Neuromuscular Blocking Agents Flashcards
Under which category does the neuromuscular blockers fall under?
Somatic Nervous System under the Peripheral Nervous System
Somatic Fiber ?
-Has no ganglia, indirectly innervates muscle
-Has nicotonic receptor
-Has Ach as a neurotransmitter
Neuromuscular Junction?
Synapse between presynaptic motor neuron and postsynapatic muscle membrane
General anethesia?
Includes analgesia, amnesia, loss of consciousness, inhibition of sensory and automatic reflexes and skeletal muscle relaxtion.
Where are neuromuscular blockers used?
Used in anaesthesia and artificial ventilation
Somatic Nervous System innervation?
Skin, sensory, organs and skeletal muscle-transmits information from CNS to the rest of the body
Two major neuron types?
*Sensory neurons (afferent
neurons): body -CNS
*Motor neurons (efferent
neurons): brain and
spinal cord muscle
fibers throughout the body
Normal neuromuscular transmission?
- Action potential (AP) conducted along the motor neuron
- Depolarization
- Ca2+ influx
- ACh release from storage vesicles into a synaptic cleft
- ACh binds on nicotinic receptors on the motor end plate
- Na+ channels on motor end plate open
- Na+ influx and depolarization (end plate potential (EPP))
- AP produced
- Muscle contraction occurs
- ACh hydrolyzed by AChE from motor end plate and process starts again
Which step of neuromuscular transmission do neuromuscular blockers ?
Step 5
5. ACh binds on nicotinic receptors on the motor end plate
Skeletal Muscle Relaxtants types?
- Peripherally-acting agents
-Depolarising NMBD’S
-Nondepolarising NMBDs - Centrally-acting agents
-act on the CNS - Directly-acting agents
-act on the muscle
Structure of NMBD’S?
Structurally polar-do not cross blood brain barrier
NMD administration?
All administered parenterally
NMD action?
Relax voluntary skeletal muscles, diaphragm and laryngeal muscles
General MOA of NMB?
structurally similar to ACh
act at the post-junction nicotinic receptors
NMB agonists or antagonists?
*agonists = depolarizing NMBDs
mimic ACh
persisting state of depolarization
*antagonists = non-depolarizing NMBDs
competitive inhibitors of ACh
prevent depolarization
Types of Peripherally acting NMB?
- Depolarizing NMBDs
- Non-depolarizing NMBDs
Can be identified by “cur”
NMB Depolarising drugs?
*Succinylcholine (suxamethonium)
NMB non-depolarising drugs types?
a) Isoquinoline derivatives
b) Steroid derivatives
NMB Isoquinoline derivative drugs?
MAD
*Mivacurium
*Atracurium
*d-tubocurarine
NMB Steroid derivatives drugs?
Very Running People
Vecuronium
Rocuronium
Pancuronium
Succinylcholine MOA?
only depolarizing NMBD in clinical use
causes ↑ EPP rapid muscle contraction,
clinically observed as muscle fasciculation
this is followed by flaccid paralysis within 30-
60 sec and lasts for 3-5 min
with repeated dose, receptors reach
tolerance rapid and complete muscle
relaxation