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D.C. Dahlin, D. Trawick, P. Zilliox, S.M. Robertson, M. Sanders, C. Struble, A.F. Clark; Design of a Specialized Cannula for Posterior Juxtascleral Delivery of Anecortave Acetate to the Retina for Treatment CNV Associated with Age-Related Macular Degeneration (AMD) . Invest. Ophthalmol. Vis. Sci. 2003;44(13):5036.
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Purpose: To design a device (cannula) for the posterior juxtascleral administration of the angiostatic agent anecortave acetate, which provides a reliable and effective clinical procedure for the delivery of drug to the macula. Methods: The design of the cannula was based on physical measurements of approximately 60 human donor eyes to determine radius of curvature of the globe as well as proper positions for cannula insertion and for drug delivery at the cannula tip. Cannula prototypes were tested by posterior juxtascleral injections of anecortave acetate in rabbit and monkey eyes, and the ocular distribution of AL-4940, the active hydrolysis product, was determined. Results: The design of the cannula met the following criteria: 1) accurate placement of the drug depot in direct contact with sclera, 2) proper position of the drug depot over the macula, 3) limited depth of insertion of the cannula to avoid contact with optic nerve, posterior ciliary arteries and vorticose veins, 4) insertion site distant from the depot to avoid loss of dose into periocular tissues, 5) avoidance of "tenting" to minimize drug reflux and to avoid possible scarring. Cannula design consisted of 19 gauge tubing with a curved portion matching the radius of the globe, a blunt tip containing an orifice facing the inner curve 1 mm from the tip, a 56o bend to self-limit the depth of insertion, and a Luer hub for attachment to a syringe. PK studies in rabbits and monkeys showed that posterior juxtascleral delivery of a single anecortave acetate injection provided therapeutic levels (>0.1 uM) of drug to the retina and choroid for approximately 6 months. Conclusions: We have designed a special, blunt-ended cannula for the posterior juxtascleral delivery of anecortave acetate. This method of delivery does not invade the globe, and a single injection provides adequate levels of drug to the retina and choroid for up to 6 months. This cannula is being used to deliver anecortave acetate in Phase III clinical trials for the treatment of subretinal neovascularization in AMD patients.
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