Temperature-dependent effect of edetate disodium on neomycin stability

When heated at temperatures in excess of 100 degrees, the stability of neomycin in aqueous ophthalmic formulations was improved by the addition of edetate disodium (0.01%). As the exposure temperature was reduced, the degree of stability enhancement diminished until the effect was reversed, and addition of edetate disodium was detrimental to neomycin stability in solutions stored at 30 degrees.