Some phosphate-acetylcholinesterase conjugates continue to react after the phosphate docks to the site, evolving into a more recalcitrant state. This process is known as aging. Aged phosphate-acetylcholinesterase conjugate are resistant to antidotes such as pralidoxime. Pralidoxime is often used with atropine (a muscarinic antagonist) to help reduce the parasympathetic effects of organophosphate poisoning. Pralidoxime is only effective in organophosphate toxicity. It has no beneficial effects if the acetylcholinesterase enzyme is carbamylated, as occurs with neostigmine, pyridostigmine, or insecticides such as carbaryl.