Combination of misonidazole and m-AMSA: effects on radiation sensitivity and toxicity in E. coli

Simultaneous administration of misonidazole and m-AMSA resulted in additive radio-sensitization and toxicity in E. coli B/r. At low drug doses the toxicities may be super-additive. However, experiments in N2 and O2 indicated that a therapeutic benefit from the combination is unlikely. Depending upon the actual sequence and the presence of O2, pretreatment by one drug could lead to enhancement or reduction of the toxicity of a subsequent exposure to the other drug. In particular, an m-AMSA pretreatment made the toxicity of misonidazole independent of the oxygen concentration. Possible implications of the interaction of the two chemicals are discussed.