Pain and Opioids

Question 1

what is pain

Answer 1

an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage

Question 2

what is nociception

Answer 2

neural process of encoding noxious stimuli

Question 3

how can pain be measured

Answer 3

pain threshold or pain tolerance level

Question 4

which fibres are involved in nociception of skin, fascia, bone (sharp, localized pain)

Answer 4

A fibers. C are the muscle and viscera ones

Question 5

which fibres are involved in nociception of muscle, viscera pain (dull, diffuse)

Answer 5

C fibers (A fibres are skin, fascia, and bone pain)

Question 6

at is the primary excitatory NT involved in nociception

Answer 6

glutamate

Question 7

_________ is increased sensitivity to noxious stimuli, while _______ is when normally non-noxious stimuli become capable of eliciting a pain response

Answer 7

hyperalgesia, allodynia

Question 8

inflammatory mediators such as prostaglandins and leukotrienes perform what 2 functions

Answer 8

activate silent nociceptors and nociceptor sensitization

Question 9

what is spinal facilitation of pain or wind up

Answer 9

high frequency APs train second order neurons to respond more vigorously to subsequent stimulation (increase glutamate and other NTs, activate inactive NMDA receptors, influx of Ca, up regulate post-synaptic membrane)

Question 10

what is pre-emptive analgesia

Answer 10

• Pain leads to increased sensitivity (increased nociceptor sensitivity, activation of “silent” nociceptors, wind‐up/spinal facilitation of pain, neuroplasticity): therefore we use PRE‐ EMPTIVE ANALGESIA - easier to control pain before nociceptive stimulus happens

Question 11

are general anesthetics generally analgesics

Answer 11

generally not. need to provide both

Question 12

_____ has a conscious component, while ______ does not

Answer 12

pain, nociception

Question 13

what do descending inhibitory pathways do

Answer 13

Decrease neurotransmitter release from primary afferents and reduce excitability of secondary neurons

Question 14

give 3 physiological pain inhibition mechanisms

Answer 14

endogenous opioid agonists, up regulation of peripheral opioid receptors at site of injury, migration of opioid-producing leukocytes to site of injury

Question 15

give 4 sites of analgesia

Answer 15

block nociception at peripheral nociceptors prevent transmission to sp cord, prevent transmission to brain, enhance descending inhibitory pathways

Question 16

most effective way to prevent and treat pain is to _____, this is referred to as balanced pain management

Answer 16

affect all of the different levels

Question 17

three types of opioid receptors are

Answer 17

mu, kappa, delta

Question 18

opioid receptors are GPCRs. how can they lead to reduced NT release?

Answer 18

inhibition of calcium channels in presyn neurons

Question 19

opioid receptors are GPCRs. how can they lead to hyper polarization?

Answer 19

increased potassium outflow in postmen neurons

Question 20

how do opioid receptors inhibit calcium inflow in primary afferent neurons

Answer 20

Inhibits calcium inflow into presynaptic neuron through direct binding to calcium channels, and through cAMP‐ modulated mechanisms, reducing NT release

Question 21

opioid receptors enhance K+ outflow from postsynaptic neurons in spinal cord. enhanced K+ outflow leads to what

Answer 21

hyperbole of postmen neurons

Question 22

give 6 effects of mu receptor

Answer 22

analgesia, respiratory depression, sedation/excitement (dose and species dependent), decrease in GI motility and secretions, euphoria, and nausea/vomiting

Question 23

give 3 effects of kappa receptor

Answer 23

analgesia, sedation, decreased GI motility (the mu receptor does these as well)

Question 24

I’ve effect of delta receptor

Answer 24

analgesia (kappa and mu do this too)

Question 25

drugs that interact with opioid receptors can be thought of in 4 ways, give em to me

Answer 25

full agonists (maximal effect), partial agonists (same effect as full agonists, but effects plateau), agonist-antagonists (vary effects depending on receptor and dose), antagonists (competitive antagonists)

Question 26

all of the opioid drugs act on which receptor

Answer 26

mu receptor. some on kappa and delta as well

Question 27

when given in combination with sedatives or anesthetics, what effect do opioids have

Answer 27

additive/synergistic sedative and analgesia effects

Question 28

give at least 3 clinically important adverse effects of opioids

Answer 28

respiratory depression (centrally mediated decrease in response to increased PCO2) vomiting (chemoreceptor trigger zone and dopamine effects) constipation/ileus severe pruritus histamine release hyperthermia in cats CNS excitation/dysphoria/seizures

Question 29

why is morphine not recommended for animals with CHF

Answer 29

variable effects on coronary blood flow

Question 30

PK of opioids: tell. me about half-life and duration of action

Answer 30

short half life, 0.5-2 hours, and duration of action also short and depends on dose/pain, 2-4 hours

Question 31

local use of opioids: opioid receptor expression is upregulated locally by what

Answer 31

inflammatory cytokines

Question 32

this gold standard opioid is a mu agonist, kappa partial agonist, is safe effective and cheap, less effective in cats than dogs, and not routinely used in horses due to CNS effects

Answer 32

morphine

Question 33

this opioid is a morphine derivative, mu agonist, emetic, less histamine response than morphine, oral bioavailability probably very low, short half-life

Answer 33

hydromorphone

Question 34

this opioid is a mu agonist, NMDA antagonist, NE and serotonin reuptake inhibitor, may be more effective for chronic pain than other mu agonists, causes fewer CNS effects and less vomiting than other mu agonists, especially in cats

Answer 34

methadone

Question 35

this synthetic mu agonist is more lipophilic than morphine and more potent, given IV or transdermally, wide safety margin in dogs, generally fewer adverse effects that with other opioids, common drug of abuse

Answer 35

fentanyl

Question 36

this is a partial mu agonist and a kappa agonist opioid, has a ceiling on analgesic and respiratory effects, transmucosal absorption, less CNS effects in cats, high affinity for mu receptor (potency) but lower efficacy

Answer 36

buprenorphine

Question 37

drug is a kappa agonist, mu antagonist or partial agonist, effective analgesic for mild/moderate pain, may reduce effects of mu agonists, prominent sedative effects, antiemetic and antitussive, occasionally used to reverse mu agonists but not in cats, commonly used in combination with sedatives

Answer 37

butorphanol

Question 38

centrally acting multimodal analgesic; active metabolite is a mu agonist, current recommendation is do not use as sole analgesic in dogs, but many be useful as adjunctive analgesic but be mindful of potential for treatment failure

Answer 38

tramadol

Question 39

reversal of opioids is performed by what kind of agonist or antagonist

Answer 39

competitive opioid receptor antagonist

Question 40

this competitive antagonist of all opioid receptors, especially mu, is also a GABA antagonist and can indue seizures. generally given at small doses to reverse respiratory depression

Answer 40

naloxone

Question 41

of fentanyl, buprenorphine, and heroin, which can induce total apnea at lowest dose

Answer 41

fentanyl

Question 42

what 3 things to base opioid decision making on in small animals

Answer 42

severity of pain, route of admin, and ok in cats

Question 43

what kind of drugs are drugs of abuse

Answer 43

opioids

Question 44

sedative effects of alpha 2 agonists are caused by decreased what release

Answer 44

norepinephrine release from brainstem neurons via negative feedback mechanisms

Question 45

how do descending inhibitory pathways work

Answer 45

decrease NT release form primary afferents and reduce excitability of secondary neurons

Question 46

all the alpha 2 receptors agonists currently used in vet med also have

Answer 46

alpha 1 activation. usually causes excitation and increased motor activity

Question 47

this drug is a short-acting general anaesthetic, common for flied procedures, and is an analgesic due to NMDA receptor antagonist and analgesic at subanesthetic doses, is useful in geriatric patients due to excellent safety profile

Answer 47

ketamine

Question 48

ketamine antagonizes ____ receptors and acts as a ____ analgesic

Answer 48

NMDA; central

Question 49

lidocaine, bupivacaine, and mepivacaine are all

Answer 49

local anesthetics, they block Na channels and stop AP conduction in nerve fibres

Question 50

By decreasing or abolishing the transient increase in permeability of excited cell membranes to sodium ions, local anesthetics basically stop what

Answer 50

nerve conduction

Question 51

adverse effects of local anesthetics are related to what

Answer 51

Na channel blockade