Toxicity, antagonism

Chemical interactions are those in which one chemical combines with another to become more or less toxic. For example, the chelating agent EDTA combines with toxic metals such as lead and decreases its toxicity (antagonism). 

If this method is used in reporting data, it will no longer be necessary to use non-quantitative terms such as toxicity, antagonism, synergism, stimulation, and etc. Because of the absolute nature of this method of reporting results and its freedom from ambiguity, all future studies of the effect of metabolites on metabolism should utilize this reporting method. 

Janowsky, D.S., Davis, J.M. and Overstreet, D.H. Anticholinesterase (DFP) toxicity antagonism by chronic donepezil a potential nerve agent treatment, Pharmacol Biochem. Behav., 81, 917, 2005. 

Derlet, R. W., and T. E. Albertson. 1990a. Acute cocaine toxicity antagonism by agents interacting with adrenoceptors. Pharmacol Biochem. Behav. 36(2) 225-31. 

Chemical analyses revealed no specific components as the cause of observed toxicity. Antagonism between sea salt and toxic chemicals is hypothesized to cause differential toxicity at varying salinities, as opposed to differential solubility of the toxicants. Extrapolation of laboratory results indicates that proposed tire reefs should not pose a serious threat to water quality in Chesapeake... 

Antagonism is appHed to a situation where two chemicals, given together, interfere with each other s action or where one interferes with the action of the other. The result will usually be a decrease in toxic injury. A special case of antagonism is in studies on antidotal action. 

Piperonyl butoxide, a common potentiator of insecticide effects that inhibits microsomal enzymes, antagonized the toxic effects of methyl parathion in mice (Mirer et al. 1977). 

Particular attention is given to the development of new mechanistic biomarker assays and bioassays that can be used as indices of the toxicity of mixtures. These biomarker assays are typically based on toxic mechanisms such as brain acetylcholinesterase inhibition, vitamin K antagonism, thyroxin antagonism, Ah-receptor-mediated toxicity, and interaction with the estrogenic receptor. They can give integrative measures of the toxicity of mixtures of compounds where the components of the mixture share the same mode of action. They can also give evidence of potentiation as well as additive toxicity. 

Antagonism With reference to toxicity where the toxicity of a mixtnre is less than the snm of toxicities of its components. 

Theophylline is also considered an alternative to inhaled corticosteroids for the treatment of mild persistent asthma however, limited efficacy compared to inhaled corticosteroids, a narrow therapeutic index with life-threatening toxicity, and multiple clinically important drug interactions have severely limited its use. Theophylline causes bronchodilation through inhibition of phosphodiesterase and antagonism of adenosine and appears to have anti-inflammatory and immunomodulatory properties as well.36... 

Caffeine is also effective in the antagonism of peripheral adenosine (type I) receptors, which are known to inhibit lipolysis by subduing adenylate cyclase activity.28 The appeal of this mechanism of action is that the majority of the pharmacological effects of adenosine on the central nervous system can be inhibited by doses of caffeine that are well within physiologically non-toxic levels comparable to only a couple of cups of coffee.5... 

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