Effect of chlorpheniramine on acute dichlorvos poisoning in wistar rats

Introduction: Pesticide poisoning is a serious public health concern worldwide. According to WHO, about 3 million cases occur every year, resulting in more than 250,000 deaths. In response to the problems of unavailability of antidotes and cost in sub-Saharan Africa, this research set out to investigate chlorpheniramine, a cheap and readily available over the counter (OTC) antihistamine for possible antidotal effects on rats acutely poisoned with dichlorvos. Methodology: The antidotal and protective effect of chlorpheniramine a H1 antihistamine on acute toxicity by dichlorvos, an organophosphorus insecticide in wistar rats was investigated and compared with atropine, the standard antidote. Chlorpheniramine (2mg/kg, 4mg/kg, and 8mg/kg), atropine (0.4mg/kg, 0.8mg/kg, and 1.6mg/kg) and dichlorvos (4mg/kg) were all administered intraperitoneally. Dichlorvos at a dose of 4mg/kg induced acute toxicity in the rats observed as tremor, convulsion, defecation, straub tail, recumbence and gasping. Results: Chlorpheniramine significantly (p<0.05) decreased the occurrence of acute signs of toxicity and also delayed the time of onset of signs of poisoning. Chlorpheniramine also prevented death of the animals with 100% survival rate after 2- 24hours of dichlorvos poisoning. Chlorpheniramine also reduced the toxicity score as compared to the control after acute toxicity testing for 14days. Conclusion: The results suggests that chlorpheniramine possesses antidotal effects against dichlorvos induced toxicity in wistar rats comparable to atropine, the standard antidote and showed an additive positive antidotal effect when administered in combination with atropine.