Mohammad, F. K., Mousa, Y. J., Al-Zubaidy, M. H. I., Alias, A. S.
الملخص العربي
Objective: The study was designed to assess the protective and ameliorative effects of the antihistamine diphenhydramine against a
model of acute organophosphate insecticide (dichlorvos) poisoning in 7-14 day-old chicks. Material and Methods: The acute (24 h) oral median
lethal doses (LD50) of dichlorvos either alone or with concomitant diphenhydramine (10 mg kg-1, i.m.) or atropine (2 mg kg 1, i.m.) were
determined in the chicks by the up-and-down method. The protective and ameliorative effects of diphenhydramine on the signs of dichlorvos
poisoning were examined and compared with those of atropine. Plasma and whole brain cholinesterase activities of chicks treated with diphenhydramine
and/or dichlorvos were measured by an electrometric method. Results: Diphenhydramine at 10 mg kg-1, intramuscularly (i.m.) immediately
after oral dosing with dichlorvos increased the oral LD50 value of the insecticide from 6.49 to 17.14 mg kg-1, whereas atropine at 2
mg kg-1, i.m. increased it to 22.55 mg kg-1. The oral dosing of dichlorvos at 8 mg kg-1 caused acute signs of cholinergic poisoning in the chicks.
The best effective dosage of diphenhydramine was at 10 mg kg-1, i.m. immediately after the oral dichlorvos dosing, which significantly increased
the latencies to onset of signs of poisoning and significantly prevented the 2 h and 24 h lethalities. Diphenhydramine also significantly
decreased the occurrence of signs of poisoning and reduced total toxicity score in the chicks. Diphenhydramine, similar to atropine, given
at times of -15, 0 and + 5 min relative to the time of dichlorvos dosing also ameliorated dichlorvos-induced poisoning in the chicks to varying
extents. Dichlorvos alone at the oral doses of 2 and 4 mg kg-1 significantly reduced cholinesterase activity in the plasma and whole brain.
Diphenhydramine at 10 mg kg-1, i.m. immediately after oral dichlorvos dosing at 4 mg kg-1 significantly but partially ameliorated cholinesterase
inhibition caused by the insecticide in the whole brain of the chicks. Conclusion: The results suggest that diphenhydramine has protective
and ameliorative effects against a model of acute organophosphate poisoning in chicks.
يعرب جعفر موسى | Yaareb Jaafar Mousa | 5584