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Hyaluronic acid useful in drug-releasing lenses
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The addition of hyaluronic acid increased drug loading and release mass in silicone hydrogel contact lenses, according to a study recently published in Eye & Contact Lens: Science & Clinical Practice.
Guidi and colleagues investigated the acid as a functional additive in terms of how it would alter the release and uptake of timolol in the contact lenses.
Researchers prepared model contact lenses with two primary formulations, as detailed in the study: "2-hydroxyethyl methacrylate (HEMA) with 3-methacryloxypropyltris (trimethylsiloxy) silane (TRIS) in a 9:1 (wt:wt) ratio or N,N-dimethylacrylamide (DMA) with TRIS in a 1:1 (wt:wt) ratio; ethylene glycol dimethacrylate (EGDMA) was used as the cross-linker."
Researchers evaluated four lens compositions: unmodified controls, lenses that contained hyaluronic acid, lenses that were imprinted with timolol maleate and lenses that both contained hyaluronic acid and were imprinted with timolol maleate. The lenses were used in studies that assessed materials characterization, drug release and drug loading.
"Hyaluronic acid was shown to have the ability to act as a functional additive in these model contact lenses, significantly increasing the drug loading and release mass," the authors reported. "This ability seemed to be independent of molecular imprinting, but its efficacy was related to the concentration of hyaluronic acid contained within model lenses and the concentration of drug loading solution used to facilitate uptake. Timolol release was sustained for a duration of approximately 2 days, and the dose of drug was shown to be controlled by both hyaluronic acid-drug interactions and molecular imprinting within the silicone hydrogels."
Researchers concluded that drug eluting contact lenses could benefit from the addition of hyaluronic acid.
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