Opioids Flashcards Preview

Neuro Block 2 > Opioids > Flashcards

Flashcards in Opioids Deck (30):
1

What is the difference between an opiate and an opioid?


an opiate is a drug derived from the opium poppy

an opioid encompasses the opiates, but includes any substance that acts on the opioid receptors (can be man-made or endogenous)

2

What are the 3 receptors opioids bind?


Mu (analgesia, respiratory depression, decreased GI motility, dependence)

kappa (analgesia, sedation, decreased GI motility)

delta (modules mu activity)

3

What are the encogenous opioids that act on the mu receptors? keppa? delta?


mu - endorphins and endomorphines

kappa = dynorphins

delta = enkephalins

4

What sort of receptor is the Mu receptor?


a GPCR

5

What  does the mu receptor do when activated? On the presynaptic terminal!


 

It inhibits a Ca2+ channel and adenylyl cyclase (less cAMP)

Because the Ca2+ channel is inhibited, you have reduced release of glutamate and substance P

thus, the signal isn't transmitted

6

In addition to blocking Ca2+ on the presynaptic terminal, what happens in the post synaptic terminal?

postsynaptic inhibition

the receptor activation opens K+ channel, allowing K+ to flow out, causing hyperpolarizaiton and decreased excitability

makes the postsynaptic neuron even less likely to fire

7

The inhibition of the ascending pain transmission pathway occurs mostly where?


in the dorsal horn, but also in the spinal cord, thalamus and maybe the periphery

8

What are opioids effect on the descending inhibitory pathway?


It enhances the descending inhibitory pathway, thus further inhibiting the ascending pain pathway

Under normal conditions, an inhibitory interneuron is constitutively releasng GABA onto the efferent presynaptic neuron, thus inhibitin the descending pathway

Opioid receptor activation blocks release of GABA from the inhigitory interneuron, so you get activation of the inhibiting descending pathway

thus, greater inhibition of nociceptive processing in dorsal horn of the spinal cord (Gate theory)

9

What are some examples of opioid agonists?


they bind the receptor and produce an effect:

morphine, methadone, oxycodone, heroin

10

How does an antagonist work and what are two examples?


it binds to the receptor but doesn't have an effect, so it's usually used to compete for the receptor in opiate addiction

examples include Nalozone and Naltrexone

11

Why would you maybe want to prescribe a partial agonist and what is an example of one?


It's less efficacious than a full agonist, but it has lower abuse potential

Buprenorphine is one

It's often used in tandem with nalozone (combo is subozone)

12

What is an example of a mixed agonist/antagonist? What is the clinical relevance?


pentazocine

it's an agonist at kappa and antagonist at Mu

this means if you change someone who is opiate dependant to this, they will enter withdrawal

13

What are the pros and cons of using opioids orally?


Pro: convenient, longer duration than parenteral routs, better for chronic treatment

Con: high first pass metabolism is limiting, slowe ronset, delayed peak effect

14

What are the pros and cons of giving opioids IV?


pro: precide and accurate dosin, rapid onset, you can do bolus or continuous and patient can control dose with button

con: increased risk of adverse effects

15

What are some of the benefits of giving opioids intra-thecally?


longer duration at lower doses than systemic

can avoid some of the brain-mediated adverse effects like respiratory depression

16

What is nice about recetal suppositories for opioids


administration can be discontinued easily

17

What is first pass metabolism and what does it mean for dosing?


a drug that is absorbed from the GI tract has to go to the liver first and opioids are rapidly and efficiently metabolized

oral morphine has to require 3-6x higher the dose you'd give parenterally

 

18

which opioid drug is less impacted by first pass metabolism?


methadone

19

What will make an opioid more addictive than another opioid?


how fast it crosses the BBB = more lipid solubility (heroin is more lipid solubel than mophine)

20

What is a pharmacologically active metabolite of morphie? Why is renal function a concern with this?


morphine 6-glucaronide

it's active, but it's excreted int he urine so if renal function is compromised, this can build up and cause opioid overdose

21

What is a toxic metabolite of an opioid? What does it cause and what does that mean for this drug's use?


normeperidine is a metabolite of meperidine

it is excitotoxic, causing tremor, twitching and convulsing

this means meperidine should only be used acutely

22

Why is miosis (pinpoint pupils) a very good indicator of opioid use?


it doesn't develop tolerance, so a person who is chronically abusing opioids will still have pinpoint pupils

23

What effect do opioids have on the GI tract? Respiratory system? Uterus? Ureters? Skin?


GI = decreased motility, constipation, cramping

Repiratory = bronchilar construction at high doses

Uterus = prolongs labor

Ureters = difficulty urinating

Skin = itching and flushing due to histamine release

24

Although opioids are sometimes used to slow progress of obstetric labor, what is the concern?


it can cross the placental barrier and caus eneonatal respiratory depression

25

What opioids are given for diarrhea?


loperamide (imodium) doesn't cross the BBB so it's not addictive

Diphenoxylate and Atropine (Lotomil) the atropine is put in for its negative seide effects to discourage abuse

26

What antagonist do you use to treate acute overdose? Which do you use to treat addiction?


OD = naloxone; injected - extremely rapid effect and short duration of action

Addiction = naltrexone - given orally and a single dose on alternate days can block heroin effects

27

Which effects of opioid reach tolerance first, which never do?


most rapid: analgesia, euphoria, sedation, respiratory depression, cough suppression, nausea, and vomiting

slower: bradycardia

Never: miosis and constipation

28

What are some symptoms of opioid withdrawl?Is it life threatening?


rhinorrhea, lacrimation, yawning, chills, gooseflesh, hyperventilation, hyperthermia, mydriasis, muscular aches, vomiting, diarrhea, anxiety and hostility

not life threatening

 

29

What does the word "narcotic" really mean


it means something that puts you to sleep, but now it's taken on more of a legal term for controlled substances

30