Crystalline Limus Balloon Coating for Sustained Vessel-Wall Drug Retention
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Solution Overview
Problem
Existing drug-coated balloon catheters face challenges in effectively delivering and maintaining sufficient drug concentrations of Limus substances in the vessel wall to prevent re-narrowing, due to low transfer and short duration of drug action.
Innovation Solution
A coating method using a solvent mixture of polar and non-polar organic solvents to crystallize Limus substances directly on the balloon surface, ensuring adherence, rapid release, and prolonged retention in the vessel wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If amorphous Limus substance coating is used on balloon catheters, then the coating adheres well to the balloon surface, but the drug concentration in the vessel wall drops quickly and is not maintained long enough to achieve the desired effect
Solution Approach 1:
The patent changes the physical state parameter of the Limus substance from amorphous to crystalline form. This parameter change fundamentally alters the release kinetics, enabling the drug to be released in a controlled manner over an extended period (at least 4 weeks) while maintaining adequate adhesion to the balloon catheter surface during delivery.
Solution Approach 2:
The patent creates a composite coating system combining crystalline Limus substance with specific polymers (polymer A and polymer B with different glass transition temperatures). This composite structure provides both secure adhesion during catheter delivery and controlled sustained release in the vessel wall, resolving the contradiction between adhesion reliability and duration of action.
2Duration of action of moving object
If crystalline Limus substance is used to delay release from stent surfaces, then the release is delayed, but the procedure becomes complicated and cannot be easily transferred to balloon catheter coating
Solution Approach 1:
The patent applies crystalline Limus substance directly to the balloon catheter surface using a simplified coating procedure, unlike the complex multi-step process required for stents. The crystalline form is applied as a suspension or solution that adheres to the balloon surface, then releases controllably during expansion, achieving delayed release without procedural complexity.
Solution Approach 2:
The patent extracts the beneficial property of crystalline Limus substance (controlled delayed release) from the complex stent coating context and adapts it to the simpler balloon catheter platform. By removing the unnecessary complexity of multi-layer crystal coatings and adapting the crystalline substance to a balloon-compatible application method, the invention achieves the same release timing benefit with much simpler procedures.
3Quantity of substance
If Limus substance coating is applied to balloon catheters, then the drug is delivered to the vessel wall, but the transfer efficiency is low and drug levels are not maintained
Solution Approach 1:
The patent uses composite polymer coatings (combining polymer A with glass transition temperature of -50°C to -50°C and polymer B with glass transition temperature of -100°C to -150°C) to create a matrix that controls drug release. This composite structure ensures both sufficient drug transfer to the vessel wall and maintenance of therapeutic levels for at least 4 weeks, resolving the contradiction between delivery quantity and therapeutic reliability.
Solution Approach 2:
The patent changes the release kinetics parameter by using crystalline Limus substance instead of amorphous form, and by selecting specific polymer combinations with defined glass transition temperatures. These parameter changes ensure that the drug is transferred efficiently to the vessel wall and maintained at therapeutic concentrations for the required duration, achieving both adequate quantity and reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves prolonged drug retention and effective drug concentrations in the vessel wall, inhibiting neointimal hyperplasia and reducing restenosis, with a half-life of ≥ 1 week in porcine coronary arteries.
Implementation Method 1
If the active ingredient is not already dissolved, individual particles or crystals are dissolved and are accessible to the solvent from all sides.
Implementation Method 2
the necessary dose must pass into the vessel wall
Data Source
AI summary
The invention relates to balloon catheters having a polymer-free coating on the balloon surface, said coating comprising at least one limus substance in crystalline form, and to methods for the polymer-free coating of balloon surfaces, in particular balloon catheters, with crystalline limus substances.