Stability after freezing and thawing of solutions of mitomycin C in plastic minibags for intravesical use.

Solutions of 0.6 mg/ml mitomycin C (Mutamycin) in NaCl solution 0.9% in plastic minibags for intravesical use were stored at -20 degrees C and -30 degrees C and thawed by microwave radiation. Both unbuffered solutions and solutions buffered to approximately pH 7.5 were investigated. Concentrations were measured with HPLC. During freezing and storage at -20 degrees C sometimes crystallization of mitomycin C occurred. However, both buffered and unbuffered solutions could be frozen at -30 degrees C during at least four weeks and subsequently thawed without loss of content. Unbuffered mitomycin C solutions could be refrozen at -30 degrees C for another four weeks. Also buffered and unbuffered solutions of another brand of mitomycin C (Mitomycin-C Kyowa) could be frozen at -30 degrees C during four weeks without significant deterioration.