NMB Flashcards
(13 cards)
Describe suxamethonium?
Depolarising muscle relaxant which is used for NMB in RSI (45s)
Physical:
- consists of a double molecule of ACH
- CCS
- 100mg vials
- stored at 4deg (fridge)
- 1-2mg IM and 3-4mg IV. Can also be given intralingually
PK:
A: 100%
D: charged so small around 0.2
M: rapid hydrolysis by plasma cholinesterase to choline and succinic acid (only 20% reaches NMJ)
E: renal
PD: binds to alpha on ACH (nicotinic) receptors, not broken down by ACHe so lasts longer until it diffuses away from cleft and PC metabolises it. Causes na influx into muscle and fasciculations followed by a flaccid paralysis.
A: nil
B: apnoea from paralysis
C: can cause arrhythmias by binding to muscarinic (SAN - worse in kids)
D: increased IOP
F: increased K release from cells
G: increased intragastric pressure
I: anaphylaxis
M: myalgia, MH
Other: no neostigmine reversal (can potentiate)
Contraindications: MH, sux apnoea, hyperkalaemia, severe muscle trauma, burns (24h-2y) and spinal cord trauma (24h- 18m)
What factors affect the speed of onset of NDMR’s?
All bulky and polar so small Vd with no significant redistribution. No first pass metabolism. So speed of onset directly related to concentration gradient. Less potent = faster onset
What are ED50 and ED95?
Dose required to produce either 50% or 95% depression of twitch height
Standard intubating is 2xED95 and RSI (within 60s) is 4x
What effects does aminosteroids metabolism have on patients?
Minimal metabolism and usually excreted unchanged. Therefore can be prolonged in renal impairment.
Tell me about vecuronium?
Amino steroid NDMR, used for muscle relaxation during intubation and certain surgeries.
Physical:
- monoquaternary analogue of panc
- Presented as a white powder in a 10mg vials
- stored in cupboard and reconstituted with water
- dose of 0.1 mg/kg gives NMB in 90-120s and lasts 45m
PK:
A - 100%
D - 0.2 L/kg and 10% bound
M - hepatic metabolism to clinically insignificant
E - 70% bile
PD:
MOA: ACH
Little else except CIM with prolonged. Minimal CVS and histamine release
Describe pancuronium?
Aminosteroid NDMR used for muscle paralysis for intubation and surgeries
Physical:
- bisquaternary
- CCS
- 4mg in 2ml in fridge
- 0.1mg/kg works in 60-90s and lasts 100min
PK
A: 100%
D: 0.2 and 20%PB
M: hepatic to some active (50% potent)
E: bile
PD:
MOA: ACH
C: SNS triggered as blocks NA reuptake and muscarinic receptors= tachy
Others: sweating, flushing and salivation
Describe rocuronium?
Aminosteroid NDMR used for muscle paralysis during intubation and surgery including RSI
Physical:
- monoquaternary analogue of vec (7x less potent)
- CCS
- stored in fridge
- 10mg/ml in 5ml
- 0.6 in 90-120 and 1 in 60s, lasts 45m
PK:
A: 100
D: 0.2 and 10% bound
M: 5% in liver
E: 60% bile (can be prolonged in failures)
PD
MOA: ACH
C: high dose = vasolytic
Painful to inject
6:100k anaphylaxis NAP6
Describe atracurium?
Benzylquinolinium NDMR for paralysis during intubation and surgery
Physical:
4 chiral and 10 stereo
- CCS
- fridge
- 10mg/ml in various
- 0.5mg/kg in 90-120s
PK
A: 100
D: 0.15 and 15% PB
M: 60% ester and 40% Hoffman
E: laudanosine = renal. Better for liver and renal disease
PD:
MOA: ACh
Histamine = hypotension and bronchospasm
CIM
Anaphylaxis 4in 100k NAP6
Describe cisatracurium?
Benzylquinolinium NDMR used for muscle paralysis during intubation, ventilation and surgery
Physical:
- Cis-cis stereoisomer of atracurium
- 2mg or 5 mg/ml vial
- CCs
- in fridge
- 0.15mg/ml = 120s
PK
A: 100%
D: 0.15 and 15%
M: almost all Hoffman
E: N/A
PD:
MOA: ACH
Very stable as little laudanosine
Describe mivacurium?
Benzylquinolinium NDNMB used for paralysis during intubation, ventilation and surgery
Physical
- chiral mix of three stereo
- CCS
- Fridge
- 2mg/ml in variety of sizes
- 0.2mg/kg =-0.0000002 120-150s lasting 20m
PK:
A: 100
D: 0.2 and PB 10
M: plasma cholinesterase so neo can proton and can have sux apnoea
E: renal
PD:
MOA: ACH
Histamine release
Describe sugammadex?
Modified cyclodextrin used to reverse NMB by R>V
Physical:
-CCS
- cupboard
- 100mg/ml in 2 or 5 ml
- dose 1-2 = 2mg, 1-2 PTC = 4mg and immediate RSI = 16mg
PK:
A: 100
D: no PB
M: nil
E: complex in urine
PD:
MOA: Ring encapsulates R/V in
Lipophillic core. This removes and gives concentration gradient for detachment of rest
C: stable, but occasional bradycardia and avoids S/E of others
Higher anaphylaxis than neo
Pill 7 days
Cost
Describe neostigmine?
Anticholinesterases drug used for NDNMB reversal, ileum and MG.
Physical:
- quaternary amine
- given as oral
- CCS of 2.5mg/ml or with 0.5 glyco
- 0.05mg/kg
- lasts 1-2h
PK:
A: OBA 1-2%, IV 100
D: 1L and 10%
M: plasma esterases and small hepatic
E: small amount bile, rest urine
PD:
MOA: estateric site of ACHE, hydrolysed more slowly than ACH. Occupies sites so allows ACH to build up in junction therefore more competition with NDMR
B: bronchoconstriction and secretions
C: brady and hypotension
D: miosis and blurred
G: secretions, peristalsis and N+V
Other = sweating
Describe the anticholinesterases briefly?
Short:
Edrophonium, competitive ACH at active site of ACHE.
Used for MG dx. Tension test 2mg then 8mg if no muscle strength improvement
Medium: all MOA as neo
Neostigmine: 1-2h
Pyridostigmine: 2-3h. rx of MG
Physostigmine: 0.5-5h. Glaucoma
Long:
Ecothiophate. Weeks. Phosphorylates active site. Glaucoma.
