Stability of mitomycin in polypropylene syringes for use in glaucoma surgery

Abstract Introduction: Outside the oncology field, mitomycin is used in glaucoma surgery. Solutions at 0.2 mg/mL are usually used to fully saturate sterile sponges that are applied to the treatment area. In hospital pharmacies, mitomycin 10 and 40 mg are classically used to prepare the solutions with a lot of losses. The objective of this work was to study the long-term stability to consider preparation in advance and reduce losses in a context of drug shortage. Methods: Two different products were used: Ametycine, which contains sodium chloride as excipient, and Mitomycin medac, which contains urea as excipient. Solutions at 0.1 mg/mL (sometimes used in our hospital) and the more classically used 0.2 mg/mL were prepared and stored in polypropylene syringes. Solutions were kept at −20°C or at 5°C and analyzed on day 28, 63, and 91. Chemical stability was studied by using a previously validated high-performance liquid chromatography stability-indicating method. pH was measured and a visual inspection was performed. Results: For each condition, solutions were not stable after long-term storage with concentrations below 90% of the initial concentration after 28 days. Frozen solutions were less stable than refrigerated solutions. pH values increased by more than 1 pH unit after 3 months. Ametycine shows precipitate after freezing but not solutions prepared with Mitomycin medac. The color of frozen solutions was changed from light blue to light green at −20°C but became light blue after thawing. Conclusion: Mitomycin 0.1 and 0.2 mg/mL showed an instability after long-term storage at 5°C or −20°C. These results do not allow the preparation in advance of large batches.