Injectable induction agents Flashcards
propofol
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
propofol solubility
minimally water soluble
what is in propofol?
can be egg, glycerin, or soy based
base makes it not bacteriostatic
propofol appearance
milky appearance
propofol storage
once open lasts 6-24 hours refrigerated
propofol mode of action
appears to affect GABA receptors
propofol onset, duration, and metabolization
rapid onset, short duration, rapidly metabolized
is propofol fat soluble?
highly fat soluble
it’s taken up by vessel rich tissues and quickly redistributed to muscle and fat
propofol complete recovery
dog: 20 min
cat: 30 min
what does propofol cause?
dose dependent CNS depression, sedation, anesthesia
may also cause muscle twitching, sneezing, yawning, head shaking, apnea, hypotension, excitement, arrhythmias
etomidate
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
what does etomidate cause?
causes hypnosis, vomiting, insignificant analgesia
may also cause brief hypotension, brief apnea, muscle twitching, pain at injection site, RBC hemolysis, adrenal suppression
alfaxolone
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)
Alfaxan
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
barbiturates history
developed in 1930s-1950s
derivatives of barbituric acid
classes: ultra short-acting, short-acting, intermediate-acting, long-acting
ultra short-acting barbiturates
ex: thiopental sodium, methohexital
used for induction of dogs, cats, horses
C-III controlled
short-acting barbiturates
ex: pentobarbital
induces/maintains anesthesia in lab animals
concentrated doses used as euthanasia
C-II (fatal plus) or C-III (Euthasol)
intermediate/long-acting
phenobarbital
anticonvulsant and sedative (increases seizure threshold)
not commonly used for sedation anymore
C-IV controlled
barbiturate mode of action
inhibits GABA, depresses CNS
ionized vs nonionized barbiturates
nonionized passes through cell membranes
acidosis = increased nonionized = increase sedation
alkalosis = decreased nonionized = decreased sedation
what do barbiturates cause?
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
dissociatives
ex: telazol (tiletamine + zolazepam), ketamine
C-III controlled
IV, IM, po
often combined with other drugs - Benzos (ketval) and opioids
dissociatives mode of action
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
dissociatives onset, duration, excretion
1-2 min IV, 10 min IM
duration: 20-30 min
redistributed and metabolized by liver
excreted by kidneys
what does dissociatives cause?
causes sedation, anesthesia, analgesia
may also cause catalepsy, tachycardia, hypertension, excitement, arrhythmias