Extended delivery of hydrophilic drugs from silicone-hydrogel contact lenses containing Vitamin E diffusion barriers

Chitosan/alginate based multilayers to control drug release from ophthalmic lens

“…The wettability, roughness, transmittance, coating thickness and refraction index of these new coated samples were determined and are shown in Table 2 (right column). This coating has very interesting properties: it is very hydrophilic, even in the dry state; it is quite homogeneous (the ellipsometric measurements easily converged in a precise value of thickness); it ensures a transmittance value above 90% which is the minimum required for ophthalmic lenses [52,53]; it has a small effect on the bulk refraction index of the hydrogel; it should resist to degradation by lysozyme (as demonstrated by QCM-D data, in Figure 1, for the coating without glyoxal). The contact angle of the hydrated sample, measured with the captive bubble technique, was considered to be null due to the bubble instability which derives from the rather hydrophilic nature of this surface.…”

Ocular Drug Delivery Role of Contact Lenses

“…61,62 Vitamin E loaded silicone contact lenses provided anaesthetic release for about 1-7 days and released 0.5 mg of lidocaine and thus could be very useful for postoperative pain control after corneal surgery such as the photorefractive keratectomy.Vitamin E loaded silicone ISSN 0972-0200 hydrogel contact lenses released 0.5 mg of lidocaine 63 and provided cyclosporine release within the therapeutic window for a period of about a month. 64 Similarily, contact lenses release of 0.5 to 0.7 mg of timolol was reported by Jung et al 25 …”

Insights to Using Contact Lenses for Drug Delivery

“…Simple drug loading methods, such as soaking a commercial CL in pharmaceutical preparations inevitably leads to rapid release kinetics [32]. While different CL material and drug combinations provide different release durations, the overall time frame for drug release is in the order of minutes and is thus not clinically useful [20,33,34]. This is not surprising as commercial CLs are intended solely for refractive error correction, but they are not designed for release of pharmaceuticals.…”

“…As a result, extensive research has been conducted in the past decade to develop CL materials capable of extended drug delivery, and the in vitro results so far have been very promising. Strategies such as molecular imprinting [35], vitamin E coatings [33] and nanoparticles [36,37] have been investigated and tested. These materials are designed to form interactions with the target drug molecule in a manner that promotes drug retention and slow release over time.…”

“…Molecular imprinting creates specific drug recognition sites within the polymer through the use of molecular templates [35]. Vitamin E coatings form diffusion barriers within the lens, which forces the target drug to take long complex paths to diffuse from the lens [33]. Nanoparticles encapsulated with the target drug can be loaded and released from the CL, and the extended release is controlled by the degradation of the nanoparticles [36,37].…”