The aim of the study was to examine the interaction and toxicity between metoclopramide and organophosphorus insecticide diazinon in mice using the up and down method. The median lethal dose (LD50) of metoclopramide was 293 mg/kg s.c, and that of diazinon was 64.1 mg/kg p.o.
The toxic interaction between metoclopramide and diazinon was examined using a ratio of 1:1 and the (LD50) value for both depending on isbolographic
analysis. Antagonistic interaction was found when metoclopromide was administered before and after 20 minutes of diazinon administration. While synergistic interaction was found when both of the drugs were administrated at the same time.
Metoclopramide at 20 mg/kg s.c significantly reduced the onset time of tremor by diazinon at 60 mg/kg p.o when administered with and after 10 minute and before 5, 15, 20 minutes from the administration of diazinon.
Diazinon at 70 mg/kg p.o significantly inhibited plasma, RBC, brain cholinesterases in mice by 74%, 46%, 12% respectively.
Metoclopramide at 20 mg/kg s.c, significantly inhibited RBC, brain cholinesterase by of 11%, 21% respectively, while plasma cholinesterase insignificantly inhibited by 5%.
The results suggest that metoclopramide. Reduced the percentage of inhibition of ChE in mice which was caused by diazinon and protected them from its toxicity.