anticholinergics

Nolli · Mar 16, 2014

To understand what anti-cholinergics are you must first understand the autonomic nervous system and how it works. The autonomic nervous system is broken down into two main branches the cholinergic or parasympathetic branch and the adrenergic or sympathetic branch. You may have heard of the expressions "fight or flight" and "feed or breed" when describing both branches. Fight or flight describes the adrenergic response. "Feed or breed" describes the cholinergic response.

Here is a chart that goes further into the specific receptors and their responses: https://www.dropbox.com/s/4qi5irch3dy90w9/Receptor%20grid%20with%20answers.doc

The cholinergic/parasympathetic branch uses the neurotransmitter Acetylcholine often abbreviated as ACh. Anticholinergic drugs block the effects of ACh. Why would anyone want to block the effects of ACh? Let's take a look at ACh does to the heart. Atropine is an anticholinergic drug that is used for symptomatic bradycardia (low heart rate) among other things. Since ACh lowers the heart rate blocking it has the opposite effect; it speeds it up. It is also used in the treatment of nerve gas and organophospate poisonings because it blocks the effects of Ach. Can you guess what other symptoms someone who was exposed to either substance would experience using the chart?

macawake, MSN · Mar 16, 2014

Anticholinergic = parasympatholytic = parasympathetic antagonist.

What do you know about the Autonomic Nervous System (ANS)?

Fight or flight. Rest and digest.

Do you know what a neurotransmitter is? What does it do?

The two major (but there are more and they are important too) neurotransmitters in the ANS are noradrenaline/norepinephrine and acetylcholine (ACh). One of them is highly interesting when answering the question you asked.

What effect does an anticholinergic agent/drug have on the neurotransmitter Acetylcholine?

Do you know what a receptor is? What happens when a neurotransmitter binds to a postsynaptic receptor?

There are two main types of autonomic receptors: adrenergic and cholinergic.

Find out more about nicotinic and muscarinic receptors. Are they adrenergic or cholinergic? Where do you find them in the body?

Do you understand the difference between an agonist and an antagonist? If you don’t, this part is a must know!

An interesting drug (nebulizer) to study and ponder is Combivent (salbutamol/albuterol and ipratropium). It’s a combination drug made from a Beta2agonist and a muscarinic antagonist (=anticholinergic).

One’s an agonist and the other is an antagonist, yet they both cause bronchodilation. Why?

Hint: increasing or stimulating one system (for example sympathetic) will have a similar effect as decreasing or blocking a system (for example parasympathetic) that has the opposite mechanism of action (compared to the other system).

What effect does an anticholinergic agent/drug have on Acetylcholine?

The ANS controls and affects many organs in the body!

Among other: the heart, lungs/airway, blood vessels, eyes/pupils, bladder and bowels as well as salivary and lacrimal glands.

Some drugs can be selective to a specific receptor subtype, some aren’t. (Some have dose-dependent effect). So most of the time the drug will also affect many different organs in the body other than the one you are attempting to treat.

For example the anticholinergic drug Atropine used to treat symptomatic bradycardia will have a common side effect: dry mouth.

Why the dry mouth? Which “system” stimulates the salivary glands? The “fight or flight” or the “rest and digest”? The “rest and digest”! And now we are administering the anticholinergic drug, thus “blocking” rest and digest”. No wonder that mouth is dry.

Atropine is clinically used to treat many other things than bradycardia. Look them up! Again, the ANS controls many organs in the body. An anticholinergic drug like Atropine that blocks the effect of acetylcholine on muscarinic acetylcholine receptors will therefore affect many organs in the body.

Look up nicotinic antagonist drugs for another group of anticholinergics!

I just found a couple of videos that look helpful. I haven’t watched more than about five minutes of each but they look like they’re good quality.

Neurotransmission:

Autonomic Pharmacology:

The first video is more for background but quite important I think, the second I believe answers your question.

Good luck!

Oops! Seems I repeated some of the information provided by the previous poster. Sorry about that.

Esme12, ASN, BSN, RN · Mar 16, 2014

here a thread to help....Pharmacology Flashcards

https://allnurses.com/nursing-student-assistance/adrenergics-and-cholinergics-838953.html

xaviersocal · Jun 23, 2014

Maybe I need to do some serious critical thinking here, but can someone touch on the uses of anticholinergics in perioperative care, I just dont get why it would be used :-(

sandytoes · Jun 24, 2014

Just stumbled upon this thread and wanted to say thanks for the review! Very helpful refresher for me :)

Christy1019, ASN, RN · Jun 24, 2014

Maybe I need to do some serious critical thinking here, but can someone touch on the uses of anticholinergics in perioperative care, I just dont get why it would be used :-(

I believe its to dry up secretions to prevent aspiration, and possibly so you don't urinate or have a BM during surgery. However, don't quote me on that LOL.