Alternative administration of glaucoma medication more than a dream
Reviewed by Sahar Bedrood, MD, PhD
Glaucoma doctors are poised to step into the future with the development of alternative methods of delivering glaucoma medications underway, according to Sahar Bedrood, MD, PhD, glaucoma specialist at Advanced Vision Care and clinical professor adjunct ophthalmology assistant at USC Roski Eye Institute in Los Angeles.
This development of alternative delivery methods is a major event given that it took 100 years for timolol to be developed, she pointed out. This was not so quickly followed by prostaglandins 30 years ago, combination drops and newer rho kinase inhibitors.
Currently, a quantum leap has occurred with the availability of intracameral anterior chamber drug delivery and sustained release products.
In addition, administration of anti-glaucoma medication may also be possible via other options such as angle-anchored drug-eluting device, contact lenses containing glaucoma medication, canalicular approach and Bedrood Port Authority reported.
On the market
Prolonged intracameral administration of bimatoprost SR (Durysta, Allergan) is now available. The drug, which is on a biodegradable polymer, requires 1 administration into the anterior chamber and releases the drug for up to 15 weeks. Longer efficacy has been reported in a subset of patients. “In these patients, no drug is in the eye, but the efficacy is thought to be related to remodeling of the trabecular meshwork leading to a chronic drop in IOP,” Bedrood explained.
Bedrood reported that the 24-month Phase 1/2 clinical trial of bimatoprost SR showed that an implant lowered IOP for up to 1 year in 40% of patients and at 2 years in 28% of patients with a second implant.1
This implant is placed in the eye usually during an office procedure. She described that the needle is inserted the same way as in a paracentesis, except the surgeon aims down to avoid going behind the iris or through the pupil (video).
Not marketed yet
Travoprost (iDose TR, Glaukos), an angle-implanted drug, is intended to provide continuous drug delivery. The implant has been shown to be safe and effective for 24 months. The implant can be replaced when the drug runs out. Analysis at 36 months showed a mean decrease in IOP of 8.5 mm Hg from fast and slow eluting membranes. A phase 3 trial is currently underway.
In the future, the travoprost device will provide a larger drug payload and longer duration of effect.
The future also holds promise for an intracameral hydrogel implant of travoprost. This implant is intended to release the drug over a period of 47 months.
Sustained-release steroids for postoperative glaucoma care are also on the horizon. The dexamethasone ophthalmic implant (Dextenza, Ocular Therapeutix) is an intracanalicular insert placed in the inferior punctum that is designed to release the steroid for 30 days.
Dexamethasone intraocular suspension is placed under the iris to ensure a long duration of steroid treatment.
Intravitreal injections of glaucoma medication aren’t yet available, but, she thinks, they’re in the works.
“Port delivery of glaucoma medication appears to be an ideal way to deliver medication to glaucoma patients long term,” Bedrood explained. “Although there is nothing on the horizon at the moment, I think the future of glaucoma includes investigating this drug delivery system,” she said.
Bedrood concluded that alternative measures are very much a reality.
“They are in the early stages of development and will be developed over time,” he concluded. “We need it for better patient adherence, better 24-hour IOP control and to reduce treatment costs.”
Sahar Bedrood, MD, Ph.D.
Email: [email protected]
This article is adapted from Bedrood’s presentation at the recent annual meeting of the American Society of Cataract and Refractive Surgery in Washington DC. She is a consultant speaker for Allergan/Abbvie and Glaukos.
1 Craven ER, Walters T, Christie WC, et al., Bimatoprost SR Study Group. 24-month phase I/II clinical trial of bimatoprost extended-release implant (bimatoprost SR) in patients with glaucoma. Drugs 2020;80:167-79; doi: 10.1007/s40265-019-01248-0.