Abstract
Purpose: :
Loteprednol etabonate ophthalmic ointment, 0.5% (Lotemax ointment) does not contain a preservative due to its low water activity. The purpose of this study was to conduct a Preservative Efficacy (PE) test on Lotemax Ointment to confirm that the unpreserved ointment demonstrates inherent biostatic properties.
Methods: :
Three lots of Lotemax ointment (including one expired lot) were evaluated for PE testing following USP <51> guidelines against 5 USP PE microorganisms (Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Aspergillus brasiliensis), 2 field isolates (Serratia marcescens, Bipolaris australiensis), 1 clinical isolate (Stenotrophomonas maltophilia), and 1 American Type Culture Collection (ATCC) fungal strain (Fusarium solani) representing a total of 5 bacterial and 4 fungal strains. Product was heated to not more than (NMT) 44°C, inoculated with ~106 CFU/mL challenge microorganism, and incubated at 20-25°C. At Day 7, 14 and 28 post-inoculation, the test products were removed from incubation and heated to NMT 44°C. Aliquots were transferred into similarly heated isopropyl myristate, and dilutions thereof were filtered for quantitative membrane colony count recovery.
Results: :
A reduction in microorganism levels was observed for all challenge microorganisms at day 7, 14, and 28 for all three lots evaluated.
Conclusions: :
The results of this study confirm that the inherent low water activity (<0.6) of the Lotemax Ointment does not provide an environment for microbial growth.
Keywords: corticosteroids • inflammation • cornea: basic science