Printing Drugs onto Nails for Effective Treatment of Onychomycosis

Abstract

Inkjet printing (IJP) is an emerging technology for the precision dosing of medicines. We report, for the first time, the printing of the antifungal drug terbinafine hydrochloride directly onto nails for the treatment of onychomycosis. A commercial cosmetic nail printer was modified by removing the ink from the cartridge and replacing it with an in-house prepared drug-loaded ink. The drug-loaded ink was designed so that it was comparable to the commercial ink for key printability properties. Linear drug dosing was shown by changing the lightness of the colour selected for printing (R2 = 0.977) and by printing multiple times (R2 = 0.989). The drug loads were measured for heart (271 µg), world (205 µg) and football (133 µg) shapes. A disc diffusion assay against Trpytophan rubrum showed inhibition of fungal growth with printed-on discs. In vitro testing with human nails showed substantial inhibition with printed-on nails. Hence, this is the first study to demonstrate the ability of a nail printer for drug delivery, thereby confirming its potential for onychomycosis treatment.

Strategies for the enhancement of nail plate permeation of drugs to treat onychomycosis

“…The drug was dissolved in ethanol and printed onto discs and human nail clippings in distinct shapes, where small droplets of the liquid were dispensed from the cartridge using thermal or piezoelectric actuation. The prepared drug formulation showed good printability, and could inhibit the growth of Trichophyton rubrum , indicating that the drug was capable of being printed onto human nail clippings 24 . This study indicates the potential of this method to improve transungual drug delivery.…”

“…The use of 3D printing technologies to improve the delivery of drugs is especially relevant in case of topical drug delivery, where patient‐specific drug doses, delivery of multiple drugs and easy application of the formulation could improve treatment outcomes and patient compliance 24 . Printing technologies can provide a high degree of control over spatial distribution, and precision (Figure 6a).…”

“…Pollard et al 24 used inkjet printing to deliver terbinafine hydrochloride. The drug was dissolved in ethanol and printed onto discs and human nail clippings in distinct shapes, where small droplets of the liquid were dispensed from the cartridge using thermal or piezoelectric actuation.…”

Inkjet drug printing onto contact lenses: Deposition optimisation and non-destructive dose verification

“…Density, surface tension and viscosity measurements of the commercial ink, DMSO:water mixture at room temperature (∼25 °C) and 4 °C, and timolol maleate loaded DMSO:water were recorded ( Table 1 ). Previous data indicates the nozzle diameter was 21.0 ± 2.2 μm, and that the commercial inks have an average density of 1.03 g/cm 3 , viscosity of 2.17 mPa.s, and surface tension of 35.61 mN/m, giving a Z -value of 12.8 ( Pollard et al, 2022 ). All the solutions showed very similar densities and reasonably similar surface tensions.…”

“…Drop On Demand inkjet printing is a form of two-dimensional (2D) printing in which ink droplets are deposited from a printer cartridge ( Lohse, 2022 ). Numerous personalised drug-loaded dosage forms have been made with inkjet printing ( Alomari et al, 2018 ; Azizi Machekposhti et al, 2021 ; Chang et al, 2021 ; Chou et al, 2021 ; Evans et al, 2021 ; Vuddanda et al, 2018 ; Zhang et al, 2021 ), including mucoadhesive buccal films ( Kiefer et al, 2021 ) and direct printing onto the nail for onychomycosis treatment ( Pollard et al, 2022 ). Inkjet printing onto contact lenses for glaucoma treatment would avoid the need for users to remove contact lenses for treatment, allow for personalised dosing and make point-of-care dispensing possible.…”