Antidotal therapy, principles

A principle of the therapy for acute poisonings with anticholinesterase compounds (OPC, carbamates) lies in the complex performance of specific antidotic therapy including methods for poison excretion and intensive resuscitation measures. 

As mentioned previously, a decrease in ChE activity is the factor indicating (after the exclusion of other factors) an exposure to OP pesticides, nerve agents, or other ChE inhibitors. This simple determination does not allow us to make certain decisions dealing with the antidotal therapy (especially toe repeated administration of reactivators) and has low prognostic validity. Therefore, a new tesf of the reactivation of inhibited enzyme has been described (Bajgar, 1991). The principle of toe reactivation test is double determination of the enzyme activity, toe first without and the second with the presence of a reactivator in toe sample. The choice of reactivator is dependent on the availability of the oxime however, in principle it is necessary to have in these parallel samples the same concentrations of reagents. The concentration of the reactivator (usually trimedoxime, but other oximes such as obidoxime, pralidoxime, or HI-6 are also possible) must be no higher than the oxime concentration that causes toe hydrolysis of toe substrate (acetyl- or butyrylthiocholine) in other words, toe oxime concentration must be lower than 10 M (Patocka et al., 1973). 

Toxicology is an interesting medical discipline. The principles of management are prevention, toxicovig-ilance and careful assessment of the clinical features of the poisoned patient, and providing timely and appropriate therapy. In most cases, these are symptomatic and supportive measures, on top of decontamination, elimination of the poison, and provision of specific antidotes. 

The principles of care for a casualty with nerve agent intoxication include termination of exposure, maintenance of ventilation, administration of antidotes, and supportive therapy. For successful medical management, early and intense therapy after severe exposure to nerve agents is necessary to prevent death. The condition of the patient will dictate the need for specific treatment procedures and the order of administration. It is of utmost importance that medical care providers are protected from contamination by use of appropriate protective clothing, otherwise they may become additional casualties. ... 

B. The medical treatment of occupational toxic illness should follow the general principles outlined earlier in this section and in Sections I and II of this book. In particular, the use of specific antidotes should be undertaken in consultation with a regional poison control center ([800] 222-1222) or other specialists. This is particularly true before chelation therapy is initiated for heavy metal poisoning. 

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