Chapter 5: Cholinergic Antagonist

Cholinergic antagonist

• is a general term for agents that binds to cholinoreceptors and prevents the effects of acetylcholine and other cholinergic receptors

anticholinergic agents, antimuscarinic agents, parasympatholytics

Other term for cholinergic antagonists

Ganglionic blockers

• shows a preference for nicotinic receptors of the sympathetic and parasympathetic ganglia

• the least important cholinergic antagonists

Neuromuscular blocking agents

• interfere with transmission of efferent impulses to skeletal muscles

• used as skeletal muscle relaxants in surgical anesthesia and as agents to facilitate intubation in surgical and ciritical care patients

Antimuscarinic agents

• commonly known as anticholinergic drugs

• these agents block muscarinic receptors, causing inhibition of muscarinic functions

• these drugs block the few exceptional sympathetic neurons that are cholinergic such as those innervating the salivary and sweat glands

belladona alkaloid

• atropine is extracted from?

Atropine

• is a tertiary amine

• it has a high affinity for muscarinic receptors and binds competitively to prevent ACh from binding

Mydriasis and Cycloplegia

Actions of Atropine in the Eyes:

Antispasmodic

Actions of Atropine to the GIT?

Bradycardia

Therapeutic uses of injectible atropine in our heart

• it is used to treat ______

Organophosphate

• insecticides, nerve gases

• farmers are mostly affected

Soman, Sarin, Tabun

• Nerve gases/agents

• Used during the time of Hitler to kill people

Malathione

• least dangerous organophosphate

Parathione

• most dangerous organophosphate

Scopolamine

• is one of the most effective drugs available for motion sickness

• it also has the unusual effect of blocking short-term memory

Scopolamine

• at higher doses it can produce excitement

Ipratropium and Tiotropium

• are quaternary derivatives of atropine

Glycopyrrolate and Aclidinium

• synthetic quaternary compounds

Ipratropium

• is classified as short-acting muscarinic antagonist

Glycopyrrolate, tiotropium, aclidinium

• are classified as Long-acting muscarinic antagonist

Benzotropine

• CNS

• treatment of Parkinson’s disease

Blurred vision, Confusion, Mydriasis, Constipation, Urinary retention

• Adverse effects commonly observed with muscarinic antagonist

curare

• the firs known NMB

• amazon hunters used to paralyze prey

Tubocurarine

• prototype

• southamerican arrowhead poison

Neostigmine

• Antidote for Non-depolarizing drugs

Dantrolene

Antidote for Depolarizing drugs

Steroid derivatives and Isoquinolone derivatives

Two types of Non-depolarizing blockers/drugs/agents

Succinylcholine

• Depolarizing agent/blocker/drugs