Chemical degradation of wastes of antineoplastic agents amsacrine, azathioprine, asparaginase and thiotepa

As a part of a program devoted to the destruction of antineoplastic agents, three chemical methods readily available in the hospital environment, viz. oxidation with sodium hypochlorite (NaClO, 5%), hydrogen peroxide (H₂O₂, 30%), and Fenton reagent (FeCl₂·2H₂O; 0.3 g in 10 ml H₂O₂, 30%), were tested for the degradation of four anticancer drugs: Amsacrine, Azathioprine, Asparaginase and Thiotepa. The efficiency of the degradation was monitored by high-performance liquid chromatography. The mutagenicity of the degradation residues mere tested by Ames test using tester strains Salmonella typhimurium TA 97a, TA 98, TA 100 and TA 102 with and without an exogenous metabolic activation system. Using sodium hypochlorite, 98.5% of Amsacrine, 99.0% of Azathioprine, 99.5% of Asparaginase and 98.7% of Thiotepa were destroyed after 1 hr. The hydrogen peroxide treatment destroyed 99% of Asparaginase and 98.7% of Thiotepa in 1 hr. However, this procedure was not efficient for the treatment of Amsacrine (28% after 16 hr) and of Azathioprine (53% degradation in 4 hr). The action of Fenton reagent resulted in the destruction of 98% of Amsacrine, and 99.5% of Azathioprine, 98.5% of Asparaginase and 98.7% of Thiotepa in 1 hr. In all cases where a high degree of degradation was achieved, the residues obtained were non mutagenic.