For Neostigmine a maximum dosage is in the range of 60 to 80 mcg/kg. Although large doses of the drug will result in more rapid antagonism, there seems to be a “ceiling effect”. The maximum effective dose, beyond which further amounts of anticholinesterase will not produce any greater antagonism.
Also, be mindful excessive neostigmine can lead to a depolarizing block. The anticholinesterase effect increases the amount of acetylcholine release. In an overdose, depolarization of the endplate cause by the excess acetylcholine can lead to a depolarization block, similar to that seen with succinylcholine