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C. J. Bishop, H. J. Sant, S. A. Molokhia, R. M. Burr, B. K. Gale, B. K. Ambati; Designing and Manufacturing a Refillable Multi-Drug Capsule Ring Platform. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5331.
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AMD treatment requires monthly intravitreal injections which are uncomfortable, risky, and costly. Because glaucoma is treated using topical polypharmaceutic regimens, patient compliance and drug-target interactions are low. A controlled delivery device would benefit both ocular diseases and transcend the patient interface. Our Capsule Drug Rings (CDR) are implanted in the capsule bag periphery during IOL placement. The CDRs are to be refilled every 6 months to 1 year in situ.
CDRs are made of well-established biocompatible materials. The inflatable shell of the CDR is a flexible polycarbonate-based polyether urethane which resists hydrolytic degradation improving longevity in vivo. A CO2 laser was used to laminate the shell edge of the CDR. Refilling Ports were made of polyimide tubing and resealing polydimethylsiloxane plugs acting as a one-way valve. One side of the shell consisted of a 1 mm2 oval window, covered by a 30 nm diameter pore-size polyethersulfone filter. Islets were placed at the ends of the device for surgical manipulation. CDRs were implanted in rabbits during intraocular lens implantation.
Each port re-seals and holds at least 40 mm Hg up to 30 insertions. The carbothane shell’s inner and outer diameters are 11.0 and 13.0 mm, respectively. The thickness of the shell pre and post-inflation is 200 µm and 750 µm, respectively. The drug reservoir holds 80 µL. Significantly, various sections of the CDR shell were laminated using different laser parameters. The edges with greater curvature required greater speed or less power. Radial lamination (vs horizontal or vertical) due to the symmetry and curvature of the ring device was far superior for proper sealing.
The CDR multi-drug platform is a promising device for treating multiple diseases simultaneously (AMD, Glaucoma, etc.). The CDR filter placement, thickness, pore size/density, window size, and drug concentration can be altered to optimize near zero order pharmacokinetics for a given drug molecule.
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