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Alex Hui, Lyndon William Jones; Material Properties of Antibiotic Releasing Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4642.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate the contact lens material properties of newly synthesized model contact lens materials designed for the sustained release of ciprofloxacin-HCl.
Poly-hydroxyethyl (pHEMA) Trimethylsiloxylsilane (TRIS) model silicone hydrogel contact lens materials were synthesized using a UV induced polymerization process in plastic contact lens moulds. The materials were formed in conjunction with a molecular imprinting strategy, in which the drug of interest, ciprofloxacin, was added to the pre-polymerization mixture along with acrylic acid to create molecular "memory" within the material to extend drug release times in vitro. The drug release characteristics from loaded lenses were evaluated by monitoring the release of antibiotic into three successive 2 mL solutions of phosphate buffered saline over the course of three days. The light transmission of the lenses were evaluated by conducting a wavelength transmission scan, and the dry weight, centre thickness and water content were also determined. The wettability of the surface was measured by assessing water contact angles using a sessile drop technique.
Release rates of the drug into solution changed over the course of three days. In contrast to the control, which released ciprofloxacin into each of the solutions quite rapidly, the modified materials released the drug at a more controlled rate, as evidenced by the continued increase in drug concentration over time. More than 80% of light transmission in the visible spectrum (400 nm - 700 nm) was observed from all lenses, with a decrease in the transmission for the modified lenses in the shorter wavelengths due to drug incorporation resulting in a yellow tint. The water content ranged from 35% to 45%, with a downward trend in water content as more ciprofloxacin was incorporated. The centre thickness ranged from 50 uM to 100 um, well within the range of modern contact lens materials. The contact angles ranged between 75 to 95 degrees, in line with non-surface treated silicone hydrogels, and decreased with more ciprofloxacin added to the polymerization mixture.
The novel lenses created with the aim of delivering sustained dosages of ciprofloxacin showed measurable contact lens properties that are similar to successful commercially available contact lenses, paving the way for future in vivo animal and human trials.
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