Terms in this set (76)
drugs that stimulate or emulate that parasympathetic nervous system (PSNS)
A cholinergic agonist that mimics the effect of the PSNS neurotransmitter: ____________
What are the three Cholinergic receptor subtypes?
NicotinicN, NicotinicM, Muscarinic
What cholinergic receptor is located in the ganglia of bothe the PSNS and the SNS?
What cholinergic receptor is located in the neuromuscular junctions?
What cholinergic receptor is located postsynaptically in the PNS?
Muscarinic receptors are located postsynaptically in smooth muscle, cardiac muscle, glands of parasympathetic fibers and effector organ of cholinergic sympathetic fibers.
Muscatinic receptors have 3 class subtypes, please match:
1) M3 a) salivation (in CNS will enhance cognition)
2) M1 b) bradycardia
3) M2 c) salivation, miosis, accomodation, tearing
What are the five Adrenergic receptor subtypes?
Alpha1, Alpha2, Beta1, Beta2, Dopamine
A direct-acting Cholinergic agent acts on receptors by...?
most cholinergic drugs act directlyat cholinergic receptors by either mimicing or blocking the actions of ACh
An indirect-acting Cholinergic agent or cholinesterase inhibitors influence receptors by...?
inhibiting the enzyme acetylcholinesterase from breaking down ACh thereby more ACh is available at receptor site.
Cholinergic drugs affect the PSNS and its effects can be remembered by SLUDGE, what effects does this class of drug elicit?
Salivation, Lacrimation, urinary incontinence, diarrhea, GI cramping, Erection.
Name 5 Muscarinic Agonisits?
What are the uses of Muscarinic agonist?
Postop abdominal distention
Adverse effects of Muscarinic agonist?
increased gastric acid
Muscarinic agonist poisoning is characterized by profuse sweating, tearing, salivation, visual disturbances, bronchospasms, diarrhea, bradycardia, and hypotension. Overdose can be attributed to direct-acting muscarinic agonists and cholinesterase inhibitors and this organic fungi?
Mushrooms of the Inocybe and Clitocybe species
What is the treatment for muscarinic posioning?
ATROPINE- a protype muscarinic antagonist or anticholinergic drug that blocks the actions of ACh and all other muscarinic agonists at the muscarinic cholinergic receptor site.
What are the effects of Atropine?
Opposite muscarinic agonist. Atropine:
1- increase heart rate
2- reduce secretions from sweat, salivary, bronchial and gastric glands
3- relaxes intestinal and bronchial smooth muscle
4- causes urinary retention by decreasing bladder tone
5- mydriasis and cycloplegia
6- in CNS, excitation in low dose and hallucination/delirium at toxic doses.
Atropine is a muscarinic antagonist and can help prevent dangerous bradycardia during surgery. It often is administered before the induction of anesthesia. Its side effects may include urinary retention, constipation, and tachycardia.
What does a Muscarinic ANTAgonist do?
muscarinic antagonist or anticholinergic drug that blocks the actions of ACh and all other muscarinic agonists at the muscarinic cholinergic receptor site.
Prototype Muscarinic antagonist is Atropine, name 2 other commonly used drugs from this class and common aplications.
Scopolamine, ipratropium (Atrovent), Benztropine (congentin)
Common applications of these drugs include: preanesthetic, ophthalmic exams, reversal of bradycardia, OAB, management of muscarinic poisoning PUD, Biliary colic.
Dry mouth (xerostomia), blurred vision, Urinary retention, photophobia, increased intraocular pressure, constipation, tachycardia, anhydrosis are all common adverse effects of what class of drug?
Anticholinergic or muscarinic antagonist or parasympatholytic.
A common class of drug used to treat OAB and are they effective?
Anticholinergic drugs are used for OAB and are only moderately effective, only slightly better than a placebo.
What other classes of drugs should be used cautiously, it at all, with anticholinergic drugs and why?
antihistamines, TCA's, phenothiazine antipsychotics b/c they have prominent antimuscarinic actions and can intensify adverse effects.
Symptoms of anticholinergic Poisoning?
Antimuscarinic poisoning often resembles psychosis and psychotic episodes. It is important to differentiate, because antipsychotic drugs have antimuscarinic properties and could intensify the symptoms of poisoning.
other symptoms include: dry mouth, blurred vision, photophobia, hyperthermia, hallucinations, delirium, skin that is hot, dry, and flushed.
Antidote for anticholinergic poisoning?
Physostigmine a cholinesterase inhibitor
Ipecac syrup followed by activated charcoal
A nurse is preparing to give bethanechol [Urecholine]. What is an expected outcome of this drug?
Bethanechol is given for treatment of nonobstructive urinary retention.
Give 1 hour before meal b/c of gastric upset.
Contraindicated in patients with PUD, UT obstruction, intestinal obstruction, hypotension, asthma, hyperthyroidism, coronary insufficiency.
Bethanechol is a muscarinic agonist and therefore activates muscarinic receptors. This can lead to relaxation of the urinary sphincter muscles and increased voiding pressure. It also can cause bradycardia and hypotension, bronchoconstriction, and dysrhythmias in hyperthyroid patients.
The nurse is caring for a 60-year-old woman who has been prescribed oxybutynin [Ditropan] for the treatment of overactive bladder (OAB). Which statement by the nurse will be the most helpful to include in the teaching plan?
"You may experience a slower heart rate. Call your doctor if it is below 60."
"Ditropan is very effective. Most patients experience significant relief."
"Sip on water and suck on hard candy to help with the problem of dry mouth." Correct
"Antihistamines, such as Benadryl, can help with some of the side effects of Ditropan."
"Sip on water and suck on hard candy to help with the problem of dry mouth."
Oxybutynin is an anticholinergic drug that commonly causes dry mouth. Other side effects include constipation, tachycardia, urinary hesitancy, urinary retention, and visual disturbances. Oxybutynin is only moderately effective (30% better than placebo). It should not be taken with other drugs with anticholinergic properties, such as antihistamines, because of the additive anticholinergic effects.
_______________________________ are drugs that prevent the degradation of acetylcholine (ACh) by acetylcholinesterase.
Cholinesterase inhibitors.... By preventing the inactivation of ACh, cholinesterase inhibitors enhance the actions of ACh released from cholinergic neurons.
What are the two categories of Cholinesterase inhibitors?
1- reversible inhibitors- The reversible inhibitors produce effects of moderate duration.
2-"irreversible" inhibitors- produce effects that are long lasting.
What class of drug is the treatment for Myasthenia Gravis?
Neostigmine is the prototype for the reversible inhibitors group. The drug's principal indication is myasthenia gravis.
Pharmacological effect: Benefit comes from accumulation of ACh at the NMJ.
Mechanism of action of Neostigmine
Cholinesterase breaks down Neostigmine slower than ACH therefore more cholinesterase remains bound to Neostigmine longer and more ACh is available, and this can intensify transmission to all junctions where ACh is the transmitter.
Neuromuscular effect of neostigmine
increase force of contraction at therapeutic levels and decrease force of contraction at toxic levels
Neostigmine and CNS
Therapeutic levels produce mild stimulation and toxic levels depress the CNS
Other uses for reversible cholinesterase Inhibitors include:
poisoning by muscarinic antagonist (Physostigmine)
Acute toxicity of Cholinesterase inhibitors can cause
Cholinergic Crisis: Excessive muscarinic stimulation
This condition results from a cholinesterase inhibitor overdose. Manifestations include: skeletal muscle paralysis (possibly from depolarizing neuromuscular blocking agent)
Salivation, sweating, miosis, bradycardia... SLUDGE
Treatment for a Cholinergic crisis...
Atropine and respiratory support by mechanical ventilation if needed.
How is Neostigmine is eliminated?
through enzymatic degradation by cholinesterase.
Cholinesterase inhibitors can be used to reverse what class of drugs?
Competetive (nondepolarizing) Neuromuscular blocking aagents.
By causing accumulation of ACh at the NMJ, cholinesterase inhibitors (neostigmine) can reverse the effects of a NMblock.
CAN NOT REVERSE THE EFFECTS OF SUCCINYLCHOLINE A DEPOLARIZING NMBLOCKER.
Other reversible Cholinesterase Inhibitors:
Physostigmine- identical to neostigmine but crosses BBB
**** Physostigmine is the drug of choice when treating poisoning by atropine or other drugs that cause muscarinic blockade
Alzheimer Cholinesterase Inhibitors
Drug used to challenge signs and symptoms of myasthenia gravis if differential diagnosis can not be made. This drug is given and if marked improvement is noted the the DX is MG. If no marked improvement noted prob a cholinergic crisis.
Irreversible Cholinesterase Inhibitors mechanism of action
same action as reversible however there longer acting
Irreverisble cholinesterase inhibitor that can be reversed, used clinically for glaucoma.
Organophosphate Cholinesterase Inhibitor
Irreversible Cholinesterase Inhibitor
While working in a rural NC clinic a farmer came in with visible bowel and bladder incontinence, audible wheeze, and excessive salivation, what would you suspect and how would you treat?
Organophosphate Cholinesterase Inhibitor poisoning or Insecticide poisoning. A toxic condition has been produced, which results in stimulation of the cholinergic nervous system and cholinergic crisis. The symptoms of cholinergic crisis include profuse salivary and bronchial secretions, urinary and stool incontinence, laryngospasm, bronchoconstriction, paralysis, and death. Miosis (pupil constriction), not mydriasis, occurs, as well as diaphoresis.
-Atropine to reduce muscarinic stimulation
-Pralidoxime to reverse the inhibition od cholinesterase
-and a benzo like diazapam to supress convulsions
Regenerates cholinesterase and prevents "aging" of enzyme, given as a reversal agent for insecticide poisoning.
has to be given quickly after exposure before the organophospahate has time to "age". Admin over SLOW push.
The nurse is preparing to give neostigmine [Prostigmin]. What best describes the action of this drug?
It prevents inactivation of acetylcholine.
What best describes the rationale for using neostigmine [Prostigmin] in the treatment of myasthenia gravis?
It increases the force of skeletal muscle contraction.
The nurse is caring for a patient with a suspected overdose of pancuronium, which was used during surgery. Which drug does the nurse anticipate will be used as a reversal agent?
Because neostigmine inhibits cholinesterase, it allows acetylcholine to accumulate at synapses. This action can help reverse neuromuscular blockade in postoperative patients, especially when a nondepolarizing neuromuscular blocker, such as pancuronium, has been used.
The nurse prepares to administer the antidote to a patient in cholinergic crisis. What medication does the nurse anticipate the healthcare provider to order?
Intravenous atropine can alleviate the muscarinic effects of cholinesterase inhibition. Pralidoxime is a specific antidote to poisoning by the irreversible (organophosphate) cholinesterase inhibitors; the drug is not effective against poisoning by reversible cholinesterase inhibitors.
What is the pathophysiology for a myasthenic crisis?
Autoimmune disease that affects nicotinic receptors fuctionality by 70-90%
Patients who are inadequately medicated may experience myasthenic crisis, a state characterized by extreme muscle weakness, Ptosis, difficulty swallowing, skeletal muscle weakness including resp. Muscles. caused by insufficient ACh at the NMJ. A cholinesterase inhibitor (eg, neostigmine) is used to relieve the crisis.
Patients who are inadequately medicated may experience myasthenic crisis, a state characterized by extreme muscle weakness caused by insufficient ACh at the NMJ. A cholinesterase inhibitor (eg, neostigmine) is used to relieve the crisis.
The provider elects to administer a medication to distinguish myasthenic crisis from cholinergic crisis. What medication would the nurse anticipate giving?
he provider may elect to administer a challenging dose of edrophonium, an ultrashort-acting cholinesterase inhibitor. If edrophonium-induced elevation of ACh levels alleviates symptoms, the crisis is myasthenic. Conversely, if edrophonium intensifies symptoms, the crisis is cholinergic.
uneven charge distribution
When a membrane depolarizes, positive charges move from the outside to the inside of the membrane and the inside membrane becomes more positive
Repolarization happens almost instantaneously after depolarization a positively charged ions are pumped out of the cell and results in the original resting membrane state with positive outside membrane and negative on the inside.
What is the oldest nondepolarizing NM blocking agent, the prototype for this class?
_________________is a competitive agonist at the nicotinincM receptor site at the NMJ thereby preventing depolarization by ACh and causes flaccid paraysis?
nondepolarizing NM blocking agent
Steps in Muscle contraction
1-Action potential dowm axon of neuron
2-Release of ACh into subneural space
3-Binding of ACh to NicotinicM receptors on the motor end-plate
4-depolarization of motor end-plate
5-muscle action potential
6-Release of Ca++ from sarcoplasmic reticulum
7-interaction with actin and myosin
______________interfer with nicotinicM receptors activation and thereby cause muscle relaxation
Competetive (NONdepolarizing) Neuromuscular blockers
agents that compete with ACh for binding at the NicotinicM receptors.
These agents are considered nondepolarizing agents b/c they do not depolarize at the end of the motor end-plate.
NM blocking agents are structually similar to ACh?
NM blocking agents can be given PO with a large meal?
False- All must be administered parentally bc not absorbed by GI tract.
NM blocking agents are poorly lipid soluable and have limited entry to CNS
Why would the autoimmune disease Myasthenia Gravis enhance the effect of a non-depolarizing NM blocker?
electrolyte imbalance.... Low K++
Duration of paralysis with Pancuronium and Atracurium?
Pancuronium 35-45 mins
Atracurium 20-35 mins
NM blockers reduce pain and cosciousness?
The major adverse effect of NM blockers is resp. depression?
Succinylcholineis a depolarizing NM agent that lasts for approximatley 5 minutes and promotes histamine release?
Rocuronium (Zemuron) relaxes muscles in about 1-3 minutes and does not promotes histamine release.
Succinylcholine maintains the end-plates in a state of constant depolarization thereby causing paralysis?
Succinylcholine [Anectine] is contraindicated in a patient with what condition?
Chronic obstructive pulmonary disease (COPD)
Major burns during the emergent phase
Major burns during the emergent phase
Succinylcholine promotes the release of potassium from tissues. Significant hyperkalemia is most likely to develop in patients with major burns during the emergent phase, multiple trauma, denervation of skeletal muscle, or upper neuron injury.
The nurse understands that tubocurarine and other neuromuscular (NM) blockers cannot be given by mouth. What is the rationale for this statement?
They carry a positive charge
All NM blockers have a quaternary nitrogen atom and therefore always carry a positive charge, making it difficult for them to cross membranes. The inability to cross membranes makes parenteral administration necessary. NM blockers do compete with ACh, cause muscle relaxation, and interact with potassium, but these factors do not necessitate oral administration.
The nurse is caring for a patient receiving inhalant anesthesia and succinylcholine [Anectine]. The patient develops muscle rigidity and a temperature of 105°F. What nursing action is essential?
The patient is showing symptoms of malignant hyperthermia, a rare and potentially fatal complication of succinylcholine and inhalation anesthesia. Treatment includes discontinuation of succinylcholine and anesthesia; application of cooling blankets and ice packs; and IV administration of dantrolene, a muscle relaxant.
Which patient undergoing surgery is at greatest risk for an intensified effect from succinylcholine?
A patient who takes aspirin 81 mg orally daily
A patient receiving gentamicin [Garamycin] 80 mg IV piggyback every 8 hours
A patient taking isosorbide mononitrate [Imdur] 60 mg orally daily
A patient receiving a continuous infusion of normal saline solution
The effects of succinylcholine can be intensified if the drug is administered concomitantly with certain antibiotics, such as aminoglycosides and tetracyclines, as well as other nonpenicillin antibiotics. Gentamicin is an aminoglycoside. Aspirin, Imdur, and normal saline would not intensify the effect of succinylcholine.
A patient with acute renal failure requires continuous NM blockade to facilitate oxygenation and mechanical ventilation. Which agent prescribed by the physician should the nurse question?
Pancuronium [Pavulon] Correct
The order for pancuronium should be questioned, because elimination of this drug is primarily renal.
Atracurium is eliminated primarily by plasma cholinesterase; cisatracurium is eliminated through spontaneous degradation; and vecuronium is excreted primarily through the bile.
Neuromuscular blockers cannot be absorbed from the gastrointestinal tract, cannot cross the blood-brain barrier, and hence have no effect on the central nervous system (CNS). Neuromuscular blockers cannot readily cross the placenta.
Succinylcholine is rapidly degraded by pseudocholinesterase
Paralysis is brief because succinylcholine is rapidly degraded by pseudocholinesterase, an enzyme present in plasma. This enzyme is called pseudocholinesterase to distinguish it from "true" cholinesterase, the enzyme found at synapses where ACh is the transmitter. Because of its presence in plasma, pseudocholinesterase is also known as plasma cholinesterase.
YOU MIGHT ALSO LIKE...
Pharmacology | USMLE Step 1/COMLEX Level 1 Guide
Evolve Q's chapters 12 - 16
Ch. 16 - Neuromuscular Blocking Agents
NR 293: Ch. 20 Cholinergic Drugs
OTHER SETS BY THIS CREATOR
Adrenergic Agonist and Antagonist Drugs
Drugs for the Eye
THIS SET IS OFTEN IN FOLDERS WITH...
Myasthenia Gravis Drugs Ch15 Pharm
Combo with Pharm - Test 2 - Gastrointestinal Disorders and 1 other
Multiple Sclerosis Drugs Ch 23 Pharm *LOOK OVER