Oxidative stress and antioxidant status in acute organophosphorous insecticide poisoning

Objective: To study the antioxidant status and the extent of oxidative stress in patients with organophosphorus insecticide (OPI) poisoning before and after specific treatment. Material and Methods: The study was conducted in eighty-four OPI poisoned patients. Superoxide dismutase (SOD) and malonyl aldehyde (MDA) levels were estimated as an index of antioxidant status and oxidative stress respectively and comparisons were made (a) between different grades of poisoning based on clinical features and anticholinesterase (AChE) levels, (b) before and after therapy with atropine sulfate plus pralidoxime (PAM) and (c) between healthy control subjects and OPI poisoned patients. Results: There was a progressive fall in both the RBC and plasma AChE levels which correlated with the severity of poisoning. Upon therapy, profound improvement in the AChE levels was observed (an increase by 20.5% and 20.9% in RBC and plasma AChE levels respectively). There was also an increase in the MDA levels which nearly doubled in OPI poisoned patients who failed to survive (3.6 + 0.92 to 6.7 + 2.3 nM/ml). SOD levels increased parallel to the severity of poisoning, but did not normalize after therapy. Conclusion: The increased level of MDA in OPI poisoned patients who failed to survive was probably reflective of accelerated lipid peroxidation, cell damage and death (oxidative stress). Significant improvement was noticed in the AChE (serum and RBC) levels of patients with specific treatment but without much change in the antioxidant status as reflected by the SOD and MDA levels.