Direct Acting Cholinergic Drugs

Direct Acting Cholinergic Drugs

At, delve into the world of Direct Acting Cholinergic Drugs. Gain comprehensive insights into their mechanisms, applications, and pivotal role in healthcare, enriching your understanding of these pharmaceuticals

Direct Acting Cholinergic Drugs

1. Acetylcholine

1Neurotransmitter , Quaternary amine= Cannot pas Blood brain barrier
2Diffuse action both on Muscarinic and nicotinic receptors
3Decrease heart rate and cardiac output


The mechanism of acetylcholine in decreasing heart rate and cardiac output involves ACh binding to muscarinic receptors on cardiac pacemaker cells (SA node), leading to an increased potassium ion permeability. This hyperpolarizes the cells, slowing down the depolarization rate, and ultimately reducing heart rate and cardiac output.
4Decreases blood pressure


Acetylcholine decreases blood pressure by binding to muscarinic receptors on vascular endothelial cells. This binding triggers the release of nitric oxide (NO), a potent vasodilator. Nitric oxide relaxes the smooth muscle in blood vessel walls, leading to vasodilation and an increase in blood vessel diameter. As a result, there is reduced resistance to blood flow, which leads to a decrease in blood pressure. Atropine work as antagonist.
-GI motility
-salivary secretion
-Gastric acid secretion
-Produce miosis
-Tone of detrusor muscle ( Bladder ) cause urination
Methacholine = diagnosis of Asthma

2. Bethanechol

1Major action: Urinary bladder and GI SYSTEM
2Duration of action : 4 hours

-Its action promotes increased motility in the intestines and bladder, leading to enhanced bowel movements and bladder emptying
4Therapeutic use:

-Used to stimulate atonic bladder particularly in postoperative and non-obstructive urinary retention
5Adverse effects:

Flushing ( reddening of face )
Decreased B.P
Atropine sulphate can be used to overcome severe cardiovascular or bronchoconstrictor

3. Carbachol


Major action: CVS, GI SYSTEM and on Eyes ( Miosis )
2Diffuse action both on Muscarinic and nicotinic receptors
3Therapeutic uses:

Long duration of action
Glaucoma = Used to treat open-angle glaucoma ,
Neurological Diagnostics = Testing to assess pupillary responses
Intraocular Surgery = used during intraocular surgery, such as cataract surgery, to induce pupillary constriction and ease surgical access to the eye.
4Adverse effects:

Due to lack of systemic penetration with ophthalmic use, few negative effects happen.

4. Pilocarpine

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