Pharmacology - Narcotics Flashcards Preview

MS 2 - Unit 3 > Pharmacology - Narcotics > Flashcards

Flashcards in Pharmacology - Narcotics Deck (60)
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1

What are the three types of endogenous opioids?

enkephalins, endorphins, and dynorphins

2

What accounts for "Stress analgesia" (e.g. in war etc.)

β-endorphin and ACTH share common precursor and are co-released with stress - result is release of cortisol + endogenous opioids

3

3 common functions of endogenous and exogenous opiods:

inhibition of pain perception,

modification of
gastrointestinal/autonomic function

reward properties

4

Name and function of 4th endogenous opioid discovered in 1995

nociceptin/orphanin FQ

drug reward and reinforcement, feeding, learning and memory

5

4 types of opioid receptors and corresponding chromosomes

MOR - mu opioid receptor, chromosome 6)
DOR - delta opioid receptor, chromosome 1)
KOR - kappa opioid receptor, chromosome 8)
NOR - N/OFQ opioid receptor, chromosome 20).

6

Common features of opioid receptors

All are G protein-coupled receptors, with extracellular,
transmembrane, and intracellular domains.

Classes have homology in the receptor types

7

How are opioid receptors activated?

Ligands are recognized on the extracellular domain; G proteins bind to the
cytoplasmic aspect of the receptor, and activate/bind GTP

8

Signaling pathway initiated by ligand binding to opioid GCPRs

• Adenylyl cyclase activity is inhibited
• Voltage-gated Ca2+ channels on the cell membrane close
• K+ current is stimulated through several channels
• PKC and PLCβ are activated

9

How do mu opioid receptors influence neuronal excitability?

via "disinhibition" of presynaptic release of GABA

10

What does activation of opioid receptors do?

agonists inhibit release of substance P and
ascending transmission of pain from dorsal horn neurons by activating pain
control circuits descending from the midbrain

11

T/F exogenous opioids are alkyloids where as endogenous opioids are peptides

true

12

binding site of peptides

extracellular loops in combination
with the core

13

What accounts for different effects and side effects as well as metabolism of different ligands?

small chemical modifications of the
ligands result in changes in signal transduction sequences

14

T/F tollerance toward and opioid over time results in decreased side effects

True

15

tollerance is associated with:

decreased effectiveness, and decreased side effects,
with repeated administration

16

Molecular basis for tolerance involves:

phosphorylation or receptor internalization

17

Side effects of opioids

Analgesia
Mood alteration; stimulation of reward centers
Miosis
Convulsions
Decreased respiration
Cough suppression (antitussive)
Nausea and emesis
Constipation
Urinary retention
dermal vasodilatation and urticaria (hives)

18

What causes opioid induced uticaria (itching/hives)

Opioids stimulate mast cell degranulation and release of histamine

can be managed with an antihistamine (non sedating are preferred to avoid synergy with analgesic e.g. loratadine, fexofenadine)

19

What causes nausea and emesis

Direct stimulation of the
medullary trigger zone for emesis

Delayed gastric emptying

20

T/F cough suppressant activity is unrelated to respiratory depression

True - may be mediated
through receptors unrelated to GPCRs

21

Mechanism for opioid induced decrease in respiration

direct stimulation
of brainstem respiratory centers

22

T/F Opioids lower seizure threshold

true

23

What causes opioid induced miosis? What receptor is involved?

direct stimulation of oculomotor complex to effect papillary constricution (mimicking parasympathetic response)

24

Mechanism for mood alteration/reward

opioids directly stimulate the dopamine pathway in the ventral striatum (VTA)
-- stimulates limbic functions (e.g. motivation and affection)

25

T/F opioid induced miosis and constipation lessen with tolerance

False

26

T/F oral, sublingual, transmucosal, rectal absorption of opioids undergo significant first pass metabolism

True

27

T/F opioid absorption is slow

False - rapid!

28

Steps of opioid metabolism:

Occurs in liver - glucuronidation is primary metabolic
pathway

Opioids and their metabolites are then excreted by the kidney

29

Factors that require dose adjustment to prevent overdose:

cirrhosis,
chronic or acute renal
insufficiency,
dehydration

30

Who should NOT have regular opioid dosing but can be treated on PRN basis?

oliguric or anuric patients

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