Drug-eluting Contact Research Articles

A drug-eluting contact lens to treat glaucoma

Purpose: To investigate the uptake and release of a novel antibiotic-steroid solution from three commercial contact lenses. Method:A0.3%ciprofloxacin(CF)and0.1%dexamethasone23phosphate (DXP) solution was prepared in acetate buffer using cyclodextrins to prevent precipitation. Concentrations of both drugs were simultaneously determined using a combination of fluorescence spectrophotometry and UV absorbance. Three commercially available contact lenses, balafilcon A, etafilcon A and lotrafilcon B were placed in 2mL of the CF-DXP solution and soaked at room temperature for 24hours. The lenses were then removed and placed in 2mL of phosphate buffered saline, and the release of CF and DXP into solution was monitored over 24hours. Results: All lens types were able to release significant amounts of CF and DXP (p 0.05). The absolute amount of CF and DXP being released was less than when the species were loaded into the lenses individually compared to previous studies, suggesting a possible interaction effect. The majority of the drug was released within the first three hours, suggesting that specifically tailored and designed lenses are needed if these drug delivery lenses are to be useful. Conclusions: Antibiotic steroid combination drops are one of the most commonly prescribed agents in the ophthalmic industry, thus theyareanatural target for those interested indevelopingcontact lens drug delivery devices. Further study is required to tailor the release rates and amounts to be clinically relevant.

In vivo performance of a drug-eluting contact lens to treat glaucoma for a month

For nearly half a century, contact lenses have been proposed as a means of ocular drug delivery, but achieving controlled drug release has been a significant challenge. We have developed a drug-eluting contact lens designed for prolonged delivery of latanoprost for the treatment of glaucoma, the leading cause of irreversible blindness worldwide. Latanoprost-eluting contact lenses were created by encapsulating latanoprost–poly(lactic-co-glycolic acid) films in methafilcon by ultraviolet light polymerization. In vitro and in vivo studies showed an early burst of drug release followed by sustained release for one month. Contact lenses containing thicker drug–polymer films demonstrated released a greater amount of drug after the initial burst. In vivo, single contact lenses were able to achieve, for at least one month, latanoprost concentrations in the aqueous humor that were comparable to those achieved with topical latanoprost solution, the current first-line treatment for glaucoma. The lenses appeared safe in cell culture and animal studies. This contact lens design can potentially be used as a treatment for glaucoma and as a platform for other ocular drug delivery applications.

Study of ocular drug delivery system using drug-loaded liposomes

Background:This project aims to formulate and characterize a drug-eluting contact lens to provide controlled release of drug for a longer period of time, using liposomes as drug delivery system.Materials and Methods:Drug delivering contact lenses were created by coating disposable soft contact lenses with ciprofloxacin entrapped in the liposomes. Reverse phase evaporation and lipid film hydration methods were used for the preparation of ciprofloxacin trapping reverse phase evaporation vesicles, that is, unilamellar vesicles (REVs) and multilamellar vesicles (MLVs), respectively. Soya lecithin and cholesterol (CH) were used in the molar ratios of 7:4 and 7:2. The spherical structure of the liposomes, the mean diameter, and their purity were determined by photomicroscopic, transmission electron microscope, and chromatographic analysis, respectively. The prepared liposomes were evaluated for their entrapment efficiency, in vitro drug release, stability, and toxicity.Results:MLVs were larger than REVs with their mean diameter 338.32 nm and also entrapped greater amount of ciprofloxacin. Drug loading and its release from the liposomal vesicles was dependent on CH content. Ciprofloxacin released from the liposomes coated on the contact lenses not only inhibited both Staphylococcus aureus and Pseudomonas aeruginosa on an agar plate but also showed an enhanced antibacterial effect as determined by minimal inhibitory concentrations. Approximately 40% of ciprofloxacin was retained up to a period of 3 months at 4°C. Furthermore, the formulation was found to be nontoxic and also a reduction in toxicity of ciprofloxacin was observed after entrapment when assessed by lymphocyte toxicity assay and chick embryo inoculation.Conclusions:An innovative drug delivery system consisting of drug-loaded liposomes coated onto the surface of contact lenses has been developed. This system is highly specific in terms of localized and sustained application of the drug.

Advancements in ocular drug delivery

This review covers both noninvasive and invasive ophthalmic drug delivery systems that can have application to therapy of veterinary ophthalmic diseases. Noninvasive approaches include gel technologies, permeation enhancement via pro-drug development, solubilization agents and nanoparticle technologies, iontophoresis, microneedles, drug-eluting contact lenses and eye misters, and microdroplets. More invasive systems include both eroding implants and noneroding technologies that encompass diffusion based systems, active pumps, intraocular lenses, suprachoroidal drug delivery, and episcleral reservoirs. In addition to addressing the physiologic challenges of achieving the necessary duration of delivery, tissue targeting and patient compliance, the commercial development factors of biocompatibility, sterilization, manufacturability and long-term stability will be discussed.

General considerations in designing a drug-eluting contact lens

Ophthalmologists are generally limited to three options in delivering drugs to the eye while minimizing systemic side effects: drops (solutions or suspensions), ointments or injections. Injections ...

A Drug-Eluting Contact Lens

To formulate and characterize a drug-eluting contact lens designed to provide extended, controlled release of a drug. Prototype contact lenses were created by coating PLGA (poly[lactic-co-glycolic acid]) films containing test compounds with pHEMA (poly[hydroxyethyl methacrylate]) by ultraviolet light polymerization. The films, containing encapsulated fluorescein or ciprofloxacin, were characterized by scanning electron microscopy. Release studies were conducted in phosphate-buffered saline at 37 degrees C with continuous shaking. Ciprofloxacin eluted from the contact lens was studied in an antimicrobial assay to verify antimicrobial effectiveness. After a brief and minimal initial burst, the prototype contact lenses demonstrated controlled release of the molecules studied, with zero-order release kinetics under infinite sink conditions for over 4 weeks. The rate of drug release was controlled by changing either the ratio of drug to PLGA or the molecular mass of the PLGA used. Both the PLGA and the pHEMA affected release kinetics. Ciprofloxacin released from the contact lenses inhibited ciprofloxacin-sensitive Staphylococcus aureus at all time-points tested. A prototype contact lens for sustained drug release consisting of a thin drug-PLGA film coated with pHEMA could be used as a platform for ocular drug delivery with widespread therapeutic applications.

Contact Lenses for Drug Delivery

The majority of ocular medications are delivered to the eye topically, often in the form of a solution, or eye drop. Contact lenses could potentially also be used to deliver medications to the eye. Recently, progress has been made in developing a drug-eluting contact lens. Different designs have been proposed and several offer the hope of expanding the therapeutic armamentarium for eye care providers.