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4Qpharm3-test1 > Opioids & antagonists > Flashcards

Opioids & antagonists Flashcards

1
Q 
Endogenous Opioid peptides (3)
and functions (2)
A

enkephalins
beta-endorphin
dynorphin

released in response to pain ↓responsiveness to pain

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2
Q

Mu receptor: effects of stimulation

A

analgesia
euphoria
sedation
side effects

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3
Q

Kappa: effects of stimulation

A

analgesia in some ppl, dysphoria in others

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4
Q

Delta, sigma: effects of stimulation

A

dysphoria

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5
Q

3 major opioid receptors

how do they work

A

Mu, Kappa, Delta
ALL are coupled to Gi/o
ALL CLOSE VOLTAGE GATED Ca2+ CHANNELS on PREsynaptic nerve terminals ( ↓ neurotransmitter release & ↓ neuronal activity in these pathways)

Mu receptors also OPEN K+ CHANNELS, causing hyperpolarization-inhibiting nerve transmission

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6
Q

Stimulation of mu, kappa & delta receptors does what?

A

↓Ca2+ influx-> ↓release of excitatory transmitters

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7
Q

stimulation of mu receptors on post-synaptic cell does what?

A

hyperpolarizes & ↓transmission

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8
Q

alpha2 receptors do what

A

↓pain transmission in this region (also where TCAs work to ↓pain)

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9
Q

Effect of Opioids on Pain transmission (5 plus 2 possibles)

A

A. Direct Action at inflamed & damaged tissue
B. inhibition of release of excitatory transmitters in the dorsal horn: spinal anesthesia
C. Thalamic action
D. periaqueductal gray, may cause release of endogenous opioids as well
E. Rostral Ventral medulla

  • NE pathway from locus coeruleus to dorsal horn may also ↓pain
  • inhibition of neurons may ↑ the activity of pathways that inhibit pain
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10
Q

Pain & GABA

A

GABA (U) inhibits descending neuronal pathways that modulate pain
-opioids ↓ the release of GABA, allowing the pathways to be activitated
this ↓pain transmission in the DORSAL HORN of the SPINAL CORD

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11
Q

Effects of Opioids (14)

A
  • Analgesia
  • Sedation/mental clouding
  • Euphoria or dysphoria
  • Emesis
  • Depression of cough reflex (antitussive)
  • Respiratory depression
  • Elevated intracranial pressure
  • MIOSIS (pupil constriction)
  • ↓body temp
  • Truncal rigidity
  • Cardiovascular
  • GI
  • GU
  • Uterus
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12
Q

Opioid analgesia

A

a. ↓sensation of pain
b. ↓reaction to pain
c. tolerance develops to analgesia

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13
Q

Opioid sedation/mental clouding

A

NOT used as sleep aids, different quality of sedation
disrupt REM
morphine causes CNS depression in overdose
codeine, meperidine may cause excitement in overdose

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14
Q

Which opioid is different, a strange drug?

A

Meperidine

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15
Q

Opioid Euphoria or dysphoria

A

-sense of floating, pleasure
-prob depends on receptor distribution in different individuals
-some fine experience dysphoric
KAPPA & DELTA receptors INVOLVED in DYSPHORIA

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16
Q

Opioid emesis

A

N/V in some ppl

Opioid stimulate chemoreceptor trigger zone in the brain (CTZ)

17
Q

Opioid antitussive: doses, which work, which don’t

A

LOWER doses than those for analgesia
VERY EFFECTIVE: CODEINE & DEXTROMETHORPHA
DXM is NOT analgesic

Meperindine (Demerol) DOESN’T suppress cough

18
Q

Opioid respiratory depression: when, why, good for, bad for

A

-more common in OD, but also at therapeutic doses
-↓ response of brain stem to elevated CO2
-USEFUL IN PULMONARY EDEMA
NOT good in ppl w/PULMONARY DZ
-may also cause bronchoconstriction

19
Q

Opioid effect on intracranial pressure

A

Elevated intracranial pressure ↑CO2 causes vasodilation, ↑cerebral blood flow & ↑pressure
WATCH OUT IN PATIENTS WITH HEAD TRAUMA!

20
Q

Effect of opioids in the eye, how to block

A

PUPIL CONSTRICTION (except w/meperidine)

  • NO tolerance develops
  • parasympathomimetic: blocked by atropine
  • common in OD, but may convert to dilation in comatose patients
21
Q

Opioid effect on body temp

A

decreases body temp due to dysregulation in hypothalamus

22
Q

Truncal rigidity in opioids: why, what does it effect, which drugs do this, what to block

A
  • supraspinal effect ↑tone of the large trunk muscles
  • may interfere with respiration or w/attempts to ventilate patient
  • most (C) with HIGHLY LIPID SOLUBLE DRUGS, like FENTANYL, IV
  • use neuromuscular blockers to prevent this effect
23
Q

Opioid effects: cardiovascular

A

BRADYCARDIA may occur
↓BP common
may result from CNS vasomotor depression &/or release of histamine (vasodilates)

but TACHYCARDIA may occur with MEPERIDINE (anticholinergic)

24
Q

Opioid effects: GI

A

↓ gastric activity both local & CNS
CONSTIPATION
↓ gastric motility
biliary colic, constriction of sphincter of Oddi
↓ biliary, pancreatic, intestinal secretions
PREPARE PATEINT & BE PRO-ACTIVE ABT PREVENTING CONSTIPATION

25
Q

Opioids: GU effects

A

antidiuretic effect: ↓urine output
↓renal blood flow
↑sphincter tone-harder to urinate
↑urethral tone: harder to pass kidney stone
so DON’T GIVE PPL. W KIDNEY STONES opioids, it makes it HARDER TO PASS STONE

26
Q

Opioids: Uterus effects

A

may prolong labor

but Miperideine DOES NOT prolong labor, unlike others

27
Q

Opioids: tolerance & dependence

A

TOLERANCE: ↑doses needed to control pain, occurs very rapidly, more (C) w/lower efficacy drugs [eg. codeine is terrible for dependence]

PHYSICAL DEPENDENCE: may result from desensitization of mu receptors
-NMDA receptor antagonists may ↓ development of tolerance

28
Q

Hyperalgesia: when and why in opioids

A

may occur w/long-term use of opioids

-may be mediated by ↑ in dynorphin in the spinal cord that makes transmission of pain MORE effective

29
Q

Does tolerance develop to all the effects of opioids?

A

tolerance develops to: analgesia, sedation, euphoria, N/V, respiratory depression

NO TOLERANCE to: MIOSIS, CONSTIPATION, SEIZURES

30
Q

Opioid AEs

A

N/V: better if take w/food
Constipation: be aggressive to tx it BEFORE it occurs

Urinary retention: worse if BPH present, due in part to constriction of urinary sphincter

Respiratory depression: dose dependent, worse w/higher doses, more naïve users, caution in pulmonary dz

31
Q

Opioids & histamine

A

opioids can produce histamine release in some peeps-> flushing, itching sweating

  • more (C) when opioids are injected
  • this is generally tx or pretx with antihistamines such as diphenhydramine (Bendryl)
32
Q

Who develops tolerance and/or addiction

A

tolerance & dependence occurs in ANYONE who uses opioids chronically, for any reason
ADDICTION most (C) when used for euphoric effect, but can occur w/med use of opioids
-ADDICTION MORE LIKELY IF UNDERPRESCRIBED:
~if pt dvlps sever pain, which is relieved by opioid, this provides reinforcement-> reward pathyway activated
~if OPIOIDS GIVEN BEFORE PAIN GETS TO SEVERE, BYPASSES THE REWARD PATHWAY

33
Q

Opioid withdrawal sxs, how to reduce them & what can precipitate withdrawal

A

sxs: dysphoria, anxiety, insomnia, anorexia, yawning, chills, goose bumps, vomiting, diarrhea, ↑BP, ↑HR, ↑temp, muscle aches & twitches

SXS CAN BE REDUCED BY CLONIDINE or another opioid (METHADONE)

Opioid antagonists can precipitate withdrawal if dependent

34
Q

Opioid OD presents as: (3)

A

CNS depression
Respiratory depression
Pin point pupils
[may dilate if severely hypoxic]

35
Q

What to do in opioid OD?

A

first: ABCs
Tx by: SUPPORTING RESPIRATION
then, use opioid antagonist like NALOXONE (NARCAN)

36
Q

Clinical uses of opioids (5)

A

ANALGESIA: acute pain trauma, CA, post surgery, chronic pain [combine w/non-opioids when possible, titrate to degree of pain]
ACUTE PULMONARY EDEMA: relieves dyspnea, mechanism not clear
RELIEF OF COUGH: codeine & dextromethorphan
TREATMENT OF DIARRHEA: Loperamide (Imodium), diphenoxylate/atropine (Lomotil)
ANESTHESIA:
general-adjunct to control pain
spinal-epidural w/local anesthetics (direct access to dorsal horn ↓ some side effects, but itching worse)

37
Q

Opioid drug interactions (4 classes and the result)

A

Sedative hypnotics: ↑CNS & respiratory depression

Antipsychotics: sedation, maybe respiratory depression

MAO Inhibitors: (MEPERIDINE & DXM CAUSE WORST INTRXNS), may inhibit serotonin reuptake to some degree but BEST TO AVOID ALL opioids w/MAOIs

CYP2D6 inhibitors:

  • codeine, oxycodone, hydrocodone NOT metabolized to active compounds
  • FLUOXETINE, paroxetine the worst for inhibition
38
Q

Opioids: CONTRAINDICATIONS (6)

A

USE OF PARTIAL AGONIST W/FULL AGONIST: can impair analgesia, cause withdrawal

Pts w/head injuries (↑intracrantial pressure)

Pregnancy (esp. at delivery can cause resp. depression in the baby)

Impaired pulmonary fxn

Impaired hepatic or renal fxn

Some endocrine dzs

39
Q

Opioid precautions (11)

A

-severe liver dz/kidney dz
-pulmonary dz
-biliary tract probs
-seizures (esp. meperidine)
pain of unknown cause (esp. abdominal)
-head trauma
-chronic non-terminal pain?
-inflammatory bowel dz
-pregnancy/breast feeding
-urinary retention/BPH

4Qpharm3-test1 (9 decks)

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