Skeletal muscle relaxants acting on the NMJ

Question 1

Name the non-depolarising skeletal muscle relaxants?
Competitive antagonists of Nm
- Isoquinolines

Answer 1

D-tubocurarine
Mivacurium 
Cistracurium
Atracurium
Doxacurium

Question 2

Which non-depolarising SM relaxant is metabolised by Pseudocholinesterase?

Answer 2

Mivacurium

Question 3

How are Cistracurium and Atracurium metabolised?

Answer 3

Spontaneous (Hoffmann-elimination)

Question 4

Which non-depolarising skeletal muscle relaxants are metabolised spontaneously?

Answer 4

Cistracurium and atracurium

Question 5

What is the duration of action of Mivacurium?

Answer 5

Short acting (10-15 mins)

Question 6

What is the duration of action of Cistracurium?

Answer 6

Intermediate acting (20-30 mins)

Question 7

What is the duration of action of Atracurium?

Answer 7

Intermediate acting (15-35 mins)

Question 8

What is the duration of action of Doxacurium?

Answer 8

Long acting

Question 9

What is the duration of action of D-tubocurarine?

Answer 9

> 35 mins

Question 10

Which drug is safe in renal and hepatic impairment?

Why?

Answer 10

Atracurium

Because it is spontaneously inactivated to Laudonosine (therefore does not use the liver or kidneys in its metabolism)

Question 11

What is the break down product of Atracurium?

Answer 11

Laudonosine

Question 12

In which patients do we not use Mivacurium?

Answer 12

In those who are quick metabolisers (pseudocholinesterase). It already has a short duration of action.

Question 13

How do you reverse the block induced by non-depolarising SM relaxants?

Answer 13

Competitive non depolarising SM relaxants are competitive so you over come the effects by increasing the concentration of the ligand of the receptor; in this case, Ach - so you use an AchE inhibitor.

You use Neostigmine (quartenary AchE inhibitor) - cannot enter the CNS.

Not physostigmine as it is a tertiary amine and can enter the CNS

Not Edrophonium as it has a short half life.

Question 14

Name the non-depolarising SM relaxants?

Steroids

Answer 14

Vecuronium
Rocuronium
Pancuronium
Pipecuronium

Question 15

Which non depolarising SM relaxants are metabolised by the Liver?

Answer 15

Vecuronium

Rocuronium

Question 16

Which non depolarising SM relaxants are metabolised by kidney filtration?

Answer 16

Pancuronium

Pipecuronium

Question 17

Which is the longest acting non-depolarising SM relaxant?

Answer 17

Pancuronium

Question 18

What is the duration of action of Vecuronium?

Answer 18

Intermediate acting

Question 19

What is the duration of action of Rocuronium?

Answer 19

Intermediate acting (dose dependent)

Question 20

What is the duration of action of Pancuronium?

Answer 20

Long acting

Question 21

What is the duration of action of Pipecuronium?

Answer 21

Long acting

Question 22

What are the long acting SM relaxants?

Answer 22

Doxacurium
Pancuronium
Pipecuronium

Question 23

What are the intermediate acting SM relaxants?

Answer 23

Vecuronium
Rocuronium
Atracuronium
Cistracuronium

Question 24

What are the short acting SM relaxants?

Answer 24

Mivacurium

Question 25

What is the time order o the curare-induced muscle paralysis?

Answer 25

1. Outer eye muscles
2. Facial muscles
3. Pharyngeal muscles
4. Extremities
5. Truncal muscles
6. Respiratory muscles
7. Full Paralysis

Question 26

How long does it take to reach full paralysis?

Answer 26

2-6 mins

Question 27

What can be used to terminate the effect of the steroid non-depolarising SM relaxants?

Answer 27

Sugammadex

Question 28

What is the depolarising non competitive SM relaxant?

Answer 28

Succinylcholine

Question 29

How is Succinylcholine metabolised?

Answer 29

Pseudocholinesterase

Question 30

What is the time order of the Succinylcholine induced muscle paralysis?

Answer 30

1. Arms
2. Neck
3. Legs
4. Respiratory muscles
5. Facial muscles
6. Pharyngeal muscles