Sustained delivery transforms glaucoma

Take-Home:

Glaucoma treatment is poised to become a more interventional discipline with the introduction of sustained-release drug delivery devices.

Dr. AhmedBy Fred Gebhart; Reviewed by Ike Ahmed, MD

Toronto-Perspectives on the treatment of glaucoma are shifting.

Direct intervention in glaucoma is about to become the norm. Instead of prescribing eye drops and hoping for adherence, ophthalmologists will soon be placing sustained-release drug delivery devices on and in the eye to ensure appropriate transmission.

“We will be seeing a transformation in the next 5 years of how medications are given and glaucoma is treated,” said Ike Ahmed, MD, assistant professor, University of Toronto. “This is part of the whole transition of glaucoma treatment from a very medication-heavy specialty to an interventionist specialty.

“The term I like to use is interventional glaucoma, where we are placing devices like microstents-using microinvasive glaucoma surgery (MIGS)-(while also) injecting medications and placing sustained-release drug depots to provide good medium term medication delivery . . . we are on the precipice of this transition,” he said.

The development of these devices is driven largely by clinical need.

Clinicians already have multiple classes of efficacious topical medications, but effectiveness is lagging. Even with the best of intentions, topical agents are difficult to administer.

If the patient is accurate in saying that he/she applies eye drops at the appropriate time, there is no way to assess whether the drops were administered properly. Even so, there is no way to assess whether the drops spread across the ocular surface as expected and needed for therapeutic activity.

“There is a huge upside with the introduction and use of drug delivery devices to address the many shortcomings of topical medications,” Dr. Ahmed said. “We have four or five classes of highly effective drugs available . . . we just have to find ways to deliver them more effectively.”

Examining the evidence

The goals of sustained-release drug delivery are clear:

·      Sustained-release devices ensure the drug is delivered to the site of action.

·      Reduce the side effects of topical drops.

·      Improve adherence.

·      Improve clinical outcomes.

Recent research found that 73% of patients are willing to undergo subconjunctival injections every 3 months, while 86% are willing to accept higher costs than current treatments.

Patients who admit to non-adherence and those who are on more medications and/or higher frequency of dosing are the most willing to accept ocular injections and increased costs.

The current generation of topical medications has just one route of administration-onto the ocular surface.

Sustained-release devices

Sustained-release devices in development are designed to exploit at least six different routes:

• The ocular surface.

• The sclera.

• The anterior chamber.

• The subconjunctival and suprachoroidal spaces.

• Intravitreally.

These multiple routes of administration offer various roles in therapy.

Sustained-release devices are an obvious choice, Dr. Ahmed said, for any patient who has problems with adherence. They also show promise for patients who are intolerant of topical agents or show significant side effects.

Device delivery could also be used to improve therapeutic outcomes in patients who cannot be managed with topical agents, as an adjunct to MIGS or as a tool to delay incisional surgery.

Sustained-release devices are more invasive than topical agents, Dr. Ahmed said, but they also offer longer duration of effect with a single application, more reliable dosing and reduced toxicities.

Devices currently in clinical trials and under development fall into two broad categories: surface therapies and injectables.

“I see ocular surface therapies-punctal plugs, ocular surface inserts, contact lenses-as more likely to be approved sooner,” Dr. Ahmed said. “Some of the injectable technologies are 3 or 4 years from approval, at least in the United States. . . . The less invasive ocular surface technologies are at a different level of scrutiny.”

It is important to question who would pay for these devices if and when they are approved, Dr. Ahmed said, because the devices would be more costly than topical agents-at least initially.

The reimbursement key, however, is to focus on cost-effectiveness.

“There are potential savings to using these more invasive techniques in terms of getting (the) drug where it needs to be with longer duration of activity,” Dr. Ahmed said. “But once we get into the cost-effectiveness analysis, I think we are going to see some substantial savings.”

Ike Ahmed, MD

E: ikeahmed@mac.com

Dr. Ahmed is a consultant for or receives research grants/speaker honoraria from Allergan, Liquidia Technology, and other device makers.

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