Succinylcholine

Question 1

What is the drug class of Succ?

Answer 1

the only depolarizing neuromuscular blocker that is used clinically

Question 2

What is the MOA of Succ?

Answer 2

attaches to one or both of the alpha subunits of the nicotinic, Ach receptors, and mimics the action of Ach (partial agonist). It depolarizes the post-junctional membrane causing a brief pd of excitation (fasciculations in muscle cells), followed by flaccid paralysis. The paralysis occurs b/c the open cholinergic channels maintain the cell membrane in a depolarized state effecting the inactivation of VG-Na channels so that they cannot open to support further action potentials

Question 3

How is succ metabolized and eliminated?

Answer 3

-metabolized rapidly by hydrolysis via plasma cholinesterases (pseudo-cholinesterases), an enzyme synthesized by the liver. It is not present in significant amounts at the NMJ

Question 4

How are the effects of Succ terminated?

Answer 4

by diffusion away from the NMJ (redistribution) and into the ECF

Question 5

What is the Vd of Succ?

Answer 5

similar to ECF 200ml/Kg

Question 6

What are the side effects of Succ?

Answer 6

• Cardiac Dysrhythmias (sinus BRADY, junctional, sinus arrest) due to mimicking of Ach at cardiac muscarinic receptors and hyperkalemia
• Hyperkalemia!!! avg increase of 0.5-1 meq/L (increased risk with burns, trauma, NM disease, Muscular dystrophy, prolonged immobility)
• Masseter spasms
• Increased IOP, ICP, IGP
• Malignant Hyperthermia!!!
• Histamine release
• Myalgia
• Myoglobinuria

Question 7

What are the contraindications to the use of Succ?

Answer 7

• Hyperkalemia
• 3rd degree burns
• Severe muscular disorders
• Stroke (CVA)
• Neurologic injury (quads/paraplegic)
• muscle wasting
• MH
• Children under 8

Question 8

What are the common drug interactions with Succ?

Answer 8

• anticholinesterases increase relaxation and prolong effects of succ
• anticonvulsants may increase hyperkalemia and prolong Succ
• Lithium prolongs succ

Question 9

What is the intubating dose of Succ?

Answer 9

1-1.5 mg/kg IV

Question 10

What is the onset of succ?

Answer 10

30-60 secs

Question 11

What is the E 1/2 t of succ?

Answer 11

2-4 minutes

Question 12

What is the DOA of succ?

Answer 12

4-8 mins (8-15 min)

Question 13

What is the Laryngospasm dose of succ?

Answer 13

20-40 mg IV

Question 14

What is the cont. infusion dose of succ?

Answer 14

2-4mg/min (dilute 1-2mg/ml)

Question 15

Who do you want to avoid giving succ to? Why?

Answer 15

Peds:

• contraindicated in routine managemnt due to SE
• must give with Atropine 0.02mg/kg
• MH trigger
• may result in malignant ventricular arrhythmias and cardiac arrest 2dary to acute rhabdomyolysis with hyperkalemia
• can result in profound bradycardia and asystole!!!!