Pharmacology Flashcards
Heart
Parasympathetic= M2
—> Decreased HR, Decreased Conduction v, AV block.
Sympathetic= Beta-1
—
Lungs
Parasympathetic= M2, M3
—> Bronchoconstriction, Increased secretions
Sympathetic= Beta-2
—> Bronchodilation
Arteries
General aa:
- Sympathetic: Alpha-1 (constriction)
- Parasympathetic: No innervation
Sk mm aa:
- Sympathetic: Beta-2 (dilation)
- Parasympathetic: No innervation
Endothelium:
- Sympathetic: None
- Parasympathetic: M3 —> NO= Dilation
GI Tract
Sympathetic:
- Motility and Tone: Alpha, Beta
- Sphincters: Alpha-1 —> Contraction
- Secretions: Alpha-2 —> Decreased
Parasympathetic:
M2 & M3= Motility and tone increase, relax GI sphincters, increase secretion
Urinary Bladder
Detrusor
- Sympathetic —> Beta-2 relaxation
- Parasympathetic —
Eyes
Radial MM/Iris
- Sympathetic —> alpha-1 = Mydriasis (dilated pupil)
- Parasympathetic —> None
Sphincter Muscle/Iris
- Sympathetic —> None
- Parasympathetic —> M2, M3 = Miosis (constricted pupil)
Ciliary epithelium
- Sympathetic: alpha-2 decreases aq humor, B-2 increases aq humor
- Parasympathetic: None
SLUDGE
Excessive cholinergic stimulation
Salivation, Lacrimation, Urination, Defecation, GI symptoms, Emesis
Acetylcholine (Endogenous cholinergic)
Direct Acting Cholinergic Agonist
- Rarely used clinically bc has both muscarinic and nicotinic stimulation @ ganglion —> both sympathetic and parasympathetic
- Rapid degeneration by AChE and plasma butrylycholinesterase
Bethanecol (choline ester)
Direct acting cholinergic agonists
- Muscarinic: some M3 selectivity —> GI and urinary selectivity —> promotes voiding
- Use ONLY WHEN OBSTRUCTION ABSENT
Muscadine (cholinergic alkaloid)
Direct Acting Cholinergic Agonist
Stimulates muscarinic receptors (ALL OF THEM)
Found in mushrooms, not used clinically
Pilocarpine (Cholinergic alkaloid)
Direct acting cholinergic agonist
Muscarinic stimulation
- Used in ophthalmic topically to induce pupil CONSTRICTION (M2 and M3 on radial mm of eye, constricts iris)
(Rare to use for salivation promotion)
Indirect acting cholinergic agonists
Usually they are Acetylcholinesterase (AChE) inhibitors: prevent hydrolysis of acetylcholine
Accumulation at ACh sites of release at autonomic effector organs/ganglia, skeletal mm, cholinergic synapses in CNS (essentially, it effects WHEREVER ACh is a mediator)
Indirect acting cholinergic agonists- Reversible Covalent Inhibitors
Physostigmine, Neostigmine
Uses:
- REVERSAL OF COMPETITIVE NON-DEPOLARIZING NM BLOCKING AGENTS
- Counter CNS symptoms of anticholinergic intoxication (PHYSOSTIGMINE)
- Myasthenia gravis
- SM atony (GI/Urinary)
- Glaucoma (topical)
PHYSOSTIGMINE HAS NO QUATERNARY COMPOUND —> CROSSES BBB
(Neostigmine has no quat compound —> can’t cross BBB)
Cholinergic Antagonists
Aka parysympatholytics, anticholinergics
Block the effects of endogenous acetylcholine at MUSCARINIC receptors (little effect on ACh at nicotinic receptors)
Effects (“Decrease Parasympathetic”, “ANTI-SLUDGE”):
- M2: Increase CO: Increase HR, conduction v
- M3: Very little effects on arteries, urinary retention favored
- M2&3: Bronchodilation and decreased secretion, Decreased GI motility, tone, secretions, pupils dilated and decreased secretions, cycloplegia (paralysis of ciliary m resulting in loss of accommodation)
Atropine (Cholinergic antagonist)
COMPETITIVELY antagonizes (shift RIGHT) to binding and stimulation of muscarinic receptors by ACh and other agonists
Used as adjunct to general anaesthesia to decrease salivary/airway secretion (ANTI-SLUDGE)
Derived from atropa belladonna (deadly nightshade)
Enters the CNS (non-quat., toxicity possible, excitation followed by depression)
Primary concerns: tachyarrhythmia, prolonged GI stasis, urine retention. Especially in horses!
