Muscle Relaxers and Neuromuscular Blockers

Question 1

Differentiate skeletal muscle relaxers from neuromuscular blockers.

Answer 1

Direct muscle relaxers: blocks release of Ca within the cell and thus blocking contraction
Indirect muscle relaxers: hyperpolarize neurons that innervate muscle groups to decrease spasm
Neuromuscular blockers: block Ach receptors in skeletal muscle system thereby preventing contraction

Question 2

What is another name for neuromuscular blocking agents?

Answer 2

Paralytics

Question 3

Which neuromuscular blocking agent differs from the others by its mechanism? Describe its mechanism.

Answer 3

Succinylcholine - depolarizing agent that first stimulates the Ach receptor before blocking it.

Question 4

What do all the non-depolarizing neuromuscular blocking agents end in? List some examples.

Answer 4

-onium –> rapacuronium, vecuronium, rocuronium

Question 5

What neuromuscular blocking agent is most likely to be used in rapid sequence intubation and why?

Answer 5

Succinylcholine –> it is rapid on and rapid off

Question 6

What infectious agent acts by blocking Ach release?

Answer 6

Clostridium Botulinum

Question 7

In what ways can a patient get acetylcholine overload pathologically?

Answer 7

Tetanus and organophosphates - nerve gas, insecticides

Question 8

What other types of medications must be given to a pateint that is given a paralytic?

Answer 8

A sedative and possibly an anxiolytic

Question 9

List two common AEs of neuromuscular blocking agents.

Answer 9

Hypertension and hyperkalemia

Question 10

Describe the “titrate to four” phenomenon clinicians use to determine an appropriate level of paralysis has been achieved.

Answer 10

A device attached to the wrist that delivers 4 shocks and would normally be followed by 4 arm twitches. The number of twitches out of four that is seen is a way to quantify their level of paralysis.

Question 11

What drugs can be used to reverse the effects of paralytics and what are the AEs of these reversal agents?

Answer 11

Acetylcholinesterase inhibitors –> GI peristalsis, bradycardia, salivation, etc.

Question 12

Are acetylcholinesterase inhibitors used to reverse paralytics reversible or irreversible inhibitors?

Answer 12

Reversible –> organophosphates and nerve gasses are irreversible

Question 13

What acetylcholinesterase inhibitor drugs are used to reverse paralytics and what other disease are they used to treat?

Answer 13

Stigmines - neostigmine, ex –> also used to treat myasthenia gravis

Question 14

What is a second generation drug used to reverse paralytic agents and what are its advantages?

Answer 14

Sugammadex –> no GI effects because it encapsulates and metabolizes the paralytic agent rather than acting on acetylcholinesterase

Question 15

List 2 PO skeletal muscle relaxers that are controlled substances in KY and state what control schedule they are.

Answer 15

Carisoprodol and Meprobamate –> C-4

Question 16

What are the clinical uses for carisoprodol and meprobamate?

Answer 16

Muscle relaxation and some anxiolytic effects

Question 17

What is the clinical use of cyclobenzaprine and what is its major AE?

Answer 17

Muscle relaxation –> highly sedating and anti-Ach effects

Question 18

How is cyclobenzaprine toxicity treated and why?

Answer 18

Bicarbonate –> cyclobenzaprine is a first cousin to TCAs

Question 19

What is the primary clinical use of baclofen?

Answer 19

Given as part of an epidural injection (intrathecal administration)

Question 20

What two medications are used to treat intractable hiccups and what patients get intractable hiccups?

Answer 20

Baclofen and chlorpromazine (anti-psychotic)

Ventilated pateints get intractable hiccups

Question 21

Which skeletal muscle relaxer is most likely to be used in a nursing home and why?

Answer 21

Metaxalone because it has reduced anti-Ach effects –> less sedation

Question 22

Which skeletal muscle relaxer is most likely to cause hypotension and why?

Answer 22

Tizanidine –> chemically related to clonidine

Question 23

Name a direct acting skeletal muscle relaxer and state two clinical uses.

Answer 23

Dantrolene –> neuroleptic malignant syndrome and malignant hyperthermia

Question 24

Name 3 other skeletal muscle relaxers we didn’t discuss further in class.

Answer 24

Orphenadrine, chlorzoxazone, methocarbamol