An ionic bond. That's what the compounds bond is.
Pyridostigmine is a acetylcholinesterase inhibitor which acts as a cholinergic drug. Acetylcholinesterase or AChE is the enzyme that breaks down the major neurotransmitter acetylcholine into acetyl-CoA and choline, rendering the neurotransmitter useless. In a patient that had major adverse effects upon administration of pyridostigmine, the correct drug to be given as antidote for a cholinergic drug is an anticholinergic drug such as atropine.
