ANS Mimetics & Lytics Flashcards
Parasympathetic Presynaptic Receptor and Neurotransmitter
N - Nicotinic (Cholinergic)
ACh - Acetylcholine
Parasympathetic Postsynaptic Receptor and Neurotransmitter
M1-5 - Muscarinic (Cholinergic)
ACh - Acetylcholine
Direct Parasympathomimetic (1)
Bethanechol (PO)
Reversible, Indirect Parasympathomimetics (3): Acetylcholinesterase Inhibitor, Cholinesterase Inhibitor, Anticholinesterase, Cholinergic
Edrophonium (inj)
Neostigmine (inj, PO)
Pyridostigmine (inj, PO, ER)
Direct Parasympatholytics (4): Muscarinic Antagonist, Anticholinergic, Antimuscarinic
Atropine (inj, PO, ophth)
Glycopyrrolate (inj)
Oxybutynin (PO, ER)
Propantheline (PO, ER)
M3 selectivity at detrusor muscle for contraction of the bladder; also stimulates contraction of GI smooth muscle
Bethanechol
Shortest to Longest Onset and Duration of Action for Reversible, Indirect Parasympathomimetics: Edrophonium, Neostigmine, Pyridostigmine
Edrophonium 1min to 10min
__________ is used for the Tensilon Response test for canine myasthenia gravis.
Edrophonium
__________ is most commonly used to treat canine myasthenia gravis.
Pyridostigmine
_________ crisis: caused by not enough ACh/receptor interactions
myasthenic
__________ crisis: caused by too many ACh/receptor interactions
cholinergic
Carbaryl ad Propoxur are examples of Carbamate insecticides, which are __________, indirect parasympathomimetics.
reversible
Chlorpyrifos, Diazinon and Malathion are examples of Organophosphate insecticides, which are __________, indirect parasympathomimetics.
irreversble
Which is metabolized faster, carbamate or organophosphate insecticides?
carbamate
Carbamate insecticides are less selective for motor end plate nicotinic receptors than Edrophonium, Neostigmine or Pyridostigmine; but more likely to cross the blood-brain barrier leading to CNS signs such as seizure. True or False
True
Primary Signs: Muscarinic (associated with Carbamate and Organophosphate toxicity)
DUMBBELS Diarrhea Urination Miosis (+++ pupil constriction) Bronchospasm Bradycardia Emesis (vomiting) Lacrimation Salivation
Secondary Signs: Nicotinic (associated with Carbamate and Organophosphate toxicity)
muscle tremors
weakness
paralysis
CNS excitement less common
Tertiary Signs (associated with Carbamate and Organophosphate toxicity)
Nicotinic Blockade
Treat carbamate or organophosphate toxicity with __________ for nonspecific counteraction of physiologic and muscarinic effects.
Atropine
__________ is required in early stages of onset of organophosphate toxicity in order to break the chemical bonds prior to “aging” (irreversible development of strong bond holding organophosphate to the active site of acetylcholinesterase)
Antidote: Pralidoxime (2-PAM)
Prototypical nonspecific muscarinic antagonist:
Atropine
Atropine is an __________ originally extracted from the belladonna plant.
alkaloid (Alkaloid, any of a class of naturally occurring organic nitrogen-containing bases. Alkaloids have diverse and important physiological effects on humans and other animals. Well-known alkaloids include morphine, strychnine, quinine, ephedrine, and nicotine.)
Glycopyrrolate has a slower onset of action and longer duration of action than Atropine. True or False
True: Glycopyrrolate onset 30min, duration 2-3h
CAUTION in __________ with atropine, since it decreases intestinal motility and may lead to adynamic ileus.
horses, equids
_________ is the paralysis of the ciliary muscle of the eye leading to loss of lens accommodation and blurred vision. CAUTION in _________ with atropine, since blurred vision can caused panic.
cycloplegia; horses
_________ have endogenous atropinases and thus metabolize atropine rapidly, limiting its clinical utility in this species.
rabbits
Atropine is indicated for __________ crisis.
cholinergic
Shortest to Longest Onset and Duration of Action for Parasympatholytics: Atropine, Glycopyrrolate
Atropine
Which is more arrhythmogenic, Atropine or Glycopyrrolate?
Atropine
Glycopyrrolate is a quaternary ammonium compound; it does not cross the blood-brain barrier and is therefore less likely to cause CNS effects. True or False
True
Glycopyrrolate is perferred over Atropine in rabbits. True or False
True
Pharmacokinetics and Indications for Oxybutynin are congruent with those of Propantheline; EXCEPT Oxybutynin is widely distributed whereas Propantheline does not cross the blood-brain barrier. True or False
True
At normal doses of Oxybutynin and Propantheline, the __________ and __________ appear to be the most affected.
bladder, intestinal tract (large intestine***)
Antispasmodic indicated for the GI tract:
Aminopentamide
Antispasmodic indicated for colic in equids and also used to treat bradycardia:
Buscopan (N-Butylscopolammonium Bromide)
Parasympathetic Effects: EYE (2)
1) contraction of ciliary muscle: lens accommodation for myopia (short/near-sightedness)
2) contraction of iris sphincter muscle for miosis (constriction)
Sympathetic Effects: EYE (3)
1) relaxation of ciliary muscle: lens accommodation for hypermetropia (long/far-sightedness)
2) contraction of iris radial muscle for mydriasis (dilation)
3) decrease aqueous humor production
Parasympathetic Effects: HEART (3)
1) decreased heart rate: bradycardia
2) decreased contractility: -ve inotropy
3) decreased AV node conduction
Sympathetic Effects: Beta 1: HEART (3)
1) increased heart rate: tachycardia
2) increased contractility: +ve inotropy
3) increased automaticity and increased AV node conduction
Parasympathetic Effects: VASCULATURE (1)
1) indirect vasodilation through release of endogenous nitrous oxide (NO) from endothelium
Sympathetic Effects: VASCULATURE (3)
1) Alpha 1 - vasoconstriction
2) Beta 2 - vasodilation
3) Alpha 2 - various (vasoconstriction/dilation)
Parasympathetic Effects: LUNG (2)
1) bronchoconstriction
2) increase respiratory secretions
Sympathetic Effects: Beta 2: LUNG (1)
Bronchodilation
Parasympathetic Effects: GI TRACT (3)
1) increase motility
2) relax sphincters
3) stimulate secretion
Sympathetic Effects: Alpha 1, Beta 1, Beta 2: GI TRACT (3)
1) decrease motility
2) contract sphincters
3) inhibit secretion
Parasympathetic Effects: URINARY BLADDER (2)
1) contract detrusor
2) relax sphincter
Sympathetic Effects: Alpha 1, Beta 2: URINARY BLADDER (2)
1) Alpha 1: contract sphincter
2) Beta 2: relax detrusor muscle
DRUG + ACTION @ urinary bladder: contract detrusor muscle
Bethanechol: Direct Parasympathomimetic (M3+++)
DRUG + ACTION @ urinary bladder: contract internal sphincter
Phenylopropanolamine, Estrogens: Mixed Sympathomimetic
DRUG + ACTION @ urinary bladder: relax detrusor muscle
Oxybutynin or Propantheline: Direct Parasympatholytics
DRUG + ACTION @ urinary bladder: relax internal sphincter
Phenoxybenzamine (Alpha nonselctive) or Prazosin (Alpha 1): Direct Sympatholytics
Cholinergic Receptors (2)
Nicotinic + Muscarinic
Nicotinic receptors are ________ receptors.
ionotropic
Muscarinic receptors are ________ receptors.
metabotropic (g protein coupled)
Nicotinic: Nm subtype represents
Nm are nicotinic receptors found at the neuromuscular junction (NMJ)
Nicotinic: Nn subtype represents
Nn are nicotinic receptors found at CNS and autonomic ganglia
There are _____ subtypes of muscarinic receptors:
5
M 1, 3, 5 are ________
stimulatory
M 2, 4 are ________
inhibitory
Adrenergic Receptors (2)
Alpha + Beta
Both Alpha and Beta receptors are ________ receptors.
metabotropic (g protein coupled)
There are _____ subtypes of alpha receptors:
2
There are _____ subtypes of beta receptors:
3
Parasympathetic signs are observed with the use of ________ and ________ drugs.
Parasympathomimetic and Sympatholytic
Sympathetic signs are observed with the use of ________ and ________ drugs.
Sympathomimetic and Parasympatholytic
Both endogenous and synthetic catecholamines have ___ oral bioavailability but are readily absorbed from the respiratory tract (inhalation or nebulisation).
low
Direct Sympathomimetics: Endogenous Catecholamines (3)
Epinephrine (inj)
Norepinephrine (inj)
Dopamine (inj)
Direct Sympathomimetics: Synthetic Catecholamines (4)
Dobutamine (inj)
Isoproterenol (inj)
Phenylephrine (inj, PO, intranasal, ophth)
Ractopamine/Zilpaterol
BUT PHENYLEPHRINE AND RACTOPAMINE IS NOT TECHNICALLY A CATECHOLAMINE
Epinephrine, an adrenergic agonist, activates 5 receptors:
1) Alpha 1
2) Alpha 2
3) Beta 1
4) Beta 2
5) Beta 3
Epinephrine @ Alpha 1:
vasoconstriction (at high doses)
Epinephrine @ Beta 2:
bronchodilation, vasodilation (at low doses)
Epinephrine @ Beta 1:
cardiac contraction
Epinephrine indications (3):
1) cardiac arrest
2) anaphylaxis
3) vasopressor effect
Norepinephrine, an adrenergic agonist, activates 3 receptors:
1) Alpha 1*
2) Alpha 2*
3) Beta 1
Which is the stronger vasocontrictor, Epi or Norepi; leading to strong baroreceptor response and decrease in heart rate and contractility in spite of Beta 1 effects?
NE (reflex vagal bradycardia as a result of baroreceptor response is therefore more common with no repinephrine)
Avoid extravasation with ________ and ________.
Norepinephrine and Dopamine
Dopamine and Dobutamine have a very _____ half life.
short (minutes)
Dopamine action @ low to medium dose
peripheral dopamine receptor agonist: dilation of vascular beds (renal, mesenteric, coronary, intercerebral)
Dopamine action @ medium to high dose
Beta 1 agonist (+ve inotrope, +ve chronotrope)
Dopamine action @ high dose
Alpha 1 agonist (vasoconstriction with NE release), Beta 1 agonist (+ve inotrope, +ve chronotrope)
Dobutamine, a synthetic catecholamine that act as direct sympathomimetics, acts primarily at ______ receptors, with minor action at ______ and ______ receptors.
Primary: Beta 1
Minor: Alpha 1, Beta 2
Isoproterenol, a synthetic catecholamine that act as direct sympathomimetics, acts primarily at ______ and ______ receptors.
Beta 1 + Beta 2
Phenylephrine is a synthetic catecholamine that acts as a direct sympathomimetic at _____ receptors, indicated for treatment of hypotension and shock.
Alpha 1
Direct Sympathomimetics: Selective Beta 2 Agonists (4)
Albuterol
Clenbuterol
Terbutaline
Isoxuprine
Albuterol, Clenbuterol, Terbutaline and Isoxuprine are agonists at _____ and minor agonists at ______ receptors.
Primary Agonist: Beta 2
Minor Agonist: Beta 1
Nonspecific alpha adrenergic antagonist or alpha blocker, direct sympatholytic, indicated for the treatment of a hypertonic urethral sphincter (drug will relax sphincter) and pheochromocytoma
Phenoxybenzamine
Specific Alpha 1 antagonist or Alpha 1 blocker, direct sympatholytic, indicated for the treatment of a hypertonic urethral sphincter (drug will relax sphincter)
Prazosin
Class II antiarrhythmics indicated for the treatment of tachycardia:
beta adrenergic antagonists or beta blockers
Nonselective beta blocker may also be considered an inverse agonist.
Propanolol
Selective Beta 1 blocker
Atenolol, Esmolol
Oral bioavailability of propanolol is ___ to ___% due to significant first-pass metabolic effect; thus the oral dose is significantly greater than the injectable on a mg/kg basis.
2 to 27%
Propanolol is indicated for its beta 2 blockade effects: (3)
bradycardia, bronchospasm, hypotension; bradycardia by decreasing SA and AV node conduction and by decreasing cardiac output and myocardial oxygen demand
Propanolol is indicated in the treatment of: (3)
supraventricular tachyarrhythmias subsequent to feline hyperthyroidism and methylxanthine/chocolate toxicosis
Propanolol is mostly secreted as metabolites in
urine
Propanolol readily crosses the blood-brain barrier. True or False
True
The half life for propanolol is ____
1-2h
Degree of passing the blood-brain barrier among beta blockers:
Propanolol (readily crosses) > Atenolol > Esmolol (does not cross)
Half life among beta blockers:
Atenolol (2h) > Propanolol > Esmolol (20min)
Propanolol has membrane stabilizing effects where as Esmolol lacks these effects.
True
Atenolol requires minimal liver metabolism (___% excreted in the urine and ___% excreted in the feces.)
50/50
Atenolol is a better choice for patients with respiratory disease due to Beta 1 selectivity with lack of Beta 2 effects that Propanolol antagonises. True or False
True
Indirect Sympatholytic, blocks vesicular monoamine transporters thus reducing norepinephrine uptake into vesicles, leading to reduced NE storage and mediator depletion: used as a calming agent for equines in situations such as long term stall rest
Reserpine
______ ______ ______ are indicated primarily for treatment of asthma (feline) and COPD (equine).
Selective Beta 2 Agonists (Direct Sympathomimetics): Albuterol, Clenbuterol, Terbutaline
Selective Beta 2 Agonist, Direct Sympathomimetic, indicated as a peripheral vasodilator and tocolytic (uterine relaxation).
Isoxuprine
Nonselective Beta Agonist: activation of Beta 1+2+3: indicated as a partitioning agent for increase of muscle deposition in late finishing food production animals
Ractopamine/Zilpaterol
Indirect Sympathomimetics: 3 Groups
1) Tricyclic Antidepressants
2) Monoamine Oxidase Inhibitors (MAOIs)
3) Illicit Drugs
Illicity Drugs as Indirect Sympathomimetics:
Amphetamine + Cocaine
Amphetamine MOA
blocks NE release
Cocaine MOA
blocks NE re-uptake
Monoamine Oxidase Inhibitor MOA
inhibit MAO-B thus inhibiting the breakdown of dopamine; at high doses can also inhibit MAO-A thus inhibiting the breakdown of norepinephrine; also metabolises amphetamine to methamphetamine
Mixed Sympathomimetics indicated for indirect increase in release of Norepi
Phenylpropanolamine + Ephedrine/Pseudoephedrine
Phenylpropanolamine (PPA) acts primarily to increase norephinephrine release at ___________: Mixed Sympathomimetic
the neck of the bladder (urethral sphincter)
Ephedrine is indicated for use as a CRI to maintain ___________ under anaesthesia.
blood pressure
Ephedrine can be a component of some Chinese Herbal Therapies such as _____ ________.
Ma Huang
________ to PPA is seen in human patients but not veterinary patients.
tachyphylaxis
________ increase expression of Alpha 1 receptors in the internal urinary sphincter; synergism is observed when PPA is used in conjunction with hormonal therapies.
Estrogens (Diethylstilbestrol, Estriol)
PPA MOI
treatment of urinary incontinence due to urethral sphincter hypotonus