BLOG: Sustained-release glaucoma therapies on the horizon
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The need for sustained-release glaucoma therapies is clear to anyone caring for patients with the disease.
Our conventional topical therapies have a number of toxic effects on the external ocular tissues. There are physical and medical limitations to eye drop instillation in our generally older patient population. The time and scheduling demands of drop instillation and pharmacy visits are intensive. And the cost associated with bottle therapy, especially in cases of spillage and premature refills, can be prohibitive over the long term. These barriers negatively affect adherence and long-term control of the disease, increasing risk for glaucomatous progression and irreversible vison loss. Potential sites of implantation for novel sustained-release therapies include the ocular surface, the eyelid puncta, the subconjunctival space, the anterior chamber and within the trabecular meshwork.
The bimatoprost sustained-release implant (Durysta, Allergan) (Figure) was FDA approved for one-time use in March 2020. The device delivers the active drug to the anterior chamber. Although the design allows for slow release of bimatoprost over 3 to 4 months, some patients will achieve IOP lowering for up to 2 years. The potential for this agent to modify the eye’s outflow system in a longer-term fashion is exciting to say the least.
Another intracameral implant, the travoprost intracameral implant (Ocular Therapeutix), is currently on the horizon, and phase 1 studies suggest powerful lowering similar to what we can expect from topical agents. Phase 2 studies with this implant will be underway soon. The punctal plug delivery system (Mati Therapeutics) has also shown promising initial results for delivery of prostaglandins to the ocular surface using a platform that is familiar to most ophthalmologists in the treatment of ocular surface disease. The travoprost intraocular implant (iDose, Glaukos) is composed of titanium and designed for implantation into the trabecular meshwork. This requires incisional surgery, but the duration of effect appears to be longer than with other platforms. Phase 3 studies with this device have completed randomization and enrollment.
Early experience with the bimatoprost sustained-release implant has shown us a new level of patient satisfaction. Some keys for future innovation in this space will be longer duration implants, optimization of safety profiles and sustained-release combination therapy. Our patients can’t wait.
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