Analysis of the Stability of 0.04% Mitomycin C Ophthalmic Solution under Various Storage Conditions

A 0.04% mitomycin C (MMC) ophthalmic solution is not commercially available and is prepared in hospitals as required. The physical properties and stability of the MMC ophthalmic solution have not been clarified because of a lack of data. This study aimed to assess the stability of the MMC ophthalmic solution under various storage conditions. The MMC ophthalmic solution was prepared by dissolving 2 mg of MMC in 5 mL of saline solution. Each batch of ophthalmic solution was stored under three conditions [cold/shaded light, room temperature/shaded light, and room temperature/scattered light (approximately 4000 lx)], and MMC concentration was determined using high-performance liquid chromatography on days 0, 1, 3, 5, 7, 14, and 21. The expiry date was calculated based on the results of the degradation analysis. pH measurements and bacterial culture tests were conducted for each storage condition. The MMC concentrations on day 21 under cold/shaded light, room temperature/shaded light, and room temperature/scattered light were 340, 287, and 227 µg/mL, respectively. MMC concentrations decreased over time, and the decrease was highest when the samples were stored at room temperature and exposed to light, and lowest under cold conditions and protected from light. The pH of MMC solutions was 5.8 after preparation, which increased to 6.9 with time under all storage conditions. Culture tests did not detect any bacteria under any storage conditions. The MMC ophthalmic solution was most stable under cold/shaded conditions, and our study clarifies its expiry date for clinical use.