LEC 7 - Opioid Analgesics Flashcards

1
Q

Full agonists (8)

A

Morphine

Methadone

Oxymorphone

Hydromorphone

Fentanyl

Alfentanil

Sufentanil

Carfentanil

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2
Q

Partial agonists (1)

A

butorphanol

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3
Q

Agonist - Antagonist (2)

A

Buprenorphine

Nalbuphine

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4
Q

Antagonists (2)

A

Nalozone

Naltrexone

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5
Q

mu-agonist 5-HT NE reuptake inhibitor (1)

A

Tramadol

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6
Q

Drugs that inhibit preception (5)

A

General anesthetics

Opioids

alpha2 agonists

Benzodiazepines

Phenothiazines

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7
Q

Drugs that inhibit transmission (2)

A

Local anesthetics

Alpha2 agonists

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8
Q

Drugs that inhibit peripheral sensitazation of nociceptors (transduction) (4)

A

Local anesthetics

Opioids

NSAID’s

Corticosteroids

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9
Q

Drugs that modulate the spinal pathway (7)

A

Local anesthetics

Opioids

Alpha 2

Tricyclic antidepressants

NMDA antagonits

NSAIDs

Anticonvulsants

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10
Q

What are the opioid receptors linked to?

A

Gi proteins

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11
Q

What does Gi protein stimulus cause?

A

decrease cAMP

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12
Q

What effects does opioids have on ion channels?

A

Close - Presynaptic Ca2+ channels (u + d + K)

Open - postsynaptic K+ channels (u)

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13
Q

What effects does closing the Ca2+ channels have?

A

Decrease NT release

ACh

NE

Glutamate

5-HT

Substance P

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14
Q

What is the effect of opening post-synaptic K+ channels?

A

Hyperpolarization

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15
Q

What are the major overall effects of opioids?

A

INhibition of pain transmitting ascending systems

Stimulating descending pain transmission inhibiting neurons

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16
Q

What are the actions of opioids at the presynaptic terminal?

A

u/d/k receptors

decrease gCa2+

decrease NT release

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17
Q

What effects does opioids have post-synaptically?

A

u receptors

Increase gK+ - IPSP

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18
Q

Where in the body are mu receptors found?

A

Brain

Dorsal horn of spinal cord

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19
Q

What are the effects of mu receptor activation?

A

Supraspinal + Spinal analgesia

Euphoria

Sedation

Miosis

Respiratory depression

Chemical dependence

Decrease GI motility (ACh effect)

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20
Q

What NT are effected by mu receptors?

A

ACh

Dopamine

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21
Q

Where in the body are kappa receptors found?

A

Cerebral cortex

Spinal cord

Brain regions

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22
Q

What is the result of kappa receptor activation?

A

Spinal + Supraspinal analgesia

Mild sedation

Dysphoria

Miosis

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23
Q

What NT is affected by kappa? What is the result?

A

Vasopressin

Stops release to induce diuresis

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24
Q

Where are the delta receptors found?

A

Limbic system

Cerebral cortex

Spinal cord

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25
Q

What occurs with delta receptor activation?

A

Spinal + Supraspinal analgesia

Cardiovascular depression

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26
Q

What NT is affected by delta receptors?

A

Dopamine

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27
Q

What are the three endogenous opioids?

A

Endorphins

Enkephalins

Dynorphins

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28
Q

What levels of analgesia occur with opioid administration?

A

Brain

Spinal cord

(rarely peripherial)

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29
Q

What receptor has the largest analgesic effects?

A

Mu

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30
Q

What is the relationship between duration of action and 1/2 life with opioids? Why?

A

Duration of action normally shorted then 1/2 life

Desensitization + Down regulation of receptors

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31
Q

What CNS occur with opioids at high and low concentrations?

A

Low - Depression

High - Excitation

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32
Q

What respiratory effects are seen with opioids?

A

mu receptors = depressants

will see panting due to change in thermoregulatory set point

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33
Q

What is the effect of the respiratory depression seen with opioids?

A

Increase in arterial CO2 tension

Decreate in arterial O2 tension

Decrease in pH

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34
Q

What are the cardiovascular effects of opiods?

A

For the most part spare the CV system

Hypotension can occur

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35
Q

What can be seen in dogs with opioid administration that effects heart rate?

A

Vagal stimulation

Bradycardia

Induce barorecptor response

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36
Q

Why do you see vasodilation with opioid administration?

A

Histamine release

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37
Q

What are the GI effects of opioid administration?

A

IM - vomiting dogs

IV decreases this effect

Constipation + decrease gastric emptying

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38
Q

What are the pupilary effects of opioids?

A

Mioisis

Mydriasis - Cats + Horses

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39
Q

Morphine - Vomit induction in Dogs

A

Stimulate chemoreceptor trigger zone

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40
Q

Morphine - Uses

A

Acute pain - dogs, cats, horses

Sedative to reduce pacing + standing procedures - horse

Antitussive - Dogs

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41
Q

Morphine - BA

A

<20 % - dogs given PO

Due to first pass effect

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42
Q

Morphine - Excretion

A

Renal

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43
Q

Morphine - Metabolism

A

Glucuronidation

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44
Q

Morphine - Adverse effects

A

Hyperexcitability

Hypotension

Cerebral hemorrhage/edema

Abnormal body temp

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45
Q

What animals see hyperthermia with morphine?

A

Cats

Horses

Ruminants

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46
Q

Why is cerebral hemorrhage + edema a concern with morphine?

A

Respiration depressed

Arterial CO2 increase

INcrease cerebral blood flow - increased pressure

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47
Q

What animals see hypothermia with morphine?

A

Rabbits

Dogs

Primates

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48
Q

Tramadol - Mechanism

A

mu-receptor agonist

inhibits reuptake of serotonin + NE

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49
Q

What contributes to tramadols analgesic effects?

A

Inhibition of serotonin + NE

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50
Q

Tramadol - use

A

Anlagesic + Antitussive

51
Q

Tramadol - Admin

A

PO

52
Q

Tramadol - BA

A

65% cats/dogs

53
Q

Tramadol - Metabolism

A

Liver

54
Q

Tramadol - 1/2 life

Dogs

Cats

Horses

A

Dogs = 0.8 to 1.7 hours

Cats - 3 to 5 hours

Horses = 1.5 to 4 hours

55
Q

Methadone - Mechanism

A

mu-agonist

May have NMDA receptor antagonist activity

56
Q

Methadone - Admin

A

IV + IM + SC

57
Q

Methadone - Use

A

Pre-med or Analgesic alternative in dogs/cats

58
Q

Methadone - BA

A

80% SC

very low with PO

59
Q

Methadone - Protein binding

A

Albulmin - 60 yo 90%

60
Q

Methadone - Metabolism

A

Liver - Cytochrome P450

61
Q

Methadone - Adverse side effects

A

Less sedation + vomiting compared to morphine

62
Q

Oxymorphone/Hydromorphone - Potency

A

ten times that of morphine

63
Q

Oxymorphone/Hydromorphone - Uses

A

Analgesia

Pre-meg

Neruoleptanalgesia

Anesthesia

64
Q

Oxymorphone/Hydromorphone - Admin

A

IV + IM + SC + Rectal

65
Q

Fentanyl - Mechanism

A

Potent mu-agonist

66
Q

Fentanyl - Admin

A

IV + Patch

67
Q

Fentanyl - Duration of Action

A

Patch - 72 hours

68
Q

Fentanyl - Use

A

Anesthetic induction

Potent analgesic

69
Q

Fentanyl - Pain control

A

Intraoperative

Postoperative

Chornic pain

70
Q

Fentanyl - Onset

A

More rapid then morphine due to increase lipid solubility

71
Q

Fentanyl - Metabolism

A

CYP450

72
Q

Fentanyl - Excretion

A

urine

73
Q

Fentanyl - Adverse effects

A

Sensitive to noise

Panting + defecation + flatulence

Bradycardia

Hypersalivation

74
Q

How can bradycardia + hypersalivation due to fentanyl be treated?

A

Anticholinergic drug

75
Q

Alfentanil - Potency

A

4x’s less potent then fentanyl

76
Q

Alfentanil - Mechanism

A

mu-receptor antagonist

77
Q

Alfentanil - Admi

A

IV + IM + SC

78
Q

Alfentanil - Metabolism

A

Liver - P450

79
Q

Alfentanil - Use

A

Analgesic + Sedative

Adjunctive anesthesia (cats)

80
Q

Sufentanil - Potency

A

5 to 10x’s more potent then fentanyl

81
Q

Sufentanil - Admin

A

IV + IM + SC + Epidural

82
Q

Sufentanil - Use

A

Adjunctive anesthesia

Epidular analgesia

Postoperative analgesia

83
Q

Sufentanil - Metabolism

A

Liver -

Small Intestine via O-demethylation

84
Q

Sufentanil - Adverse effect

A

CNS + respiratory depression

85
Q

Carfentanil - Potency

A

10,000 x’s more then morphine

86
Q

Carfentanil - Admin

A

IM

87
Q

Carfentanil - 1/2 life

A

2 to 24 hours

needs a reversal due to this

88
Q

Carfentanil - Adeverse effects

A

Disruption of body temp

CNS + respiratory depression

89
Q

Carfentanil - Reversal Agent

A

Naltrexone

Longer duration of action

90
Q

Butorphanol - Mechanism

A

Parital agonist for mu-receptor

Full Agonist for kappa-receptor

91
Q

Butorphanol - Use

A

Not a great alnalgesic

Opioid reversal - reverses mu-receptor effects

(sedation + respiratory depression)

Antitussive - Dogs with chronic cough

Analgesia in cats + cattle

Colic

Anti-emetic for chemotherapy

Chemical resitrant in cattle

92
Q

Butorphanol - Withdrawl

A

5 days meat withdrwal

93
Q

Butorphanol - BA

A

Horses - 37% via IM in adults

67% in Foals

94
Q

Butorphanol - 1/2 life

A

Horses

6 hours - adults

2 hours - foals

95
Q

Butorphanol - Adverse effects in horses

A

Transient ataxia

Sedation/Excitement

Ileus

Startle to loud Noises

96
Q

Butorphanol - Dogs elimination

A

P-glycoprotein mediates elimination from CNS

97
Q

Butorphanol - Adverse effects in Dogs

A

MDR1 mutation

hets - 25% reduction in dose

homos - 50% reduction in dose

98
Q

What are the subtypes of the opioid agonist/antagonists?

A

1 - antagonize mu + activate kappa

2 -partial agonist for mu + antagonist for kappa

99
Q

Buprenorphine - Potency

A

30x’s the analgesic effect compared to morphine

100
Q

Buprenorphine - Mechanism

A

Partial Agonist for mu

Antagonist for kappa

Very strong affinitiy for mu

101
Q

Buprenorphine - Reversals

A

Resistant to Naloxone due to strong mu affinity

102
Q

Buprenorphine - Admin

A

IV + IM + SC + Transmucosal + Topical

103
Q

Buprenorphine - Use

A

Analgesic/Premed in Small Animals

Analgesic in horses

104
Q

Buprenorphine - Protein binding

A

96% binding

105
Q

Buprenorphine - 1/2 life

A

5 to 6 hours

Horses

Cats

Dogs

106
Q

Buprenorphine - Metabolism

A

Liver via

N-dealkylation

Glucuronidation

107
Q

Buprenorphine - Adverse effects

A

respiratory depression + sedation

108
Q

Nalbuphine - Mechanism

A

Antagonist for mu-receptor

Agonist for kappa-receptor

109
Q

Nalbuphine - Potency

A

equal to morphine

110
Q

Nalbuphine - Admin

A

IM

topically

111
Q

Nalbuphine - Use

A

Mild to moderate pain

Pre-med

Corceal ulcerations

112
Q

Nalbuphine - Duration of action

A

Dogs = 45 minutes

Cats = 2 to 3 hours

113
Q

Nalbuphine - Protein binding

A

does not bind

114
Q

Nalbuphine - Metabolism

A

Liver - Glucoronidation

115
Q

Nalbuphine - Excretion

A

Urine

116
Q

Nalbuphine - 1/2 life

A

Dogs = 1.2 hours

117
Q

Naloxone - Mechanism

A

High affinity for mu-receptor

Low affinity for kappa + delta

Antagonist

118
Q

Naloxone - Use

A

Post-op reverseal

119
Q

Naloxone - Metabolism

A

Liver - CYP450

120
Q

Naloxone - Excretion

A

Urine

121
Q

Naltrexone - Mechanism

A

Long- acting antagonist

mu/kappa/delta

122
Q

Naltrexone - use

A

reversal

123
Q

Naltrexone - Admin

A

IV + IM

Oral

124
Q

When is naltrexone given orally to dogs? How?

A

To treat behavioral problems in dogs

Reduced endorphine binding