L1: Parasympathomimetics - muscarinic/parasympatholytics - muscarinic & nicotinic/ AChE inhibitors

summary:

pilocarpine

-tx neurogenic keratoconjunctivitis sicca

-used to dx CN III problems

brand names:

Pilocarpine

-Isopto-Carpine®

-Pilocar®

-Ocu-carpine®

-Ocusert Pilo®

-Pilopine-HS®

-Minims Pilocarpine®

summary:

CN III

-paired motor nerve

-O: midbrain

-controls eye movements, upper eyelid elevation, pupil constriction

It innervates four extrinsic eye muscles:

• medial

• superior

• inferior recti

  • inferior oblique

damage:

CN III

-"down and out" eye positioning

-ptosis

-dilated pupils

how is pilocarpine administrated?

-1% or 2% opthalmic solution

-oral

mode of action:

pilocarpine

-M3 direct acting cholingeric agonist

-sm mm contraction

-pupil constriction

-contraction of cililary m (to inc aqeous humor flow)

molecular:

• Gq protein-coupled receptors → inc Ca²⁺ → sm m contraction

side effects:

pilocarpine

-general cholingeric: vomiting, diarrhea, increased salivation, and frequent urination

-optha: squinting, redness, long-term pupil constriction, retinal detachment

biggest side effect of bethanechol?

-dec HR

summary:

atropine

M1-5 competitive antagonist

-inhibits parasympathetic system

-Block ACh

effects:

Atropine

-dilates pupils

-inc HR

-decrease G.I., bladder

-decreased secretions/dry mouth/eyes

-mydriasis, cycloplegia

Side effects:

Atropine

-dry mouth

-blurred vision

-sensitivity to light (photophobia)

-tachycardia (fast heart rate)

-constipation

-urinary retention

Side effects:

Glycopyrrolate

-dry mouth, constipation, urinary retention, blurred vision, nasal congestion, and reduced sweating

summary:

Glycopyrrolate

-ammonium anticholinergic agent

-pre-anesthetic:

• reduce drooling, salivation

• reduce gut motlity

• prevent brady

-fewer side effects than atropine

Mode of action:

Glycopyrrolate

– M2 receptors

– Does not cross BBB, unlike atropine

– Reduces stimulation of SA node

– Onset:

• IV: 1 min

• Duration: 2 to 4 hours

brand names:

propathaline

Pro-Banthine

summary:

propatheline

tx:

• gastrointestinal spasms

• chronic diarrhea

• urinary incontinence (detrusor instability)

spp:

• k9

• fel

• eq

Mode of action:

propatheline

-nonselective M receptor blocker

-relaxes smooth m

-does not cross BBB → few CNS side effects

Side effects:

propatheline

-dry mouth/eyes

-constipation

-urine retention

-tachycardia

-vomiting

-drooling (fel)

general muscarinic agonist effects:

methacholine - largest effect

-HR

general muscarinic agonist effects:

bethanecol - largest effect

-GIT motility

-bladder contraction

(semi - myosis)

general muscarinic agonist effects:

pilocarpine - largest effect

-GIT motility

-myosis

(semi - bladder contraction)

general muscarinic agonist effects:

carbachol - largest effect

-GIT motility

-bladder contraction

(semi - myosis)

general muscarinic agonist effects:

Ach - largest effect

-HR

-GIT motility

-bladder contraction

-N receptor activation

brand names:

atropine

-Isopto-Atropine: optha drops

possible, Med-4-Vet: atropine ointment

summary:

pancuronium

-NMJ block

-nicotinic antagonists

-adjunct to GA

effects:

pancuronium

-relaxes muscles for intubation

-paralyzes mm

-relaxation during mechanical ventilation

side effects:

pancuronium

-complete paralysis of respiratory mm → apnea

-if no mechanical ventilation → resp acidosis

brands:

pancuronium

note: human meds used off brand in vet → manufacturers

-Pfizer: Pancuronium Bromide Injection, USP

-Teva

-Abbott

moa:

pancuronium

-competitive antagonist to Ach

uses:

botulinum toxin (botox)

-localized use

-mm spasms

-chronic pain

-contractures

side effects:

botox

-localized irritation at injection site

-toxicity possible with ingestion

moa:

botulinum toxin (botox)

-acts on cholinergic nerve terminals to block the release of Ach

brands:

botulinum toxin (botox)

note: vet trials

-Botox → onabotulinumtoxinA by Allergan/AbbVie

-Dysport → (abobotulinumtoxinA by Galderma): better for larger mm groups

brands:

bethanechol

-Urecholine

-Duvoid

-Myotonachol

-Myocholine

-Myotonine

-Urocarb

uses:

bethanechol

-stimulate smooth muscles of the bladder and gastrointestinal tract

indications:

bethanechol

-non-obstructive urinary retention

-bladder atony

general side effects:

bethanechol

-note: non-specific so stimulates all receptors

-frequent or urgent urination

-drooling

-nausea

-diarrhea

-watery eyes, sweating

severe side effects:

bethanechol

-Bronchospasm, wheezing, difficulty breathing

-brady

-⬇ BP

-cardiac collapse

contraindications:

bethanechol

-urinary blockages (❌)

-gastrointestinal obstructions (❌)

-ulcers

-asthma

-epilepsy

-hyperthyroidism

🐱 uses:

suxamethonium

-used in intubation to stop arytenoids from spasming and collapse

general use:

suxamethonium

-rapid, short acting m paralysis

-can be: pre-med to in euthanasia to eliminate agonal movements

brands (human):

suxamethonium

-Anectine

-Quelicin

uses:

Edrophonium/Tensilon

-used to dx myasthenia gravis

-antidote to nondepolarizating m relaxants

general side effects:

Edrophonium/Tensilon

(quickly dissipates)

-cholinergic (muscarinic) effects

side effects - severe:

Edrophonium/Tensilon

cholinergic crisis

-brady

-⬇ breathing

-spasms

-loss of GI control

uses:

Physostigmine/neostigmine

-antidote anticholinergic toxicities (can cross BBB

-antidote to anesthesia & Ivermectin toxicosis

-tx for myasthenia gravis

side effects:

Physostigmine/neostigmine

-stimulation of parasympa NS

-cholinergic crisis

-too fast → parasympa effects

brands:

Physostigmine

-Anticholium* (German brand to address US shortage) *2026

-Antilirium → Physostigmine Salicylate Injection

brands:

neostigmine

-Bloxiverz

-Prostigmin

-Neostigmine Omega