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56 Cards in this Set
- Front
- Back
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what is succinylcholine?
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depolarizing NMJ blocker
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what is the action of drugs that are non-depolarizing NMJ blocking drugs?
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competitive inhibiton of acetylcholine at the skeletal muscle nicotinic receptor site
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what do all NMJ blocking agents bear structural resemblance to?
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two ACh molecules placed end to end = bisquaternaries - having two fixed positive charges
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what are the implications of the drugs being bisquaternaries?
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they are poorly absorbed orally - must be given by IV
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what can antagonize non-depolarizing NMJ blockers?
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neostigmine - an anticholinesterase
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do the non-depolarizing NMJ blockers or neostigmine enter the CNS?
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no
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what should NOT be used to antagonized non-depolarizing NMJ blockers?
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physostigmine because it enters the CNS
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what is atracurium?
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isoquinolines - non-depolarizing NMJ blocker
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what is cisatracurium?
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isoquinolines - non-depolarizing NMJ blocker contains 15% atracurium and 50% of its NMJ blockade
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what is doxacurium?
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isoquinolines - non-depolarizing NMJ blocker
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which isoquinolines is not spontaneously hydrolyzed to be elimated?
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doxacurium - it is elimated by the kidneys
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which isoquinolines has the longest duration?
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doxacurium
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which isoquinoline has slight histamine release?
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atracurium
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what is pancuronium?
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steroid - non-depolarizing NMJ blocker
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what is pipecuronium?
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steroid - non-depolarizing NMJ blocker
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what is rocuronium?
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steroid - non-depolarizing NMJ blocker
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what is vercuonium?
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steroid - non-depolarizing NMJ blocker
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which two steroid non-depolarizing NMJ blockers are elimiated hepatically?
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rocuronium and vecuronium
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which steroid non-depolarizing NMJ blocker is eliminated renally?
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pancuronium
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which steroid non-depolarizing NMJ blocker is eliminated both hepatically and renally?
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pipecuronium
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do isoquinolines produce sinus tachycardia?
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no
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which steroid non depolarzing NMJ blockers produce sinus tachycardia?
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pancuronium (more) and rocuronium
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do steroid non-depolarizing NMJ blockers release histamines?
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no
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what muscles are most senstiive to competitive neuromusclar blockers?
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small muscles of the eye and hand - blockage appears there first and recovers last
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what muscle is somewhat resistant to NMJ blockage?
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diaphragm
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which NMJ blocker would last longer in patients with impaired renal function?
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doxacurium
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which NMJ blocker would last longer in patients with impaired hepatic function?
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rocuronium and vecuronium
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which drug caused major histamine release
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t-tubocurarine - histamine release would produce bronchospasm, transietn hypotension and flushing
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which drugs show an advantage by reducing histamine release
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cisatracurium over atracurim
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what is the initial NMJ blockade of succinylchoine mediated by?
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direct stimulation of the receptor
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how long does the NMJ blockade last when giving succinylchoine by IV?
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5-10 minutes
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what are the side effects of succinylchoine?
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hyperkalemia (warn children), increased ocular pressure, increased intragastric pressure, muscle pain and myoglobin release
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how is succinylcholine metabolized?
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it is an ester that is broken down by plasma and tissue cholinesterases
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in which patients are the actions of succinylcholine prolonged?
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in patients with atypical choinesterase (recessive disorder) - malignant hypothermia may occru
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what can cause malignant hyperthermia?
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succinylcholine in susceptible patients
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what are the effects of local anestetics and non-depolarizing NMJ blockers?
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local anesthetics may facilitate NMJ blockate
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what do gaseous general anesthetics do to NMJ blockade?
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they facilitate it
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what facilitates NMJ blockade by non-depolarizing blockers due to inhibitio of presynaptic actetylcholine release?
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aminoglycoside antibiotics
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what will happen if you mix non-depolarizing NMJ blockers with depolarizing NMJ blockers?
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non-depolarizing blockers will antagonize the NMJ blocking action of succinylcholine
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define skeletal muscle spasticity
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exaggerated tonic stretch reflexes and increased basal muscle tone combined with muscle weakness mediated by an accenuated reflex arc controlling basal skeletal muscle tone and movement
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when is skeletal muscle spasticity seen?
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post stroke, cerebral palsy or MS
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other than skeletal muscle what else may be affected by spasticity?
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bowel and bladder function
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what are carisoprodol, chlorzoxazone, metaxalone and orphenadrine?
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spasmolytics that depress the reflex arc at the level of the brain stem - produce some degree of sedation and somnolence
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what is the action of benzodiazepines that causes spasmolytic effects?
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they increase negative feedback to direct excitation of motor neurons - act in spinal cord so they are effective in patients even following spinal cord trasaction
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what is bacofen?
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orally effecitve congener of GABA
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what receptor dose bacofen work on?
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GABA-b - producing presynpatic inhibition of excitatory transmitter release from 1a fibers of the afferent limb
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is the force of skeletal muscle contraction altered with bacofen?
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no
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what can happen with rapid withdrawal of bacofen?
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convolutions
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what is gabapentin?
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GABA conger that is an anticonvulsant that also relieves muscle spasm
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what is tizanidine?
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a conger of clonidine that increases both presynaptic and postsynpatic inhibiton in the spinal cord
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how does tizanidine inhibit pain transmission?
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by mediated substance P release in neurons in the dorsal horn
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what is the side effect of tizandine?
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sedation, dry mouth and hypotension
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what is dantrolene?
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spasmolytic that directly acts on muscle fibers by interfering with release of calcium from the SR
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is the force of skeletal muscle contraction altered with dantrolene?
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yes
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are the side effects of caridac and smooth muscle contraction inhibition with dantrolene?
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no- it is releatively selective for skeletal muscle
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which receptor is deficient in those susceptible to malignant hyperthermia?
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ryanodine receptor protein in the SR
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