ACTIVE-SUBSTANCE COATING FOR BALLOONS OF BALLOON CATHETERS

Abstract

The invention relates to a method for coating the surface of the balloon of a balloon catheter with an active substance, with the balloon being made of an elastic material and being expandable by pressurization with a fluid, with the balloon being designed for expansion at a target site, wherein the coating of the surface of the balloon being applied at a pressure which is lower than the pressure used to expand the balloon at the target location. In this way, due to the generation of shear forces a particularly effective delivery of the active substance from the balloon to the inner wall of the blood vessel or the surrounding tissue is achieved. Furthermore, the invention relates to a relevant balloon as well as a balloon catheter.

Claims

1. Method for coating the surface of the balloon of a balloon catheter with an active substance, wherein the balloon being made of an elastic material and being expandable by pressurization with a fluid, with the balloon being designed for expansion at a target site, wherein the coating of the surface of the balloon being applied at a pressure which is lower than the pressure used to expand the balloon at the target location.

2. Method according to claim 1, wherein the pressure at which coating takes place is at least 20%, preferably at least 30% lower than the pressure that is exerted when the balloon is dilatated at the target site.

3. Method according to claim 2, wherein the pressure at which coating takes place amounts to a maximum of 50% of the pressure that is exerted to expand the balloon at the target site.

4. Method according to claim 1, wherein the elastic material comprises a polyurethane, a polyolefin copolymer, a polyethylene or a silicone.

5. Method according to claim 1, wherein the elastic material comprises a thermoplastic elastomer, in particular a polyether block amide.

6. Method according to claim 1, wherein, starting from the rated pressure at which the balloon reaches its nominal diameter, the diameter increase of the balloon when doubling the pressure is at least 5%.

7. Method according to claim 1, wherein the active agent used is selected from the following group: Tretinoin, orphan receptor agonists, elafin derivatives, corticosteroids, steroid hormones, paclitaxel, rapamycin, tacrolimus, hydrophobic proteins, heparin and/or hormone-like or cell proliferation-modifying substances.

8. Method according to claim 1, wherein at least the part of the balloon surface coated with the active substance is wetted with a liquid containing water and/or at least one alcohol.

9. Method according to claim 1, wherein at least the part of the surface of the balloon coated with the active substance is provided with a coat of polysaccharide before or after the active agent coating is applied.

10. Method according to claim 9, wherein the mean molar mass of the polysaccharide amounts to between 10,000 and 100,000,000 Da.

11. Method according to claim 10, wherein the mean molar mass of the polysaccharide amounts to between 20,000 and 80,000 Da.

12. Method according to claim 9, wherein the polysaccharide is a dextran.

13. Balloon of a balloon catheter, the surface of which is provided at least partially with a coating comprising an active agent obtainable through a method in accordance with claim 1.

14. Balloon catheter comprising a balloon in accordance with claim 13.

15. Method according to claim 6, wherein, starting from the rated pressure at which the balloon reaches its nominal diameter, the diameter increase of the balloon when doubling the pressure is at least 10%.

16. Method according to claim 7, wherein, starting from the rated pressure at which the balloon reaches its nominal diameter, the diameter increase of the balloon when doubling the pressure is at least 20%.

17. Method according to claim 8, wherein, starting from the rated pressure at which the balloon reaches its nominal diameter, the diameter increase of the balloon when doubling the pressure is at least 30%.

Description

EXAMPLE

[0051] A balloon made of an elastic polyurethane is pressurized from the inside with a pressure of 3 bar. At this pressure, the balloon has a diameter of 4.5 mm. In this state, the balloon is immersed into a solution consisting of paclitaxel in methylene chloride and then slowly withdrawn. The concentration of paclitaxel amounts to 200 mg/ml. The coating process takes place at room temperature. Following this, the pressure is released, after which the balloon folds up tightly.

[0052] The balloon forms part of a balloon catheter that is inserted into the human body and advanced through the blood vessel system to the target site, where pressurization takes place at 6 bar. At this pressure, the diameter amounts to 6 mm, which means the diameter and surface area have increased by 33% compared to the initial coating step. This causes the development of strong shear forces resulting in the active agent layer to spall off and be transferred to the inner wall of the vessel.