Opioids

Question 1

Where are the mu receptors in the CNS?

Answer 1

Periqueductal grey matter (brain)
Substantial gelatinous (cord)

Question 2

What do the kappa receptors do?

Answer 2

Spinal analgesia

Sedation

Question 3

What do the delta receptors do?

Answer 3

Analgesia
Behavior change
Epileptogenic

Question 4

What does the theta receptor do?

Answer 4

Hallucinations

Dysphoria

Question 5

When is the peak effect of morphine?

Answer 5

90 minutes

Question 6

What is the metabolite of morphine?

Answer 6

Morphine 6 glucuronide - Renally excreted

Question 7

What is the peak effect time of dilaudid?

Answer 7

5-10 minutes

Question 8

What is the effect site half life of fentanyl?

Answer 8

30 minutes

Question 9

What opioid has the fastest onset?

Answer 9

Alfentanil (90 seconds due to pka of 6.5 (highly nonionized) so crosses bbb fast

Question 10

What does alfentanil cause more of?

Answer 10

N/v adds
Chest wall rigidity
Respiratory depression

Question 11

What is the peak effect time of remifentanil?

Answer 11

90 seconds

Question 12

What is the peak effect time of meperidine?

Answer 12

15 minutes, lasts 2-4 hours

Question 13

What is the metabolite of meperidine and what does it do?

Answer 13

Normeperidine - accumulates in renal failure and lowers the seizure threshold.

Question 14

What are the side effects of meperidine?

Answer 14

Anticholinergic effects : tachy, flushing, dry, mad
Agitation, hyperpyrexia, rigidity - DONT USE WITH MAOi
Hypotension, hypoventilation, coma
Histamine release
Less respiratory depression than other opioids

Question 15

Why can’t opioids be used as a sole anesthetic?

Answer 15

There is a sub-MAC ceiling effect

Question 16

What are the three most effective opioids for reducing MAC?

Answer 16

Fentanyl
Remifentanil

Almost 80%!

Sufentanil (10 times more potent)

Question 17

What percentage does morphine lower MAC?

Answer 17

20-60%

Question 18

How does meperidine cause seizures?

Answer 18

It’s metabolite normeperidine is a CNS stimulant

Question 19

What is the half-life of meperidine?

Answer 19

2.5-4 hours

Question 20

What is the half-life of normeperidine?

Answer 20

15-30 hours

Question 21

How is normeperidine metabolized?

Answer 21

By the liver and then eliminated by liver and kidney

Do NOT use in liver and kidney disease!

Question 22

What is the maximum daily dose of meperidine?

Answer 22

10 mg/kg/day

Question 23

What are the 3 mechanisms of action of meperidine?

Answer 23

1. Mu opioid agonist
2. NMDA antagonist
3. Serotonin reputable inhibitor

Question 24

What are the contraindications for using meperidine?

Answer 24

MAOi
SSRI/SNRI
Liver disease
Kidney disease

Question 25

What enzyme metabolizes codeine?

Answer 25

CYP2D6

Question 26

How can hydrocodone be metabolized?

Answer 26

Metabolized CYP2D6 to more potent hydromorphone, but this is not its main effect

Question 27

What is hydromorphone metabolized to?

Answer 27

Hydromorphone-3-glucoronide which has no analgesic effects

Question 28

What can buildup of hydromorphone-3-glucoronide lead to?

Answer 28

Neuroexcitatory effects including agitation, restlessness, myoclonus

Question 29

What is oxycodone dependent on?

Answer 29

Conversion to oxymorphone via CYP2D6

It is a prodrug

Question 30

How does hydrocodone give its analgesic effect?

Answer 30

Via hydrocodone

Question 31

What is remifentanil’s duration of action due to?

Answer 31

Metabolism by plasma esterases

Question 32

What is the elimination half life of remifentanil?

Answer 32

10-20 minutes

Question 33

How long does it take for fentanyl transdermal to reach maximum plasma concentration?

Answer 33

30 hours

Question 34

How long does it take for onset of transdermal fentanyl latch?

Answer 34

6-8 hours

Question 35

How should fentanyl and remifentanil be dosed?

Answer 35

LBW