(585aq) Encapsulation, Protection and Programmed Release of Active Ingredients from Silicone Gel Particles for Topical Applications

New active pharmaceutical ingredients (APIs) are developed each year to address major challenges in skin care (e.g., for treating psoriasis, eczema and various carcinomas). However, many of these APIs fail to impact current dermatological practices due to the instability, poor solubility and/or narrow therapeutic windows of the APIs, leading to limited therapeutic benefits, or in some cases, deleterious side effects. While some have looked to microencapsulation to overcome these challenges, current technologies fail to meet all of the key demand drivers: increased stability of API, controlled release of the API, low cost, size control of the delivery platform, high payloads, regulatory compliance, and marketability. To address these needs, we have developed a highly scalable process to synthesize programmable silicone particles via sol-gel chemistry that enables direct control over the release of APIs. Our process allows us to control the size (i.e., 0.15 to 15 μm) and stiffness of the particles (600 MPa to 2.50 GPa), while maintaining a narrow size distribution (i.e., C.V. <15%), even when scaling the reaction up to gallons at a time, which is critical for manufacturing and standardization. We have shown that the particles can encapsulate retinol (a proof-of-concept molecule used in the skin care industry that is highly sensitive to breakdown from light and oxygen) with efficiencies up to 85%, that our particles can protect retinol from degradation 6x longer than unencapsulated retinol, and that our particles can slowly release retinol over several hours, thus leading to less irritation (23% less irritation on human skin compared to a predicate technology). Importantly, we will discuss how modifying the composition of the particles (i.e., crosslink density) through regulating the silane monomers used in the reaction imparts the ability to tune the release rate of APIs over two orders of magnitude. These findings reveal that these particles can encapsulate, protect and controllably release retinol and a variety of hydrophobic APIs limited by narrow therapeutic windows. We will show that this technology can be used to encapsulate prescription drugs (i.e., ingenol mebutate, brand name Picato®, which is for treating actinic keratosis) with efficiencies up to 70%. We will also show that these particles have been used to encapsulate fluorescent dyes, antioxidants and pesticides, establishing this technology as a true platform technology. The methodology for particle synthesis and encapsulation is currently patent-pending and serves as the basis of Encapsio LLC, which is a startup company that spun out of Duke University in 2016.