InSite Vision Incorporated has received a notice of allowance from the U.S. Patent & Trademark Office for claims covering the use of azalide antibiotic formulations to topically treat ocular infections. InSite Vision uses azithromycin, an azalide, in ISV-401, the Company's ocular antibiotic designed for the topical treatment of bacterial conjunctivitis.

ISV-401 combines azithromycin with DuraSite, the Company's patented drug-delivery vehicle that offers the benefits of prolonged release of an active ingredient. In September 2002, the Company reported positive safety and efficacy results from the ISV-401 Phase 2 study and last month announced FDA acceptance of InSite Vision's Phase 3 clinical trial protocol. InSite plans to initiate Phase 3 clinical trials in the second quarter of 2003.

"This allowance, combined with our previously issued patent on DuraSite/azalide formulations, creates a strong patent position for the ISV-401 program and any other azalide ophthalmic dosage form we may wish to pursue in the future," stated S. Kumar Chandrasekaran, InSite Vision's president and chief executive officer.

Azalide antibiotics are a class of macrolides effective against gram-positive and gram-negative bacteria with the additional property of having long biological half-lives. While azalides are currently dosed systemically, they have not previously been used in ophthalmology due partially to the difficulty of creating a stable aqueous formulation. InSite Vision used its drug delivery technology DuraSite to overcome the azalide stability issue. ISV-401 combines the long residence time attributable to DuraSite with the biological properties of the azithromycin to penetrate the eye tissues and form a reservoir, leading to significantly reduced dosing compared to currently marketed products.