New Delivery System for Glaucoma Medication

CHICAGO — A novel sustained-release travoprost punctum plug (TTP) is able to achieve therapeutic drug delivery levels over 30 days. The TTP may be an alternative to topical drops, particularly in patients with poor compliance.

Shamira Perera, MBBS, of the Singapore National Eye Center, presented the results of his TPP feasibility study in patients with ocular hypertension or open angle glaucoma here at the American Academy of Ophthalmology (AAO) 2012 Annual Meeting.

Primary outcomes were TTP retention and mean intraocular pressure (IOP) at each time point. The study was performed at 2 sites in Singapore.

The prospective, single-group study included 17 patients. If both eyes met eligibility criteria, a TPP was inserted in both. Only the eye with the higher IOP was included in the study.

The TTP consists of a rod-shaped, dried polyethylene glycol–based hydrogel. The medication is embedded in the hydrogel. The TPP was inserted into either the upper or lower punctum after punctal dilation. The TPP then released drug to the ocular surface.

When describing the insertion, Dr. Perera noted that, "interestingly, it was probably easier with the superior plugs." Overall, however, the plugs were difficult to insert if the patient did not cooperate.

Elevated IOP is the most important risk factor for glaucoma. Dr. Perera reported a sustained, constant, and significant reduction in IOP in his patients who received the TTP. The amount of lowering of IOP from baseline was 4.4 mmHg to 8.2 mmHg (17% - 30%), depending on the time point. The reduction in IOP was sustained after patients exited the study after 30 days.

Preliminary results suggest good retention of the TPP. One patient had an epiphora on day 0, which resolved immediately after removal of both punctum plugs on day 1.

Dr. Perera explained that the study was limited by the small number of patients and the fact that it was not designed as a randomized controlled trial. The TPP will now enter a 2-month pilot phase 2 clinical trial.

The majority of glaucoma patients require long-term medical treatment. Janet B. Serle, MD, of Mount Sinai Hospital in New York City, sat on the panel for the glaucoma session. She said, "it's a very exciting potential new modality for treating our patients."

The panel noted, however, that many questions remain to be resolved with this device. For example, is there a difference, in terms of efficacy, between a pulse effect as obtained with drops or a constant effect seen with the plugs? What is the effect of long-term bathing in the medication? Will the device be able to contain and elute multiple medications?

As a chronic disease that affects more than 2 million Americans, glaucoma must be monitored and treated for life. Currently, patients are given topical prescription drops, which must be administered at regular intervals daily to prevent disease progression.

Many patients, however, are not compliant with the eyedrop regimen, and this can lead to costly and invasive surgeries, vision impairment, and possibly blindness. Although 97% of patients have reported that they are compliant with their dosing, studies have indicated that as many as 60% of patients do not administer ophthalmic drugs as prescribed.

The study was funded by Ocular Therapeutix. Dr. Serle has disclosed no relevant financial relationships.

American Academy of Ophthalmology (AAO) 2012 Annual Meeting: Abstract PA009. Presented November 11, 2012.