PLLA Coating of Active Implants for Dual Drug Release

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Cochlear Implant Technology

Background:

• Cochlear implants require precise electrical stimulation, but fibrous encapsulation can impede function.
• Developing effective drug delivery systems is crucial for managing inflammation and improving cochlear implant outcomes.

Purpose of the Study:

• To create a dual drug release system using a PLLA coating and bulk material for sustained anti-inflammatory drug delivery.
• To evaluate the in vitro cytocompatibility and release profiles of diclofenac and dexamethasone.
• To assess the impact of coating properties on the electrical impedance of cochlear implant contacts.

Main Methods:

• Fabrication of a PLLA coating with diclofenac on a silicone base containing dexamethasone.
• Determination of drug release profiles under various coating thicknesses and diclofenac loadings.
• Measurement of electrical contact impedances with and without pulsatile electrical stimulation.
• In vitro assessment of drug cytocompatibility in the inner ear.

Main Results:

• Dual drug release with distinct short-term and long-lasting kinetics was achieved.
• Diclofenac was found to be safe for inner ear application at concentrations ≤ 4 × 10^-5 mol/L.
• While PLLA coatings acted as insulators, their effect on dexamethasone release was partial and could be modulated by diclofenac concentration.
• Masking techniques can overcome insulation issues, preserving electrical stimulation integrity.

Conclusions:

• A dual drug delivery system for cochlear implants is feasible, offering controlled release of anti-inflammatory agents.
• This system can be tailored to provide both immediate and sustained therapeutic effects.
• The developed system demonstrates potential for enhancing cochlear implant performance and longevity by managing tissue response.