Drug-Eluting Stent Crystalline Sirolimus Coating

Solution Overview

Problem

Current drug-eluting stents face challenges such as residual physical, chemical, and therapeutic legacy in the vessel, inadequate thickness for deployment flexibility, and increased vessel wall intrusion, which can lead to complications like neointimal hyperplasia and restenosis.

Innovation Solution

A method of coating stents with a polymer and sirolimus, where at least a portion of the sirolimus is in crystalline form, using a process involving electrostatic deposition and sintering, to achieve a thin, flexible coating that is fully absorbed within 90 days, minimizing neointimal hyperplasia and reducing the risk of restenosis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a thicker coating is applied to the stent, then drug delivery capacity is improved, but deployment flexibility and access to difficult lesions deteriorate

Engineering Contradiction:

Core Design Contradiction:

Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The patent applies multiple thin layers (first, second, and third polymer layers with varying thicknesses) rather than a single thick coating, changing the structural parameters of the coating to achieve both adequate drug delivery capacity and maintained flexibility for deployment

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The coating is segmented into multiple discrete layers deposited at different stages, with each layer contributing differently to the overall drug delivery function while collectively maintaining flexibility. The first polymer layer, second polymer layer, and third polymer layer are applied sequentially with different formulations and thicknesses

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If a thicker coating is applied to the stent, then drug delivery capacity is improved, but vessel wall intrusion increases

Engineering Contradiction:

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

The patent uses multiple thin layers instead of a single thick coating, changing the geometric parameters to reduce vessel wall intrusion while maintaining adequate drug delivery capacity through optimized layer thicknesses and drug loading in each layer

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Different polymer layers have different local qualities and compositions optimized for specific functions - the first polymer layer provides initial drug delivery, the second polymer layer adds additional drug capacity, and the third polymer layer provides final drug delivery, with each layer locally optimized to minimize intrusion

Inventive Principle:

Principle #3Local quality

3Device complexity

If a single thick coating is applied, then manufacturing process is simplified, but coating uniformity and conformality deteriorate

Engineering Contradiction:

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The manufacturing process is segmented into multiple deposition stages (first polymer layer deposition, second polymer layer deposition, third polymer layer deposition) with sintering steps between layers, which improves coating uniformity and conformality compared to a single thick coating application

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The coating process uses periodic action with alternating deposition and sintering steps, where each polymer layer is deposited and then sintered before the next layer is applied, ensuring uniformity and conformality at each stage while building up the total drug delivery capacity

Inventive Principle:

Principle #19Periodic action

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 coated stent achieves rapid neointimal coverage with low inflammation and complete endothelialization, reducing neointimal hyperplasia and restenosis risks, while maintaining stent flexibility and minimizing long-term thrombosis risks.

Implementation Method 1

providing a first cloud of charged particles of polymer to the stents by rapidly expanding a pressurized solution of the polymer in densified 1,1,1,2,3,3-hexafluoropropane through a first orifice, wherein a first polymer layer of the polymer particles is formed on the stent by electrostatic deposition

Methodology Applied

Scientific EffectElectrostatic deposition: Electrostatic Deposition

Implementation Method 2

providing a first cloud of charged particles of polymer to the stents by rapidly expanding a pressurized solution of the polymer in densified 1,1,1,2,3,3-hexafluoropropane through a first orifice

Methodology Applied

Scientific EffectRapid expansion of pressurized solution: Supercritical Fluid

Implementation Method 3

sintering the first polymer layer at >40°C in ambient pressure

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentEP2696815B1Stents having controlled elution

Publication Date: 2019.03.20

Figure 1
Figure 2
Figure 3

AI summary

Provided herein is a device comprising: a. stent; b. a plurality of layers on said stent framework to form said device; wherein at least one of said layers comprises a bioabsorbable polymer and at least one of said layers comprises one or more active agents; wherein at least part of the active agent is in crystalline form.