» Polymyxin B Sulfate and Trimethoprim Ophthalmic Solution is a sterile, isotonic, aqueous solution of Polymyxin B Sulfate and Trimethoprim Sulfate or of Polymyxin B Sulfate and Trimethoprim that has been solubilized with Sulfuric Acid. It contains not less than 90.0 percent and not more than 130.0 percent of the labeled amount of polymyxin B and the equivalent of not less than 90.0 percent and not more than 110.0 percent of the labeled amount of trimethoprim (C₁₄H₁₈N₄O₃). It contains one or more preservatives.