03 - Opioids and Context Sensitive Half Time Flashcards

0
Q

Opioid subreceptors and what they do?

A
Mu - analgesia, resp depression, pruritis, constipation, urinary retention
Kappa - analgesia, sedation
Delta - constipation, urinary retention
Sigma - ??
?? - constipation, urinary retention
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1
Q

Most opioids bind to which receptor?

A

Mu

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2
Q

Mechanism of opioids and where their receptors are found

A

Inhibit release and response of excitatory neurotransmitters in nociceptive neurons
Receptors exist through out CNS and peripheral nerves

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3
Q

Most rapid and complete route of opioid absorption

A

IV

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4
Q

IM morphine and meperidine takes

A

20-60 min

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5
Q

Transmucosal absorption of fentanyl takes

A

10 min

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6
Q

Transdermal absorption of fentanyl takes

A

14 to 24 min (reservoir in dermis)

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7
Q

Benefits of neuraxial opioid absorption

A

No sympathectomy, motor blockade, or loss of proprioception

Specific visceral > somatic analgesia

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8
Q

How does neuraxial opioid abs work?

A

Diffusion to opioid receptors in the spinal cord

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9
Q

The effects of neuraxial abs are less true with __________ due to

A

Lipid soluble opioids like fentanyl

More systemic absorption

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10
Q

Distribution half life of opioids

A

5-20 min

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11
Q

First pass uptake of opioids

A

In the lungs

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12
Q

Which opioids have active metabolites

A

Morphine and meperidine (Demerol)

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13
Q

The template for opioids

A

Morphine

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14
Q

Morphine acts on ______ receptors

A

Mu

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15
Q

Onset and peak of morphine

A

5 min onset

Peak in 10-40 min

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16
Q

Morphine can decrease MAC by

A

65%

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17
Q

Redistribution of ________ is age dependent

A

Morphine

7-8 hours in neonates and 4.5 hours for ages 61-80

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18
Q

Elimination half life of morphine

A

1.7 - 3.3 hours

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19
Q

Which opioid should be used with caution in renal failure?

A

Morphine

Meperidine should not be used at all!!

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20
Q

Neuro effects of morphine

A

Sedation, cognitive impairment, euphoria
Decr CMRO2, CBF, ICP if normocarbia maintained
Miosis and pruritis
Muscle rigidity after large doses
Nausea/vomiting - stimulates CTZ in medulla

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21
Q

Resp effects of morphine

A

Blunts hypercapnic drive
Hypoventilation
Rousable apnea
Suppresses cough reflex

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22
Q

GI effects of morphine

A
Decreased motility (constipation), slower gastric emptying
Increased common bile duct tone
Biliary spasm (sphincter of Oddi)
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23
Q

GU effects of morphine

A

Urinary retention

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24
Q

CV effects of morphine

A

Hypotension at higher doses

Can cause brady at high doses

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25
Q

5-10x more potent than morphine

A

Hydromorphone (Dilaudid)

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26
Q

Length of action for hydromorphone

A

3-4 hours

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27
Q

How is heroin produced?

A

Acetylation of morphine

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28
Q

Which receptor is responsible for reducing shivering?

A

K

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29
Q

Max daily dose of meperidine (Demerol)

A

600 mg, 1000 mg

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30
Q

Synthetic mu receptor agonist

A

Fentanyl (sufentanil, alfentanil)

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31
Q

100x more potent than morphine

A

Fentanyl

32
Q

Fentanyl reduces MAC by

A

50-70%

33
Q

Onset of fentanyl

A

10 seconds
Recovery starts within 5 min
Complete recovery in 60 min

34
Q

1000x more potent than morphine

A

Sufentanil

35
Q

__________ has a shorter redistribution half life than fentanyl

A

Sufentanil (30 min)

36
Q

Short duration of action even in large doses (opioid)

A

Alfentanil

37
Q

Alfentanil can decrease MAC by

A

Up to 70%

38
Q

Strong opioid agonists

A
Morphine
Hydromorphone
Methadone
Heroin
Meperidine (Demerol)
Fentanyl
Remifentanil (Ultiva)
39
Q

Ultra short acting opioid

A

Remifentanil (Ultiva)

40
Q

Remifentanil can decrease MAC by

A

Up to 90%

41
Q

Can cause post operative hyperalgesia

A

Remifentanil

42
Q

Partial agonists

A
Codeine
Hydrocodone (lortab)
Oxycodone and OxyContin (ER)
Tramadol
Propoxyphene
43
Q

A full agonist + partial agonist, the partial agonist will act as a

A

Competitive antagonist

44
Q

What is a competitive antagonist?

A

Competes with full agonist for receptor occupancy

45
Q

Ceiling effect

A

Net decrease in clinical effect compared with full agonist alone

46
Q

Tylenol 2, 3, 4 is acetaminophen and

A

Codeine

47
Q

What is codeine converted to in the body?

A

Morphine

48
Q

Vicodin or lorcet is acetaminophen and

A

Hydrocodone

49
Q

Roxie’s, Percocet, and percodan is acetaminophen and

A

Oxycodone or OxyContin

50
Q

Tramadol inhibits

A

spinal norepinephrine and serotonin uptake

51
Q

Tramadol has possible interaction with

A

Coumadin

52
Q

Darvocet is acetaminophen with

A

Propoxyphene

53
Q

This opioid causes arrhythmia and is no longer on the US market

A

Propoxyphene

54
Q

IV __ mg meperidine ~ __ mg morphine ~ __ mg hydromorphone ~ __ mcg fentanyl ~ __ mcg sufentanil

A
100
10
1
100
10
55
Q

Mixed agonist-antagonist

A

Nalbuphine (Nubain)
Buprenorphine (buprenex)
Butorphanol

56
Q

When a mixed agonist-antagonist is given with a low dose of full agonist, the effect

A

Is additive up to the max effect of the partial agonist

57
Q

Why can pretreatment with mixed agonist-antagonist prevent euphoria associated with morphine use?

A

The mu receptor is competitively antagonized

58
Q

Nalbuphine (Nubain)

A

Strong k agonist and mu antagonist

59
Q

Resp depression with nalbuphine has a ceiling effect similar to

A

30 mg morphine

60
Q

Can reverse morphine-induced resp depression without compromise of analgesia

A

Nalbuphine (Nubain)

61
Q

Can precipitate withdrawal in opioid dependent patients

A

Nalbuphine (Nubain)

62
Q

Elimination half life of nalbuphine

A

3-6 hours

Similar to morphine

63
Q

Buprenorphine (buprenex)

A

Partial mu agonist and k antagonist

64
Q

Often given sublingually to avoid significant first pass effect

A

Buprenorphine

65
Q

Binds more strongly to receptors than other opioids

A

Buprenorphine

Has 50x greater affinity for mu receptor than morphine

66
Q

Opioid with slow dissociation from receptors

A

Seen with buprenorphine

Causes prolonged duration of action

67
Q

Resistant to antagonism with naloxone

A

Buprenorphine

Because of slow dissociation

68
Q

Buprenorphine is used for

A

Management of chronic pain as well as opioid dependence because it binds more strongly to receptors than other opioids

69
Q

Which opioid should be used with caution in surgical patients?

A

Buprenorphine because it causes uncontrolled post op pain

70
Q

Suboxone is

A

Buprenorphine + naloxone

71
Q

Opioid antagonist

A

Naloxone

72
Q

Naloxone

A

Pure antagonist at m, k, and d

73
Q

How is naloxone administered?

A

Careful titration to prevent sudden, severe pain (HTN, tachycardia, pulmonary edema)

74
Q

Dose of naloxone

A

Dilute one vial (0.4 mg) in 10 mL and titrate 20-40 mcg every 1-2 min

75
Q

Does naloxone have a long or short duration of action?

A

Short, repeated dose or infusion may be required

76
Q

What is context sensitive half time?

A

Amount of time required for drug conc in central compartment to decrease by 50%

77
Q

What is context in context sensitive half time?

A

Duration of the infusion prior to stopping it

78
Q

Context sensitive half time increases as a function of duration of infusion before it was stopped

A

Due to movement of drug stored in peripheral compartments back into central compartment