6. Skeletal Muscle Relaxants Flashcards
All of the following are what kind of neuromuscular blocking drugs? Isoquinoline derivatives: Atracurium Cisatracurium Doxacurium Mivacurium Tubocurarine Steroid Derivatives: Pancuronium Pipercuronium Rocuronium Vecuronium
Nondepolarizing neuromuscular blocking drugs
All of the following are what kind of neuromuscular blocking drugs?
Succinylcholine
Depolarizing neuromuscular blocking drugs
All of the following are what kind of skeletal muscle relaxants? Ambenonium Donepezil Echothiophate Edrophonium Galantamine Neostigmine Physostigmine Pyridostigimine Rivastigmine Tacrine
Acetylcholinesterase Inhibitors
All of the following are what kind of skeletal muscle relaxants?
atropine/ glycopyrrolate
Antimuscarinic compounds
All of the following are what kind of skeletal muscle relaxants?
palidoxime
Cholinesterase Reactivators
All of the following are what kind of muscle relaxants (spasmolytics)? Baclofen Carisprodol Cyclobenzaprine Diazepam Tizanidine
Centrally Acting Spasmolytics
All of the following are what kind of muscle relaxants (spasmolytics)?
Dantrolene
Botulinum Toxin
Non-centrally acting spasmolytics
All of the following are what kind of drugs? Glucocorticoids Glatiramer acetate Interferons: beta-1a and beta-1b Mitoxantrone
Immunologic drugs for MS
Neuromuscular blocking drugs are also called antinicotinic drugs interfere with transmission at the NM end plate and block CNS activity, used primarily in anesthetics to acheive muscle relaxation and have no known affects on consciousness or pain threshold, what is a nondepolarizing NM blocking agents whose MOA is antagonism of the nicotinic acetylcholine receptor (which doesnt allow ACh to reach receptor = relaxation (nAChR)?
Tubocurarine (prototype)
What is the prototype medication which is a depolarizing neuromuscular blocking agent in which it binds to the channel (nAChR) and causes it to remain open, resulting in overexhaustion and flaccid paralysis?
Succinycholine
NM blockers selection depends on the pharmcokinetics and or how quickly they last. Succinylcholine is ultra short (given for malignant hyperthermia) and is usually given and then maintained by an intermediate acting nondepolarizing NM blocker. Mivacurium is the only short acting nondepolarizing NM blocker, recuronium, vecuronium, cisatracurium, and atracurium are all?
Intermediate acting neuromuscular blockers- they are the MC used due to flexibility
Doxacurium, pancuronium and pipecuronium are what type of nondepolarizing NM blocking agents?
Long acting- never used
The effects of nondepolarizing NM blockers last too long (tubocurarine*) which may cause profound hypotension and tachycardia with LARGE doses, histamine release is common among them causing bronchospasm, hypotension, bronchial and salivary secretion, can premedicate to abate these symptoms and or use the steroid- derivative nondepolarizing meds which cause less histamine SE, which are pancuronium, pipercuronium, rocuronium, and?
Vecuronium
Note: along with hypotension/tachycardia, also causes LARGE histamine release with very long duration of action so tubocurarine is never used anymore
Reversal of the NMJ blockade is done via what, which antagonize nondepolarizing blockage by increasing amounts of ACh at the NMJ, drugs such as neostigmine, pyridostigmine and edrophonium, what are often admin WITH anticholinergic agents to minimize effects at mAChR (atropine/glycopyrrolate)?
Cholinesterase Inhibitors
Drug drug interactions associated with nondepolarizing NMJ blockers include inhaled anesthetics which potentiate blockage (isoflurane and sevoflurane), also antibiotics such as aminoglycosides enhance effects, blockade is enhanced in pt with hepatic/renal dysfunction and with myasthenia?
gravis >_>
What steroid derivative nondepolarizing muscle relaxant has the most rapid time of onset and is used as an alternative to succinylcholine?
Rocuronium
What is the only clinically useful depolarizing agent with ultra short duration of action, polymorphism in pseudocholinesterases and for its reversal of the block all you need is TIME- no drugs are needed, MOA if via two phases- 1) depolarizing block 2) desensitizing block?
Succinylcholine (causes twitches for 30 seconds at paralysis in less than 90s - reversed by time- due to cholinesterase degredation)
Succinylcholine is similar to ACh but produces a longer effect, Phase 1 block: depolarized membranes remain depolarized and unresponsive to subsequent impulse, results in flaccid paralysis due to lack of repolarization, this phase is AUGMENTED by cholinesterase inhibitors, phase 2 desensitizing block: continued exposure to succinycholine causes initial end plate depolarization to decrease and the membrame becomes repolarized, nAChR behaves as if in a prolonged closed state, but then there is receptor desensitization, this phase is ANTAGONIZED or REVERSED by?
cholinesterase inhibitors
SE of succinycholine include CV effects like arrhythmias, hyperkalemia, increase IOP, contraindicated in family history of malignant hyperthermia, myopathies and there is a black box warning for acute?
rhabdomyolysis with hyperkalemia and death usuall in male less than 8 with undiagnosed SM myopathy)
Tx of malignant hyperthermia (caused by abnl release of calcium from stores in skeletal muscle) with dantrolene
MEOW
The main clinical use of NM blocking drugs includes surgical relaxation, tracheal intubation, control of ventilation and treatment of convulsions, in which pharmacokinetics dictate their use such that drug of choice for RAPID intubation is succinylcholine (rocuronium or vecuronium), and drugs of choice used in adjunct to general anesthesia for muscle relaxants are those of longer duration such as atracurium/cistacurium (intermediate) and?*
Pancuronium (long acting)
Quarternary/charged AChE inhibitors are insoluble and donot go to CNS = neostigmine, pyridostigimine, edorphonium, echothiophate, tertiary/uncharge AChE inhibs GO TO CNS, including physostigmine, donepzil, tacrine, rivastigmine, galantamine. Organophosphates (echothiophate) are readily absorbed and between AChE is irreversible so regen of ACHE is required to reestablish termination of ACh signaling at NMJ which what is used?
Pralidoxime
Myasthenia gravis is treated with pyridostigmine, neostigmine and or ambenonium are the standard AChE inhibitors since they DO NOT CROSS THE BBB. If trying to decide between myasthenia and cholinergic crisis, edrophonium can be given– if the patient is in myasthenic crisis the symptoms will IMPROVE, if the patient is in cholinergic crisis what would happen?
The symptoms would get worse (cause inc ACh)
What AChE inhibitor is used for reversal of NM blocking drug induced paralysis, also used to treat paralytic ileus, atony of the bladder and congenital megacolon?
Neostigmine
