• Rarely used clinically
• muscarinic and nicotinic stimulation
• rapid degeneration by AChE, plasma butyrylcholinesterase

Bethanechol

(choline ester)

• Direct acting cholinergic agonist
• muscarinic stimulation
• some M3 selectivity: urinary bladder, GI
• promotes voiding
• treats urinary retention when NO OBSTRUCTION
• Synthetic choline ester

Muscarine

(alkaloid)

• Direct acting cholinergic agonist
• Muscarinic receptor stimulation
• Not used clinically; found in some mushrooms
• SLUDGE symptoms with mushroom toxicity

Pilocarpine

(alkaloid)

• Direct acting cholinergic agonist
• Muscarinic stimulation
• Topical ophthalmic used to induce pupil constriction and decrease intraocular pressure with glaucoma
• Rarely used systemically (incr salivation)

• AChE inhibitor
• Reversible
• For sm mm atony, glaucoma (topical), reversal of competitive non-deopol NMJ blockers
• Counteract CNS signs seen with anticholinergic intoxication. 
• Crosses BBB

• AChE inhibitor
• Reversible
• For sm mm atony, glaucoma (topical), reversal of competitive non-deopol NMJ blockers
• Does NOT cross BBB
• Stimulates visceral sm mm

AChE Inhibitors 

(irreversible)

• Organophosphate compounds
• Insecticides
• Nerve gases
• SLUDGE signs
• Can treat with 2-PAM to restore AChE activity
• Treat symptoms with anticholinergics

Atropine

(Natural alkaloid)

• Cholinergic antagonist
• Competitively inhibits the binding and stim of muscarinic receptors by ACh and other muscarinic agonists
• Enters CNS: possibly toxicity, excitation followed by depression
• Tachyarrhythmia, prolonged GI stasis, urine retention
• Decreases salivary and airway secretions: Used with sx.
• Can see increased salivation if it drains into the mouth; bitter, stim. salivation reflex
• Won't work in rabbits, use catiously in horses (colic)
• use to relieve AChE poisoning

Scopolamine

(Natural alkaloid)

• Cholinergic antagonist
• Similar effects as atropine (tachyarrhythmia, prolonged GI stasis, urine retention, decr. salivation, relieve AChE poisoning)
• Enters CNS: Low dose = slight sedation. High dose = excitement
• Antiemetic

Glycopyrrolate

(synthetic)

• Cholinergic antagonist
• Little CNS effects (doesn't cross BBB)
• Use with general anesth. to decrease airway and salivary secretions and to prevent vagally mediated bradycardia

Tropicamide

(synthetic)

• Cholinergic antagonist
• Topical use to produce mydriasis and cycloplegia (loss of ability to maintain focus on an object as it gets closer to the eye)
• Shorter duration of action than atropine

• Cholinergic antagonist
• Decrease bronchoconstriction and airway secretions
• Restricted distribution; inhalation to limit systemic effects, doesn't cross BBB
• For cat asthma, chronic bronchitis in dogs, horses with recurrent airway inflammation

• Cholinergic antagonist
• Decreases detrusor contraction adn increases trigone/sphincter contraction
• Used for incontinence due to detrusor instability
• Urine retention