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Parasympathomimetic drug

A parasympathomimetic drug, sometimes called a cholinomimetic drug[1] or cholinergic receptor stimulating agent[2], is a substance that stimulates the parasympathetic nervous system (PSNS).[3][2] These chemicals are also called cholinergic drugs because acetylcholine (ACh) is the neurotransmitter used by the PSNS.[1][4] Chemicals in this family can act either directly by stimulating the nicotinic or muscarinic receptors (thus mimicking acetylcholine), or indirectly by inhibiting cholinesterase, promoting acetylcholine release, or other mechanisms.[5]

Some chemical weapons such as sarin or VX, non-lethal riot control agents such as tear gas, and insecticides such as diazinon fall into this category.

Structure activity relationships for parasympathomimetic drugs[6]

For a cholinergic agent, the following criteria describe the structure activity relationship:

  1. Ing's Rule of 5: there should be no more than five atoms between the nitrogen and the terminal hydrogen for muscarinic (or cholinergic) activity;
  2. the molecule must possess a nitrogen atom capable of bearing a positive charge, preferably a quaternary ammonium salt;
  3. for maximum potency, the size of the alkyl groups substituted on the nitrogen should not exceed the size of a methyl group;
  4. the molecule should have an oxygen atom, preferably an ester-like oxygen capable of participating in a hydrogen bond;
  5. there should be a two-carbon unit between the oxygen atom and the nitrogen atom.

Pharmaceuticals/Supplements

Direct-acting

These act by stimulating the nicotinic or muscarinic receptors.

Indirect-acting

Indirect acting parasympathomimetic substances may be either reversible cholinesterase inhibitors, irreversible cholinesterase inhibitors or substances that promote ACh release or anti-adrenergics. The latter inhibits the antagonistic system, the sympathetic nervous system.

See also

References

  1. ^ a b Dowd, Frank (2017). Pharmacology and therapeutics for dentistry: Chapter 6 - Cholinergic Agonists and Muscarinic Receptor Antagonists. St. Louis, Missouri: Elsevier. p. 82-97. ISBN 978-0-323-39307-2. OCLC 958121223.
  2. ^ a b Forrester, John V.; Dick, Andrew D.; McMenamin, Paul G.; Roberts, Fiona; Pearlman, Eric (2016). "General and ocular pharmacology". The Eye. Elsevier. pp. 338–369.e1. doi:10.1016/b978-0-7020-5554-6.00006-x. ISBN 978-0-7020-5554-6. Parasympathomimetics are a group of drugs that act either by directly stimulating the muscarinic receptor, for example pilocarpine, or by inhibiting the enzyme acetylcholinesterase, which hydrolyses the acetylcholine in the synapse.
  3. ^ "Dorlands Medical Dictionary:parasympathomimetic".
  4. ^ Parasympathomimetics
  5. ^ Brenner, G. M. (2000). Pharmacology. Philadelphia, PA: W.B. Saunders Company. ISBN 0-7216-7757-6
  6. ^ Medicinal Chemistry of Adrenergics and Cholinergics
  7. ^ Karadsheh, N; Kussie, P; Linthicum, DS (1991). "Inhibition of acetylcholinesterase by caffeine, anabasine, methyl pyrrolidine and their derivatives". Toxicology Letters. 55 (3): 335–42. doi:10.1016/0378-4274(91)90015-X. PMID 2003276.

External links