41: Opiod Analgesics Flashcards Preview

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Flashcards in 41: Opiod Analgesics Deck (42):
1

what 5 things are opiods traditionally used for?

euphoria
analgesia
sedation
relief from diarrhea
cough suppression

2

opium combined with alcohol =

laudanum

3

the exudate from poppy seeds containing 20 biologically active components including morphine and codeine

opium

4

drug extracted from the exudate of the poppy

opiate

5

natural or synthetic drug that binds to opiod receptors producing agonist effects

opioid

6

term used to characterize pharmacological compounds used to treat moderate to severe pain

narcotic

7

natural opiods occur ...

-in the exudate of the opium poppy
- as endogenous endorphins, enkephalins and dynorphins

8

all non-natural opiods are derived from...

morphine and precursor compounds

9

located outside the spinal cord and responsible for central interpretation of pain - supraspinal analgesia

Mu1

10

located throughout the CNS- brainstem and spinal cord

responsible for supraspinal and spinal analgesia, respiratory depression, constipation, physical dependence, and euphoria

Mu2

11

three endogenous opiod receptors

Mu
Kappa
Delta

12

what gprtn is assocaited with opiod receptor activation

Gi/Go

13

upon opiod receptor activation, the Gi/Go coupling results (3)

1. inhibition of adenyly cyclase
2. reduced opening of presynaptic voltage-gated Ca2+ channels resulting in loss of intracellular calcium and decreased release of neurotransmitters
3. increase postsynaptic opening of K+ channels (hyperpolarization and decreased firing)

14

mechanisms of analgesia on the ascending pain pathways (3)

1) inhibition of afferent pain transmission (blockade of pain impulses from the periphery to the brain)
2) peripheral effects (activation of opiod receptors on distal ends of afferent neurons decreases their activation and excitability)
3)dorsal horn of the spinal cord (reduction in incoming pain signaling and reduction in pain signaling up the spinal cord)

15

how do opiods work presynaptically v. postsynaptically?

presynaptic : opiods block release of pain-mediating Nt from afferent neurons via inhibtion of Ca channels

postsynaptic: opioids inhibit activation of afferent neurons via increased K conductance that leads to hyperpolarization

16

how do opioids work in descending pathways?

opiods block inhibtior GABAergic interneurons to produce disinhibiton

leads to enhanced inhibition of nociceptive processing in the spinal cord and overall pain relief

17

site of action of opioids

periaqueductal gray-midbrain

rostral ventral medulla - brainstem

locus coeruleus - pons in brainstem

18

reduce both sensory and affective aspects of pain

analgesia

19

what special precaution needs to be taken with use of opiods in head trauma?

increased pCO2 --> reflexive cerebral vasodilation

respiratory depression is a general pharmacological effect of opioids and leads to reduction in respiratory center sensitivity to pCO2 tension

20

do opioids cause dilated or constricted pupils?

miosis - constriction of pupils

21

why do opiods cause cough suppression?

suppress the cough center in the brain -- action is predominately via the brainstem chemoreceptor trigger zone

22

what is the main GI effect of opioids?

constipation

relieve diarrhea by decreasing gut motility and increasing the tone of intestinal smooth muscle

23

how do opioids affect the uterus and urinary tract?

diminished force of contractions in labor

urinary retention

24

what are the cardiovascular effects of opioids?

hypotension
bradycardia

25

urticaria (hives) may be a side effect of opioid use. why?

histamine release -- stimulates mast cell degranulation and release of histamin causing urticaria, itching, diaphoresis and vasodilation

26

what is a contraindication for meperidine use?

MAOi drug interaction with opioids

hyperpyrexic rxn including hypertension

27

dextromethorphan

cough suppressant

28

diphenoxylate

antidiarrheal agent

29

loperamide

antidiarrheal agent

30

tramadol

mu agonist plus 5HT/Ne uptake inhibitor

31

pros and cons of mixed opioid agonist-antagonists

mixed act differently at specific opioid receptors

pros: provide adequate analgesia with less risk of side effects and addiction

cons: enhanced psychotropic effects

32

which mixed opioid agonist-antagonist is a partial activator of mu rec, blocks kappa rec.

buprenorphine

all the others activate kappa rec. and block or partially activate mu rec

33

which receptors does morphine work on?

mu
kappa
delta

34

latency to onset and duration of action for morphine

15-60;
3-6 hrs

PO administration -other routes are preferred

35

7-10x more potent analgesic than morphine

hydromorphone

36

which opioid is transdermal?

fentanyl

works 72 hours transdermal

more potent than morphine and hydromorphone

37

what happens when a normal person takes opioid antagonists?

in normal individuals with no opiates present, these drugs produce no effects

38

what drug would you use to reverse effects of acute opioid overdose?

naloxone (opioid antagonist)

IV produces a reversal of CNs and respiratory depression within 30 sec

39

what drug might be used as a maintenance drug for addicts in treatment programs?

naltrexone (opioid antagonist)

PO administration with long duration of inhibitory action

40

physiological tolerance involves changes in...

decrease in number and sensitivity of opioid receptors

41

what is cross-tolerance?

tolerance to one drug produces tolerance for another drug

one who is tolerant to morphine will also be tolerant to the analgesic effect of fentanyl and other opioids

42

primary pharmacologic intervention used to treat opioid addiction

methadone

substituted for heroin and slowly withdrawn with milder withdrawal symptoms