Optimising mitomycin C activity during intravesical instillation.

Walker 256 carcinosarcoma was shown to be sensitive to mitomycin C in vitro. In order to make practical recommendations for the clinical intravesical use of mitomycin C, this cell line was used to evaluate the activity of mitomycin C under different conditions. Mitomycin C loses its antitumour activity rapidly at pH's below 6. At higher pH's (up to 10) mitomycin C is stable and suitable for intravesical application. To secure a sufficiently high pH in the bladder during intravesical treatment, phosphate buffer 0.05 M with a pH of 7.4 is recommended. Constituents of urine very little decrease the activity of buffered mitomycin C during a 2 h application. Prednisolone, which has been suggested to prevent the harmful chemical cystitis, has no inhibitory effect on the activity of mitomycin C.