Cholinergic Medications

Muscarinic agonists

bethanechol

muscarinic antagonists

atropine

neuromuscular blocking agents

succinylcholine

cholinesterase inhibitors

neostigmine, physostigmine

Muscarinic receptors

stimulation of parasympathetic response

-feed and breed or rest and digest

bradycardia

increased salivation, sweat, bronchial, gastric secretions

GI and urinary movement

near vision

Bethanechol: Muscarinic Agonist (promoting this activity) use

Use: treatment for urinary retention (nonobstructive)

Bethanechol MOA

Can elicit all responses typical of muscarinic receptor activation

• promotes contraction of detrusor muscle and relaxation of urinary sphincter

Bethanechol contraindicated (who shouldn’t take this medication?)

asthma, low blood pressure, coronary insufficiency, intestinal or urinary obstruction

Bethanechol ADEs

Common- overstimulation of the cholinergic receptors—too much of all these symptoms (slow HR, low bp, etc)

Serious- Acute toxicity(poisoning)

• Reversal agent: Atropine

• A lot of salivation, tearing, visual disturbances, bronchospasms, diarrhea, bradycardia, and hypotension

Atropine: Muscarinic antagonist (use)

many applications and is dose related

MOA of atropine

competitive blockade at muscarinic receptors

no direct effects

all effects result from preventing receptor activation

Dosage of atropine

Atropine impacts

eyes: dilates and dries

smooth muscle: slows GI tract, urinary bladder, relaxes bronchial

exocrine glands: slows production of saliva, tears, sweat, bronchial secretions, and stomach acid

heart: increases heart rate

Atropine contraindications/precautions

anyone with similar pre-existing conditions-asthma, urinary retention, ileus, etc

BEERS criteria designation

ADEs of atropine

relating to its MOA

ex. tachycardia, constipation, thickened mucous membranes

Toxicity: activated charcoal to slow absorption or physostigmine is the antidote

Atropine route

IV, IM, SubQ

Other muscarinic cholinergic antagonists aka anticholinergic drugs

Scopolamine patch-multiple uses; impacts secretions, motion sickness, end of life (manage oral secretions)

Ipratropium bromide (Atrovent)- respiratory drug; COPD or other pulmonary disease

oxybutynin (Ditropan XL)- management of overactive bladder

MOA of anticholinergic drugs

they all block cholinergic activity

Cholinesterase inhibitors

prevent the breakdown of acetylcholine

cholinesterase inhibitors are beneficial for diseases like…

myasthenia gravis, Alzheimer’s, Parkinson’s-benefit from increased acetylcholine

If you are poisoned by a cholinergic antagonist (atropine) what is the reversal agent?

cholinesterase inhibitors

Cholinergic crisis-too much of cholinesterase inhibitor

atropine is the antidote

Pyridostigmine

Cholinesterase inhibitor

Pyridostigmine use

drug of choice for Myasthenia Gravis

Myasthenia Gravis

an autoimmune disorder that is characterized by fluctuating muscle weakness and predisposing to rapid fatigue

-body is attacking nicotinic M receptors on your skeletal muscle

Pyridostigmine MOA

blocks the activity of cholinesterase preventing the breakdown of available acetylcholine (only muscarinic receptors on organs and nicotinic receptors on skeletal muscle)

Who shouldn’t use Pyridostigmine (contraindicated)

individuals with peptic ulcer disease, asthma or bradycardia

intestinal or urinary obstruction

Pyridostigmine ADEs

Acute toxicity (poisoning) -reversal agent: atropine

profuse salivation, tearing, visual disturbances, bronchospasms, diarrhea, bradycardia, and hypotension

Neuromuscular blockade

other cholinesterase inhibitors

Reversible: neostigmine and physostigmine—antidote for atropine

Irreversible: echothiopate—used for glaucoma and insecticides

Drugs that block Nicotinic cholinergic transmission

you can’t move (paralytic drugs)

can’t breathe

does not affect your level of consciousness

Succinylcholine (blocking agent)

produces a state known as depolarizing neuromuscular blockade

binds to receptors but then doesn’t let them go —initial contraction but then relaxation —cannot reengage those receptors

short ½ life

Pyridostigmine ADE

hyperkalemia/malignant hyperthermia

when muscles contract can allow potassium to leave cell

Pancuronium (neuromuscular blocking agent)

competitive or nondepolarizing

competes with acetylcholine for binding to those nicotinic_m receptors does not allow for muscle contraction

Pancuronium use

intubation, general anesthesia, and mechanical ventilation

Pancuronium reversal agent

cholinesterase inhibitor