CHOLINERIC AGONISTS

carbachol

A quaternary compound that has a carbamic acid-ester bond that is not hydrolyzable by cholinesterase.

carbachol

Activates both muscarinic and nicotinic receptors.

carbachol

Used topically to produce miosis in ophthalmology to
treat narrow-angle glaucoma.

carbachol

Not widely used today because of its severe side effects.

bethanechol

Only stimulate muscarinic receptors and is more resistant to cholinesterase.

bethanechol

Used primarily to increase bladder contractility in small animals.

bethanechol

GI absorption is nil after oral administration and it does not penetrate the CNS.

bethanechol

DO NOT USE in patients with urinary outflow obstruction, GI obstruction, asthma, and hypotension.

bethanechol

No commercially available injectable preparations.

pilocarpine

A tertiary amine alkaloid that acts on muscarinic receptors only.

pilocarpine

Rarely used as an ophthalmic solution to induce miosis and decrease the intraocular pressure seen in glaucoma.

pilocarpine

Still used orally as the primary treatment of neurogenic keratoconjunctivitis sicca in dogs.

pilocarpine

Adverse effects include local irritation and inflammation of the uveal tract and may cause systemic effects on repeated use.

methacholine

A quaternary ammonium compound muscarinic receptor agonist with long duration of action.

methacholine

Primarily known for its use in Methacholine Challenge Tests to diagnose asthma and bronchial hyperreactivity.

methacholine

Limited therapeutic uses in veterinary medicine.

physostigmine

A tertiary amine that mimics the effect of ACh

physostigmine

Used topically to treat simple and secondary glaucoma.

physostigmine

Used for the adjunctive treatment of ivermectin toxicity in dogs.

physostigmine

A provocative agent for the diagnosis of narcolepsy in dogs and horses.

physostigmine

Used as treatment for anticholinergic toxicity (atropine/scopolamine).

tensilon test

Also called Edrophonium Test, is used for diagnosing myasthenia gravis.

tensilon test

A positive result, indicating a potential diagnosis of myasthenia gravis, would be marked by a noticeable improvement in muscle strength following the
injection.

pyridostigmine

Similar to neostigmine and has the longest duration of action (4-6 hours).

pyridostigmine

Used orally for the long-term treatment of myasthenia gravis in dogs and cats (rarely).

pyridostigmine

Only marginally absorbed from the GI tract.

edrophonium

Identical with neostigmine but has the shortest duration of action (10-15 minutes).

edrophonium

Used in Tensilon Test for the diagnosis (only) of myasthenia gravis and for antagonizing tubocurarinelike drugs.

edrophonium

Used to reverse supraventricular arrhythmias

edrophonium

It is only given parenterally.

echothiophate

A quaternary organophosphate (OP) with long duration of action (>12hrs)

echothiophate

Used topically to treat open angle glaucoma.

carbamate poisoning

Results from the excessive inhibition of AChE by carbamates which is reversible in nature.

carbamate poisoning

Similar clinical signs with OP toxicity (cholinergic crisis).

carbamate poisoning

Atropine is sufficient to reverse its effects.

organophosphate poisoning

Results from the excessive inhibition of AChE by organophosphates which is irreversible in nature due to “aging” of the enzyme.

organophosphate poisoning

Atropine + Pralidoxime (2-PAM) can reverse the effects if aging has not occurred yet.

neostigmine

Contains quaternary ammonium with similar effects to physostigmine

neostigmine

Used for rumen atony, GI peristalsis, bladder emptying, and skeletal muscle stimulation in livestock.

neostigmine

Used in treating non-depolarizing neuromuscular blocking agents (curare-type) overdoses in dogs and ivermectin overdoses in cats.

neostigmine

Used in the diagnosis and treatment of myasthenia gravis.