Purpose: To ascertain the causes of the formation of gelatinous material observed on the ocular surface of a patient using a betamethasone sodium phosphate ophthalmic solution containing fradiomycin sulfate (Rinderon^®-A) together with a timolol maleate long-acting ophthalmic gel-forming solution (Timoptol^®-XE).
Methods: The gellan gum in the Timoptol^®-XE was suspect as it might have been gelatinized by the fradiomycin sulfate in the Rinderon^®-A. Mixtures of the chemical compounds such as fradiomycin sulfate with the Timoptol^®-XE was tested in vitro to find out whether any resulted ingelation.
Results: It was confirmed that Timoptol^®-XE was gelatinized by the aminoglycoside drugs in vitro. The density of the aminoglycoside drugs needed for the gelation was only about 0.2 mM on average. Gelation was also observed with benzalkonium chloride and vancomycin.
Conclusion: The results suggest that the gellan gum in the Timoptol^®-XE gelatinized by the fradiomycin sulfate in the Rinderon^®-A and that aminoglycocide compounds act strongly on gellan gum as polycation.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 116: 554-559, 2012.