Antidotes nerve agent exposure therapy

TABLE 6.7. Recommended antidote protocol for emergency nerve agent exposure therapy ... 

TABLE 9.7 Recommended Antidote Protocol for Emergency Nerve Agent Exposure Therapy ... 

Nerve agent intoxication requires rapid decontamination to prevent further absorption by the patient and to prevent exposure to others, ventilation when necessary, administration of antidotes, as well as supportive therapy. Skin decontamination is not necessary with exposure to vapor alone, but clothing should be removed to get rid of any trapped vapor. With nerve agents, there can be high airway resistance due to bronchoconstric-tion and secretions, and initial ventilation is often difficult. The restriction will decrease with atropine administration. Copious secretions which maybe thickened by atropine also impede ventilatory actions and will require frequent suctioning. For inhalation exposure to nerve agents, ventilation support is essential. 

The choice of appropriate treatment for nerve agent intoxication depends on the agent as well as extent and route(s) of exposure. Very mild exposure to nerve agent vapor may necessitate only decontamination and observation severe exposure to vapor or liquid requires immediate decontamination, antidote administration, artificial respiration, monitoring, and supportive therapy over hours to multiple days (ATSDR, 2007 Sidell, 1997 Vale et al, 2007 Pulley and Jones, 2008). Convenient triage classifications have been developed by ATSDR (2007) in collaboration with the US Army Medical Research Institute of Chemical Defense. 

FIGURE 10.6 Posttreatment with galantamine/atropine effectively counteracts nerve agent and insecticide toxicity in guinea pigs. Lower the level of OP exposure, longer the time within which the antidotal therapy effectively maintains 100% survival of the animals with no signs of toxicity. (From Albuquerque, E.X. et al., Proc. Natl. Acad. Set USA, 103, 13220, 2006. With permission.)... 

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. ... 

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). 

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