Anethestic Drugs Flashcards

1
Q

What effect does hypoalbuminemia have on anesthetic drugs

A

Decreases bound fraction of some drugs (increases free drug) which can result in changes in volume of distribution, plasma concentration, and drug effect (e.g. NSAIDs are tightly protein bound)

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2
Q

Which direction do opioids shift the CO2 response curve when given alone

A

When given alone, opioids shift the CO2 response curve to the right with little change in slope

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3
Q

What is the primary analgesic effect of tramadol

A

Metabolism of tramadol to M1 and M1 acts as a full mu opioid agonist

Analgesia via opioid and non-opioid (monoamine uptake inhibition) mechanisms

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4
Q

How is tramadol excreted

A

Excreted largely unchanged in the urine - no liver metabolism

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5
Q

Why is efficacy of tramadol weak in dogs

A

Dogs do not produce large amounts of M1 and studies show in humans that don’t form M1 from tramadol have little to no effect of the drug.

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6
Q

Fentanyl potency

A

100x more than morphine

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7
Q

Fentanyl pitfalls

A

More likely to cause apnea and bradycardia when given as a bonus compared to other opioids
Can cause wooden chest - chest wall rigidity

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8
Q

Remifentanil - what is it, metabolism, and benefit

A

Analogue of fentanyl
Metabolized by plasma esterases therefore it has a short half life.
Good if you want a patient to wake up quickly

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9
Q

Methadone potency

A

2x more than morphine

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10
Q

Why does methadone cause less excitation in cats

A

It is an NMDA antagonist

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11
Q

Buprenorphine potency

A

40x more potent than morphine

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12
Q

Buprenorphine advantages

A

Causes less ileus
Ceiling effect - not associated with increased analgesia but higher doses do cause longer duration

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13
Q

Advantages of Alfaxalone over propofol

A

Less decrease in cardiac output and apnea
Can be given IM

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14
Q

Alfaxalone MOA

A

Steroid anesthetic
Enhances GABA and glycine mediated CNS depression

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15
Q

Propofol MOA

A

Unrelated to steroid anesthetic
GABA agonist: Inhibits CNS

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16
Q

Disadvantages of propofol compared to Alfaxalone

A

Benzyl alcohol formulation shouldn’t be given repeatedly or in CRI to cats (can cause CNS toxicity - hyperesthesia and depression)
More likely to cause apnea
CV effects: Hypotension from vasodilation; decrease in SVR and CO

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17
Q

Propofol advantages

A

Appropriate for patients with liver failure - extrahepatic metabolism sites
Used to treat refractory status epilepticus and reduces ICP

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18
Q

Lipid solubility of morphine

A

Relatively low lipophilicity

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19
Q

Dopamine MOA

A

Stimulates endogenous norepinephrine from presynaptic storage sites at adrenergic receptors to cause sympathomimetic effect

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20
Q

Dopamine dosing and what receptors predominate

A

Low dose (1-2 mcg/kg/min) - dopamine and DA-2 receptors
Medium dose - B1 and B2 adrenergic receptors
High dose >10 mcg/kg/min - A1-adrenergic receptors

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21
Q

Effects of B1 and B2 adrenergic receptor stimulation by dopamine

A

Increases myocardial contractility, HR, CO, and coronary blood flow

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22
Q

Effects of A1-adrenergic receptor stimulation by dopamine

A

Increases SVR, pulmonary vascular resistance, venous return, and PCV (via splenic contraction)

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23
Q

MOA of vasopressin

A

Non-catecholamine vasopressin that acts on the peripheral vessels (V1a, V1b, and V) while decreasing cellular hyperpolarization and increasing intracellular calcium concentration

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24
Q

What is the MOA of doxapram and its effects on glottal gap

A

Analeptic (CNS stimulant) with central and peripheral effects. Increases activity of the respiratory nuclei of the medulla
When given to dogs with larpar: glottal gap area at inspiration was reduced and significantly greater during exhalation

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25
What class of drugs are atropine and glycopyrrolate
Anticholinergics, parasympatholytics, antimuscarinics
26
Anticholinergics and GI motility and other GI effects
Dose required to decrease GI motility via blockade of M3 receptors is higher than that required to treat bradycardia Decreases lower esophageal sphincter function which may lead to increased risk of gastroesophageal reflux
27
Atropine MOA Does it cross the BBB
Anticholinergic- competitive, reversible antagonist of muscarinic receptors (M1- M5) inhibiting ACh release Yes and blood placenta barrier Can cause sedation
28
Glycopyrrolate and GI motility
Decreased for up to 30 minutes in dogs
29
Glycopyrrolate BBB and blood placenta barrier
Does not cross
30
Dobutamine MOA
Synthetic catecholamine Primarily B1 adrenergic Higher doses - B2 and A1 adrenergic receptors Augments CO states associated with reduced myocardial function
31
Dobutamine effects
Limited effects on BP Increases CO, HR, and SVR
32
Dexdormitor and its receptors
Mainly alpha 2 agonist with some peripheral alpha 1 agonist
33
What are the alpha 1 agonist effects of dexdormitor
Vasoconstriction, hypertension, arrhthmogenicity, and paradoxical excitation. Reflex bradycardia due to hypertension which leads eventually to hypotension
34
Side effects of dexdormitor
Hyperglycemia, diuresis, and respiratory depression
35
What are the consequences of giving an Anticholinergics with dexdormitor
Greater hypertension which increases the myocardial work
36
Gabapentin MOA
Structural analogue of GABA but does not interact with GABA, NMDA, or dopamine Inhibits N-type voltage dependent neuronal calcium channels
37
Gabapentin excretion
By the kidneys
38
What was amantadines original use
Antiviral agent then for Parkinson’s, TBI and pain
39
Amantadine MOA
Dopamine agonist and NMDA agonist
40
Ketamine in terms of somatic pain and dosing
Subanesthetic doses of ketamine produce profound analgesia especially in situations of somatic pain
41
Can ketamine be given via an epidural
Yes
42
Ketamine side effects
Catatonic state Increases salivation, ICP and IOP Eyes remain open and swallowing reflex is maintained Produces mild sympathomimetic effect - increases myocardial work
43
What are the two categories of NMBAs and name an example of each
Depolarizing - Succinylcholine Non-depolarizing - Atracurium
44
Atracurium duration of action
Dose dependent duration of action 5-30 minutes
45
Succinylcholine MOA and possible disadvantage
Mimics effects of acetylcholine Initial depolarization of all skeletal muscle - looks like fasciculations Trigger for malignant hyperthermia
46
Elimination of Atracurium
Degraded by Hofmann elimination - independent of liver and renal excretion
47
What is the TOF - train of four
In relation to NMBA When 70% of receptors are occupied by a NMBA the twitches will fade beginning with the 4th, then the 3rd, then the 2nd then the 1st
48
NMBA reversals
Anticholinesterase Edrophonium, neostigmine, and pyridostigmine
49
NMBA reversals MOA and side effects
Inhibit enzyme anticholinesterase increasing the concentration of ACh molecules at the neuromuscular junction Can cause cholinergic crisis - SLUDD signs - give Anticholinergic to treat
50
Edrophonium MOA
Reversible inhibition of electrostatic attachment to the an ionic site and by H bonding at the esteratic site on acetylcholinesterase
51
Neostigmine and pyridostigmine MOA
Inhibit acetylcholinesterase by forming carbamyl-ester complex at the esteratic site of acetylcholinesterase
52
List opioids from least to most potent
Meperidine -> Morphine -> Methadone -> Hydromorphone -> oxymorphone -> buprenorphine -> fentanyl
53
Meperidine disadvantage
Causes severe histamine rerelease When given with MAOI can cause serotonin syndrome
54
NSAIDs MOA
Arachidonic acid is the predominant fatty acid in animal cell membranes and biotransforms into eicosanoids. Prostanoids are eicosanoids metabolized by prostaglandins (PGD2, PGF2a, and PGE2), PGI, and TXA2. Arachidonic acid is acted upon by COX or LOX enzymes to form eicosanoids. NSAIDS inhibit COX enzymes and alter the formation of prostanoids
55
COX - 1 (prostaglandin synthase-1): type of enzyme? Responsible for?
Constitutive enzyme Responsible for normal physiologic function
56
COX -2 (prostaglandin synthase-2): type of enzyme? Responsible for?
Inducible enzyme Usually unregulated (induced) by inflammation May be unregulated during renal stress as a protective mechanism GI stress - protective and healing.
57
Robenacoxib with or without food
Give fasted - cats absorption was 49% vs 10% when given with food. In dogs 84% absorption without food and 62% with food.
58
NSAIDs effects on the spinal cord
NSAIDs inhibit prostaglandin in both the peripheral and nervous systems (spine and brain)
59
NSAID GI toxicity
Direct irritation of the drug on the GI mucosa and prostaglandin inhibition Inhibition of prostaglandins results in decreased cytoprotection, diminished blood flow, decreased synthesis of protective mucus, and inhibition of mucosal cell turnover and repair.
60
What type of drug is carprofen
Selective COX-2 inhibitor
61
Carprofen and phenobarbital
Animals on phenobarbital are more susceptible to hepatotoxicity
62
NSAIDs mechanism of renal injury
Prostaglandins modulate tone of blood vessels and regulate salt and water balance in the kidneys COX 1 and COX 2 maintain renal blood blow and ion transport within the nephron AKI from inhibition of renal prostaglandin synthesis AKI is characterized by decreased renal perfusion, sodium, and fluid retention, decreased tubular function, and azotemia
63
Meloxicam in cats
Labeled for chronic use in cats outside of US Give with food and when cats are euvolemic at a low dose 0.01-0.03 mg/kg/day
64
How do NSAIDs aid in treating OA
Canine chondrocyte cell cultures revealed that carprofen increases rate of PGAG synthesis which can be chondroprotective Dual inhibitors (COX and lipoxygenase) may slow progression of OA
65
NSAIDs and liver injury
Idiosyncratic - carprofen and others Intrinsic - aspirin and acetaminophen Undergo extensive hepatic metabolism and the liver is exposed to high concentrations of the parent drug and its metabolites Usually reversible with supportive care
66
Misoprostal type of drug and what its used for
Synthetic PGE analog that prevents and helps heal GI ulceration
67
Name four effects of PGE on the kidney
Maintains renal blood flow and ion transport within the nephron Increases salt excretion and increases water excretion Maintains water hemostasis and tubular function Regulates the release of renin
68
Name 5 effects of PGE on the stomach
Maintains gastric mucosal layer Quality of gastric mucous Mucosal blood flow Production of gastric acid Bicarb secretion
69
Acetaminophen in cats and MOA of injury
Cats have a phase II/ acetaminophen metabolizing enzyme deficiency acetaminophen is shunted to phase 1 enzymes which produce toxic oxygen radicals leading to methemoglobinemia and potentially hepatic necrosis