ABSTRACT
I. INTRODUCTION This small group of chemicals includes agents having antagonistic, antidotal, or inhibitory properties to other chemicals. Chief in the group are the heavy metal antagonists, those chemicals that react with metals to form tightly bound complexes. They act by preventing or reversing the binding of toxic metals to body ligans; their efficacy as therapeutic agents is attributable to the fact that they form a specific complex with metals as a chelate; thus they have antidotal properties to poisoning by metals (Gilman et al., 1985). There are also some that are drugs in the strict therapeutic sense. Also included in the group are a number of miscellaneous chemicals that antagonize the properties of other chemicals, but have no therapeutic use in this regard; they are included here because it is their most natural classification. One group commonly referred to as antimetabolites would normally be considered here, but are included in Chapter 18 because of their important use in cancer chemotherapy. So too with chemicals having antihormonal effects considered in Chapter 9.
