Neostigmine

Neostigmine (Prostigmin, Vagostigmin) (from Greek neos, meaning "new," and "-stigmine," in reference to its parent molecule, physostigmine, on which it is based) is a parasympathomimetic compound that acts as a reversible acetylcholinesterase inhibitor. Given that it is a quaternary amine (unlike physostigmine, which is a tertiary amine), it penetrates the central nervous system poorly and has lower propensity to cause side effects there.