In Vitro Evaluation of the Drug Reservoir Function of Human Amniotic Membrane Using Moxifloxacin as a Model Drug

PURPOSE:To evaluate the in vitro, extended drug reservoir function of human amniotic membrane (HAM) of different thicknesses impregnated with moxifloxacin. METHODS:HAM buttons (12 mm) were soaked with freshly prepared 0.5% wt/vol topical moxifloxacin at different soaking time intervals3 hours (group I), 6 hours (group II), 12 hours (group III), 24 hours (group IV), and 48 hours (group V). They were then transferred into 1 mL of fresh simulated tear fluid (pH-7.4) and incubated at 37°C. The release kinetics of moxifloxacin was studied by analyzing the amount of drug in simulated tear fluid collected at different time intervals from each pretreated HAM for 3 weeks. In another experiment, thin and thick HAMs were selected based on weight and soaked with moxifloxacin for 24 hours, and the release kinetics was studied for 7 weeks. All samples were stored at −80°C until analysis by high-performance liquid chromatography. RESULTS:No significant difference was observed between different soaking times and the release of moxifloxacin. The cumulative amount of moxifloxacin released from thick HAM was found to be statistically significant compared with thin HAM (P < 0.05). CONCLUSIONS:Our in vitro data showed that the sustained release of moxifloxacin from HAM was achieved up to 7 weeks. The entrapment efficiency of moxifloxacin was significantly higher in thicker HAM than in thin HAM. Moxifloxacin-impregnated HAM application can be considered in bacterial keratitis to provide sustained drug delivery through a biological bandage system for up to a period of 7 weeks.