Neuromuscular Blocking Agents Flashcards
What are the chemical properties of Succinylcholine?
Composed of 2 acetylcholine molecules, quaternary ammonium, water-soluble, does not cross BBB.
What is the mechanism of action of Succinylcholine?
Depolarizes nicotinic receptors → transient activation → neuromuscular blockade.
How is Succinylcholine metabolized?
Plasma cholinesterase hydrolyzes to succinic acid and choline; only 10% reaches the neuromuscular junction.
What are the uses of Succinylcholine?
Rapid sequence intubation (RSI).
What is the dosage of Succinylcholine?
IV: 0.5 - 1.5 mg/kg; ED95 ~0.30 mg/kg.
What is the onset time for Succinylcholine?
30-60 sec.
What is the duration of action for Succinylcholine?
5-15 min, full recovery in 12-15 min.
What are the CNS effects of Succinylcholine?
No direct effect, but increases ICP.
What are the cardiovascular effects of Succinylcholine?
Bradycardia (esp. in children), tachycardia with repeat doses.
What are the respiratory effects of Succinylcholine?
No direct effect but may cause airway issues in myopathies.
What are the contraindications for Succinylcholine?
Contraindicated in malignant hyperthermia, hyperkalemia, neuromuscular disorders, and severe trauma.
What are the risks associated with prolonged use of Succinylcholine?
Risk of myalgia, fasciculations, and Phase II block.
What are the chemical properties of Rocuronium?
Monoquaternary aminosteroid, pH 4.0, stable at room temp, 46% protein binding.
What is the mechanism of action of Rocuronium?
Competitive antagonist at nicotinic receptors → prevents depolarization.
How is Rocuronium metabolized?
Liver via deacetylation, excreted in bile/kidneys.
What are the uses of Rocuronium?
RSI when succinylcholine is contraindicated, muscle relaxation.
What is the dosage of Rocuronium?
0.6 – 1.2 mg/kg.
What is the onset time for Rocuronium?
45-90 sec (rapid).
What is the duration of action for Rocuronium?
30-60 min (intermediate).
What are the CNS effects of Rocuronium?
No CNS penetration.
What are the cardiovascular effects of Rocuronium?
No histamine release, minimal hemodynamic effects.
What are the respiratory effects of Rocuronium?
Dose-dependent paralysis of diaphragm.
What are the notes regarding Rocuronium?
Prolonged effect in liver and renal disease. Sugammadex reversal available. Priming technique accelerates onset.
What are the chemical properties of Vecuronium?
Monoquaternary aminosteroid, more lipophilic than pancuronium.
What is the mechanism of action of Vecuronium?
Competitive antagonist at nicotinic receptors → muscle relaxation.
How is Vecuronium metabolized?
Liver metabolism (40-80% excreted in bile), renal elimination (20-30%).
What are the uses of Vecuronium?
Muscle relaxation for intubation and surgery.
What is the dosage of Vecuronium?
0.1 mg/kg.
What is the onset time for Vecuronium?
2-4 min.
What is the duration of action for Vecuronium?
30-60 min.
What are the CNS effects of Vecuronium?
No CNS penetration.
What are the cardiovascular effects of Vecuronium?
No histamine release, minimal effects.
What are the respiratory effects of Vecuronium?
Dose-dependent respiratory paralysis.
What are the notes regarding Vecuronium?
Prolonged effect in hepatic and renal disease. Reliable in elderly. Sugammadex reversal available.
What are the chemical properties of Cisatracurium?
Nondepolarizing benzylisoquinoline, aqueous solution, pH 3.25 – 3.65.
What is the mechanism of action of Cisatracurium?
Competitive antagonist at nicotinic receptors → muscle relaxation.
How is Cisatracurium metabolized?
Hofmann elimination (pH and temperature-dependent), minimal renal involvement.
What are the uses of Cisatracurium?
Muscle relaxation, preferred for renal/liver failure patients.
What is the dosage of Cisatracurium?
0.1 mg/kg.
What is the onset time for Cisatracurium?
2-4 min.
What is the duration of action for Cisatracurium?
30-60 min.
What are the CNS effects of Cisatracurium?
No CNS penetration.
What are the cardiovascular effects of Cisatracurium?
No histamine release, maintains cardiovascular stability.
What are the respiratory effects of Cisatracurium?
No direct effects.
What are the notes regarding Cisatracurium?
Safe for renal and hepatic patients. Reliable for elderly and obese patients (dose based on ideal body weight).
What are the chemical properties of Atracurium?
Benzylisoquinoline, competitive bisquaternary NMBA.
What is the mechanism of action of Atracurium?
Competitive antagonist at nicotinic receptors → muscle relaxation.
How is Atracurium metabolized?
Hofmann elimination + ester hydrolysis (minimal liver/renal involvement).
What are the uses of Atracurium?
Muscle relaxation in general anesthesia.
What is the dosage of Atracurium?
0.5 mg/kg.
What is the onset time for Atracurium?
2-4 min.
What is the duration of action for Atracurium?
30-60 min.
What are the CNS effects of Atracurium?
No CNS penetration.
What are the cardiovascular effects of Atracurium?
Histamine release → may cause hypotension, bradycardia.
What are the respiratory effects of Atracurium?
Histamine release may cause bronchospasm.
What are the notes regarding Atracurium?
Safe in renal/hepatic patients. Histamine release can be mitigated with antihistamines.
What is Neostigmine?
An anticholinesterase and NMBA reversal agent.
What are the chemical properties of Neostigmine?
Carbamic acid ester of alcohol, contains quaternary ammonium group.
What is the mechanism of action of Neostigmine?
Inhibits acetylcholinesterase (AChE) → increases acetylcholine (ACh) concentration → displaces NMBA at nicotinic receptors → reverses neuromuscular blockade.
How is Neostigmine metabolized?
Hepatic metabolism, renal excretion.
What are the uses of Neostigmine?
Reversal of non-depolarizing NMBAs (e.g., Rocuronium, Vecuronium, Cisatracurium).
What is the dosage of Neostigmine?
25-75 mcg/kg IV.
What is the onset time for Neostigmine?
5-15 min.
What is the duration of action for Neostigmine?
45-90 min.
What is the CNS effect of Neostigmine?
Does not cross BBB (quaternary ammonium).
What is the cardiovascular effect of Neostigmine?
Bradycardia (must co-administer with anticholinergic such as glycopyrrolate or atropine).
What is the respiratory effect of Neostigmine?
Risk of bronchospasm (due to increased ACh).
What are other notes regarding Neostigmine?
Does not reverse deep blockade. Causes PONV. Pair with glycopyrrolate (10-20 mcg/kg) to offset muscarinic effects.
What is Edrophonium?
A short-acting anticholinesterase and NMBA reversal agent.
What are the chemical properties of Edrophonium?
Quaternary ammonium, short-acting.
What is the mechanism of action of Edrophonium?
Reversibly binds acetylcholinesterase → mild increase in ACh levels → weak NMBA reversal.
How is Edrophonium metabolized?
Hepatic metabolism, renal excretion.
What are the uses of Edrophonium?
Short-acting reversal agent for non-depolarizing NMBAs.
What is the dosage of Edrophonium?
0.5 -1 mg/kg IV.
What is the onset time for Edrophonium?
5-10 min.
What is the duration of action for Edrophonium?
30-60 min.
What is the CNS effect of Edrophonium?
Does not cross BBB.
What is the cardiovascular effect of Edrophonium?
Bradycardia (requires atropine co-administration).
What is the respiratory effect of Edrophonium?
Minimal effect.
What are other notes regarding Edrophonium?
Weaker than neostigmine. Less effective for deep blockade reversal.
What is Sugammadex?
A selective NMBA reversal agent for Rocuronium & Vecuronium.
What are the chemical properties of Sugammadex?
Modified gamma-cyclodextrin, water-soluble, biologically inactive.
What is the mechanism of action of Sugammadex?
Encapsulates Rocuronium/Vecuronium → prevents binding to nicotinic receptors → rapid reversal.
How is Sugammadex metabolized?
Renal elimination (80% excreted in urine within 24 hours).
What are the uses of Sugammadex?
Rapid and complete reversal of Rocuronium/Vecuronium.
What are the dosages for Sugammadex?
2 mg/kg: Given when TOF 2/4 twitches or more.
4 mg/kg: Given when no TOF response, but 1-2 PTC (Post-Tetanic Count).
16 mg/kg: Given for immediate reversal after 1.2 mg/kg of Rocuronium.
What is the onset time for Sugammadex?
1-2 min (very fast).
What is the duration of action for Sugammadex?
2-16 hrs.
What is the CNS effect of Sugammadex?
None (does not cross BBB).
What are the cardiovascular effects of Sugammadex?
Can cause bradycardia, hypotension, allergic reactions (anaphylaxis), nausea, vomitting, headaache (Watson say hypertension as well)
What is the respiratory effect of Sugammadex?
No direct effect.
What are other notes regarding Sugammadex?
Avoid in renal failure. Binds oral contraceptives → alternate birth control needed for 7 days. Anaphylaxis risk highest within first 4 min post-administration.
What is Atropine?
An anticholinergic co-administered with reversal agents.
What are the chemical properties of Atropine?
Belladonna alkaloid, tertiary amine (crosses BBB).
What is the mechanism of action of Atropine?
Blocks muscarinic receptors → prevents ACh-induced bradycardia from AChE inhibitors (e.g., Neostigmine, Edrophonium).
How is Atropine metabolized?
Hepatic metabolism, renal excretion.
What are the uses of Atropine?
Prevents bradycardia when reversing NMBAs.
What is the dosage of Atropine?
7 - 15 mcg/kg (0.4 – 0.6 mg IV).
What is the onset time for Atropine?
1-2 min.
What is the duration of action for Atropine?
1-2 hrs.
What are the CNS effects of Atropine?
Can cause sedation, delirium, hallucinations.
What is the cardiovascular effect of Atropine?
Increases HR by blocking vagal tone.
What is the respiratory effect of Atropine?
Reduces secretions.
What are other notes regarding Atropine?
Best paired with Edrophonium due to rapid onset match.
What is Glycopyrrolate?
An anticholinergic co-administered with reversal agents.
What are the chemical properties of Glycopyrrolate?
Quaternary ammonium, does NOT cross BBB.
What is the mechanism of action of Glycopyrrolate?
Blocks muscarinic receptors → prevents ACh-induced bradycardia.
How is Glycopyrrolate metabolized?
Excreted 85% unchanged in urine, minimal hepatic metabolism.
What are the uses of Glycopyrrolate?
Prevents bradycardia when reversing NMBAs, preferred over Atropine due to stable HR control.
What is the dosage of Glycopyrrolate?
10-20 mcg/kg IV.
What is the onset time for Glycopyrrolate?
1-2 min.
What is the duration of action for Glycopyrrolate?
2-4 hrs.
What are the CNS effects of Glycopyrrolate?
No CNS effects (does not cross BBB).
What is the cardiovascular effect of Glycopyrrolate?
Milder tachycardia than Atropine.
What is the respiratory effect of Glycopyrrolate?
Reduces secretions without causing excessive CNS effects.
What are other notes regarding Glycopyrrolate?
Best paired with Neostigmine (matched onset).
What is Scopolamine?
An anticholinergic used for PONV & sedation.
What are the chemical properties of Scopolamine?
Belladonna alkaloid, tertiary amine (crosses BBB).
What is the mechanism of action of Scopolamine?
Blocks muscarinic receptors → strong anti-nausea and sedation effects.
How is Scopolamine metabolized?
Hepatic metabolism, renal excretion.
What are the uses of Scopolamine?
PONV prophylaxis, sedation, amnesia.
What is the dosage of Scopolamine?
1.5 mg patch applied behind ear 4 hrs before anesthesia.
What is the duration of action for Scopolamine?
3 days.
What are the CNS effects of Scopolamine?
Sedation, dizziness, amnesia.
What is the cardiovascular effect of Scopolamine?
Mild tachycardia.
What is the respiratory effect of Scopolamine?
Reduces secretions.
What are other notes regarding Scopolamine?
Best for PONV prevention, not typically used for NMBA reversal.
