Chp. 25: Anesthetic & Analgesic Adjunctive Drugs

Question 1

Dantrolene

Answer 1

Peripherally acting muscle relaxant, producing skeletal muscle relaxation through ryanodine receptor antagonism and inhibition of the dihydropyridine receptor calcium channel

Question 2

Dantrolene MOA

Answer 2

Reduced calcium release from SR into the cytoplasm via RyR1 receptor, thereby dissociating excitation-contraction coupling

Question 3

What muscles does dantrolene affect?

Answer 3

Limited to skeletal muscle, though cardiac depression has been reported in dogs when administered at high doses (>5mg/kg) or in combination with verapimil

Question 4

What is the effect of dantrolene on respiration?

Answer 4

Minute ventilation under GA is reduced through depression of both RR and TV.

Question 5

What are the indications for use of dantrolene?

Answer 5

Treatment and prevention of malignant hyperthermia and rhabdomyolysis

Question 6

What are the CV effects of dantrolene?

Answer 6

Reduced CO, HR, and ABP

Question 7

How is dantrolene metabolized?

Answer 7

Hepatic metabolisms, primarily hydroxylation, in the dog and horse

Question 8

Dantrolene dosing

Answer 8

Horse: 1.9mg/kg IV with 2.5mg/kg PO q60min OR 2-4mg/kg PO

Dogs and Cats: 1-3mg/kg IV or 5-6mg/kg PO for prophylaxis

Pigs: 1-3mg/kg IV (treatment) or 5mg/kg PO (prophylaxis)