Opioid Analgesics Masserano

Question 1

Integumental pain

Answer 1

Dermis, mucosa, muscle, joints, headache. Controlled by NSAIDs

Question 2

Visceral pain

Answer 2

Pain within body cavities. . Best treated with opioids

Question 3

Ascending pain pathway

Answer 3

Perception, localization and discrimination of pain

Question 4

Descending pain pathway

Answer 4

Upper brain and brainstem use descending serotonin and norepinephrine neurons to reduce pain transmission through dorsal horn of the spinal cord

Question 5

Spinal Cord Site of Action of Opioid Compounds

Answer 5

1. ) Glutamate and nueropeptides
2. ) Decrease Ca influx in the presynaptic neuron
3. ) Increase K+ efflux in the postsynaptic neuron
4. ) Decrease calcium influx by NE & 5HT

Question 6

Morphine analgesia mechanism

Answer 6

1. Raising the pain threshold at the spinal cord level

2. Altering the central nervous system perception of pain

Question 7

Hyperalgesia

Answer 7

Persistent administration of opioid analgesics can increase the sensation of pain

Question 8

Morphine euphoria mech

Answer 8

Mu agonists enhance DA release in nucleus accumbens and induce euphoria. Produces sense of well being

Question 9

Morphine respiratory depression mech

Answer 9

Decreases response of brain stem respiratory neurons to CO2. Rate may fall 3 to 4 breaths per minute

Question 10

Meperidine and Misosis

Answer 10

Does not develop with Meperidine and a choice narcotic for abuse by healthcare professionals

Question 11

Morphine GI tract mech

Answer 11

1. Decreases peristatic gut motility
2. Increasing tone (persistent contraction)
   Antidiarrheal w/ loperamide

Question 12

Relistor MOA

Answer 12

Selective mu-opioid receptor that doesn’t cross BBB to relieve OIC

Question 13

Eluxadoline (Viberzi)

Answer 13

New drug for IBS with diarrhea.
Mu and kappa receptor agonist/Delta receptor antagonist
Only modestly effective and very expensive

Question 14

Morphine Urinary retention mech.

Answer 14

1. Inhibits urinary voiding reflex
2. Increases the tone of the external sphincter
3. Water retention by increasing ADH and decreasing blood pressure

Question 15

Morphine histamine release mech.

Answer 15

Causes mast cell degranulation with the release of histamine. Itching and diaphoresis common. Can be reversed by antihistamines

Question 16

Hormonal actions of chronic therapy or abuse

Answer 16

1. Decreased LH and FSH
2. Decreased testosterone
3. Decreased estrogen

Question 17

Morphine for LV heart failure mech

Answer 17

• Reduces preload and afterload leading to a decrease in myocardial oxygen consumption
• Relieves the dyspnea associated with pulmonary edema due to LV failure

Question 18

Mepergan (meperidine + promethazine)

Answer 18

Preanesthetic medication when analgesia, sedation, and anti-nausea are indicated.

Question 19

Meperidine lil tid bits

Answer 19

• Less smooth muscle spasms, constipation, and depression of cough reflex.
• No miosis
• Tachycardia (most cause brady)
• Strong agonist

Question 20

Codeine analgesia mech

Answer 20

Bioactivation 10% of codeine to morphine by CYP2D6.

Question 21

Apomorphine MOA

Answer 21

• Little analgesic activity

- D2 receptor agonist that induces vomiting by direct action on the chemoreceptor trigger zone

Question 22

Pentazocine (Talwin)

Answer 22

• Weak mu antagonist or partial agonist
• Blocks morphine analgesia and induces opioid withdrawal
• Agonist at kappa and sigma receptors

Question 23

Butrophanol (Stadol)

Answer 23

• Anestheia and post-op analgesia

- Mu antagonist and Kappa agonist

Question 24

Buprenorphine

Answer 24

Partial agonist at mu receptors with high affinity and slow dissociation
-Replacement for methadone as maintenance for opioid use disorder

Question 25

Tramadol

Answer 25

Affinity for mu (30%) and also blocks 5HT and NE reuptake (70%) which contribute to analgesia.
Risk for seizures and serotonin syndrome

Question 26

Tapentadol (Nucynta)

Answer 26

1. Mu opioid receptor agonist

2. Inhibition of NE reuptake

Question 27

Dextromethorphan

Answer 27

D-isomer of the opiate agonist levorphanol. 5-10 times normal dose can cause PCP like effects

Question 28

Naltrexone

Answer 28

24 hour duration of action for opioid and alcohol dependance