Dichlorvos; organophosphorus pesticide is among the most widely used pesticides for insect control. In Nigeria and most other developing countries it is used indiscriminately by people with little or no knowledge of its toxic effects as a household and agricultural insecticide. The acute effect and antidotal therapy of dichlorvos was studied in laboratory animals. The LD50 in rats was determined to be 28.28 mg/kg i.p, with acute poisoning symptoms of micturation, restlessness, pupil constriction, respiratory distress and convulsion. Atropine was found to be the most effective antidote as it significantly (P < 0.05 – 0.001) reduced all symptoms of poisoning and gave 100%
survival rate. There was however no significant difference between the animals treated with atropine alone and those treated with combination of atropine and diazepam. The results also showed that diazepam significantly reduced symptoms like restlessness (P < 0.05), pupil constriction and convulsion (P < 0.001).
Key Words: Dichlorvos, Acute Poisoning, Antidotal Therapy, Atropine, Diazepam