Local delivery of pharmacotherapy to the eye has long been used for anterior segment disease, but various routes for delivery have also been investigated, said Timothy Olsen, MD.
Intravitreal injections represent the current standard of care for treating retinal disorders, but the injection systems are very inexpensive, running about $0.15 for the syringe. Yet, the diffusion of drug from the vitreous means most agents have a relatively short half-life.
“The suprachoroidal space is the next logical space after the sclera to investigate,” said Dr. Olsen, Emory University, Atlanta.
Bigger molecules will move slowly across the sclera, and smaller ones will move much quicker. He described the cannulation of the suprachoroidal space using a flexible catheter for sustained delivery to the choroid and retina that involves first creating the sclerectomy at the suprachoroidal space.
“We then have the cannula loaded with Healon and triamcinolone" and pass the catheter into the sclera, Dr. Olsen added. “We can deliver drugs through the suprachoroidal to the nerves.”
Biologics in the suprachoroidal space, he noted, have been demonstrated to have a dramatically shorter half-life. Optimizing the formulation of the small molecule or biologic may improve sustained delivery in the suprachoroidal space, and could represent a unique avenue for better drug delivery.
“Cellular delivery is a real possibility and has great potential,” Dr. Olsen said.
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