Injection May Replace Drops to Lower Intraocular Pressure

Miriam E. Tucker

March 06, 2014

WASHINGTON, DC — A nanoliposomal formulation of latanoprost (Lipolat) produced a sustained reduction in intraocular pressure over 3 months in a pilot study of 6 patients with ocular hypertension or open-angle glaucoma.

"Liposomal latanoprost presents a promising and feasible new method for lowering intraocular pressure in place of eye drops," Tina Wong, MD, from the Singapore National Eye Center, said here at the American Glaucoma Society 24th Annual Meeting. "This would be most beneficial to known prostaglandin responders," she said.

"Currently, patients must use eyedrops on a daily basis," Dr. Wong, the coinventor and patent holder of the technology, told Medscape Medical News. "Liposomal latanoprost works by providing round-the-clock action for several months, so there is no need to use daily drops."

A previous animal study showed that a single injection of the liposomal formulation lowered intraocular pressure for 120 days, which is similar to results with daily latanoprost ophthalmic solution (Int J Nanomedicine. 2012;7:123-131). This is the first human study, Dr. Wong reported.

 
This study is truly, truly exciting.
 

"This study is truly, truly exciting," said session moderator James Tsai, MD, from the Yale School of Medicine in New Haven, Connecticut. "We know how difficult it is for patients to take eye drops. For a subconjunctival injection to demonstrate significant intraocular pressure lowering with 1 shot every 3 months, I definitely believe it will change the effectiveness of some of the therapy," he told Medscape Medical News.

However, this research is early and more study is needed, Dr. Tsai added.

Liposomal nanotechnology is currently used in other types of medications, particularly for cancer, and other sustained-release latanoprost products are in development. However, "liposomal latanoprost is the first reported extended-release nanomedicine in ophthalmology — a technological breakthrough in terms of nanomedicine development," Dr. Wong said during an interview.

The pilot safety and feasibility study enrolled 6 patients with either ocular hypertension or primary open-angle glaucoma with unmedicated pressures of 24 mm Hg or greater. Five patients had been using prostaglandin eye drops, which were washed out before the study, and 1 was taking a beta-blocker.

Patients received a single subconjunctival injection of liposomal latanoprost 100 µg in 1 eye, and their pressure was measured at 1 hour and at several other time points during the 3-month study. Diurnal intraocular pressure was measured at months 1 and 3.

One patient complained of ocular discomfort and was found to have dry eye, which was resolved with lubricants; there were no other problems with the subconjunctival injection, and there were no signs of ocular inflammation.

The pressure lowering was reportedly immediate. "We were actually amazed. Within an hour, there was at least a 50% reduction in intraocular pressure from baseline," Dr. Wong said.

Significant Pressure Lowering

The pressures then stabilized, achieving and maintaining a statistically significant average reduction of 9 mm Hg for the 3-month period, or a mean percentage reduction from baseline of about 30% (P < .05). The only patient who did not experience a significant lowering was the one taking a beta-blocker, she noted.

After the presentation, Dr. Tsai asked about use of the product across ethnic and racial groups, given that the study was conducted in Singapore. Dr. Wong said that 1 subject was white, 1 was Malaysian, and the rest were Chinese. "I think we're going to have to do larger trials looking at different ethnic responses," she noted.

When asked about potential scarring with multiple injections over time, Dr. Wong explained that no scarring was seen in animal studies.

 
This is revolutionary.
 

She said she anticipates patient acceptance of the product. In a survey she and her team conducted of 151 glaucoma patients, 74% said they'd be willing to trade their daily drops for 1 shot every 3 months (J Glaucoma. 2013;22:190-194).

Her group is planning a larger controlled study, but there are "no disclosable details" yet, she told Medscape Medical News.

Dr. Tsai said that he would like to see more data regarding the use of liposomal latanoprost in various ethnic and racial groups and in the different forms of glaucoma. The appropriate dosing still needs to be established; nonetheless, this is revolutionary," he said.

Dr. Wong is the coinventor and patent holder of liposomal latanoprost. Dr. Tsai is a consultant for Allergan, Sucampo Pharma, and Quark Pharmaceuticals.

American Glaucoma Society 24th Annual Meeting: Abstract 14. Presented February 28, 2014.

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