Injectable Anesthetic Agents

Question 1

Etomidate

Answer 1

• OK TI
• good cardiovascular stability !
• minimal respiratory depression
• decreased ICP
• poorly water soluble, formulated with propylene glycol
• bad endocrine effects: inhibits 11-beta-hydroxylase which converts cholesterol to glucocorticoids and mineralcorticoids resulting in decreased cortisol, corticosterone, and aldosterone (really bad long term suppression)

Question 2

Ketamine

Answer 2

• highest TI, safest
• dissociative anesthetic
• never used solo
• has S confirmation (more potent) and R confirmation
• lipophilic
• non competitive NMDA receptor antagonist
• direct myocardial depression
• increases sympathetic tone in intact animal
• increases muscular tone, so used in conjunction with drugs that promote relaxation
• does provide some analgesia

Question 3

Alfaxalone

Answer 3

• OK TI
• very expensive
• water soluble
• does not cause histamine release
• GABA action
• good for muscle relaxation
• respiration depression
• decreases BP but increases HR
• ideal drug for sick pets

Question 4

Propofol

Answer 4

• LOW TI, not safe
• GABA: Cl gets in and Ca does not leave the cell
• short acting, fast clearance
• smooth induction and recovery
• short context sensitive half life
• possible extra hepatic metabolism, ok for patients with liver issues
• can lead to severe respiratory and cardiovascular depression (short lived)
• vehicle is composed of oil: bad for drug interactions
• bad for long term use: oxidative injury

Question 5

Thiopental

Answer 5

• LOW TI, not safe
• Barbiturates (GABA: Cl gets in and Ca does not leave the cell)
• decreases CBF, very good to prevent high ICP
• short lasting, long context sensitive half life
• repeated bolus is not recommended
• liver P450 dependent, carful with patients with low hepatic function

Question 6

time of awakening is dependent on

Answer 6

distribution NOT elimination

Question 7

context sensitive half life

Answer 7

• redistribution sites hold on to drug and keep releasing it even after you stopped giving it, causes prolonged effect
• this is the time it takes to wake up after that
• “time needed for plasma drug concentration to decrease by 50% after discontinuing constant infusion”

Question 8

Barbiturates

Answer 8

-GABA: Cl gets in and Ca does not leave the cell