OPIOIDS Flashcards Preview

ANESTHESIA PHARM 2 > OPIOIDS > Flashcards

Flashcards in OPIOIDS Deck (69):
1

what is the source of nociceptive somatic pain?

tissues (skin, muscle, joints, bones, ligaments)
often known as musculoskeletal pain

2

what is the source of nociceptive visceral pain?

internal organs of the main body cavities (thorax, abdomen, pelvis)

3

characterize somatic nociceptive pain vs. visceral pain

* somatic pain – sharp and well localized, can be reproduced by touching or moving the area/tissue involved
* visceral pain – poorly localized, dull pain (ache, cramping). frequently produces referred pain to the back

4

differentiate useful medications for somatic vs. visceral pain

* somatic pain – may respond to combinations of weak or strong opioids AND NSAIDS
* visceral pain – very responsive to weak and strong opioids

5

name a natural opioid

morphine

6

name a synthetic opioid

fentanyl

7

name a semisynthetic opioid

heroin

8

name an opioid agonist

morphine

9

name an opioid agonist/antagonist

nalbuphine

10

name an opioid antagonist

naloxone

11

what is the mechanism of action of opioids?

bind specific G protein-coupled receptors (in brain and spinal cord regions) involved in transmission and modulation of pain

12

where do opioid agonists work?

* opioid receptors in the pre/post-synaptic CNS
* peripheral afferent nerves

13

what endogenous ligands do opioids mimic the effects of?

* enkaphalins
* endorphins
* dynorphins

14

what neurotransmitters are released in response to pain (release is decreased with opioids)

acetylcholine, dopamin, norepi, substance p

15

which opioid receptor's 1º action is analgesia, produces N/V, pruritits, and bradycardia, and has low abuse potential?

Mu1

16

which opioid receptor is found only in the spinal cord (as opposed to spinal AND supraspinal)?

Mu2

17

Mu1 and Mu2 both produce euphoria. which one also produces sedation?

Mu2

18

which opioid receptors are responsible for physical dependence?

Mu2 and delta

19

which opioid receptor does not produce respiratory depression?

Mu1

20

which opioid receptor is responsible for dysphoria and diuresis?

kappa

21

which opioid receptor is the principle site for agonist-antagonists, and is highly resistant to high intensity pain?

kappa

22

where does nalbuphine work?

nalbuphine is an agonist-antagonist opioid – agonist at kappa receptors, and an antagonist at mu receptors

23

three opioid receptors modulate the body's ability to retain or excrete urine. describe the two

* kappa receptors produced diuresis (increase excretion)
* delta and Mu1 receptors produce urinary retention

24

which receptors are responsive to endorphins, morphine, and synthetic opioids?

Mu1 and Mu2

25

which receptors are responsive to dynorphins?

kappa

26

which receptors are responsive to enkaphalins?

delta

27

where are the targets of neuraxial opioids?

mu receptors in substantia gelatinosa of spinal cord

28

what kind of pain are neuraxial opioids designed to suppress?

visceral pain

29

what are the 4 classic side effects of neuraxial opioids?

pruritis, N/V, urinary retention, ventilatory depression

30

what are the dosing recommendations for morphine (IV, epidural, intrathecal)

10mg IV, 1mg epidural, 0.1mg intrathecal (1/10 ratio; very hydrophilic)

31

what are the dosing recommendations for hydromorphone (IV, epidural, intrathecal)

1mg IV, 0.2mg epidural, 0.04mg intrathecal (1/5 ratio; intermediate hydro-/lipo-philicity

32

what are the dosing recommendations for fentanyl (IV, epidural, intrathecal)

100mcg IV, 33mcg epidural, 6-10mcg intrathecal (1/3 – 1/5 ratio; very lipophilic)

33

how well are opioids absorbed?

* well absorbed by many routes
* some have high first pass metabolism (PO)

34

how well are opioid distributed?

* rapidly leave blood compartment for highly perfused areas
* muscle and fat act as a reservoir

35

describe the metabolism of opioids

* converted to polar metabolites then excreted by kidneys
* morphine-6-glucoronide (4-6x analgesic potency than morphine – morphine is a prodrug)
* tissue esterases (heroin, remifentanil)
* normeperidine (demerol)

36

what are the cardiovascular side effects of opioids?

* decreased sympathetic tone
* decreased BP
* decreased HR
* minimal contractility effects

37

what are the cardiovascular side effects of demerol?

anti-muscarinic effect (like atropine) – increase HR

38

what are the respiratory effects of opioids?

* respiratory depression due to agonist effect at Mu2
* dose dependent depression of ventilatory response to CO2
* increased PaCO2 (almost becomes an anesthetic)
* decreased RR
* increased tidal volume
* decreased minute ventilation
* cough suppression (dextramethorphan – no analgesia or ventilatory depression)

39

what are the CNS effects of opioids?

* sedation and analgesia vs. euphoria
* reduces MAC
* decreased CBF and CMRO2
* increases ICP with hypoventilation
* seizures with meperidine use (normeperdine buildup)
* miosis (edinger-wetphal nucleus of oculomotor nerve – no developed tolerance)

40

describe biliary colic side effect of opioids

* spasm of sphincter of Odi (can present similarly to angina)
* less with meperidine
* naloxone relieves pain
* glucagon 2mg IV reverses

41

how are opioid side effects expressed in the GI?

* N/V
* constipation
* delayed gastric emptying
* biliary colic

42

how are opioid side effects expressed in the GU?

* urinary retention due to increase in tone of ureter and vesicle sphincter

43

how do opioids affect histamine release?

increase histamine release – flushing, itching (more with morphine and meperidine)

44

describe side effects observed in the thoracic cavity

truncal rigidity

45

for which side effects do pts develop tolerance?

tolerance to depression of ventilation

46

what is the onset, peak effect, and duration times of morphine?

* onset: 15-30min
* peak effect: 45-90min
* duration: 3-4hr

47

how is morphine metabolized?

metabolized via conjugation with glucuronic acid in hepatic, extra hepatic, and kindneys

48

what is the active metabolite of morphine?

morphine-6-glucaronide
* accumulation of morphine and metabolite in kidney failure pts leading to prolonged narcosis and ventilatory depression

49

how potent is meperidine compared to morphine?

0.1 potency of morphine

50

meperidine peak effect, duration

* peak effect: 5-7min
* duration: 2-4hr

51

describe the local/atropine-like side effects of demerol

* block Na channels
* tachycardia, dry mouth, mydriasis

52

how is demerol most of used?

Tx for post op shivering (12.5-25mg)

53

fentanyl peak effect, duration

* peak effect 3-5min
* duration 30-60min

54

how much fentanyl undergoes 1st pass pulmonary uptake?

75% (metabolized in lungs, not liver)

55

what characteristic of fentanyl makes it last so long?

highly lipid soluble and protein bound

56

which opioid is hemodynamically stable?

fentanyl

57

induction dose – fentanyl

2-6mcg/kg with a sedative hypnotic

58

what is the infusion rate of fentanyl

0.5-5mcg/kg/hr

59

how potent is sufentanil compared to fentanyl?

10X as potent as fentanyl (greater affinity for opioid receptor – great for neurosurgery)

60

peak, duration – sufentanil

same as fentanyl — peak 3-5min, duration 30-60min

61

what is the dosing of sufentanil?

* 0.3-1.0mcg/kg 1-3min before DL
* 0.5mcg/kg followed by 0.5mcg/kg/hr

62

how potent is alfentanyl compared to fentanyl?

1/10 as potent as fentanyl

63

what procedures is alfentanyl good for?

anesthetic for RBB, DL
* 5-10mcg/kg provide good analgesia with rapid recovery

64

how potent/long acting is remifentanyl compared to fentanyl?

similar potency to fentanyl, short duration (~10min)

65

where is remifentanyl metabolized?

plasma and tissue esterases

66

compare dilaudid to morphine

* 8x more potent than morphine but shorter acting (~2hr)
* more sedation but less euphoria
* less histamine release

67

what are opioid antagonists useful for?

Tx overdose, respiratory depression

68

what is the duration of opioid antagonists?

30-45min

69

what is the dose of opioid antagonists?

1-4mcg/kg