Opioid Analgesics

Question 1

opioid analgesics purpose

Answer 1

To relieve moderate-to-severe pain.

Question 2

endogenous opioid peptides
name the 3 families:
peptide function:

Answer 2

three families: endorphins, enkephalins, & dynorphins

• peptides control pain and inflammation, regulate immune system, GI function, cardiovascular responses

Question 3

Mu

Answer 3

strong agonist, high affinity with mu receptors in the CNS
–severe pain***
– possible symptoms: sedation, respiratory depression, constipation

Question 4

strong agonist common drugs

Answer 4

1. hydromorphone
2. meperidine
3. methandone **
4. morphine **
5. tramadol **

Question 5

mild to moderate agonists

Answer 5

• treat moderate pain
  common drugs:
  1. codeine
  2. hydrocodone
  3. oxycodone
  4. propoxyphene

Question 6

mixed agonist-antagonists function

Answer 6

• exhibit agonist and antagonist like activity at the same time
  – ex: activate kappa receptions and block or partially activate mu receptors
  -

Question 7

mixed agonist-antagonists
strengths

Answer 7

Less risk of the side effects associated with mu receptors.

Question 8

mixed agonist-antagonists
weaknesses

Answer 8

➢ May produce more psychotropic effects.
➢ Maximal analgesic effect may not be as great as strong mu agonists

Question 9

antagonists
function

Answer 9

do not produce analgesia, used to treat opioid ODs and addiction

Question 10

antagonist primary agent

Answer 10

naloxone

Question 11

pharmacokinetics
where does metabolic inactivation take place?

Answer 11

primarily in the liver, partially in kidneys, lungs, and CNS

Question 12

mechanism of action
name the 3

Answer 12

1. spinal effects
2. supraspinal [brain] effects
3. peripheral effects

Question 13

mechanism of function
functions

Answer 13

1. decreased ascending (Afferent) pain transmission + activate descending (efferent) pathways that decrease pain (spinal and supraspinal effects)
2. At peripheral sensory nerve endings, opioids decrease
   excitability of the neuron and inhibit the neuron from initiating
   transmission of painful stimuli toward the spinal cord (peripheral effects).

Question 14

spinal effects

Answer 14

Inhibitory effect is mediated
by opioid receptors that are
located on both presynaptic
and postsynaptic membranes
of pain- mediating synapses

Question 15

supraspinal effects

Answer 15

*goal is to decrease pain
1. opioids bind to specific receptors in the midbrain periaqueductal gray matter (PAG) and disinhibit descending pathways that decrease pain.
2. Increased activity of descending pathways travels through the ventromedial medulla (VMM) to reach the dorsal horn of the spinal cord.
3. Neurons in descending pathways release serotonin and norepinephrine onto dorsal horn synapses and inhibit the ability of these synapses to transmit
painful impulses to the brain.

Question 16

peripheral effects

Answer 16

decreased peripheral nerve endings’ sensibility and inhibit neuron from sending pain signals to brain

Question 17

clinical applications
when are they used

Answer 17

• acute mod to severe pain following surgery, trauma, myocardial infarction
• chronic pain [cancer]
• not effective in treating sharp and intermittent pain

Question 18

how are opioids administered

Answer 18

• orally administered opioids work best when given at scheduled intervals
• patient-controlled analgesia

Question 19

opioids side effects

Answer 19

► Mental slowing and drowsiness (sedative properties)
► Respiratory depression (slow the breathing rate)
—— Can be sever or even fatal in seriously ill patients
► Orthostatic hypotension
► GI distress
—–Nausea, vomiting, and constipation (due to its anti-peristaltic
action

Question 20

addiction

Answer 20

When an individual repeatedly ingests certain substances for mood-altering and pleasurable
experiences, such as the heroin

Question 21

tolerance

Answer 21

The need to progressively (periodically) increase the dosage of a drug to achieve a therapeutic effect (to provide adequate relief) when the drug is used for prolonged periods

Question 22

tolerance mechanisms

Answer 22

▪ Receptor down-regulation (removed by endocytosis) and desensitization.
▪ Loss of communication between the opioid receptor and the G protein.

Question 23

how long does tolerance last

Answer 23

Tolerance seems to last approximately 1 to 2 weeks after the drug is removed

Question 24

when does tolerance begin

Answer 24

Begins after the first dose of the narcotic, but the need for increased amounts of the drug usually becomes obvious after 2 to 3 weeks of administration.

Question 25

physical dependence

Answer 25

The onset of withdrawal symptoms when the drug is abruptly removed

Question 26

physical dependence

Answer 26

Withdrawal symptoms become evident within 6 to 10 hours after the last dose of the drug, and peak on day 2 or day 3 after the drug has been stopped; last about 5 days.

• risk of addiction is low when opioids are used appropriately

Question 27

opioid-induced hyperalgesia

Answer 27

Certain patients may fail to respond to opioids or may report increased pain sensitivity (hyperalgesia)
- pain may worsen when drugs are reaching peak effect
- pain may reduce when effects are minimal

Question 28

methadone

Answer 28

Methadone
➢ Offers several advantages, such as milder withdrawal symptoms

Question 29

buprenorphine

Answer 29

An alternative; a mixed agonist– antagonist

Question 30

hyperalgesia PT implication