Testing the long term stability of vancomycin ophthalmic solution

Some patients with a keratoprosthesis (artificial cornea) are required to use prophylactic vancomycin ophthalmic solution daily for life to prevent infection, a regimen which has proven to be highly successful. The objective of this study was to determine whether such vancomycin solutions would remain stable at room temperature for an extended period of time, beyond that suggested by available published stability data and used in current practice. By relaxing the storage requirement and extending the expiration date of this solution, it was hoped that patient adherence and satisfaction would increase. The studied vancomycin ophthalmic solutions were compounded at the Massachusetts Eye and Ear Infirmary, Department of Pharmacy Services, Boston, Massachusetts, and were sent to an outside laboratory for high-performance liquid chromatography potency testing at predefined time points. Vancomycin 14-mg/mL ophthalmic solution compounded with 0.005% benzalkonium retains potency for at least 60 days at room temperature and 6 months frozen. Extending the beyond-use dating of vancomycin may lead to improved patient adherence by lowering costs and increasing convenience of storage and shipment of the medication.