The Effect of Ondansetron on Pyridostigmine-Induced Blood Acetylcholinesterase Inhibition in the Guinea Pig

ABSTRACTThe purpose of this study was to assess the compatibility, in terms of red blood cell acetylcholinesterase (AChE) inhibition, of ondansetron (OND; a 5-hydroxytryptamine subtype-3 receptor antagonist) with the organophosphorus pretreatment compound pyridostigmine (PYR) after simultaneous oral (p.o.) administration to guinea pigs. the time-course of PYR-induced (0.94 mg/kg, p.o.) AChE inhibition was determined in the absence and presence of OND. Ondansetron (10, 20 and 30 mg/kg; p.o.) did not modify AChE inhibition, whereas concurrent administration of PYR with OND (10 or 20 mg/kg; p.o.) produced significantly greater decreases in AChE activity than PYR alone. the decreases in AChE activity for PYR plus OND, 10 and 20 mg/kg, (between 30 -240 min) were 12.3 ± 2.8% and 16.1 + 2.3% (mean ± SD) respectively relative to PYR alone. the slope for recovery of AChE activity (120 -240 min) was 0.0914 for PYR alone; recovery rates (slopes) for PYR plus OND, 10 and 20 mg/kg, were 0.0796 and 0.0433 respectively....