DRUG DELIVERY IMPLANTS IN OPHTHALMIC PRACTICE
• Vitrasert implant
• Retisert
• Posurdex
• Encapsulated cell therapy
Vitrasert Implant
One of the initial drug delivery devices for vitreoretinal disease is the Vitrasert implant for AIDS-related cytomega-lovirus retinitis.
The product was developed by Control Delivery Systems (Watertown Mass) using its Aeon technology, a controlled rate and duration of release delivery system.
The device is surgically implanted into the vitreous where it releases the antiviral drug ganciclovir.
The device is replaced when the drug is depleted, usually after six to eight months.
Retisert
Using a technology similar to Vitrasert called Envision TD.
Bausch Lomb and Control Delivery Systems are developing Retisert, an intravitreal device containing the steroid fluocinolone acetonide, which is currently in clinical studies for posterior uveitis, diabetic macular edema and AMD.
Posurdex
Another steroid-releasing device being developed by Oculex is Posurdex, a slow-released dexamethasone intravitreal implant currently in human trials for persistent macular edema associated with diabetic retinopathy, uveitis, vein occlusion and Irvine-Gass syndrome.
Posurdex uses a completely biodegradable polymer that dissolves over time.
Encapsulated Cell Therapy
An interesting technology being developed by Paris’ Neurotech S.A. is Encapsulated Cell Therapy.
Their lead product, NT-501, consists of encapsulated retinal pigment epithelial cells, which are genetically modified to secrete ciliary neurotrophic factor for the treatment of retinitis pigmentosa. CNTF is a protein that may prevent generation of photoreceptors in RP.
The cells are inside a membrane designated to permit the intake of oxygen and nutrients and the release of CNTF.
The cells are maintained in a biological matrix that supports their long-term survival in vivo.
The current prototype is about 10 mm long and may be able to be implanted into the vitreous and anchored to the sclera in 15 minutes.
OPTOMETRY-SHARP VISION
Optometrist