Indication for the treatment of myasthenia gravis.pharmacodynamics pyridostigmine is a parasympathomimetic and a reversible cholinesterase inhibitor. since it is a quaternary amine, it is poorly absorbed in the gut and doesn t cross the blood-brain barrier. pyridostigmine has a slightly longer duration of action than neostigmine. it is used in the treatment of myasthenia gravis and to reverse the actions of muscle relaxants.mechanism of action pyridostigmine inhibits acetylcholinesterase in the synaptic cleft by competing with acetylcholine for attachment to acetylcholinesterase, thus slowing down the hydrolysis of acetylcholine, and thereby increases efficiency of cholinergic transmission in the neuromuscular junction and prolonges the effects of acetylcholine.