EVA implants for controlled drug delivery to the inner ear

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Cochlear Drug Delivery

Background:

• The blood-cochlea barrier impedes effective drug delivery to the inner ear.
• Miniaturized implants are needed for localized and controlled therapeutic administration.

Purpose of the Study:

• To evaluate poly(ethylene vinyl acetate) (EVA) copolymers as matrix formers for controlled inner ear drug delivery.
• To investigate the impact of vinyl acetate content and implant diameter on drug release characteristics.

Main Methods:

• EVA implants containing dexamethasone were fabricated using hot melt extrusion.
• Drug release was quantified in artificial perilymph.
• Extensive material characterization was performed (microscopy, DSC, X-ray diffraction, microtomography, texture analysis).

Main Results:

• EVA implants exhibited higher dexamethasone release rates compared to silicone implants.
• Decreasing vinyl acetate content increased copolymer crystallinity and reduced drug release.
• Dexamethasone was homogeneously distributed as microcrystals within the EVA matrix.
• Implants showed minimal swelling/shrinking over 10 months and possessed suitable mechanical properties.

Conclusions:

• EVA copolymers are effective matrix formers for controlled inner ear drug delivery.
• Tunable drug release profiles can be achieved by adjusting vinyl acetate content.
• EVA implants demonstrate stability and appropriate mechanical characteristics for inner ear administration.