A pharmaceutical formulation comprises a pharmaceutically acceptable preservative and a material selected from the group consisting of D-glucose, sucrose, maltose, D-mannose, trehalose, glutamic acid, mixtures thereof, and combinations thereof, wherein the formulation has enhanced preservative efficacy against spore-forming microorganisms. The formulation can further comprise boric acid and/or phosphate. A method for enhancing the preservative efficacy of a pharmaceutical formulation against spore-forming microorganisms, comprising adding a pharmaceutically acceptable preservative, and a material selected from the group consisting of D-glucose, sucrose, maltose, D-mannose, trehalose, glutamic acid, mixtures thereof, and combinations thereof, to the pharmaceutical formulation. The formulation optionally includes an active agent for treating or controlling a disease or disorder of the eye. The formulation may be used to treat, clean, disinfect, store, wet, or rewet contact lenses.
