How is mechanism of action of competitive non depolarizing blockers

At low doses (Prevent Ach binding, prevent depolarization of muscle membrane inhibit muscle contraction. Can be overcome by increasing concentration of Ach in synaptic cleft (admin anticholinesterases)) At high doses (Block ion channels at end plate, lead to weakening of neuromuscular transmission, reduces anticholinesterase action reverse actions of non depolarizing muscle relaxants)