon or drug layer may be provided. A protective cover may be provided in accordance with the above, and the protective cover may be folded together with the balloon and the drug layer by pleating or wrapping.

  FIG. 11 shows a plan view when a balloon equipped with protective covers 22a and 22b having a fragile portion 23 in the circumferential direction of the balloon catheter is expanded. When the balloon is expanded, the protective cover is broken starting from the weakened portion 23 provided in the axial direction, and peeled and moved from the drug layer or the balloon outer surface so as to be pushed away in the peeling direction 28 shown in FIG. Converge at least partially. At this time, the drug layer disposed on the outer surface of the balloon is exposed to body fluid such as blood in a portion other than the range where the protective cover is converged.

  The balloon in which the protective covers 22a and 22b having fragile portions in the circumferential direction of the balloon catheter are attached to the balloon straight tube portion 14 as compared with the balloon in which the protective cover 22 having the fragile portions 23 in the axial direction of the balloon catheter is attached. Since a wider range is exposed, the drug can be transferred from the drug layer to the blood vessel wall more efficiently. On the other hand, a balloon equipped with a protective cover 22 having a fragile portion in the axial direction of the balloon catheter is protected even after balloon expansion, as compared with a balloon equipped with protective covers 22a and 22b having a fragile portion in the circumferential direction of the balloon catheter. The cover 20 is not divided into two parts, and is fixed at at least two locations of the balloon, so that the protective cover 20 is difficult to drop off.

  When the balloon catheter having the protective cover thus obtained is delivered to the treatment site, the drug layer is protected by the protective cover, so that the drug is treated without dropping or losing in the body fluid such as blood. The balloon can be delivered to the part. When the balloon is expanded at the treatment site, for example, as shown in FIG. 7, after the protective cover is peeled off and at least a part of the outer surface of the drug layer and the balloon is exposed to the outside, the drug layer touches the blood vessel wall. The drug can be transferred from the drug layer into the blood vessel wall or blood vessel tissue. Therefore, a higher therapeutic effect can be obtained by delivering the drug in the drug layer on the outer surface of the balloon to the treatment site without losing the drug.

  The protective cover is lost not only when the balloon catheter is delivered to the treatment site, but also when, for example, the operator or assistant prepares the drug holding balloon for use in surgery, and the drug falls off from the outer surface of the balloon. Can be prevented.

(Coating part)
The balloon catheter of the present invention has a covering portion in which at least a part of the outer surface of the balloon or the drug layer is covered with a protective cover, and in the covering portion, a contact portion where the drug layer and the protective cover are in contact with the drug layer, It has a non-contact part where the protective cover is not in contact, and the area of the contact part between the drug layer and the protective cover is small.

  A conventional balloon catheter provided with a protective cover is in contact with almost all of the installation surface of the drug layer and the protective cover, and does not have a non-contact portion. However, the balloon catheter of the present invention can be used as the balloon expands. When the protective cover is peeled off, the coating portion has a non-contact portion, so that friction generated at the contact portion where the drug layer and the protective cover come into contact can be suppressed, so that the drug is vascularized without damaging the drug layer. Can be transferred to the wall.

In the balloon catheter of the present invention, the area of the contact portion between the protective cover and the drug layer is preferably 80% or less, more preferably 60% or less, and more preferably 40% or less with respect to the area of the covering portion. It is particularly preferred that
Further, in a cross section formed when a balloon partially covered with a protective cover is cut at an arbitrary position, the circumferential length of the contact portion is 80% or less of the circumferential length of the protective cover. Preferably, it is 60% or less, more preferably 40% or less.

(Protruding part)
In the balloon catheter of the present invention, as a method for reducing the area of the contact portion between the drug layer and the protective cover at the outer surface of the balloon and / or the coating portion of the drug layer covered with the protective cover, the area of the contact portion is reduced. Although it is not particularly limited as long as it can be reduced, for example, by forming a protrusion protruding outward in the radial direction of the balloon on the outer surface of the balloon or the outer surface of the drug layer, the protective cover and the drug layer can reduce the area of the contact portion. Thus, friction generated between the protective cover and the drug layer can be reduced. In addition, the protrusion part of this invention may be formed in places other than a coating | coated part.

Specifically, this can be realized by providing a protrusion on the outer surface of the balloon as shown in FIG. 12, or by providing a protrusion on the outer surface of the drug layer as shown in FIG.
12 (a) is a cross-sectional view taken along the line C-C of the balloon catheter 1 shown in FIG. 1, and shows an example in which a protruding portion is formed on the outer surface of the balloon. FIG. An enlarged view is shown.
FIG. 13A is a cross-sectional view taken along the line CC of the balloon catheter 1 shown in FIG. 1 and shows an example in which a protruding portion is formed on the outer surface of the drug layer, and FIG. The figure which expanded the part is shown. The shape of the protruding portion shown in FIGS. 12 and 13 is an example, and there is no particular limitation as long as there is a portion protruding outward in the radial direction of the balloon on the outer surface of the balloon or the outer surface of the drug layer.
When the distance between the apex of the protrusion 25 from the bottom surface of the balloon outer surface or the drug layer outer surface as shown by 26 in FIG. 12B and 27 in FIG. 13B is the height 26 of the protrusion, The lower limit of the height of the protrusion is preferably 0.01 mm or more, more preferably 0.05 mm or more, and further preferably 0.1 mm or more. The upper limit is preferably 2 mm or less, and 1.5 mm or less. Is more preferable, and 1 mm or less is particularly preferable.

  When manufacturing a balloon catheter having a protruding portion on the outer surface of the balloon, for example, it is manufactured by using a mold that can form a protruding portion on the outer surface of the balloon in the step of resin molding a resin tube into a balloon shape. can do.

After forming the balloon as shown in FIG. 14, the protrusion may be formed on the outer surface of the balloon by placing the structure on the outer surface of the balloon.
When manufacturing a balloon catheter having a protrusion on the outer surface of the drug layer, for example, after applying a drug or the like on the outer surface of the balloon, a method of removing a part of the surface of the resulting drug layer, or a protrusion It is possible to manufacture a method of covering with a dedicated metal mold to be formed, a method of applying a drug with a shade on the outer surface of the balloon, and the like.

  The protrusions 25 may be randomly arranged on the outer surface of the balloon or the outer surface of the drug layer as shown in FIG. 19 or may be continuously arranged in a linear manner as shown in FIGS. 20 may be discontinuously arranged in a broken line shape as shown in FIG.

In the present invention, a pattern formed by the protrusions is referred to as a “protrusion pattern” when a certain pattern is provided in the arrangement of the protrusions regardless of random, linear, or broken lines. By having the protrusion pattern, friction between the drug layer and the protective cover can be reduced.
The protrusion pattern may be arranged in the circumferential direction of the balloon catheter as shown in FIG. 15, may be arranged in the axial direction as shown in FIG. 16, or arranged in a spiral shape as shown in FIG. Also good. In addition, they may be arranged in a random pattern, may be net-like, or a plurality of various protrusion patterns may be combined.

  The protrusion or protrusion pattern is a continuous line shape as in FIGS. 15 to 17, a discontinuous broken line shape as in FIG. 19, or a protrusion pattern having an approximate straight line 29 as shown in FIG. It is preferably formed on the outer surface of the balloon or the drug layer. Hereinafter, in the present invention, a continuous line, a broken line, or an approximate straight line of the protrusion or protrusion pattern is referred to as a line formed by the protrusion.

  The protrusion is such that the line 29 formed by the protrusion is substantially parallel to the vector 28 in the direction in which the protective cover is peeled off so that the protective cover is broken by balloon expansion to expose the drug layer. More preferably, it is formed. Thereby, the frictional force generated between the protective cover and the protruding portion is reduced, and the protective cover tends to be peeled off more smoothly. Here, “substantially parallel” refers to the direction in which the protective cover is smoothly peeled off within an angle of 45 degrees or less between the line formed by the protrusion and the vector of the direction 28 in which the protective cover peels off.

  For example, when the protective cover peeling direction 28 is the circumferential direction as shown in FIGS. 6 and 7, it is preferable to arrange the protruding portions so that the line formed by the protruding portions is in the circumferential direction as shown in FIG. When the protective cover peeling direction 28 is in the axial direction of the balloon as shown in FIGS. 10 and 11, the protruding portion is arranged so that the line 29 formed by the protruding portion is in the axial direction as shown in FIG. Is preferred. At this time, the angle formed by the line 29 formed by the protruding portion and the vector 28 in the peeling direction of the protective cover can be peeled more stably. Within the range of 45 degrees or less, the lower limit is 0 degree or more. Preferably, 5 degrees or more is more preferable, and 10 degrees or more is particularly preferable. Further, the upper limit of the angle formed by the line 29 formed by the protruding portion and the vector in the peeling direction of the protective cover is preferably less than 45 degrees, more preferably 35 degrees or less, and particularly preferably 25 degrees or less.

  As shown in FIG. 17, even when the protrusion pattern is arranged in a spiral shape, the angle formed by the line 29 (approximate straight line of the curve 25 by the protrusion) 29 and the peeling direction 28 of the protective cover is 45 degrees. Is preferably within the above range.

Furthermore, in order to improve the stability of peeling of the protective cover, the same protrusion or pattern as the balloon outer surface or the drug layer outer surface may be provided on the inner surface of the protective cover.
In addition, in the protruding portion or protruding portion pattern of the protective cover, similar to the protruding portion or protruding portion pattern formed on the outer surface of the balloon or the drug layer, a continuous line or broken line of the protruding portion or protruding portion pattern, or an approximation. A straight line is referred to as a line formed by the protrusions. The approximate straight line in the present invention refers to a regression line obtained by the least square method of each protrusion if the protrusion pattern is a dot, and when the protrusion is a curve, it is equally spaced in the circumferential direction. It refers to the regression line obtained by the least square method for 36 points (every 10 ° in the circumferential direction).

  The protrusion arranged on the inner surface of the protective cover is substantially perpendicular to the line formed by the protrusion of the protective cover and the line formed by the protrusion on the outer surface of the balloon or the outer surface of the drug layer. It is preferable to form such that they intersect. “Substantially vertical” means that the angle formed by the line formed by the protrusion on the outer surface of the balloon or on the surface of the drug layer and the line formed by the protrusion pattern of the protective cover is 45 ° or more, and the smooth protective cover is Refers to the direction of peeling.

  The lower limit of the angle at which the line formed by the protrusion on the outer surface of the balloon or the outer surface of the drug layer intersects the line formed by the protrusion disposed on the protective cover lumen side surface may exceed 45 degrees. Preferably, 55 degrees or more is more preferable, and 65 degrees or more is particularly preferable. The upper limit is preferably 90 degrees or less, more preferably 80 degrees or less, and particularly preferably 70 degrees or less.

  When forming a continuous linear protrusion as shown in FIGS. 15 to 17, for example, an elongated structure such as a fiber or a metal wire is wound on the outer surface of the balloon or the outer surface of the drug layer. can do.

  In addition, when forming a protrusion part on a balloon outer surface, it is preferable to form so that the height 26 of a protrusion part may become larger than the thickness of a chemical | medical agent layer. Since the height 26 of the protrusion formed on the outer surface of the balloon is larger than the thickness of the drug layer, it is easy to obtain an effect of preventing the drug layer and the protective cover from coming into direct contact with each other. There is a tendency to be able to suppress damage to the skin and drug loss.

  Furthermore, by giving a scoring effect that bites into the diseased blood vessel wall, such as by using a structure that is thicker than the thickness of the drug layer, more drug can be transferred deeper into the diseased blood vessel wall. There is a tendency that a stenosis suppressing effect can be exhibited. The lower limit value of the thickness or height of the specific elongated structure at this time is preferably 0.01 mm or more, more preferably 0.05 mm or more, particularly preferably 1 mm or less, and the upper limit value is preferably 2 mm or less. 1.5 mm or less is more preferable, and 1.0 mm or less is particularly preferable.

  The structure is preferably formed mainly from a material such as resin or metal from the viewpoint of reducing friction with the protective cover, or from the viewpoint that a sufficient scoring effect is easily exhibited. When the structure is mainly formed of a resin, it is more preferably formed of a fiber material, and may be a monofilament or a multifilament. The fiber material is not particularly limited, but is preferably a material having high hardness and low elongation (high modulus of elasticity) from the viewpoint of easily reducing friction or scoring. Examples of such a fiber material include polyarylate fiber, aramid fiber, ultrahigh molecular weight polyethylene fiber, PBO fiber, and carbon fiber.

  When the structure is mainly made of metal, it is more preferable to have a wire shape or a cable shape. Although it does not specifically limit as a metal raw material, It is preferable that it contains at least 1 or more from iron, nickel, titanium, cobalt, chromium, platinum, copper, zinc, and magnesium.

  When an elongated material such as a fiber material, a wire, or a cable is used for the structure, for example, as shown in FIG. 21, the structure can be knitted in a braided shape and arranged. Thereby, a semi-compliant property or a non-compliant property can be further imparted to the balloon. In the present invention, semi-compliant or non-compliant refers to the ability to suppress radial expansion or axial expansion in proportion to the normal balloon expansion pressure. A compliant balloon refers to a balloon in which the axial or radial expansion during balloon expansion is more suppressed than that of a semi-compliant balloon.

  In this way, by setting the balloon to a semi-compliant type or a non-compliant type, the upper limit of the expansion pressure when the balloon is inflated and the balloon is expanded can be set high. Therefore, the lesioned blood vessel can be expanded with high pressure, and sclerotic lesions such as calcified lesions can be treated, and a high restenosis suppressing effect can be obtained. In addition, even if a shortage occurs during treatment, etc., and excessive expansion pressure is applied to the balloon, the protective cover will fall off the balloon without causing the balloon to expand excessively in the axial direction or outer circumferential direction. Thus, embolization in the blood vessel can be prevented.

  It should be noted that semi-compliant or non-compliant balloons are not limited to the methods shown here, for example, a material having a high strength when the balloon is made thicker or a balloon is manufactured. It can be realized by selecting an appropriate material such as a material having low elongation and elasticity.

  From the viewpoint of providing a balloon of the balloon catheter of the present invention as a semi-compliant type or a non-compliant type with higher expansion performance for sclerosing lesions such as calcified lesions, the rate of change in axial length is 1 The length in the axial direction of the straight pipe portion when pressurized at 0.02 MPa (10 atm) is L10, the outer diameter is D10, and the length in the axial direction of the straight pipe portion when pressurized at 2.03 MPa (20 atm) is L20, outside When the diameter is D20, the axial length change rate (L20-L10) / L10 is preferably 7.5% or less, more preferably 5% or less, and even more preferably 3% or less. The outer diameter change rate (D20-D10) / D10 is preferably 12.5% or less, more preferably 10% or less, and even more preferably 7.5% or less.

  Furthermore, when the pressure applied to the balloon is in the range of high expansion pressure, the length of the straight pipe portion in the axial direction when pressurized to 2.03 MPa (20 atm) is L20, the outer diameter is D20, and 3.05 MPa (30 atm). ) When the length in the axial direction of the straight pipe portion during pressurization is L30 and the outer diameter is D30, the rate of change in the length in the axial direction (L30-L20) / L20 is preferably 5% or less, 3% or less is more preferable, and 1.5% or less is more preferable. The change rate of the outer diameter (D30-D20) / D20 is preferably 10% or less, more preferably 7.5% or less, and even more preferably 5% or less.

  In addition, when the pressure applied to the balloon is in the range of low expansion pressure, the length in the axial direction of the straight pipe portion when 0.51 MPa (5 atm) is applied is L5, the outer diameter is D5, and 1.01 MPa ( 10 atm) When the axial length of the straight pipe portion during pressurization is L10 and the outer diameter is D10, the rate of change in axial length (L10−L5) / L5 is preferably 10% or less. 7.5% or less is more preferable, and 5% or less is more preferable. The outer diameter change rate (D20-D10) / D10 is preferably 15% or less, more preferably 12.5% or less, and even more preferably 10% or less.

  On the other hand, in the balloon catheter of the present invention, when the balloon is expanded, the protective cover is more reliably peeled off, or the protective cover is prevented from falling off due to excessive expansion of the balloon. It is preferable to control the rate of change in elongation in the axial direction or radial direction. Specifically, regarding the rate of change in the axial length, the length in the axial direction of the straight pipe portion when the protective cover is pressurized to such an extent that it is not sufficiently ruptured at the fragile portion is LS, and the outer diameter is DS, When the length of the straight pipe portion in the axial direction is LL and the outer diameter is DL when the protective cover is pressurized immediately before or after rupturing at the fragile portion, the fragile portion shown in FIGS. In the case of a drug holding balloon catheter equipped with a protective cover, the axial length change rate (LL-LS) / LS is preferably smaller than the outer diameter change rate (DL-DS) / DS. In the case of a drug holding balloon catheter equipped with a protective cover in which weak portions shown in 8 to 11 are arranged in the circumferential direction, the rate of change in length in the axial direction (LL-LS) / LS is the rate of change in outer diameter (DL- DS) / DS is preferably larger.

1: Balloon catheter 2: Shaft 3: Inner tube 4: Outer tube 5: Hub 6: Pressurized lumen port 7: Guide wire port 10: Balloon 11: Balloon outer surface 12: Drug layer 14: Straight tube portion 15: Proximal Side taper portion 16: Distal taper portion 17: Proximal sleeve 18: Distal sleeve 20: Protective cover 21: Cylindrical body 22: Protective cover having a fragile portion in the axial direction 22a, 22b: fragile portion in the circumferential direction 23: fragile part 24: protective cover sleeve 25: protrusion 26: height of protrusion on the outer surface of the balloon 27: height of protrusion of the drug layer 28: peeling direction of the protective cover 29: protrusion Line formed by

Claims (11)

A balloon catheter having a shaft and an expandable balloon provided outside the shaft,
A drug layer is provided on at least a part of the outer surface of the balloon,
At least a part of the outer surface of the balloon and / or the drug layer has a covering portion covered with a protective cover,
The protective cover is provided in the covering portion so as to peel from the outer surface of the balloon and / or the drug layer when the balloon is expanded, and to expose at least a part of the drug layer to the outside.
The said covering part has a non-contact part which does not contact the contact part which the outer surface and / or the said medicine layer of the said balloon, and the said protective cover contact, and contacts.   The balloon catheter according to claim 1, wherein an area of the contact portion is 80% or less of an area of the covering portion.   The balloon catheter according to claim 1 or 2, wherein, in a cross section of the balloon, a circumferential length of the contact portion is 80% or less of a circumferential length of the protective cover.   The balloon catheter according to claim 1, wherein the drug layer has an intermediate layer between the drug cover and the protective cover.   The balloon catheter according to any one of claims 1 to 4, further comprising a protruding portion that protrudes radially outward on at least one outer surface of the balloon or the drug layer.   6. The protruding portion is formed so that a line formed by the protruding portion is substantially parallel to a vector in a direction in which the protective cover peels from the drug layer when the balloon is expanded. The balloon catheter according to 1.   The balloon catheter according to any one of claims 1 to 6, further comprising the protective cover that is at least partially broken when the balloon is expanded.   The balloon catheter according to any one of claims 1 to 7, wherein a part of the protective cover has a fragile portion whose strength is weaker than that of the surrounding area.   The protective cover is disposed so as to cover at least a part of the outer surface of the balloon and / or the drug layer when the balloon is in a contracted state or a folded state. The balloon catheter according to any one of the above.   The balloon cover according to claim 1, wherein the protective cover is formed with pleats.   The balloon catheter according to any one of claims 1 to 9, wherein the protective cover is folded when the balloon is in a contracted state or a folded state.