New Solutions for Ophthalmic Drug Delivery Using Biodegradable Silica Matrix

tion (AMD), glaucoma, dry eye and diabetic retinopathies is increasing steadily. Drug treatment for ocular diseases is challenging due to the complex and protected structure of the eye, which prevents the penetration of active compounds at the site of action, e.g. the retina, after systemic administration. Although topical administration of eye drops is an easy and non-invasive method of ocular drug therapy, it suffers from low and easily saturated dose, poor bioavailability (less than 5% even in the front part of the eye) due to rapid drainage, and low patient compliance, especially in elderly patients. Invasive systems such as intravitreal (IVT) injections are used to treat the back of the eye. However, IVT injections cannot be given repeatedly in a short period of time because they are associated with potential severe side effects, such as increased pressure in the eye or infection, and they would generate a significant burden in ophthalmology clinics. For small molecules, which are typically rapidly eliminated within hours in the vitreous, immediate-release IVT formulations are not a realistic option because of the need for frequent injections. It is clear that there are unmet medical needs in ophthalmic drug treatment and these needs are not well served by current drug delivery systems. New concepts, tools and approaches should be generated and tested for the development of novel ocular therapies. Amorphous silica matrix prepared by the sol-gel method is a well-known biomaterial for controlled drug delivery. Silica can be processed into several dosage forms, addressing a number of challenges in DelSiTech, a Finnish drug delivery company, has developed a proprietary nonmesoporous, biodegradable silica matrix technology where release of the active pharmaceutical ingredient (API) is based on the dissolution of silica in tissue. Here, Mika Jokinen, DSc, Research Director, Cora Griffin, PhD, Business Development Director, and Lasse Leino, PhD, President and Chief Executive Officer, all of DelSiTech, describe the novel opportunities that biodegradable silica matrix technology offers to ophthalmic drug delivery, and the different silica dosage forms for various types of APIs, ranging from large biological agents, such as proteins and viruses, to small molecules, covering injectable silica hydrogels, silica microsphere-silica hydrogel composites and silica implants. NEW SOLUTIONS FOR OPHTHALMIC DRUG DELIVERY USING BIODEGRADABLE SILICA MATRIX