Abstract
Purpose: :
Our previously presented in vivo animal data demonstrates that antibiotic soaked hydrophillic lenses produce aqueous concentrations above MIC for common post-operative pathogens. These experiments have been performed to quantify the in vitro delivery characteristics of the Staar Collamer (SC), Bausch & Lomb Akreos (BLA), and the Alcon Acrysof (AA) with a standard concentration of antibiotics varied by soak time.
Methods: :
Standardized spectrophotometry curves were created using serial dilutions of each of four antibiotic solutions (moxifloxacin 0.5%, cefuroxime 1%, gatifloxacin 0.3% and linezolid 0.2%). IOLs were soaked in 1 ml of each solution for 10, 30, 60, 120 and 360 minutes, removed, washed with 2 ml of BSS before being placed in 1-2 ml of BSS soak for 5 minutes. The lenses were removed and placed into a new solution of BSS for 5 minutes and repeated for a total of eight cycles. Seven additional cycles of 15 minute soaks were performed. The resulting supernatant was then evaluated by spectrophotometry. Previous standardized concentration curves and Beer's law were used to correlate absorbance with drug concentration over time. Accumulated drug release and rate of release over time was plotted.
Results: :
While both hydrophobic lenses demonstrate significant release of antibiotics over time, the SC lens released approximate 10 times more antibiotic over time compared to the BLA lens for all soak times. Rate and total concentration of antibiotic released demonstrated a correlation with the amount of time the lenses were soaked in antibiotic solution. Further, in the SC lens system there was fourfold more moxifloxacin released as compared to cefuroxime. The hydrophobic AA lens demonstrated almost no drug release after five minutes.
Conclusions: :
This data supports our previous in vivo data demonstrating clinically significant levels of drug release from hydrophilic lenses over time. Total drug delivered is related to the duration of antibiotic soak time. There are significant differences in drug delivery between Akreos, Starr Collamer and Acrysof lenses in this in vitro model. This may be related to the water content and chemical composition of the lenses. Each antibiotic also demonstrated different release curves which may correspond to their molecular size, charge, and solubility. Further research and eventually human controlled trials should be performed to establish the safety and efficacy of these drug delivery systems.
Keywords: cataract • antibiotics/antifungals/antiparasitics • endophthalmitis