Razi Journal of Medical Sciences

Organophosphate (OP) compounds have largely been used as pesticides and also as nerve agents in Chemical Wars. OP pesticides have frequently been imported and freely available to the public without usage control. Therefore, OP poisoning, mainly intentional type, is very common and accounts for 21.8% (250 patients) of the total admission to the hospital between 21 March 1994 and 20 March 1995.

OP compounds induce accumulation of acetyl choline by inhibition of acetyl cholinestrase leading to the stimulation of muscarinic and nicotinic receptors. Muscarinic effects are counteracted successfully by atropine sulfate, but the therapeutic effects of oximes on nicotinic receptors and cholinestrase reactivation have not been observed in clinical practice. Clinical obervations of the author and a report from Sri Lanka (Lancet 339,1992), indicates no therapeutic effects of oximes in OP poisoning. Case notes of 317 Treatment Centres between 21 March 1993 and 20 March 1995 were studied.

There were significant positive correlations between the oxime doses and either hospitalization days (r=0.625, p<0.001) or mortality rate (= 0.718, p<0.01).

It seems that oximes had no therapeutic effects on OP pesticide poisoning. However, a prospective investigation is currently undertaken to confirm this hypothesis.