Cholinergic drugs

The drugs which have similar role as acetylcholine are collectively referred to cholinergic drugs. According to its role in different principles, they can be divided into cholinergic like receptor agonists and cholinesterase inhibitors.
Choline receptor agonists can directly bind to the cholinergic receptor, resulting in a similar effect to acetylcholine.
Acetylcholine is a cholinergic neurotransmitter that activates the M-cholinergic receptor and the N-cholinergic receptor. When the M receptor is agitated, its effect often manifest as heart suppression, vasodilation, visceral smooth muscle contraction, sphincter relaxation and increased glandular secretion. These effects are called M-like effect. When the N receptor is agitated, its effect often manifest as ganglion excitement, skeletal muscle contraction and these effects are called N-like effect.
Because of the instability of chemical nature of acetylcholine in human body, it could quickly loose its effect by cholinesterase hydrolysis. It has been used widely so there is not a high selectivity. So it has no clinical value. Some compounds which has the similar chemical structure as acetylcholine are more stable and has high selectivity. So they has wide clinical applications.