Neuromuscular Junction Agents

Question 1

Name the receptor found at the NMJ.

Answer 1

Nicotinic (ionotropic) receptor

Question 2

Succinylcholine

Answer 2

Nicotinic (Ach) agonist

Causes NMJ paralysis

Depolarizing blocker -> Persistent contraction

Can NOT be reversed

Question 3

Name the two types of NMJ blocking agents.

Answer 3

Competitive (non-depolarizing) agents

Non-competitive (depolarizing) agents

Question 4

Competitive (non-depolarizing) agents (ex. curare) lead to what kind of paralysis?

Answer 4

Compete with Ach for binding to receptor and leads to flaccid, relaxed paralysis

CAN be reversed with AchE inhibitors

Question 5

Non-competitive (depolarizing) agents (ex. sux) lead to what kind of paralysis?

Answer 5

Transient fasciculations followed by paralysis

NMJ block NOT reversed by AchE inhibitors

Question 6

What type of NMJ blocking agent is curare like compounds?

Answer 6

Competitive (non-depolarizing) agent (competes with Ach for binding to receptor)

Question 7

What type of NMJ blocking agent is succinylcholine?

Answer 7

Non-competitive (depolarizing) agent

Can NOT be reversed (neostigmine does not work)

Question 8

3 adverse reactions of succinylcholine

Answer 8

1. Atypical AchE (poor in metabolizing sux -> leads to longer duration)
2. Hyperkalemia (High potassium due to up regulation of nicotinic receptors) (esp in burn, trauma patients, response delayed 2-7 days)
3. Malignant hyperthermia (esp with halothane)

Question 9

One of the adverse effects of succinylcholine is malignant hyperthermia (Ca release from SR). How would you treat this?

Answer 9

Dantrolene

Question 10

How is sux metabolized?

Answer 10

Pseudocholinesterase