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ANAESTHESIA > 2. Preanesthetic Medication > Flashcards

2. Preanesthetic Medication Flashcards

1
Q

What are some reasons that we might pre-med a patient for anesthesia?

A
  1. to calm or sedate an excited, frightened, or vicious animal
  2. to minimize adverse effects of concurrently administered drugs
  3. to reduce req dose of concurrently administered agents
  4. to prod smoother anesthetic inductions and recoveries
  5. to dec pain and discomfort pre, peri, and postoperative.
  6. to prod muscle relaxion
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2
Q

What does preemptive analgsia do and help with?

A

to provide analgesia b4 tissue injury, including surgery (and after)

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3
Q

What are some reasons to provide pre-emptive analgesia?

A
  1. more effective analgesia and takes less meds than treating pain that already exists
  2. Liminited pain b4 it occurs also allows overall amount of anesthetic req and therefore dex drug risks
  3. speeds up recovery times
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4
Q

What should we consider when selecting a preanesthetic protocol?

A

signalment, temperament, patient hx, physical status, availability and compatibility of drugs, available routes (PO, IV, IM, or SQ)
comfort with specific drugs, procedure, facilities available

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5
Q

When we are administering the premedication, how long does it take for SQ, IM and IV before the patient is induced?

A

30-40min before induction of SQ
10-29min for IM
3-10 for IV (effects more pronounced and faster, more pronounced side-effects), often requires an IV catheter)
Leave patient in quiet area, excited patients will req a higher dose

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6
Q

How do we assess sedation?

A

Parasympathetic signs like drooling, constricted pupils, or prolapsed 3rd eyelid
Ataxia - do not leave unattended; anxiety
Recumbency
Dec in HR, RR, (BP)
Certain drugs can relax inhibitions and animals can become aggressive or exhibit other unusual behaviours

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7
Q

What are some precautions to keep in mind with preanesthesia?

A

Overdose can result in sufficient CNS depression to cause death
In very sick animals, recommended doses can cause lethal overdose
Horses that develop ataxia as a result of sedation can become anxious and enter “fight or flight:
Brachycephalic breeds should be continuously monitored under sedation - relaxation of the elongated soft palate can cause airway to close

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8
Q

What are the main 3 groups of premedications for preanesthesia?

A

Anticholinergics
tranquilizers and sedatives - phenothiazines, benodiazepines, alpha2adrenoceptor agonist (alpha2-agonists)
Opiods

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9
Q

What are anticholinergics and what are some indications for it?

A

Aka parasympatholytics, non-controlled drugs
to controll parasymp effects of many of other drugs used in balanced anesthesia such as preventing and treating bradycardia
decreased salivary secretions from parasymp stimulation (aids in intubation)
mydriasis (prevents rolling of the eyeball and open pupl for eye surgeries?

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10
Q

What are some routes that anticholinergics are administered by?

A

IM, SQ, IV, IT (intratracheal)
EX. atropine, glycopyrrolate

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11
Q

What are the major effects and adverse effects of anticholinergics?

A

prevention of bradycardia
inc HR
cardiac arrhythmias
reduction and thickening of resp secretions
bronchodilation
mydriasis
reduction of GI, salivary, and lacrimal secretions
inhib of peristalsis - colic horses

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12
Q

What are tranquilizers and sedatives main effects? Are they apart of a balanced anesthesia? Are they a controlled drug?

A

Centrally-acting, causes depression of CNS.
Part of balanced anesthesia - smoother induction, allows dec dose of general anesthetic, patients recovery after
Many are controlled drugs so must record!

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13
Q

What is a sedative’s main effect?

A

Causes reduced mental activity and sleepiness

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14
Q

What is a tranquilizaer’s main effect

A

reduce anxiety but does not necessarily dec awareness and awakeness

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15
Q

What are some main drugs we’ll see phenothiazines, benzodiazepines, alpha2-adrenoceptor agonists

A

Pheno - Acepromazine
Benzo - Diazepam (valium), midazolam (Versed)
Alpha2 - xylazie (rompun), dexmedetomidine (DexDomitor)

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16
Q

What are phenothiazines?

A

Non-controlled, approved for horses, dogs, and cats
injectable and oral formulations
No reversal
Major effects and adverse side effects like reduction of seizure threshold, tachycardia, or bradycardia. Antiarrhythmic effects, peripheral vasodilation, hypotension, antiemetic effects

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17
Q

What is the mechanism of action for phenothiazines like acepromazine?

A

blocks dopaminergic receptors in the basal ganglia -> CNS depression
blocks alpha1 adrenergic receptors
some anti-histamine effects

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18
Q

What are the physiological effects of phenothiazines like acepromazine

A

causes calming, reluctance to move and dec interest in surroundings
dec spontaneous activity, ataxia.
vasodilation (due to blocking a1-receptors)
Suppressors chemoreceptor trigger zone (anti-emetic)
will slowly cross the placenta

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19
Q

What are the clinical uses for phenothiazines like acepromazine

A

anti-anxiety and sedation(relatively mild)
chemical restraint to ease handling
travel-stress
dec dose of general anesthetic
eases induction and recovery
blocks morphine-induced excitement in cats
anti-spasmodic
Anti-emetic (dec vomiting when used together with hydromorphone as pre-anes)

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20
Q

What are common side effects of phenothiazines like acepromazine?

A

Vasodilation (a1 receptor blockage); causes hypotension so monitor BP
Hypothermia in sm animals
sequestering of RBC’s in spleen to cause spleen enlargement and drop in PVC. Caution in splenectomies, anemia
overdose may cause rigidity or tremors
Ptosis, prolapsed 3rd eyelid in dogs and cats
can cause aggression or excitement

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21
Q

What are some other considerations to keep in mind when working with phenothiazines like acepromazine?

A

bradycardia, but less than many other agents
no analgesia
antiemetic
prevents histamine release and dec allergic response
worsens depressive effect of other drugs in the resp system
metabolized by liver

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22
Q

What are some side effects specific to horses when using phenothiazines like acepromazine

A

penile prolapse - facilitates sheath cleaning, examination, can be irreversible, caution in breeding stallions

possible excitement, sweating, tachypnea

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23
Q

What are some relative contraindications for acepromazine, “never use in…”

A

Breeding stallions bc of penile prolapse
Boxers which may exacerbate underlying arrhythmias
alow avoid in severely debilitated, neonates, geriatics, pre-existing hypotension (blood loss, shock, dehydration), CHF, liver dz, CRF - related to vasodilation and resultant hypotension
always use caution when sedating brachcephalic breeds

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24
Q

When we actually USE ace, how long does it last, any max dose or drug combinations>

A

can use alone for anti-anxiety and minor restraint
used in combo with other drugs for pre-anesthesia but not with demedetomidine
there is a mg/kg dose AND a mx dose
inc the dose does NOT inc sedation, but inc hypotension due to peripheral vasodilation
works better if not already excited; excitement dec the effect
lasts 4-8hrs
no reversal. if OD’d, provide supportive care by fluids and inc symp response

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25
Q

What is azaperone/strensnil and where is it used? what’s its main action

A

A butyrophenones, only used in pigs
blocks dopamine and norepinephrine activity in the CNS

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26
Q

What are the clinical indications for azaperone?

A

dec aggression/fighting during weaning and mixing
premed and sedation for castrations
anti-emetic
dec malignant hyperthermia - potentially fatal genetic condition; inc metabolic rate and muscle activity in response to isoflurane, transport/handling stress
common in pigs

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27
Q

Are benzodiazepines controlled? What administration forms are available?

A

Controlled, most not labelled for vet use, injectable and oral (tabs) avail.

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28
Q

What are the major effects and adverse effects. Reversal?

A

anti-anxiety and calming
anticonvulsant activity
disorientation and excitement in yg, healthy dogs
dysphoria and aggression in cats
muscle fasciculation in horses
ataxia or recumbency in lg animals
few cardiopulmonary effects
skeletal muscle relaxant
no analgesia
reveal is flumazenil

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29
Q

What is the mechanism of action of benzodiazepines?

A

inc GABA lvls in brain - GABA is an inhib neurotransmitter

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30
Q

What are indications of benzodiazepins?

A

part of a balanced anesthesia - premed to smooth induction and recover, can combine with ketamine for induction
Other common indications - antianxiety to sedation; behavioural modifer
anticonvulsant for treating seizures
skeletal muscle relaxant (including urethral relaxation)

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31
Q

What are the benefits of benzodiazepins?

A

minimal CV effects at appropriate dose
does cause dose-dependent respiratory depression
smoother induction and recovery
decrease amount of inhalant GA req
inc skeletal muscle relaxation
Reversal drug class - in event of OD or adverse reaction, can give reversal agent (aka antagonist or antidotes)

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32
Q

What are the precautions of benzodiazepines? What specifically in horses?

A

sedation is not always reliable when used alone in animals
dysphoria/excitement can occur
may unmask latent aggression in some animals (animals lose inhibitions)
in horses, muscle fasciculation, weakness, ataxia, do not give alone except for seizures in adults

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33
Q

What are contraindications of benzodiazepines?

A

avoid in pregnancy/cesarean bc it will cross the placenta and may lead to floppy baby syndrome which is skeletal muscle relaxation in the neonate and asphyxiation from relaxation of resp muscles

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34
Q

What are clinical indications for diazepam? Common animals?

A

Commonly used in dogs, cats, horses and pigs
indications are anticonvulsant for emerg tx of seizures
anti-anxiety (noise phobias_ @ lower dose
Sedation @ higher dose (must be used in combo w/ other drugs in cats/horses (and some dogs) or may cause excitement
skeletal muscle relaxant
relaxes urethral sphincter (blocked cats and dogs)
can mix with ketamine for induction (Ketval)

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35
Q

What are the indications of diazepam?

A

inexpensive
can be administered by IV - painful/unreliably absorbed if given IM/SQ, can give intra-rectal if seizuring patient, also available as oral tablets
dose varies depending on route of admin
lasts 30min-2hr
may cause a prolonged hangover effect
hx’cally used as appetite stimulant in cats-doesn’t really work

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36
Q

How is diazepam handled and storage?

A

controlled drug
not water soluble so will form precipitate if mixed with other drugs - never use if precipiate forms), only exception is ketamine
Store IV solution in glass containers as drug binds to plastic with time, keep from light
Flush IV lines immediately after administering - binds to plastic and will form precipiate if still in line/veing when next drug is administered

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37
Q

What are the adverse effects/contraindications for diazepam?

A

contraindicated for cesarean bc of floppy baby syndrome, depressed, poor muscle tone, excessive sedation
Aggressive dogs, can bring out latent aggression
Used alone in horses - excitement and ataxia
cats - can cause sudden liver failure, increased with increased doses (avoid use as an appetite stimulant

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38
Q

What are differences of diazepam vs midazolam/versed?

A

easier to use, more expensive
exceptions - twice as potent, shorter acting, compatible w/ many agents as it is water-soluble, can give IM, SQ, IV, cannot use alone, not used as anti-convulsant

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39
Q

What does the antagonist flumazenil do and how does it work?

A

reversal agent for benzodiazepines including diazepam and midazolam
binds to and blocks GABA receptors - more attraction for the GABA receptor than the benzodiazepines and therefore knocks off any benzodiazepine drug already bound to the receptor
little to no effect on its own
seldom used bc $$$ and short duration of action of diazepam/midazolam

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40
Q

What are the major effects and adverse effects of Alpha 2 adrenergic agonists?

A

dose-dependant sedation profound
analgesia
agitation or aggression when touched
reaction to loud noices
muscle tremors in horses
cattle often lie down
initial hypertension, bradycardia and pale mucus membranes followed by hypotension, dec cardiac output and a little further dec in HR

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41
Q

What else might a2 adrenergic agonists has a major effects and adverse effects?

A

severe dec in HR, BP, cardiac output, tissue perfusion especially when high doses are given
resp depression can be severe
muscle relaxation
vomiting in cats/dogs
adverse GI effects (bloat and colic)
hyperglycemia
hypothermia
inc urination
premature parturition in cattle
horses may sweat

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42
Q

What are common a2 adrenergic agonists in lg anim and sm anims? Are they reversible?

A

Lg - xylazine (rompun), detomidine (dormosedan), romifidine (sedivet)
Sm - dexmedetomidine (dexdomitor)
reversible drug clas

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43
Q

What is the mechanism of action of alpha2 adrenergic agonists?

A

binds to a2 adrenergic receptors
activation of a2 receptors causes inhib of release of norepinephrine and dopamine
dec overall symp response
metabolized by liver;excreted by the kidnehys

44
Q

What is the main physiological effect of a2 receptor activation?

A

overall CNS depression - dec overall ability to respond to stimuli, action is enhanced if given together with an opioid or other sedative or tranquilizer
Dec symp response - bradycardia that is consistent, immediate, significant; as low as 12bpm in a large dog. Resp depression
Inc parasym NS for increased GI motility (except in ruminants)

45
Q

What are the indications of a2 adrenergic agonists

A

rapid and reversible sedation
mild analgesia on its own
can be used for neuroleptanalgesia which occurs when a2 agonist is combined w/ an opioid and given at a fairly high dose, a state of lack of awareness is associated w/ very heavy sedation combined with strong analgesia, used for minor procedures like suturing laceration sin horses
centrally-mediated muscle relaxation

46
Q

What is neuroleptanalgeisa?

A

occures when a2 agonist is combined with an opioid and given at a fairly high dose that produces a lack of awareness associated w/ a very high sedatio combined with a strong analgesia

47
Q

What are adverse effects of a2 adrenergic agonists?

A

severe hypotension bc of bradycardia, dec pulse, MM very pale, don’t use w/ acepromazine in SA
can hypovent on room air - dec rr and resp volume, enhances resp depressant effect of other sedatives/anes, resp distress in brachycephalic dogs, ruminants sensitive to resp effects
possible arrhythmias w/ some older dogs
inc risk if given too fast IV or given atropine
ataxia, cattle can become recumbent with dec rumen motility, risk of bloat and abortion
horses can become reaction to stimuli if given alone - noise, touch
emesis in catsW

48
Q

WHat are some warnings and contraindications for a2 adrenergic agonists?

A

avoid or use extreme caution in pediatrics, geriatric
avoid if severely dehydrated, in shock, CV dz, severe resp dz, or severe renal dz
avoid if advanced liver dz
avoid or use extreme care with acepromazine bc of the severe hypotension from combo of bradycardia and vasodilation; will plummet the BP and there is no way to bring it back other than reversal
however, fairly safe IF you have reserval on hand
MONITOR MONITOR MONITOR

49
Q

What should we know about using A2-adrenergic agonists in terms of duration, onset, avoiding routes?

A

IM (15-20 onset), IV (1-3min onset)
duration of 30-60 min
don’t give IV too fast or will enhance the respiratory and cardiac depression effects - when using IV, should “give to effect” only until desired degree of sedation is achieved
Avoid SQ - very lipophilic, drug will bind to fat and absorption will be unpredictable (can severe delay effect)
Dec effect if stressed or fearful

50
Q

What are the indications ofr xylazine/rompun

A

equine and bovine, a premed
“standing sedation” for castrations, wound repairs, cesareans, sedates animal w/o becoming recumbent
Colic - excellent visceral analgesia, 30min of analgesia if given as an epidural
part of “triple drip” injectable GA; to be discussed with ketamine

51
Q

Why are there 2 concentrations of xylazine/rompun? What are routes of administration and onset

A

2 concs of 20mg/ml or 100mg/ml bc lower conc in cattle b/c of inc resp and GI effects
IV “to effect” Ive more pronounced heart/resp effects
IM - onset is 10-15m after IM injection, duration is approx 30 min
Epidural - visceral analgesia
Often combined with an opioid or valium for better sedation and longer duration

52
Q

What are adverse effects of xylazine/rompun?

A

Cattle require 1/10 of dose compared to hosees even @ recommended dose can have severe resp effects, cause GI stasis, risk aspiration pneumonia
Horses - sweating, ataxia, wide-based stance, horses can become excited if used alone, never give intra-arterial in hose as it will cause excitement, seizure, collapse, avoid in neonatal foals as the lowered HR cannot maintain blood flow

53
Q

Where might detomidine/dormosedan be used? What is it similar to? What class is it?

A

a2 adrenergic agonist, labelled for horses
similar to xylazine - visceral analgesia, give slowly IV to effect, can give alone or with opioid, severe hypotension and bradycardia
twixe the duration and stronger sedation
used for standing sedation
never use with sulphonamides - heart failure

54
Q

What class is romifidine/sedivet? what is it labelled for?

A

labelled for horses, sedative or premed, can use at low dose for anxiolytic(anti-anxiety) with minimal ataxia
Similar to xylazine, detomidine - fast acting, long lasting, severe hypotension and bradycardia

55
Q

What is dexmedetomidine used for? duration? What class is it?

A

SA, alpha2 adrenergic agonist
sedation of 60-90 min, analgesia for 30 min
For sedation for hip rads, minor procedures with local anes, quills
Premed for sedation and preemptive analgesia
on-going sedation if given as a CRI

56
Q

What are indications of demedetomidine?

A

usually give in combo with opiod
better analgesia, better sedation
dec the mg/kg dose of demedetomidine req - dec adverse side effects
most commonly with butorphanol or buprenorphine
will see more resp depression if combined with hydromorphone

57
Q

What are the dosing indications for demedetomidine?

A

label dose is 10x to 20x what is used in-clinic
label dose intended for heavy sedation with dexmedetomidine alone
when combined with opioids and/or with balanced anesthesia, only use lat 1/10 to 1/20 the labelled dose
lower dose is much safer
is labeled for induction at higher doses (not usually done)
As animal size increases the mg/kg dose decreases

58
Q

How is demedetomidine administered?

A

IV or IM
IM takes 15-20 onset
NEVER give SQ as the drug deposits in fat and released unpredictable
give IV to effect, dogs only, do NOT give too rapidly as it can stop breathing, 1-3 min onset
can give 1/2 IM, wait 15 min and give remainder IV to effect

59
Q

What are adverse effects of demedetomidine?

A

profound bradycardia and resp depression (more noticable in dogs)
monitor HR and BP - HR will drop significantly; 16(lg K9), 40 (sm k9), must monitor BP and pulse strength
Monitor MM - will be pale but never cyanotic
Monitor oxygenation - extend neck, place on flow-by 100% O2 if available
place IV cath - if in doubt, place on IV fluid support

60
Q

What are some caution and contraindications with dexmedetomidine

A

do NOT use with atropine - heart block, heart failure
extreme caution or avoid with acepromazine - profound hypotension
Extreme caution when followed by isoflurance in cats - causes more extreme vasodilation than acepromazine
avoid if hypotensize, dehydrated, geriatric, debilitated

61
Q

What are the common reversals for LA and SA for a2 agonists?

A

LA - a2 agonist (zylazine, detomidine, romifidine) a2 antagonist (yohimbine or Yobine, tolazoline or tolazine)
SA - demedetomidine, reversal is atipamezole (antiseden)

62
Q

How do a2 antagonists work?

A

effects specific to a2 agonists - does not affect other drugs
reversal of the sedative, CV AND analgesic effects of the corresponding agent
few adverse effects at clinical doses, but significant adverse effects if too much is given by inc sympathetic tone
GI, neurologic and CV effects like excitement, muscle tremors, hypotension, tachycardia, salivation, vomiting, diarrhea

63
Q

What are some indications for opiods?

A

ANALGESIA! Strongest available
Also a preanesthetic to give for pre-emptive analgesia, giving b4 pain occurs results in less post op analgesia required and shorter recovery times, also for sedation, dec total dose of GA required
Also as an anesthetic induction - at higher doses, some opioids produce unconsciousness (uncommon)
Majority have wide margin of safety at therapeutic dose (higher potency -> lower therapeutic index)
Metabolized by liver w/ renal excretion so caution in yg, old, debilitated, very ill, if resp system compromised
ALL CONTROLLED

64
Q

What is neuroleptanalgesia?

A

A profound state of sedation and analgesia
induced by simultaneous administration of an opioid and a sedative
Ex. Dexmedetomidine + hydromorphone; Xylazine + fetanyl
Commonly given for minor procedures or induction
causes CNS depression to state of borderline unconsciousness, can be aroused by extreme stimulation or noise

65
Q

What routes can Opioids be given?

A

IM, SQ, IV, Oral, rectal, transdermal, subarachnoid, intra-articular (joints), epideral
if given IV, must be done slowly to avoid CNS stimulation

66
Q

What is the mode of action of opioids?

A

work by binding to opioid receptors
although opioid receptors found on neurons throughout the body, analgesic and sedative effect are primarily the result of their action on receptors located in the brain and spinal cord
Brain - sedation and analgesia
Spinal cord - analgesia
smooth muscle in the rest, GI tract, urinary tract

67
Q

What are the 3 major types of opioids?

A
  • Mu (μ)
  • Kappa (κ)
  • Delta (δ)
68
Q

What is the summary of effects that Mu can do?

A

Supraspinal analgesia
* Moderate to severe pain
* Sedation
* Respiratory depression
* Bradycardia
* Mioisis (mydriasis in cats)
* Hypothermia (hyperthermia in
cats)
* Euphoria/dysphoria
* GI stasis (constipation)
* Urinary Retention
* CRTZ (Chemoreceptor trigger
zone) for vomiting
* Anti-emetic at the vomiting
center

69
Q

What is the summary of effects that Kappa can do?

A

Spinal analgesia
* Mild to moderate pain
* Miosis
* Mild sedation
* Little respiratory depression
* Diuresis

70
Q

How are opioids classed?

A

based on which receptor they bind and whether binding causes the receptor to be turned on (agonist), partially on (partial agonist) or turned off (antagonist)

71
Q

What are the four major classes of opioids?

A

Pure agonists
Partial mu-agonists
Agonist-antagonist
Pure antagonist

72
Q

What are pure agonists

A

Drugs that bind to and turn on the mu-receptor
may also turn on kappa receptor
Provides best analgesia (treats mod to severe pain) Higher mu-receptor binding = more analgesia
Also prods sedation
EX> morphine, hydromorphone, oxymorphone, fentanyl, meperidine, hydrocodone, tramadol

73
Q

What are the side effects of pure agonists

A

For the Mu receptor (Resp depression, GI stasis, hypothermia, ocassional hyperthermia in cats)
Analgesia and sedation are better if also has kappa activity
highest risk of addiction

74
Q

What are partial mu-agonists?

A

Binds to and PARTIALY activates the mu-receptor
physiological affects - (when compared to pure agonists) less analgesia, resp depression, GI stasis, euphoria and less hypothermia
Indicated for slight to moderate pain
Also used to partially block the effects of a pure mu agonist that is given at the same time (acts as part reversal)
Ex. Buprenorphine (partial mu-agonist; kappa antagonist)

75
Q

What is an agonist-antagonist?

A

Simultaneously turns on kappa-receptor (kappa-agonist) while blocking mu-receptor (mu-antagonist)
physiological effects: mild analgesia, sedation, less resp depression and GI effects than pure or partial agonists, may cause dysphoria
Can be used to completely block either mu-agonist or partial mu-agonist activity

76
Q

What are pure antagonists?

A

Binds to both mu-receptors AND kappa-receptors but does not prod any activity
effectively acts as a block. “reversals”
EX naloxone, naltrexone, diprenorphine (M-50) is the reversal agent specifically created for etorphine (M-99)

77
Q

What are the major side effects of opioids?

A

resp depression - common in case of OD’s, centrally-mediated; dec RR and tidal volume, also inhibs CO2-dive that stims breathing, ventilation should be monitored and O2 available
Bradycardia, hypothermia, sedation
Can inc brain swelling in patients with brain trauma or cerebral edema

78
Q

Why might we be worried about hyperthermia in cats when using an opioid?

A

Hyperthermia in certain cats is due to a mu-receptor response especially hydromorphone and can be fatal if not treated

79
Q

What are some non-life threatening side effects of using opioids?

A

Emesis - activates chemoreceptor trigger zone in the brain, often w/ 1st dose of mu-agonists in healthy pain free anims, can block/decrease with acepromazine or diazepam
GI stasis (constipation), more likely with chronic use, avoid or caution in colic, bloat, FB surgeries (enterotomies)
Dysphoria, excitement, hallucinations, startle response in cats
Addiction - mu-receptor mediated, receptor down-regulation means may need to inc dose or dose frequency to manage chronic pain

80
Q

What is the #1 side effect of acepromazine, A2 agonists and opioids?

A

Ace - Hypotension by vasodilation
A2 agonist - Bradycardia (hella low HR)
Opiods - resp depression

81
Q

What are the various side effects of opioids that vary among specific opioid, dosage, route of admin and species

A

Antitussive (codeine, hydrocodone, butorphanol; to treat cough)
Vomit (apomorphine, IM hydromorphone)
Diarrhea and flatulence
Miosis in dogs, mydrasis in cats/eq
Excitement, dysphoria, whine/bark (dogs), inc motor activity (horse), inc sensitivity to noise
Hypo/hypertension
changes in urination, excess salivation
panting in dogs, hyperthermia in cats, sweating in horses

82
Q

What is the action of morphine, hydromorphone and meperidine and what are their effects?

A

Mu-agonists and kappa-agonists
for mod-severe pain, sedation, resp depression, GI stasis, used for analgesia, sedation, premeds

83
Q

What is the action of sufentanil etorphine (M-99) carfentanil and what is their effects

A

Super mu-agonist
wildlife capture
100-100000 times the activity of morphine; very low therapeutic index

84
Q

What is the action of butorphanol and their effects

A

kappa-agonist; mu antagonist
mild paid and sedation, least resp depression, can block mu-agonists

85
Q

What is the action of naloxone and naltrexone and what is its effects?

A

Pure antagonist
reversal agents; block mu- and kappa-receptors
no effect on own, not controlled

86
Q

What class is morphine? What are the indications for it and what is it’s duration? How can it be given?

A

Pure mu agonist
Mu and kappa agonist
indications “opioid standard of reference” everything is compared to it
mild to mod sedation dose dependent
analgesia for mod to severe pain
Routes - IM, IV, SQ, PO, intra-articular, epidural
Duration of 3-4hrs

87
Q

What are the side effects of morphine?

A

excitement or dysphoria in cats, horses
mydriasis in cats, horses
drowsiness in dogs
severe resp depression with high doses
nausea/vomiting
GI stasis (oral form is worse)
Histamine release can cause systemic vasodilation

88
Q

What class is fentanyl? What is the indications and duration of action? What route can it be given?

A

Pure mu agonist
Mu and kappa agonist
50-100x potency of morphine
Indications: neuroleptanalgesia, induction, analgesia (w/ frequent administration)
Routes: IV bolus, CRI (preferred IV method), slow-release transdermal action patch, epidural
Duration: 1-2 min onset; 10 min duration of action IV
Usually CRI or slow release transdermal patch for analgesiaWh

89
Q

What are the side effects of fentayl, is it approved for food animals?

A

Side effects
* Defecation or constipation
* Respiratory depression
* Bradycardia
* Hypothermia
* Panting, drooling
* Dysphoria, agitation
* Sedation
* NOT approved for food animals

90
Q

What class is hydromorphone? WHat is the indications and duration of action or it?

A

Pure mu agonist, mu and kappa agonist
indications: 5-10x the potency of morphine, mod to severe pain (visceral and somatic), pre, peri and postoperative pain control, more sedation than morphine, rarely used in lg animals bc of lack of info about efficacy or adverse side effects
Duration for IV is 1-2
IM 2-4h in dogs, longer in cats
SQ up to 6-8hrs
Epidural 8hrs

91
Q

What are the side effects of hydromorphone?

A

reliable emetic with first dose, especially if SQ/IM
diarrhea with first dose; constipation with chronic use
pant, drool
mydriasis in cats/horses
excitement/hallucinations in cats/horses

92
Q

What are the adverse effects of hydromorphone?

A

Resp depression, use with caution if severe resp dz
Bradycardia
hypothermia in all species
can cause occasional hyperthermia in cats which can be fatal
In event of severe adverse reaction, can partially reverse with buprenorphine or butorphanol; can completely reverse with naloxon, naltrexone

93
Q

What class is methadone, what are its indications and duration of action?

A

Pure mu agonist, mu and kappa agonist
Indication for 5-10x the potency of morphine. Mod to severe pain (visceral and somatic), low incidence of vomiting (compared to morphine or hydromorphone); other side effects similar to other pure mu agonits
~4hrs of duration (slightly longer than morphine or hydro)

94
Q

What is methadone lisenced for in Canada?

A

Licensed in Canada for 0.5mg/kg IM in cats prior to spay or neuter
ONLY IN CATS
Extra Label Use: commonly used 0.2-0.5mg/kg administered IV, IM or SQ

95
Q

What class is meperidine/Demerol? What is the indications, duration of action and routes?

A

Pure mu agonist, mu and kappa agonists
Indications 1/10x morphine, mild to mod pain
Routes: IM injection, NOT IV or SQ
Histamine release with IV use
Duration of action - 30-90min
Side effects - no vomiting or bradycardia, used as premed when no vomiting is req

96
Q

What class is sufentanil and what are the indications of it?

A

“Super mu-agonist”
500-1000x the power for morphine but shorter acting than fentanyl
indications - intra-operative analgesia for dogs/cats as an infusion, induction

97
Q

What class is carfentanil? Indications? Reversal?

A

Super mu-agonist
10,000-100,000x the power of morphine
Indications - wildlife capture and immobilization
Potentially fatal if handler scratches/injects self - use with extreme caution so wear double gloves when handling closed bottle
Reversal req naltrexone for reversal
draw up BEFORE handling carfentanil

98
Q

What class is buprenorphine and the indications and routes for it?

A

Partial mu agonist, kappa antagonist
1/20x morphine
mild to mod pain, less sedation
onset of action ~30min
Routes - IV, IM, SQ, epidural or transmucosal (in cats)
place in the buccal cavity or sublingual and allow absorption through the oral mucosa, will NOT work if swallowed

99
Q

What is the duration of action, side effects and reversal for buprenorphine?

A

duration is 6-8hrs in dog and cat
2hrs in sheep
fewer side effects than hydromorphone due to partial mu-activity, slight dysphoria
reversal - higher affinity than naloxone, therefore req much high doses or infusion of naloxone to reverse buprenorphine

100
Q

What class is butorphanol/torbugesic, what is its indications?

A

Agonist-antagonist (kappa agonist, mu antagonist)
1/2-1x morphine, mild to mod pain - analgesia and sedation via the kappa-receptor. EX. colic
Sedation, antitussive, reversal of hydromorphone
SA (0.5mg/ml) and LA (10mg/ml) conc

101
Q

What are the routes and side effects that butorphanol/torb has?

A

IV, IM, SQ, and PO
No mu-receptor mediated side effects so less resp depression, no excitement, GI stasis or panting in dogs

102
Q

What happens if both butorphanol and hydromorphone are present in the body?

A

butorphanol will bind to the receptor bc is has 30x the affinity for the receptor compared to hydromorphone
result is to kick out the hydromorphone and/or prevent the hydromorphone from binding to receptor

103
Q

What are opioid antagonists? What are the indications, routes and effects of them?

A

reversal of desirable and undesirable effects of opioid agonists, partial agonist, or agonist-antagonist including sedation and analgesia - CNS and resp depression
Routes of admin - IM and slow IV
Effects/adverse effects - sedation, dysphoria, panting, resp depression, hypotension, bradycardia, GI effects and analgesia
The action of opioid antagonists is often dramatic, causing the patient to appear nearly unaffected shortly after administration

104
Q

What class is naloxone/Narcan? What is their indications, duration, onset time? What happens with aggressive use?

A

pure antagonist
complete reversal of both mu- and kappa- agonist, will lose all adverse effects AND all analgesia
dog, cat, horses, exotics, people
1 drop under tongue of neonates after C-section to reverse resp depression of opioid given to mother
Duration of action 30-40 min, will need to top-up
Time of onset 2 min IV
aggressive use can cause catecholamine-related cardiac arrhythmias and vasoconstriction leading to pulmonary edema

105
Q

What class is naltrexone? what are the indications and duration of action?

A

pure antagonist
both Mu and kappa antagonist
more potent than naloxone
used to reverse carfentanil in wild-life - can be used intra-nasally
action - longlasting (hours)

106
Q

Can butorphanol/torb work as a partial antagonist?

A

yur - only blocks mu-activity; adds to kappa-activity
not a very strong reversal as it leaves sedation and some analgesia. WIll reverse resp depression and hypo/hyperthermia

ANAESTHESIA (8 decks)

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