Indirect-Acting Cholinergic Agonists: Pharmacological Actions

Recall that indirect-acting cholinergic agonists or anticholinesterases increase the ACh concentration, potentiating cholinergic actions in the body.

Their pharmacological effects are most prominent at the autonomic cholinergic synapses, neuromuscular junction, and within the CNS.

At the neuromuscular junction, continuous depolarization by anticholinesterases prolongs the end plate potential and muscle fasciculations. This makes them useful in the treatment of myasthenia gravis.

At cholinergic synapses in the ANS, anticholinesterases activate parasympathetic signaling to enhance cholinergic responses across the body.

In the eye, they reduce intraocular pressure and are prescribed for treating glaucoma .

They also help treat supraventricular tachycardia and induce bradycardia.

Furthermore, they promote smooth muscle contractions, proving effective in the treatment of neurogenic bladder and bowel atony.

Once in the CNS, anticholinesterases augment cholinergic transmission and are useful in Alzheimer's disease.

At low doses, these agents cause an initial excitation with improved cognitive functions. However, higher doses can cause depression and convulsion, which can lead to respiratory failure and coma.