What are the two groups of AChE inhibitors?

AChE (Acetylcholinesterase) inhibitors prevent the enzyme acetylcholinesterase from breaking down the neurotransmitter acetylcholine (ACh), extending the during of its action. 

Based on the mode of action, AChE inhibitors can be divided into two groups: 

1. Reversible AChE inhibitors
2. Irreversible AChE inhibitors.