Bioabsorbable punctal plugs show significant clinical potential for intraocular drug delivery, according to clinical data from a proof-of-concept trial of intracanalicular plugs (Ocular Therapeutix).
Austin, TX-Bioabsorbable punctal plugs show significant clinical potential for intraocular drug delivery, according to clinical data from a proof-of-concept trial of intracanalicular plugs (Ocular Therapeutix).
“You can place this device in either the upper or the lower canalicula after cataract surgery, and the patient does not then have to dose with steroid eye drops postoperatively,” said Thomas Walters, MD, Texan Eye,PA, Austin, TX. “The drug-eluting device saves on the cost and inconvenience of eye drops.
“This device is great for cataract surgeons and their patients because it gets us closer to achieving ‘no drops’ cataract surgery,” he continued. “It is a huge convenience for the patient and it absolutely resolves all of the questions surrounding patient adherence to post-op steroid eye drops.”
Dr. Walters was lead author on the study, “Evaluating Hydrogel Punctum Plugs for Retention and Patient Visualization as Means of Drug Delivery.”
Punctal plug drug delivery devices have been discussed for years, Dr. Walters said.
The concept is appealing because it is a small, drug-eluting plug that can be placed within the canalicula to delivery precise drug doses for a predetermined period, he said. Ideally, the device could be seen by both physician and patient to verify dosing and it would be difficult for the patient to remove either by accident or on purpose and it would slowly absorb so it would not need to be removed.
This early trial tested two versions of the plug: one designed for 60 days of use and one designed for 90 days. The two versions were made of a similar hydrogel, one designed for bioabsorption after 60 days and one for bioabsorption after 90 days.
Both versions were a resounding success on all counts, Dr. Walters said.
Retention rates were extremely high, as patients reported no major comfort problems and the plugs were easy to visualize after insertion. The plug was also found not to block functional lacrimal drainage, as epiphora was not an issue during clinical trials.
Insertion itself was easy and painless, Dr. Walters said.
Investigators verified retention of the plug on a regular basis and trial participants verified retention on a daily basis.
“This product is stained with a fluorescent molecule so that under fluorescent light, it is very easy to visualize the plug to confirm its placement and retention,” Dr. Walters said. “But the plug is not visible under normal light or to the naked eye, so it is also cosmetically very acceptable to the patient.”
Retention was 85% through day 40 of the trial-significantly higher than retention for commercial plugs used to block the canalicula to treat dry eye, he said.
Patients did not complain of either discomfort or epiphora during the course of the trial.
Ocular Therapeutix has launched three hydrogel punctum plug trials:
· One is this placebo vehicle trial designed to test comfort, retention and visualization. An ongoing arm of the trial is designed to optimize the 90-day formulation and test safety over four consecutive 90-day insertions.
· A second trial uses hydrogel plugs loaded with travoprost for the reduction of intraocular pressure over 2 to 3 months of therapy.
· A third trial uses hydrogel plugs loaded with dexamethasone for the resolution of post-operative inflammation and pain.
Dr. Walters was also an investigator on the dexamethasone trial.
“Our results suggest that the fluorescent hydrogel punctum plug could be a viable alternative for sustained drug delivery in the eye,” he said. “It offers significant advantages to both the ophthalmologist and the patient, and it offers the promise of overcoming poor compliance issues that are a constant problem with topical eye drops and assures a steady dosing of steroid to the postoperative cataract eye.”
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