Injectable induction agents

Question 1

propofol

Answer 1

it’s its own class
ultra short-acting (nonbarbiturate)
wide dosing margin
can use for induction and total IV anesthesia
also used for uncontrolled seizures
can be used CRI

Question 2

propofol solubility

Answer 2

minimally water soluble

Question 3

what is in propofol?

Answer 3

can be egg, glycerin, or soy based
base makes it not bacteriostatic

Question 4

propofol appearance

Answer 4

milky appearance

Question 5

propofol storage

Answer 5

once open lasts 6-24 hours refrigerated

Question 6

propofol mode of action

Answer 6

appears to affect GABA receptors

Question 7

propofol onset, duration, and metabolization

Answer 7

rapid onset, short duration, rapidly metabolized

Question 8

is propofol fat soluble?

Answer 8

highly fat soluble
it’s taken up by vessel rich tissues and quickly redistributed to muscle and fat

Question 9

propofol complete recovery

Answer 9

dog: 20 min
cat: 30 min

Question 10

what does propofol cause?

Answer 10

dose dependent CNS depression, sedation, anesthesia
may also cause muscle twitching, sneezing, yawning, head shaking, apnea, hypotension, excitement, arrhythmias

Question 11

etomidate

Answer 11

not controlled
used for induction in cardiac patients
also an emetic
IV
inhibits GABA
ultra short-acting (redistributed away from brain and rapidly metabolized)
not used CRI

Question 12

what does etomidate cause?

Answer 12

causes hypnosis, vomiting, insignificant analgesia
may also cause brief hypotension, brief apnea, muscle twitching, pain at injection site, RBC hemolysis, adrenal suppression

Question 13

alfaxolone

Answer 13

old drug (1970s) - discontinued cause of histamine release and anaphylactic reactions
neuroactive steroids, binds to GABA receptors
Alfaxan is now a water-soluble neuroanesthetic (metabolized by liver, no histamine release)

Question 14

Alfaxan

Answer 14

C-IV controlled
no preservative
discard after 6 hours of 1st puncture
shelf life of 56 days after 1st puncture for multidose
synergistic
dose: dog- 1-3 mg/kg, cat- 2-5 mg/kg
CRI okay
administer slow
IM or IV

Question 15

barbiturates history

Answer 15

developed in 1930s-1950s
derivatives of barbituric acid
classes: ultra short-acting, short-acting, intermediate-acting, long-acting

Question 16

ultra short-acting barbiturates

Answer 16

ex: thiopental sodium, methohexital
used for induction of dogs, cats, horses
C-III controlled

Question 17

short-acting barbiturates

Answer 17

ex: pentobarbital
induces/maintains anesthesia in lab animals
concentrated doses used as euthanasia
C-II (fatal plus) or C-III (Euthasol)

Question 18

intermediate/long-acting

Answer 18

phenobarbital
anticonvulsant and sedative (increases seizure threshold)
not commonly used for sedation anymore
C-IV controlled

Question 19

barbiturate mode of action

Answer 19

inhibits GABA, depresses CNS

Question 20

ionized vs nonionized barbiturates

Answer 20

nonionized passes through cell membranes
acidosis = increased nonionized = increase sedation
alkalosis = decreased nonionized = decreased sedation

Question 21

what do barbiturates cause?

Answer 21

causes mild sedation, hypnosis, unconsciousness, CNS depression (excitement at low doses)
may also cause cardiac depression, hypotension, cardiac arrhythmias and blocks, decreased RR and apnea, coughing, sneezing, laryngospasms

Question 22

dissociatives

Answer 22

ex: telazol (tiletamine + zolazepam), ketamine
C-III controlled
IV, IM, po
often combined with other drugs - Benzos (ketval) and opioids

Question 23

dissociatives mode of action

Answer 23

cause disruption of nerve transmission in parts of the brain and stimulation in others
N-methyl-D-aspartate (NMDA) inhibitors so responsible for windup and respond to low-intensity pain stimuli

Question 24

dissociatives onset, duration, excretion

Answer 24

1-2 min IV, 10 min IM
duration: 20-30 min
redistributed and metabolized by liver
excreted by kidneys

Question 25

what does dissociatives cause?

Answer 25

causes sedation, anesthesia, analgesia
may also cause catalepsy, tachycardia, hypertension, excitement, arrhythmias