Exam 2: Lecture 9: Induction Drugs Flashcards
T/F: The ideal injectable drug should provide adequate and reliable sedation, analgesia, and muscle relaxation
true!
T/F: We want our injectable drugs to cause minimal changes in cardiovascular or respiratory function as well has a wide safety margin
true!
Should the idea injectable drug be reversible and have a rapid onset but long duration?
no, we want the drug to be reversible and have a rapid onset BUT it should also be short acting
The ideal injectable drug should be readily _______ and _____ by the body
metabolized and excreted
How long should the shelf like be for the ideal injectable drug
it should have a long shelf life and be stable in heat/light
T/F: Ideal injectable drugs should be inexpensive and a controlled substance
false, it should be inexpensive BUT not controlled so there is less potential human abuse
T/F: Ideal injectable drugs should require a large volume needed to achieve sedation
false, we should use a SMALL volume
Describe the make up of propofol
milky white oil in water emersion….1% propofol, 10% soybean oil, 2.25% glycerol, and 1.2% egg phosphatide
T/F: There are preservatives in propofol and it has a long life once opened
false, there are NO preservatives and the open vial should be discarded after 6 hours
What is the name of the propofol that has benzyl alcohol preservatives to prevent bacterial fungal growth
Propofol28
how long does propofol28 last once it is opened and is it approved for dogs and cats
28 days and no, only dogs
describe the MOAo of propofol
activates GABAa receptors to increase Cl- conduction and blocks Na channels leading to hyperpolarization
T/F: Propofol causes CNS depression and loss of consciousness
true
What are the pharmacokinetics of propofol
rapid distribution followed by a slower clearance phase and rapid hepatic metabolism and excretion by kidneys
T/F: You cannot use propofol as a CRI in many species
false, you can use as a CRI
What 2 species/breeds do not rapidly metabolize propofol via hepatic system and do not excrete it by the kidneys
cats and greyhounds
What happens to the CNS system with propofol (pharmacodynamics)
decreases intracranial pressure and cerebral metabolism of oxygen and has anticonvulsant effects
T/F: Propofol is a reasonable choice for patients with head trauma
true! Due to the decrease of intracranial pressure
What happens to the cardiovascular system with propofol (pharmacodynamics)
decreases BP due to vasodilation
What comorbidities should we not use propofol with (3 things)
hypovolemia, advanced age, or decreases left ventricular function
What happens to the respiratory system with propofol (pharmacodynamics)
dose-dependent respiratory depression and transient apnea (often with cyanosis)
Finish this sentence: Rapid injection of propofol = ______ is more likely
apnea
What happens to the musculoskeletal system with propofol (pharmacodynamics)
produces muscle relaxation, transient myoclonus (involuntary brief muscle contractions) can occur
What happens to with fetal/neonatal system with propofol (pharmacodynamics)
crosses the placenta but is rapidly cleared from neonate, acceptable choice for dogs getting a c-section
What are specific considerations for use of propofol in greyhounds
need same dose for induction but takes longer to recover
What are specific considerations for use of propofol in cats
use caution with repeated daily use
What are specific considerations for use of propofol in horses
rarely used for induction due to excitation and volume/cost but can be used as CRI, bolus intra-op, or facilitation of a smooth recover
What are specific considerations for use of propofol in swine
does not induce malignant hyperthermia
What are specific considerations for use of propofol in small ruminants and camelids
provides a smooth, rapid induction with a recovery that is good but need to consider cost for food animal
Describe what drug was used for this clinical scenario:
- induction dose is tritiated to effect given over 60-90 secs
- swift induction in 20-30 secs
- be ready to ventilate if needed
- recovery in about 2-12 mins (dose and species dependent)
- no analgesia
- pain on infection esp in small vessels
propofol
What is the definition of dissociative anesthetics
characterized by dissociation from thalamocortical (consciousness) and limbic (emotion/memory) leading to a change in awareness
what is the main MOA of dissociative anesthetics
mainly act via antagonist effects at NMDA receptors
what are the 7 other MOAs of dissociative anesthetics (other than NMDA)
- AMPA
- BDNF
- opioid
- endocannabinoid
- monoaminergic receptors
- muscarinic receptors
- voltage-gated calcium channels
What is important about ketamine and MOAs
ketamine has multiple MOAs that lead to its clinical effects
What are the 2 most common dissociative anesthetics used
ketamine and tiletamine
what 2 drugs make up telazol
tiletamine and zolazepam
T/F: You can give dissociative anesthetics IM, IV, SQ, OTM, IN, or rectally
true!!
what is the onset time (IV and IM) for dissociative anesthetics
IV = about 60 seconds
IM = about 10 minutes
How long on average do dissociative anesthetics last and how long does telazol last
7-23 minutes
telazol = 35-70 mins
T/F: Dissociative anesthetics are highly lipophilic but cannot cross the blood brain barrier
false, they ARE highly lipophilic and CAN cross the BBB
How are dissociative anesthetics metabolized and excreted
metabolized = liver
excreted = kidneys
what is the active metabolite that cats can form when using dissociative anesthetics
nor ketamine, excreted unchanged in the urine
In dogs, is tiletamine or zolazepam metabolized quicker
tiletamine > zolazepam
In cats, is tiletamine or zolazepam metabolized quicker
zolazepam > tiletamine
what happens to the CNS system when using dissociative anesthetics
cataleptic state of not being asleep but not responding to external stimuli
what CNS signs do we see with emergence delirium when using dissociative anesthetics
ataxia, hyper-reflexive, sensitivity to touch, increase motor activity
what happens to the cardiovascular system when using dissociative anesthetics
direct negative cardiac inotropic effects but usually overcome by sympathomimetic effects
What are the sympathomimetic effects we see with dissociative anesthetics
increased BP, HR, cardiac output, myocardial oxygen requirements and cardiac work
T/F: When using dissociative anesthetics, it inhibits NE reuptake to increase plasma catecholamines
true!
What 2 cardiovascular comorbidites should we avoid using dissociative anesthetics
critically ill patients with decreased reserve (causes decreased BP) and in patients with severe cardiovascular disease
what happens to the respiratory system when using dissociative anesthetics
does not cause significant respiratory depression
What are the pharmacodynamics of the respiratory system with dissociative anesthetics
- apneustic respiratory pattern
- bronchial smooth muscle relaxant (bronchodilation)
- pharyngeal and laryngeal reflexes remain intact
what happens to the musculoskeletal system when using dissociative anesthetics
can cause muscle rigidity and spontaneous movements which can be diminished with use of benzo’s
what happens to intraoccular pressure during the use of ketamine
can increase due to increase tone of extraocular muscles
what happens to the fetal/neonatal system when using dissociative anesthetics
crosses the placenta and should avoid using in c-section due to fetal depression
What are specific considerations for use of dissociative anesthetics in dogs
combine ketamine with benzo for induction or can also use alpha-2 agonist or opioid
What are specific considerations for use of dissociative anesthetics in cats
can spray into mouth of fractious cats because of absorption via oral mucosa
What are specific considerations for use of dissociative anesthetics in horses
be sure to adequately sedate before induction and use ketamine with a benzo, alpha-2 agonist or guaifenesin
telazol inductions are smooth but recovery is rough
What are specific considerations for use of dissociative anesthetics in ruminants
combine ketamine with benzo or guaifensin and give a ketamine stun (sub-therapeutic dose of ketamine give prior to castration)
What are specific considerations for use of dissociative anesthetics in swine
does not induce malignant hyperthermia, calm/slow recovery and not recommended for pot belly pigs
T/F: ketamine is commonly administered with a benzodiazepine or alpha-2 agonist
true
can you give ketamine as a CRI
yes at a sub-anesthetic dose to reduce inhalant requirements and provide analgesic effecrs
T/F: ketamine and tiletamine are reversible
false! They are NOT reversible
_____, ______, and _____ reflexes remain intact with ketamine or telazol
oral, ocular, and swallowing reflexes
What was the historical problem with alfaxalone
it was poorly water soluble so older formations were combined with caster oil leading to histamine release and anaphylaxis in dogs
Now a days, what is alfaxalone combined with
with non-cremophor vehicle to no longer cause histamine release and increases water solubility
What are the 2 ways to give alfaxalone
IV or IM
what is the shelf life of alfaxalone
56 days after vial is opened
what is the MOA of alfaxalone
neuroactive steroid molecule that binds to GABAa receptor to increase Cl concentrations leading to hyperpolarization
T/F: Alfaxalone has P450 hepatic metabolism and eliminated via kidneys
true
what happens to the CNS when using alfaxalone
decreases cerebral blood flow, intra-cranial pressure, and CMRO2 (rate of O2 consumption via brain)
what happens to the cardiovascular system when using alfaxalone
you have hemodynamic stability at clinically relevant doses but CAN cause dose-depended hypotension via vasodilation
what happens to the respiratory system when using alfaxalone
dose-dependent respiratory depression and/or apnea
what happens to the musculoskeletal system when using alfaxalone
relaxation
what happens to the fetal/neonatal system when using alfaxalone
crosses placenta and causes dose-dependent fetal depression but is generally safe for c-sections
Describe what drug was used:
1. NO Analgesia
2. used for induction usually but can be a CRI
3. safe for c-sections
4. good induction agent for at anesthetic risk dogs
5. can increase IOP
6. no pain on IV injection
7. schedule IV controlled substance
8. can cause excitement (cats), and vocalization (dogs) during recovery and usually has a ROUGH recovery in horses
alfaxalone
What is the make up of etomidate and the pH
0.2% soln in 35% propylene glycol
pH of 6.9
T/F: Etomidate is soluble in water
FASE! insoluble in water
what is the MOA of etomidate
enhances action of GABA (inhibitory) at GABAa receptor to increase Cl concentrations causes hyperpolarization
What are the pharmacokinetics of etomidate
- rapid penetration of brain leads to quick induction
- rapid recovery
- large therapeutic index
- metabolism via liver and plasma esterases but excreted in urine
what happens to the CNS when using etomidate
cerebroprotective effects, vasoconstriction of cerebral vessels, reduced CBF and CMRO2, decreases IOP and ICP
what happens to the cardiovascular system when using etomidate
minimal to no changes in HR, SV, CO, MAP, and CVP
Baroreceptors maintain function
what happens to the respiratory system when using etomidate
minimal effects
what happens to the endocrine when using etomidate
adrenocortical suppression (up to 6 hours in dogs and 5 hrs in cats)
what happens to the musculoskeletal system when using etomidate
myoclonus or tremors can occur
what happens to the fetal/neonatal system when using etomidate
minimal effects
Describe what drug was used:
1. preferred induction agent in patients with hemodynamic instability, increased ICP or cirrhosis
2. NO analgesia
3. caution use in patients with addisons/highly stressed
4. not recommended as a CRI due to adrenocortical suppression
5. adequate premed
6. usually only in referral practices
7. can have pain on injection, vomiting, or excitement
etomidate
When should we use mask or chamber inhalant inductions
for exotics or very aggressive patient where injectables are not possible
What should we consider when using inhalants for induction
use caution due to exposure to personnel and potential harm to patient
What is considered an “opioid induction”
ex - fentanyl + benzodiazepine
what is “ketofol”
ketamine + propofol
what is “double drip”
guaifenesin + ketamine
what is “triple drip”
guaifenesin + ketamine + xylazine
What drugs are “TKX” or “TKD”
telazol + ketamine + xylazine or dexmedetomidine
1 yr F DSH for an OVH. weight = 4kg, BCS 4/9. Easy to handle and rexieved aq premed of ace + hydro IM about 30 mins ago. IVC has been placed. What induction agent should we use?
pretty much anything other than propofol28 (cant be used in cats)
10 yr MN mini poodle who is 6kg for a dental cleaning +/- extractions. Hx of 3/6 heart murmur due to MV insufficiency. Currently on lasix and enalapril. What induction agent should we use?
etomidate if available… if not alfaxalone
7 yr F greyhound presents for biopsy of 3cm mass over left shoulder. It is planned as an out patient procedure and owner wants to take her home ASAP. what induction agent should we use?
a ketamine based protocol would be best due to quick recover
