Pyridostigmine is an inhibitor of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE; IC50s = 0.35 and 1 μM, respectively, for the human enzymes). Pyridostigmine (10 μM) reduces decreases in AChE activity induced by the organophosphate pesticides diisopropyl fluorophosphate, chlorpyrifos-oxon, diazinon-oxon, paraoxon, and malaoxon in isolated bovine red blood cells. It also reduces soman-induced membrane depolarization and decreases in AChE activity in isolated human muscle bundles in a concentration-dependent manner. Pyridostigmine (3 mg/kg per day for four weeks) prevents tachycardia and increases in sympathetic tone in mice following myocardial infarction induced by left coronary artery ligation. Formulations containing pyridostigmine have been used in the treatment of myasthenia gravis and as neuromuscular protective agents against organophosphate poisoning.
