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Cholinergic Drugs
n/a
53
Pharmacology
Graduate
09/04/2012

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Term
What are the different classes of cholinomimetic/parasympathomimetic drugs?
Definition
Direct acting (cholinergic agonists) and indirect acting (acetylcholinesterase inhibitors)
Term
What are the different classes of cholinergic antagonist/parasympatholytic drugs?
Definition
Muscarinic antagonists and nicotinic antagonists
Term
What choline esters act as cholinergic agonists?
Definition
Acetylcholine, methacholine, carbachol, bethanechol
Term
What natural alkaloids at as cholinergic agonists?
Definition
Muscarine and pilocarpine
Term
What neurotransmitters/drugs are hydrolyzed by acetylcholinesterase?
Definition
Acetylcholine and methacholine
Term
Which cholinergic drugs have receptor specificity for both muscarinic and nicotinic receptors?
Definition
Acetylcholine, methacholine, and carbachol. Others are only specific for muscarinic receptors
Term
What are the clinical uses of Bethanechol (Duvoid)?
Definition
Disorders associated with decreased parasympathetic tone, postoperative or postpartum urinary retention and/or inadequate emptying of bladder, postoperative abdominal distention of GI atony or paresis. Acts at muscarinic receptors to contract detrusor muscle or increase GI motility
Term
What are the clinical uses of pilocarpine (ocusert, pilocar)
Definition
Topical formulations to reduce intraocular pressure in certain glaucomas, treat dry mouth (xerostomia), or to reverse the effects of atropine (used to dilate pupil)
Term
How does pilocarpine reduce intraocular pressure?
Definition
Improves drainage by contracting the sphincter pupillae (M3 receptor) and reducing angle block (however, crossing the conjunctiva may lead to systemic effects)
Term
How does pilocarpine reduce xerostamia (dry mouth)?
Definition
M3 receptors on salivary gland
Term
What are the clinical uses of cevimeline (Exovac)
Definition
Treats xerostamia following head irradiation or xerostamia associated with Sjogren's syndrome
Term
What is the mechanism of action of cevimeline?
Definition
Acts as M3 receptor specific agonist, selective for salivary and lacrimal glands, fewer side effects than pilocarpine
Term
What are some side effects of muscarinic agonists?
Definition
Diarrhea, diaphoresis, miosis, nausea, salivation, urinary urgency, CNS disturbances with drugs that cross the blood brain barrier such as pilocarpine
Term
What are some contraindications for use of muscarinic agonists?
Definition
Patients with asthma due to induced bronchoconstriction and increased mucous secretions, patients with heart disease due to slowed conduction of cardiac APs through the AV node and potential hypotension and reduced coronary blood flow if given intravenously
Term
What is the difference between real and pseudo cholinesterase?
Definition
Acetycholinesterase (real) resides in the synapse and degrades Ach, plasma cholinesterase and butyryl cholinesterase (pseudo) circulate and are non-specific esterases that removes circulating Ach (reason why Ach cannot be used pharmacologically)
Term
What are the potential sites of action for acetylcholinesterase inhibitors?
Definition
All effector organs innervated by parasympathetics such as the eye, GI, urinary bladder, the nueromuscular junction, all autonomic ganglia
Term
What are the short lasting (~10 min) reversible AChE inhibitors?
Definition
Erdophonium (phonies can't make it!)
Term
What are the intermediate lasting reversible AChE inhibitors?
Definition
PHYSOSTIGMINE, NEOSTIGMINE, PYRIDOSTIGMINE, RIVASTIGMINE, GALANTAMINE, AMBENONIUM, DONEPEZIL, TACRINE
Term
What are the irreversible, long lasting AChE inhibitors?
Definition
Synthetic organophosphates - ecothiophate and isofluorophate - and nerve gasses such as sarin and soman
Term
Which AChE inhibitors are used to treat myasthenia gravis?
Definition
Edrophonium (diagnostic test only), Neostigmine, Pyridostigmine, Ambenonium
Term
Which AChE inhibitor is used to treat hypertonia of the bladder and GI?
Definition
Physostigmine
Term
Which AChE inhibitors are used to treat glaucoma?
Definition
Physostigmine and ecothiophate
Term
What AChE inhibitors are used to treat alzheimer's disease?
Definition
Donepezil, rivastigmine, tacrine, and galantamine
Term
What is the cause for deficient Ach receptors at the neuromuscular junction in cases of myasthenia gravis?
Definition
Auto-immune antibodies mistakenly destroy receptors
Term
What are the clinical characteristics of neostigmine?
Definition
Cannot enter the brain, used to treat myasthenia gravis, effect at NMJ is greater than that of physostigmine, can have general cholinergic effects and drop blood pressure, overdose can cause cholinergic crisis and muscle paralysis
Term
What are the clinical characteristics of physostigamine?
Definition
Plant alkaloid that can cross the BBB, potentiates Ach effects at muscarinic and nicotinic receptors of the ANS and nicotinic receptors at the NMJ. Used as an antidote for atropine and other anticholinergic drugs, reverses CNS side effects, reduces intraoccular pressure much like pilocarpine
Term
What are some adverse effects of physostigamine?
Definition
Diarrhea, nausea, sweating, miosis, urinary urgency, can cause convulsions, bradycardia, and hypotension at high doses
Term
What is organophosphate poisoning?
Definition
Found in many insecticides and pesticides, exhibits symptoms involving activation of nicotinic and muscarinic receptors due to long acting AChE inhibitors: SLUD = Salivation, Lacrimation, Urination, Defecation
Term
What are organophosphates?
Definition
Long acting AChE inhibitors, inactivates Ach permanently via an "aging" process
Term
How is organophosphate nerve gas poisoning treated?
Definition
Pyridostigmine used prophylactively, high doses of muscarinic antagonist atropine or scopolamine followed by an injection of pralidoxime (reactivates Ach but is ineffective once "aging" begins) can also treat poisoning
Term
Which belladona alkaloids are muscarinic receptor antagonists?
Definition
Atropine, scolopamine
Term
Which synthetic and semi-synthetic muscarinic receptor antagonists should you know?
Definition
Ipratropium, triotropium, and tolterodine
Term
What are the clinical uses of atropine?
Definition
Reverses severe bradycardia, produces mydriasis and cycloplegia for eye exams, antispasmodic, represses respiratory secretions prior to surgery, treats organophosphate poisoning and mushroom poisoning
Term
What is the mechanism of action of atropine?
Definition
Belladonna alkaloid is a tertiary amine that can cross the BBB, is a non-selective muscarinic antagonist, blocks all parasympathetic effects in the eye (causes mydriasis and loss of accommodation), reduces GI motility, and reduces salivary/lacrimal secretions
Term
What are some side effects of atropine?
Definition
Dry mouth, constipation, dilated pupils (mydriasis), blurred vision, hot/dry flushed skin, tachycardia, fever, CNS disturbances
Term
What are the clinical uses of scopolamine?
Definition
Prophylactic for motion sickness, adjunct drug in anesthesia to produce sedation and amnesia, has ophthalmic use. Crosses BBB much more than atropine
Term
What are some side effects of scopolamine?
Definition
Similar to what is seen with atropine except CNS effects are more prominent
Term
What are the clinical uses of ipratrapopium bromide?
Definition
Used in asthma and chronic obstructive pulmonary disorder (COPD)to cause bronchodilation as an adjunct to albuterol (can also be a substitute for people unable to take adrenergic agonists)
Term
What is the mechanism of action of ipratrapopium?
Definition
Blocks muscarinic receptors, reduces bronchoconstriction, minor mucocilliary effect and CNS effects
Term
What are the clinical uses of tiotropium bromide (SPIRIVA)?
Definition
Used to treat COPD and asthma, very selective at the bronchioles and greater affinity for M3 over M2 receptors
Term
What are the clinical uses of tolterodine (DETROL)?
Definition
Treats overactive bladder by blocking M3 receptors on detrusor muscles, reducing parasympathetic mediated contraction. Also blocks parasympathetic tone to the sphincter and prevents leaks
Term
What other drugs are M3 antagonists similar to tolterodine?
Definition
Fesoterodine (Toviaz), Solifenacin (Vesicare), Darifenacin (Enablex), Oxybutynin (Ditropan)
Term
What are some contraindications for using M3 antagonists?
Definition
Not appropriate for individuals with urinary retention problems
Term
What are some contraindications for using muscarinic antagonists?
Definition
Glaucoma, benign prostatic hyperplasia or any urinary condition or kidney condition with urinary problems, myasthenia gravis, excessive constipation
Term
What is the function of ganglionic blockers? Examples?
Definition
Blocks ganglionic Nn receptors, very few are used clinically, ex. Hexamethonium bromide and trimethopham
Term
What is the function of neuromuscular junction blockers?
Definition
Blocks cholinergic transmission at motor end plate between somatic nerve and nicotinic receptors, used as muscle relaxants
Term
What non-polarizing NMJ blocker should you know?
Definition
Atracurium (all of them end with "curium")
Term
What NMJ blocker is depolarizing?
Definition
Succinyl choline
Term
What is the function of non-polarizing NMJ blockers?
Definition
Blocks nicotinic receptors at the NMJ, prevents action of Ach, can be overcome with increasing Ach at the synapse (w/ AChE inhibitor)
Term
What makes up succinyl choline? How is it metabolized?
Definition
Two Ach molecules linked end to end, metabolized by plasma cholinesterase but not by AChE, has rapid onset and short duration of action
Term
What is the phase 1 in the mechanism of action by depolarizing NMJ blockers (succinyl choline)?
Definition
Acts as an agonist at nicotinic receptors, initially depolarizes muscle membrane which is then removed, causing muscle paralysis. AChE inhibitors worsen initial phase
Term
What is phase 2 in the mechanism of action by depolarizing NMJ blockers (succinyl choline)?
Definition
Membrane becomes repolarized but is then resistant to further activation by Ach in the NMJ due to being resistant to hydrolysis by AChE, remains in the junction longer, high doses can cause phase II blockase
Term
What are some side effects of succinyl choline?
Definition
Muscle pain postoperatively possibly due to fasciculations, hyperkalemia, blockage of ganglionic nicotinic recpeotrs may also decreased heart rate and increased intraocular pressure, may cause malignant hyperthermia (treat with Dantrolene)
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