Abstract
Sustained delivery of protein therapeutics remains a largely unsolved problem across anatomic locations. Miniaturized devices that can provide sustained delivery of protein formulations have the potential to address this challenge via minimally invasive administration. In particular, methodologies that can optimize protein formulation independent of device manufacture have the greatest potential to provide a platform suitable for wide applications. The techniques developed here demonstrate the fabrication of tubular devices for sustained release of protein therapeutics. Utilizing a dip-casting process, fine-scale tubes can be reliably produced with wall thickness down to 30 μm. Techniques were developed that enabled effective loading of either solid or liquid formulations, while maintaining a cylindrical form-factor compatible with placement in a 22-gauge needle. Further, highly compacted protein pellets that approach the expected density of the raw materials were produced with a diameter (∼300 μm) suitable for miniaturized devices. Release from a solid-loaded device was capable of sustaining release of a model protein in excess of 400 days. Given significant interest in ocular applications, intravitreal injection was demonstrated in a rabbit model with these devices. In addition, to simulate repeated injections in ocular applications, serial intravitreal injection of two devices in a rabbit model demonstrated acceptable ocular safety without significant intraocular inflammation from clinical exam and histology.