A number of eye conditions can be treated by administering drugs directly into the eye. Yet, conventional needles have a bunch of drawbacks, including the patients’ fear of needles entering such fragile parts of the body and the difficulty of accurately administering medication into a targeted region of the eye. For glaucoma, for example, eye drops are prescribed which have a shorter active lifetime and are often skipped by the patients. An easy injection that works for months at a time would help control the disease considerably better.
Researchers at Georgia Tech and Emory University have been working on microneedles and formulations to safely and effectively deliver drugs into the eye. The microneedles are designed to only penetrate to the correct depth and the formulations need to be viscous enough to stay in place and release their therapeutic compounds in a controlled fashion. The researchers have already tested the microneedles on laboratory animals and showed that they can place drugs within the targeted sections of the eye.
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The microneedle therapy would inject drugs into space between two layers of the eye near the ciliary body, which produces the aqueous humor. The drug is retained near the injection side because it is formulated for increased viscosity. In studies with an animal model, the researchers were able to reduce intraocular pressure through the injections, showing that their drug got to the proper location in the eye.
Because the injection narrowly targets delivery of the drug, researchers were able to bring about a pressure reduction by using just one percent of the amount of drug required to produce a similar decline with eye drops.
To treat corneal neovascularization, the researchers took a different approach, coating solid microneedles with an antibody-based drug that prevents the growth of blood vessels. They inserted the coated needles near the point of an injury, keeping them in place for approximately one minute until the drug dissolved into the cornea.
In an animal model, placement of the drug halted the growth of unwanted blood vessels for about two weeks after a single application.