ACh Agonists/Antagonists Flashcards
where does Botulinum toxin bind
presynaptically to cholinergic nerve terminals
what is the MOA of BoNT
cleaves SNAP and VAMP to decrease Ach release
what are the uses of BoNT
cosmetic, muscle spasms, dystonia and spasticity
what splits Ach into Choline
Acetylcholinesterase (AChE) and butyrylcholinesterase (pseudo cholinesterase)
What’s the difference between true vs. pseudo AChE
True: very fast, works @ all cholinergic sites, more sensitive to physostigmine
Pseudo: slower, works primarily in plasma, more sensitive to organophosphates
What is the route of elimination for Atracurium
plasma esterase
What is the route of elimination for Cisatracurium
Spontaneous chemical degredation-Laudanosine (Hofmann elimination)
What is the route of elimination for pancuronium
renal excretion
What is the route of elimination for Rocuronium
Biliary and renal excretion
What is the route of elimination for Vecuronium
Biliary and renal excretion; hepatic metabolism
What is the route of elimination for succinylcholine (depolarizing)
Plasma butyryl (pseudo cholinesterase)
What is the suffix for the majority of Nm blockers
“curium” or “curonium” (exception succinylcholine)
name a Nm blocker with the shortest duration of action
Succinylcholine
one side effect of succinylcholine is hyper/hypokalemia
hyperkalemia via efflux from muscles
What are the major side effects of succinylcholine
prolonged apnea, hyperkalemia, postoperative myalgia, malignant hyperthermia
What drug blocks muscarinic receptors
Atropine
What are Ach actions on the heart (M2)
SA node hyperpolarization, reduced force of contraction
What are Ach actions on the blood vessels (M3)
Penile erection, otherwise limited to skin of face and neck (vasodilation)
What are Ach actions on smooth muscle (M3)
Contraction of all SM; i.e. voiding of bladder, diarrhea, etc.; can induce asthma attack
What are Ach actions on the glands (M3)
Increased secretions
What are Ach actions on the eye (M3)
miosis (constriction); increased outflow and reduced IOP
What side effects can you expect in a patient taking a cholinergic drug
SLUDGE MOBBB
salivation, lacrimation, Urination, defecation, gastrointestinal distress, emesis, bradycardia, bronchorrhea, bronchospasm
What is the MOA of bethanechol and what are its clinical uses
muscarinic agonist; ileus, urinary retention
______ is used as a broncho provocative test
methacholine (muscarinic agonist)
cevimeline is used to treat ________
xerostomia
xerostomia can be treated with the muscarinic agonist, __________
cevimeline
what muscarinic agonist is used to treat glaucoma
pilocarpine
What is the MOA of pilocarpine
opens iridocorneal angle to treat glaucoma
what are the three synthetic reversible anticholinesterases that work on skeletal muscles
neostigmine, pyridostigmine, edrophonium
What two synthetic reversible anticholinesterases target the CNS
Donepezil and rivastigmine
what is the only naturally occurring reversible anticholinesterase?
Physostigmine
What are the common names for the irreversible anticholinesterases
tear gas and insecticides
what type of bond do reversible anticholinesterases form with AchE
ionic (weaker)
what is the MOA of anticholinesterases
inhibition of the hydrolyses of acetylcholine to acetic acid and choline
what type of bond do irreversible anticholinesterases form with AchE
covalent bond at esteric site
How does the MOA differ between carbamates and phosphates as it relates to irreversible anti-AchE
carbamates react with water quicker than phosphates, making them incapable of aging
What does aging mean as it relates to phosphates (anti-AchE)
resistant to hydrolysis due to the stability caused by the loss of alkyl group(s)
physostigmine/neostigmine has good oral absorption
physostigmine
physostigmine/neostigmine can cross the BBB
physostigmine (tertiary amine vs neostigmine being quaternary)
neostigmine can be used to treat eyes/myasthenia gravis?
myasthenia gravis. it cant cross BBB
neostigmine and (synthetic/natural) whereas physostigmine is (synthetic/natural)
synthetic; natural
what drug is used to Dx myasthenia AKA “tensilon test”
Edrophonium (this is used because in pts w MG, when you inject it you’ll see improvement in muscle contraction
what is the antidote used in atropine overdose
physostigmine
what drugs can be used to reverse nondepolarizing NM blockers
Neostigmine, pyridostigmine
what two anti-AchE drugs are used to treat alzheimers
donepezil and rivastigmine
What is the treatment for OPC poisoning
Atropine, gastric lavage, airway maintenance/BP/fluid and electrolytes, cholinesterase reactivators (oximes)
what is the MOA of cholinesterase Reactivators (oximes)
provide reactive group of OH to the enzymes
Are oximes effective in carbamate poisoning?
NO
At what point are cholinesterase reactivators not effective for OPC poisoning?
once aging has set it (about 30 min)
what type of drugs are carbaryl and propoxur
carbamates
whats another name for carbaryl and propoxur
baygon (carbamates)
what type of drugs are echothiophate, parathion and malathion
organophosphorus compounds (OPC)
The drugs, tabun, sarin, and soman are otherwise known as _____
tear gas
what receptors do anticholinergic drugs target?
muscarinic (M1-5) and nicotinic (NN and NM)
nicotinic NN antagonists are otherwise known as
ganglion blockers
NM blockers are otherwise known as
neuromuscular blockers
what is the clinical use of the antiAch drug atropine
antispasmodic, antisecretory, OPC poison antidote, mushroom poisoning, antidiarrheal
what is the clinical use of the antiAch drug scopolamine
motion sickness (given as patch), causes sedation
what is the clinical use of the antiAch drug Ipratropium and Tiotropium
Asthma and COPD (inhalational)
what is the clinical use of the antiAch drug Tropicamide
Eye (topical) mydriatic (short-acting– most widely used at the eye doctor)
what is the clinical use of the antiAch drug benztropine and trihexyphenidyl
CNS (lipid-soluble), used in parkinsonism and in EPS induced by antipsychotics
what is the clinical use of the antiAch drug oxybutynin
used in overactive bladder (urge incontinence)
atropine has a long duration of action for ____
eyes
what is the clinical use of the antiAch drugs TCA’s, phenothiazines and antihistaminics
significant antimuscarinic action
can small doses of atropine be overcome by a large concentration of Ach/muscarinic agonist
yes
Atropine does not distinguish between M1, M2, or M3 TRUE or FALSE
True
atropine can cause loss of what eye reflex?
accommodation
Why is atropine hazardous in narrow angle glaucoma patients?
it causes a rise in IOP
is atropine safe for COPD and asthma patients
yes, it is a bronchodilator
what is the first line therapy for symptomatic bradycardia
atropine
what are the two contraindications of atropine
narrow angle glaucoma and BPH
what is the antidote for atropine poisoning (belladonna)
physostigmine (SC or IV)
what are the two selective ganglion agonists/stimulants
nicotine and varenicline
Ach, carbachol, pilocarpine are all examples of ganglion stimulants/blockers?
stimulants
what type of drug is hexamethonium
competitive ganglion blocker
what type of drug is mecamylamine
competitive ganglion blocker
what are the effects of mecamylamine and hexamethonium
tachycardia, vasodilation, hypotension, decreased venous return and decreased CO
what can varenicline and bupropion be used to treat
nicotine dependence
what is the MOA of varenicline
partial agonist of alpha4 B2 nicotinic receptors
what is the MOA of bupropion
inhibition of reuptake of NE and dopamine as well as a nicotinic ach antagonist