Pharm -7- Cholinergic Agents Flashcards

Muscarinic acetylcholine receptor
Terms Definitions
What do cholinomimetics, parasympathomimetics, muscarinic agonists have in common
they are all cholinergic agonists
What are acetylcholine, methacholine, carbacol and Bethanechol
Choline Esters
What are muscarine, pilocarpine
Natural Alkaloids
What is the new M1/M3 specific agonist
Cevimeline
Why would you use other choline esters in place of just admnisitering acetylcholine
Acetylcholine is very susceptible to cholinesterase and gets broken down faster than other choline esters
Drug used for disorders associated with decreased Parasymp tone, used postoperative and postpartum for urinary retention and/or inadequate emptying of bladder. Helps correct abdominal distention and GI tract atony after surgery
Bethanchol
What is the MOA of bethanechol
acts at the muscarinic receptors to contract detrusor muscle and increase GI motility
What drug is used in acute and chronic glaucoma to reduce intraocular pressure and is better tolerated than AChE inhibitors. Also used to counteract atropine used in pupillary dilation and to treat dry mouth
Pilocarpine,
What is the MOA of pilocarpine
acts on M1/M3 receptor of constrictor pupillae to cause constriction of pupil and acts on M1/M3 receptors of salivary gland to increase secretion to combat xerostomia(dry mouth)
Why do you need to be careful in administering pilocarpine in the eye
it is a tertiary amine and can cross the conjunctiva leading to systemic effects
Drug that is used to treat Xerostomia(dry mouth) following head and neck irradiation, or associated with Sjoogren's syndrome
Cevimeline (evoxac)
What is the MOA of Cevimeline (evoxac)
newer M3 receptor agonist selective potent action at salivary glands and lacrimal glands, with fewer side effects than pilocarpine
What are the muscarinic agonists s/e
SLUD, salivation, lacrimation, urination urgency, defecation (diarhhea). Can cause hypotension and reduce coronary blood blow
What are some of the s/e of pilocarpine
CNS disturbances, excess salvation
why are muscarinic agonists contraindicated in asthma patients
they can cause bronchoconstriction and increase mucus secretions,
Why are muscarinic agonists contra ind in hyperthyroidism
they can cause hypotension which can trigger reflex increase in sympathetic activity to heart leading to arrythmia
What do the following have in common-
atropine, scopolamine, homatropine, pirenzepine, ipratropium, tiotropium, and tolterodine
All are muscarinic Receptor Antagonists
What are the belladona alkaloids
atropine, scopolamine and homatropine
What are the synthetic and semisynthetic derivates of belladona alkaloids that are muscarinic receptor antagonists
Pirenzepine, ipratropium, tiotropium, tolterodine
What are the clinical uses of atropine
produces mydriasis and cycloplegia for eye exam
antispasmodic
treat organophosphate insecticide poisoning
suppress respiratory secretions prior to surgery
What is the MOA of atropine
non selective muscarinic antagonist
in the Eye- blocks all parasympathetic effects on the eye causing mydriasis and cycloplegia(loss of accomodation)
GI- Reduces GI motility
Salivary, sweat and lacrimal glands- reduces all secretions
What problems do you start to see as you increase the dose of atropine
low dose you get cardiac slowing, dryness of mouth and inhibition of sweating. But as dose increases you get rapid heart rate, palpitation, marked dryness of mouth and some blurring of near vision and with high dose you get hallucinations and coma
What are the clincial uses of scopolamine a muscarinic receptor antagonist
prophylactic for motion sickness, adjunct drug in anesthesia to produce sedation and amnesia
Which drug cross the BBB better at clinical doses atropine or scopolamine
Scopolamine crosses much more than atropine (which barely crosses in therapeutic doses)
What are the s/e of scopolamine
CNS depression, drowsiness, amnesia, fatigue, loss of REM sleep
Drug used in asthma & COPD to cause bronchodilation either as an adjunct to albuterol or instead of albuterol in patients who can't take adrenergic agonists
Ipratropium Bromide (atrovent)
What is the MOA of Ipratropium Bromide (atrovent)
Blocks muscarinic receptors and reduces bronchoconstriction mediated by parasympathetic system, Less CNS effects and minimal inhibitory effect on mucocilary clearance
What are the clinical uses of Tiotropium Bromide (spiriva)
used in COPD and asthma alot more bronchoselective greater affinity for M1/M3 than M2
What are the clincal uses for tolterodine (detrol)
treatment of overactive bladder, Reduces number of incontinent episodes, increase amount of urine the bladder can hold, reduces frequency of urniation and urgency
what is the MOA of tolterodine (detrol)
Blocks M3 receptors on detrusor muscle reducing PSNS mediated contraction of the Bladder, Also Block M2 receptors and presynaptic SNS terminal enhancing SNS B2 relaxation of the detrusor
-Also act on the trigone and internal sphincer preventing leaks
What are
Solifenacin (Vesicare)
Darifenacin (Enablex)
Oxybutynin (Ditropan)
they are M3 antagoinists like Tolterodine
When are M3 antagonists like Tolterodine and Solifenacin (Vesicare), Darifenacin (Enablex),Oxybutynin (Ditropan) Contraindicated
they slow voiding and therefor are not appropriate in individuals with urinary retention such as Benign Prostatic Hyperplasia,
what are the s/e of muscarinic antagonists
blurred vision, confusion, mydriasis, constipation, urinary retention
Are ganglionic blockers if nicotinic receptors widely used
NO very few drugs in this category are clinically used
Since nicotinic ganglionic blockers are widely used where would you use nicotinic blockers
neuromuscular junction
What do NMJ blockers do
block cholinergic transmission between somatic motor nerve endings and the nicotinic receptors of skeletal muscles
What are the clinical uses of neuromuscular juction nicotinic blockers
skeletal muscle relaxants/ used in surgery to produce complete muscle relaxation
What type of NMJ blocker is succinyl choline
depolarizing blocker
what are the two types of NMJ blockers
non-depolarizing and depolarizing blockers
what type of NMJ blocker are
Atracurium
Cistracurium
Vecuronium
Rocuronium
Pancuronium
Tubocurarine
are non-depolarizing NMJ blockers competitive or non-competitive blockers
competitive
What is succinyl choline made of
two acetylcholine molecules linked end to end
What is the onsent and duration of succinyl choline
rapid onset but short duration because it gets metabolized by plasma cholinesterase
What is a phase 1 block of NMJ nicotinic receptors
membrane depolarizes resulting in initial discharge that produces fasciculation followed by falccid paralysis
Can A phase 1 block be reversed by AchE inhibitors
NO
What is a Phase II block of NMJ nicotinic receptors
membrane repolarized but is desensitized to the effect of acetylcholine
What are the s/e of using succinylcholine NMJ depolarizing blocker
muscle pain postoperatively due to damaged muscle by hyperkalemia, at high doses can block ganglionic nicotinic receptors (decreasing heart rate and increased IOP)
-serious s/e is malignant hyperthermia
What is the MOA of AchE (acetylcholine esterase) inhibitors
Inhibit acetylcholineesterase and prolong enhance actions of acetylcholine
What are the potential sites of action of AchE inhibitors
all effector organs innervated by PSNS, NMJ and all autonomic ganglia
What are the three main types of AchE inhibitors
Short, Intermediate, Irreversible
What are the clinical uses of AchE inhibitors
tx of myasthenia gravis, hypotonia of bladder and GI and glaucoma
What is the clinicla use of Physostigmine an AchE inhibitor
used to treat Glaucoma, or as an antidote to atropine and other anticholinergic drug poisonings
What problems can physostigmine an AchE inhibitor cause at high doses
convulsions, bradycardia leading to fall in cardiac output and muscle paralysis
What is the clinical use of Neostigmine
cannot cross BBB and has greater effect at NMJ so is used to treat myasthenia Gravis
what are the adverse effects of neostigmine an AchE inhibitor
generalized cholinergic stimulation and drop in b/p overdosage can cause cholinergic crisis and muscle paralysis
What can be administerd in organophosphate poisoning
pralidoxime which can reactivate acetylcholinesterase cannot penetrate BBB
Review Slide 52
review Slide 52
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