What is the Difference Between Anticholinergic and Anticholinesterase

The main difference between anticholinergic and anticholinesterase is that anticholinergic drugs block the transmission of acetylcholine in the central and peripheral nervous system whereas anticholinesterase inhibits all types of cholinesterase.

Anticholinergic and anticholinesterase are two types of medicines that act on neurotransmitters. Both medicines block the action of the corresponding neurotransmitter.   

Key Areas Covered

1. What is Anticholinergic
    – Definition, Characteristics, Importance
2. What is Anticholinesterase
    – Definition, Characteristics, Importance
3. Similarities Between Anticholinergic and Anticholinesterase
    – Outline of Common Features
4. Difference Between Anticholinergic and Anticholinesterase
    – Comparison of Key Differences

Key Terms

Anticholinergic, Anticholinesterase, Antispasmodics

What is Anticholinergic

Anticholinergics are a broad class of drugs that act on the neurotransmitter, acetylcholine. Antispasmodics is another name for anticholinergic medicines. The blocking of acetylcholine occurs in the central and peripheral nervous systems. The main importance of anticholinergic medicines is that they prevent impulses from the parasympathetic nervous system. They also block impulses from coming to the parasympathetic nervous system. Generally, this prevents the contractions, spasms, and cramps of smooth muscles.

Figure 1: Acetylcholine

Furthermore, anticholinergic medicines are important in blocking the function of smooth muscles by blocking the action of acetylcholine. Therefore, they are important in the treatment of gastrointestinal and bladder conditions. In addition, they are important in treating some respiratory movement disorders. Some examples of dicyclomine, scopolamine, clidinium, atropine, etc. The synonyms of anticholinergics are cholinergic antagonists, parasympatholytic drugs, and cholinergic blockers. In general, they have the antagonizing effect of acetylcholine. These drugs act on the nicotinic and muscarinic receptors. However, some of the anticholinergic drugs act on the ion channels of the nicotinic receptors, blocking the acetylcholine release.     

What is Anticholinesterase

Anticholinesterase medicines are the class of medicines that blocks the action of all cholinesterases. There are two types of cholinesterases: acetylcholinesterase (ACHE) and butyrylcholinesterase (BCHE). The main difference between acetylcholinesterase and butyrylcholinesterase is that acetylcholinesterase hydrolyzes acetylcholine and butyrylcholinesterase hydrolyzes butyrylcholine. However, both types of hydrolysis reactions occur more quickly. 

Figure 2: Synapse Acetylcholine

Moreover, the action of anticholinesterases blocks the function of cholinesterases. Therefore, it increases the concentration of acetylcholine. The main function of acetylcholine is to transmit nerve impulses in the parasympathetic nervous system. The parasympathetic nervous system is a part of the autonomic nervous system that induces the secretion, contracts of smooth muscles, and dilates blood vessels.

Similarities Between Anticholinergic and Anticholinesterase

• Anticholinergic and anticholinesterase are two types of medicines that act on the action of neurotransmitters.
• They block the action of the corresponding neurotransmitter.
• Moreover, the non-depolarizing neurotransmitter block is important in surgery.

Difference Between Anticholinergic and Anticholinesterase

Definition

Anticholinergic refers to inhibiting the physiological action of acetylcholine, especially as a neurotransmitter, while anticholinesterase refers to drugs that prolong the existence of acetylcholine after it is released from cholinergic nerve endings by inhibiting both acetylcholinesterase and butyrylcholinesterase.

Significance

Anticholinergic drugs block the transmission of acetylcholine in the central and peripheral nervous system while anticholinesterase inhibits all types of cholinesterase.

Blocked Neurotransmitters

Moreover, anticholinergic drugs block the action of acetylcholine while anticholinesterase inhibits acetylcholinesterase (ACHE) and butyrylcholinesterase (BCHE).

Acetylcholine

Anticholinergic medicines block the action of acetylcholine while anticholinesterase medicines increase the concentration of acetylcholine.  

Conclusion

In brief, anticholinergic and anticholinesterase are two types of medicines that block neurotransmitters.  Anticholinergic neurotransmitters block the action of acetylcholine in the central and peripheral nervous system, while anticholinesterase is a medicine that blocks the action of all types of cholinesterase. In general, there are two types of cholinesterase: acetylcholinesterase (ACHE) and butyrylcholinesterase (BCHE). Therefore, the main difference between anticholinergic and anticholinesterase is the type of neurotransmitters blocked by each medicine.                            

References:

1. V Priya Nair, MB BS FRCA, Jennifer M Hunter, MB CHB PHD FRCA, Anticholinesterases and anticholinergic drugs, Continuing Education in Anaesthesia Critical Care & Pain, Volume 4, Issue 5, October 2004, Pages 164–168, https://doi.org/10.1093/bjaceaccp/mkh045

Image Courtesy:

1. “Acetylcholine-3D-balls” By CCoil – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Synapse acetylcholine” By Pancrat – Own Work (CC BY-SA 3.0) via Commons Wikimedia