Nondepolarizing NMB Flashcards
Structurally similar to ACh with one or two quaternary nitrogens
- high polar, highly ionized (H2O soluble)
- cannot cross lipid barries (no CNS effects, no placental cross, poor oral absorption)
chemical characteristics of nondepolarizing NMB
- d-tubocurarine (curare)
- astracurium (tracrium)
- cisatracurium (nimbex)
- doxacurium (nuromax)
- mivacurium (mivacron)
benzylisoquinoline class NMB
- pancuronium (pavulon)
- vecuronium (norcuron)
- pipecuronium (arduan)
- rocuronium (zemuron)
- rapacuronium (raplon)
steroidal class NMB
NMB that end with “urium”
-except for one that ends with urarine
benzylisoquinoline class
NMB that end with ronium
steroidal class
competes with ACh to bind with alpha subunits on the postjunctional AChReceptor, which, prevents the ion channel from opening…which prevents depolarization (no muscle movement)
MOA of nondepolarizing NMB
- small, rapidly contracting muscles (eye, fingers, toes)
- long muscles (adductor pollicis, intercostals)
- diaphragm *first to recover
sequence of relaxation after dose of NMB
- decreased twitch response to single stimulus
- fade with tetanus, TOF
- enhanced by other nondepolarizing NMB
- antagonized by anticholinesterase drugs
characteristics of nondepolarizing NMB
- onset
- duration
- side effects
- metabolism
agent related determinants of NMB
- co-existing diseases (renal, hepatic, cardiac, neurom)
- current medical therapy
- surgical procedure
patient related determinants of NMB
cost
determinants of NMB selection
The less potent the drug, the ____ the ED95, and the more ____ onset
higher, rapid
more molecules must be given per dose, resulting in more molecules reaching the NMJ
What drug is the least potent and has the highest ED95
rocuronium
facilitates rapid intubating conditions by giving a small dose (1/10 intubating dose or 1/3 ED95) of the NMB prior to induction which allows some receptors to be occupied and minimizes the time required for the remaining receptors to be blocked by intubating dose
priming principle
What happens when you increase dose of NMB?
speed up onset, increase side effects, and prolong duration
What is the one short acting nondepolarizing NMB?
mivacurium (mivacron)
- astracurium (tracrium)
- cisatracurium (nimbex)
- vecuronium (norcuron)
- rocuronium (zemeron)
intermediate acting nondep NMB
- pancuronium (pavulon)
- doxacurium (nuromax)
- pipecuronium (arduan)
long acting nondep NMB
if nondep excreted by kidneys, do they have longer half lives and duration or shorter?
longer half lives, longer duration (>60 mins)
if nondep NMB excreted by liver, does that mean shorter half lives and duration or longer? and what family is this?
shorter half lives, shorter duration and steroid family
how is atracurium eliminated
primarily by hofmann elimination and a bit hepatic
how is mivacurium eliminated?
plasma cholinesterase
just like SCh, which is a depolarizing NMB
- naturally occurring benzylisoquinoline obtained from the plant chondodendrum tomentosum
- horrific histamine release
- LONG ACTING - eliminated renal and hepatic
d-tubocurarine (curare)
- ED95: 0.07 mg/kg (potent)
- intubating: 0.1 mg/kg
- onset: 3-5 mins
- duration: 60-90 mins
- elimination: renal and liver (10-40%)
pancuronium (pavulon)
- cards - vagolytic effect due to vagal blockade at cardiac muscarinic receptors and stimulation of sympathetic nervous system (norepi release)
- increase HR, CO, BP, MAP (especially when AV conduction is altered, think afib)
pancuronium (pavulon) side effects
- ED95: 0.030 mg/kg
- intubating: 0.05-0.08 mg/kg
- onset: 4 to 6 mins
- duration: 60 - 90 mins
- elimination: mostly kidneys, some liver
doxacurium (nuromax)
- decreased renal/hepatic function causes prolonged duration
- elderly have prolonged effect
- indicated for long cases where extubation immediately post-op is not necessary, or for ventilated patients in the unit
- NO CARDS EFFECT
doxacurium (nuromax)
- ED95: 0.050 mg/kg
- intubating: 0.085 mg/kg
- onset: 3-5 mins
- duration 60 to 90 mins
- elimination: renal (unchanged)
pipecuronium (arduan)
- no cards effects
- no histamine release
- prolonged duration in renal failure
- used for prolonged ventilation, cards stability, liver patients
pipecuronium (arduan)
ED95: 0.05 mg/kg
intubating: .1 mg/kg
onset: 2.3 mins
duration: 45 to 60 mins
elimination: hepatic (40% in bile), urine
vecuronium (norcuron)
metabolizes by deacetylation in the hepatocytes to two metabolites which have less than one-tenth of the NMB properties of drug
vecuronium (norcuron)
- more lipid soluble allowing greater passage into hepatocytes for clearance
- do not give to infants (>duration)
- rarely histamine release
- no vagolytic effect
vecuronium (norcuron)
- ED95: 0.3 mg/kg
- intubating: 0.6 mg/kg
- onset: 1 to 2 mins
- duration: 20 to 35 mins
- elimination: unchanged in bile and urine
rocuronium (zemuron)
- priming dose no impact
- > duration in liver/kidney patients
- no histamine release
- anaphylactoid reactions
- rapid sequence
- NO DIFFICULT AIRWAYS
rocuronium (zemuron)
ED95: 0.2 mg/kg (not super potent) Intubating: 0.5 mg/kg onset: 2 to 3 mins duration: 20-35 mins elimination: hoffman elimination, plasma esterases
atracurium (tracrium)
- elimination independent of organ function
- laudanosine (metabolite) causes seizures
- histamine release (can be avoided by slow admin, h1/2 blockers)
- increased HR
- decreased MAP, SVR, flushing
atracurium (tracrium)
ED95: 0.05 mg/kg
intubating: 0.2 mg/kg
onset: 2 to 3 mins
duration: 20 - 35 mins
elimination: hofmann elimination, no ester hydrolysis
cisatracurium (nimbex)
- elimination independent of organ function
- good for infusions
- minimal histamine release
- minimal CV effects (really none)
- indicated: organ failure, intermediate length case, the need to avoid histamine release, infusion
cisatracurium (nimbex)
what two drugs are used for rapid sequence
SCh and rocuronium
ED95: 0.08 mg/kg
intubating: 0.15 to 0.2 mg/kg
onset: 1.5 to 3 mins
duration: 12 to 20 mins
elimination: plasma cholinesterase (slower than SCh)
mivacurium (mivacron)
- good bigger peds pt
- laryngeal muscles relax and recover quicker than long muscles
- histamine release, avoid by dividing doses
- CV effects at 3x ED95
- neostigmine can slow recovery
- use edrophonium
mivacurium (mivacron)
- will cause prolonged blockade in pts with atypical plasma cholinesterase
- monitor oo
- not organ dependent, > duration renal/liver
mivacurium (mivacron)
vagolytic, tachycardia, htn, dysrhythmias, enhanced av conduction
pancuronium (pavulon)
histamine release from mast cells causes hypotension and tachycardia
mivacurium (mivacron) atracurium (tracurium)
doesn’t release histamine, may interfere with catabolism of it causing more to remain active (inhibits histamine-n-methyl-transferase)
vercuronium (norcuron)
