Update on uveitis

Newark, NJ-Some older and newer treatments being studied for treating uveitis include iontophoresis, contact lenses, and nanoparticles, according to David Chu, MD.

“Iontophoresis uses electricity to facilitate delivery of medication or ions into tissue for therapeutic purposes. It is based on the physical principle that like charges repel each other. The potential advantages include improved safety, avoiding systemic toxicity, and the physician-controlled dosing,” he commented. Dr. Chu is clinical associate professor of ophthalmology, New Jersey Medical School, Newark.

The EyeGate II Delivery System (EyeGate Pharmaceuticals) is the first commercial ocular iontophoresis system. Using this system, Dr. Chu explained, the medication is loaded into a sponge with a cylindrical device and an electrode is attached to the device. The other end of the electrode is placed on the patient’s forehead and the current is controlled by a hand-held current modulator.

This technology is in a phase I/II multicenter, double-masked, randomized, trial (EyeGate Study) in which dexamethasone phosphate delivered by ocular iontophoresis is being evaluated for treating noninfectious anterior uveitis to determine the safe and effective doses of the drug (EGP-437) formulated for iontophoresis and to evaluate systemic drug exposure.

Forty subjects were randomly assigned to one treatment with one of four different doses that vary by the amount of current used: 1.6 mA-min, 0.4 mA; 4.8 mA-min, 1.2 mA; 10.0 mA-min, 2.5 mA; and 14.0 mA-min, 3.5 mA.

The pharmacokinetic data showed that after one treatment the maximal serum concentration was less than that with one oral dose of 0.5 mg of dexamethasone and much lower than with one subconjunctival injection of 2.5 mg, he reported. By day 28 after one treatment, the uveitis resolved completely in 60% of patients. The study found that the lowest current used was the most effective, Dr. Chu said. All adverse events were minor; conjunctival hyperemia was the most common.

The phase III trial will compare two doses of iontophoresis 1 week apart with topical prednisolone acetate ophthalmic suspension.

Contact lenses can absorb drugs and release them over time. Silicon-hydrogel lenses loaded with vitamin E extended the release period of dexamethasone from 1 day to 7 to 9 days.

Nanoparticles may be the first nanodevice to have practical application to deliver drugs, antibodies, and genetic material. Nanoparticles may penetrate tissue better with more controlled release of drug over a longer time.

“There are new and exciting drug delivery options on the horizon for treating uveitis. Iontophoresis is not a new technology, but a commercially available system for treating uveitis seems within reach. Other treatment options include advancements in contact lenses as a drug delivery device; nanoparticles may offer targeted and sustained delivery of drugs, antibodies, and genetic material to ocular tissue for treatment of uveitis,” Dr. Chu concluded.

This article is based on a presentation by Dr. Chu during Uveitis Subspecialty Day at the 2012 American Academy of Ophthalmology annual meeting. He did not indicate any financial interest in the topic.

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