Cataract affects more than 20 million people worldwide each year and is the major cause of visual impairment. Its treatment implies the removal of the opacified natural lens and its substitution by an intraocular lens (IOL). Post-operatory complications, such as endophthalmitis, are usually prevented through the topical application of eyedrops containing antibiotic and anti-inflammatory. Such drug delivery method may lead undesirable side effects, low bioavailability of the drug and low patient compliance.
In this work, the possibility of using IOLs as platforms for the simultaneous delivery of both types of drugs is explored. An antibiotic (moxifloxacin (MXF)) and an anti-inflammatory (diclofenac (DFN)) were loaded in acrylic IOLs by soaking in the drugs solutions. Loading was carried out in two ways: in a solution containing MXF+DFN, and sequentially in solutions containing just one of the drugs. The loaded lenses were autoclaved and submitted to in vitro drug release experiments were carried out in sink conditions. Relevant properties for the IOLs performance, such as the swelling capacity, optical properties (transmittance) and mechanical properties (Young’s modulus), were investigated.
The results show that the double loaded lenses released an higher amount of MXF than the single loaded lenses, while for DFN no difference was observed. Sterilization did not affect the release. The application of a mathematical model, that takes into account the volume and renovation rate of the aqueous humour, suggests that these devices are able to release effective amounts of the drugs for 2-4 weeks. The presence of drugs increases the swelling capacity of the lenses. Changes in optical and mechanical properties do not compromise the use of the lenses.
In sum, the sterilized double loaded lenses seem to be promising devices for the endophthalmitis prophylaxis, complying with both antibiotic and anti-inflammatory therapeutic needs.