Dual drug delivery from intraocular lens material for prophylaxis of endophthalmitis in cataract surgery.

Cataract is highly prevalent among old population worldwide and replacement of the opacified crystalline lens by an intraocular lens (IOL) is the safest and the most effective treatment. Although not very frequently (0.02-0.33% of the cases), the patients who undergo cataract surgery may develop endophthalmitis, which is a serious problem eventually leading to blindness. To avoid this complication, the postoperative instillation of antibiotics and anti-inflammatories is almost universally used in clinical practice. The aim of this work was to study the possibility of loading an IOL material with an antibiotic and an anti-inflammatory, which could be simultaneously released and successfully substitute the frequent instillation of topical drops for the prevention of endophthalmitis. The IOL material commercially available under the name of CI26Y (Contamac Products) was chosen and two pairs of drugs consisting of one antibiotic and one anti-inflammatory were tested: moxifloxacin + ketorolac and moxifloxacin + diclofenac. The drug loading was done by soaking under optimized conditions. Simultaneous drug loading improved the release profiles, especially in the case of moxifloxacin + ketorolac. The effect of sterilization by steam heat (carried out on the first day of loading) and by gamma-radiation upon the release profiles was negligible. The optical and mechanical properties of the sterilized, double-loaded IOL materials were kept at adequate levels. Application of a mathematical model to predict the in vivo released concentrations suggested that the most efficient system complied with the therapeutic needs: the lens loaded with moxifloxacin + ketorolac was effective against S. aureus and S. epidermidis up to 15 days, and the amount of released ketorolac remained active against inflammation for a minimum of 16 days.