Timolol microdrops delivered via adaptor lower IOP as effectively as conventional drops
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Key takeaways:
- Timolol maleate 0.5% microdrops delivered with a volume-reducing adaptor provided noninferior IOP reduction compared with conventional drops.
- The microdrops also had slightly less effect on heart rate.
Timolol microdrops administered with the Nanodropper Adaptor were as effective as conventional drops at lowering IOP among patients with open-angle glaucoma and ocular hypertension, according to a study published in Ophthalmology.
“There are multiple barriers to adherence [to glaucoma medications], including but not limited to medication adverse events, difficulty obtaining medications and cost,” Jennifer S. Steger, PhD, chief scientific officer and co-founder of Nanodropper, and colleagues wrote.
“Smaller eye drops, or microdrops, have been posited as part of a solution to several of the aforementioned adherence barriers,” they added.
Therefore, Steger and colleagues conducted a prospective, multicenter, randomized, parallel-group, single-masked, active-controlled noninferiority trial to determine if 12.5 µl timolol maleate 0.5% microdrops administered with the Nanodropper (Nanodropper Inc.), a volume-reducing adaptor for eye drop bottles, lowered IOP as effectively as 28 µl timolol drops administered with a conventional eye drop bottle.
The analysis included 419 treatment-naive individuals aged 18 years or older (mean age, 57.32 ± 11.07 years; men, 63.48%) who were recently diagnosed with open-angle glaucoma and ocular hypertension at the Madurai and Pondicherry hospitals of the Aravind Eye Care System in India.
The researchers randomly assigned the individuals in a 1:1 ratio to receive a single dose per eye of 12.5 µl adaptor-mediated microdrops of timolol maleate 0.5% (n = 212) or 28 µl conventional drops (n = 207).
The primary outcome measure was IOP; secondary outcomes included change in IOP, resting systolic and diastolic blood pressure and resting heart rate. The researchers measured these outcomes at baseline and at 1, 2, 5 and 8 hours after timolol administration.
Steger and colleagues observed that both conventional drops and adaptor-mediated microdrops of timolol maleate 0.5% significantly decreased IOP among the patients at all post-drug administration timepoints relative to baseline, with the results meeting the noninferiority criteria of 1.5 mmHg at 1, 2 and 8 hours after timolol administration.
In both treatment groups, the greatest mean IOP reduction relative to baseline occurred at 5 hours, with an 8.53 mmHg reduction (27.24 ± 4.61 mmHg to 18.71 ± 4.79 mmHg) after delivery of conventional drops and a 7.78 mmHg reduction (27.21 ± 4.37 mmHg to 19.42 ± 4.24 mmHg) after delivery of timolol microdrops.
Additionally, the researchers found that the patients in the conventional drops group experienced significantly greater heart rate decreases from baseline compared with those in the microdrops group. Notably, at 2 hours after timolol administration, the heart rate decrease in the conventional drops group was 3.02 beats per minute greater than that in the microdrops group, representing a 3.99% greater HR reduction.
Researchers observed no significant between-group differences in absolute or relative changes in systolic or diastolic blood pressure.
Steger and colleagues acknowledged several study limitations, including the fact that they were unable to evaluate subject performance and usability of the Nanodropper Adaptor because timolol eye drops were administered by a trained technician.
“Despite these limitations, the results of our study provide evidence supporting the Nanodropper Adaptor as a possible clinical tool to limit systemic absorption and improve tolerability of topical ophthalmic medications,” the researchers wrote.
“Future directions include an outpatient glaucoma study that evaluates long-term usability of the adaptor and the safety — including potential contamination — and efficacy of IOP-lowering microdrops compared with conventional drops,” they continued. “This study will allow for adverse events, bottle exhaustion, medication cost and adherence to be assessed and ultimately quantified.”
Perspective
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Adherence to glaucoma eye drops is critically important for preventing disease progression and preserving visual function. However, adherence is frequently suboptimal due to factors such as multiple dosing requirements, medication costs, potential side effects and difficulties with drop instillation.
In this prospective, multicenter trial, Steger and colleagues found that timolol conventional drops and microdrops, instilled with the Nanodropper, had similar IOP-lowering efficacy. However, the microdrop group demonstrated that less systemic absorption may provide a more favorable cardiovascular profile.
The Nanodropper, an adaptor compatible with most multidose eye drop bottles, is designed to reduce the volume of eye drops administered compared with conventional eye drops. This device is a promising tool for improving adherence to glaucoma eye drops by offering IOP reduction with smaller, more manageable doses, thereby potentially improving patient compliance while also potentially reducing side effects and patient cost.
I’m optimistic that continued research on this FDA-listed device will help guide our treatment protocols.
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