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Editors Selection IGR 23-3

Medical Treatment: Piezo-electric Eyedrop Microdosing

Comment by Eytan Blumenthal on:

74692 High-precision piezo-ejection ocular microdosing: Phase II study on local and systemic effects of topical phenylephrine, Ianchulev T; Weinreb R; Tsai JC et al., Therapeutic delivery, 2018; 9: 17-27

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Eye drops are the time-honored way we deliver topically applied medications to the eye. While cheap, simple and readily available, several limitations and disadvantages include the use of far more active ingredient than needed, systemic absorption of medication that escapes through the nasolacrimal tract and absorbed by the nasal mucosa, and spillage of excessive drops down the periocular skin. Additional limitations include limited compliance (eye-drops often do not drop into the eye), occasionally multiple drops are required to complete the task, and a proportion of elderly patients unable to self-administer their drops.

Ianchulev et al. present a phase II clinical trial evaluating a novel microdosing system based on piezo-ejection of a small volume of spray aimed at the cornea. An electronic device sprays a micro-dose of the desired medication onto the eye as the patient fixates on an LED targeting light. Very accurate volumes can be ejected, in this study 8 microliter, one quarter the volume of the drop used in the control arm of the study. The medication chosen for this trial was phenylephrine, chosen as both the clinical effect (dilation of the pupil), systemic effect (pulse rate and blood pressure) as well as its concentration in the blood can all be readily and objectively evaluated.

This clinical trial concludes that a device spraying topical medication directly onto the cornea in minute volumes, much smaller than the volume of an eyedrop, can achieve similar clinical efficacy, with significantly lower plasma concentrations. Eight microliters of phenylephrine 10% delivered via this novel piezo-ejection technique outperformed the same amount of active ingredient delivered as 2.5% drop of quadruple volume. When compared to a 10% conventional drop containing 4-times the active ingredient, similar efficacy resulted, but with significantly higher plasma concentrations suggesting higher systemic absorption.

The authors conclude that beyond reducing systemic and allergic side effects, this novel approach may benefit compliance, the ability to monitor compliance objectively, as well as eHealth communication between patient and physician. This novel delivery system also may benefit treatment with rare and expensive drugs, nanoparticles and perhaps one day also stem-cell and gene-therapy.

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