Medical Device Coating Excipient Removal for Sterilization Integrity

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Solution Overview

Problem

Current medical devices for local therapeutic agent delivery face challenges in achieving uniform drug distribution and maintaining mechanical integrity during sterilization, particularly with hydrophilic polymers that can lead to coating degradation and ductile failure.

Innovation Solution

A method involving selective post-processing to remove a substantial portion of the excipient from the coating matrix, ensuring a high therapeutic agent to excipient ratio while preserving mechanical properties, using a hydrophilic polymer or oligomer excipient that retains drug density and aids in drug transfer across the body lumen tissue interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If hydrophilic polymer excipient is used in the coating matrix to enable rapid drug dissolution and transfer, then drug delivery efficiency is improved, but coating mechanical integrity deteriorates during sterilization

Engineering Contradiction:

Improvedrug delivery efficiencyVSAvoidcoating mechanical integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies extraction by removing a substantial portion of the hydrophilic polymer excipient through post-processing steps (washing, solvent extraction, or enzymatic degradation) after the coating is formed. This reduces the polymer content to a level that maintains mechanical integrity during sterilization while preserving sufficient excipient to enable rapid drug dissolution and transfer, thus resolving the contradiction between drug delivery efficiency and coating mechanical integrity.

Inventive Principle:

Principle #2Taking out (Extraction)

2Reliability

If conventional EtO sterilization process is applied to the coated medical device, then sterilization is achieved, but coating degradation and ductile failure occur

Engineering Contradiction:

Improvesterilization effectivenessVSAvoidcoating strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent applies preliminary action by performing post-processing to remove excess hydrophilic polymer excipient before the EtO sterilization process. This pre-treatment step reduces the coating's susceptibility to sterilization-induced degradation by lowering the polymer content that would otherwise swell and compromise mechanical integrity during sterilization, thereby protecting coating strength while still achieving sterilization effectiveness.

Inventive Principle:

Principle #10Preliminary action

3Strength

If high polymer content is maintained in the coating matrix, then coating mechanical properties are improved, but drug transfer efficiency to tissue decreases

Engineering Contradiction:

Improvecoating mechanical propertiesVSAvoiddrug transfer efficiency

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent applies parameter changes by precisely controlling the amount of hydrophilic polymer excipient remaining in the coating after post-processing. By adjusting the extent of excipient removal through various post-processing conditions (washing time, solvent type, enzymatic treatment duration), the coating achieves an optimal polymer content that provides sufficient mechanical properties while maintaining adequate drug transfer efficiency to tissue.

Inventive Principle:

Principle #35Parameter changes

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

This approach results in uniform tissue dosage with improved coating integrity and mechanical properties, maintaining clinical efficacy and preventing embolic hazards by ensuring the therapeutic agent is effectively delivered and retained within the body lumen.

Implementation Method 1

the polymer may have a hydrophilic character in order to partially dissolve or swell rapidly in the body, so as to help transfer the drug to the tissue upon contact with body fluids

Methodology Applied

Scientific EffectDissolution:

Implementation Method 2

the polymer can be hydrophobic to prevent dissolution in the aqueous environment of the body, so that the drug releases over time from the matrix via Fickian diffusion

Methodology Applied

Scientific EffectHydrophobic effect: Hydrophobe

Implementation Method 3

the polymer may have a hydrophilic character in order to partially dissolve or swell rapidly in the body

Methodology Applied

Scientific EffectSwelling:

Data Source

PatentUS10328247B2Post-processing of a medical device to control morphology and mechanical properties

Publication Date: 2019.06.25 SPECTRANETICS CORP

AI summary

A method of forming a coated medical device is described in which a coating including a therapeutic agent dispersed in a polymer or oligomer matrix is applied to an outer surface of the medical device. The coating is then post-processed to selectively remove a substantial portion of the polymer or oligomer matrix from the coating. The post-processed coating is then sterilized.