Flashcards in Muscle Relaxants Deck (41):
What are the two groups of skeletal muscle relaxants?
1) Muscle Paralyzers AKA neuromuscular blocking agents or neuromuscular blockers
2) Spasmolytics- reduce muscle spasm
When are neuromuscular blocking agents (muscle paralyzers) used?
-when we want muscle paralysis
- surgery or in ICU on ventilator
MOA of neuromuscular blocking agents
Block transmission of signal from the nerve to the muscle at the junction where the nerve meets the muscle (AKA neuromuscular endplate)
Do neuromuscular blocking agents have an effect of the brain?
NO. The patient is aware they can't move if they are awake
Route of administration for neuromuscular blocking agents
Can neuromusclar blocking agens get into the CNS
no they are polar
What are the two methods the neuromuscular blocking group can block the neuromuscular jxn?
1) Nondepolarizing blocade- prevent accsess of transmitter and prevent depolarization
2) Depolarizing blockade- cause depolarization by producing excess acetylcholine
List the Nondepolarizing Neuromuscular Blockers
- Curare- first discovered, darts
pancuronium- long acting
MOA of nondepolarizing blockers
competitive antagonists to acetylcholine (nicotinic subtype) receptor at the neuromuscular junction but does not activate receptor
How do you reverse nondepolarizing blockers?
acetycholine esterase- floods synapse with acetylcholine
What is the progression of paralysis with nondepolarizing neuromuscular blockers?
motor weakness - skeltal muscles flacid- larger muscles paralyzed last - diaphragm very last
What is the only depolarizing neuromuscular blocker? how long does it last?
SHORT 5-10 minutes
MOA of succinycholine (depolarizing neuromuscular blocker)
Succinylcholine binds & activates the nicotinic receptor once causing one transmission of an impulse to the muscle.
Then it doesn't transmit anymore and doesn’t leave the receptor either.
muscle stays in depolarized state
CVS effects of depolarizing neuromuscular blockers are
1) hypotension from histamine release
what can you give to prevent hypotension with depolarizing neuromuscular blockers?
What patient dispositions leads to hyperkalemia in they are given depolarizing neuromuscular blockers?
Inhaled anesthetics combined with nondepolarizing neuromuscular blockers may cause
What do you treat malignant hyperthermia with?
What are three clinical uses of neuromuscular blockers?
1) Surgical relaxation
2) Control of ventilation
3) Tracheal intubation
Neuromuscular blockers in surgical relaxation
-when you cut into muscle it contracts
-intra-abdominal and intra-thoracic surgeries
How do you monitor neuromuscular blockade during surgery?
transdermal electrical stimulation of peripheral nerves (hands or face) and record the evoked contractions
What are acetycholine esterase inhibitors you can give pts. to undoe nondepolarizing neuromuscular blocers?
Neuromuscular blockers used in ventilation
get better control of ventilation and better oxygen exchange if paralyzed as opposed to just sedated
Neuromuscular blockers used in intubation
relaxes upper airway muscles and can make it easier to place tracheal tube.
increase in tonic stretch reflexes and flexor muscle spasm
modify the stretch reflex arc or interfering directly with the skeletal muscle
bring relief to muscle spasms
What is the only spasmolytic that is not centrally acting?
Addresses muscle spasms caused by what?
-facilitates gaba action
- muscle spasm of any origin
Agonist at the GABA receptors which results in decreased release of excitatory neurotransmitters in brain & substance P
increased seizure threshold
less sedating than valium
Addresses muscle spasms caused by what?
MOA: some effects as a CNS alpha 2 adrenergic agonist
clinical use: spasticity from cerebral or spinal injury
sense of weakness & loss of strength without true loss of strength
Gabapentin/Pregabalin used in what Dz?
Gabapentin/ Pregabalin dosage?
800mg 4 times a day, takes a while to get up to this dose
MOA: works on muscle fibers and prevents release of calcium
clinical use: spasms from spinal cord or CNS, & malignant hyper thermia
ADR of Dantrolene (Dantrium)
- true muscle weakness
-heritable disorder induced when given general anesthetics and succunylcholine
prolonged release of calcium from the muscle, causing massive muscle contraction, lactic acid production, fever, death
What is the treatment of malignant hyperthermia?
Other drugs grouped together that treat muscle spasms (list)
Cyclobenzaprine (Flexeril), the protoype
Carisoprodol (Soma)- abused
What does the Misc group of spasmotics do?
When do you not use them?
treat muscle spasm from trauma
DO NOT USE FOR CNS OR SPINAL INJURIES
STONGLY ANTICHLONINERGIC- Hallucinations
List of Rxs muscle relaxants used in true muscle spasms from neurologic injury