Opioids and Analgesics

Question 1

physiologic pain

Answer 1

Defensive role. Acute in nature (labor, surgery, trauma). Easy management.

Question 2

pathologic pain

Answer 2

No known benefit. Chronic and spontaneous. Low pain threshold to both noxious and innocuous stimuli. Associated with nerve damage (trauma, amputation, diabetes mellitus, HIV and VZV. Difficult to treat.

Question 3

ascending pain transmissionpathway

Answer 3

From primary afferent nociceptors to dorsal horn cells.

Question 4

descending pathway. Pain response.

Answer 4

Inhibitory regulation. Starts in Frontal Cortex, Amygdala, and Cingulate Cortex. Synapses PAG, RVM, then Dorsal Horn Cells.

Question 5

desscending pathway receptors/transmitters

Answer 5

5HT, norepinephrine, glycine, GABA, and opioids.

Question 6

Opioid Mu receptor

Answer 6

stabilize neuronal membrane by enhancing K+ conductance, and inhibiting voltage gated Ca++ channels. 1 - dependence, analgesia. 2 - euphoria, respiratory depression,

Question 7

Opioid K receptor

Answer 7

Inhibitory.

Question 8

Opioid D receptor

Answer 8

Inhibitory.

Question 9

physical dependence

Answer 9

diaphoresis, insomnia, restlessness, abdominal cramps, N/V/D

Question 10

psychological dependence

Answer 10

mediated by the ventral sriatum. Interactions between opioids and dopaminergic system in Nucleus Accumbens.

Question 11

tolerance

Answer 11

Mediated by NMDA signaling (Glutamate). Normally cosmetic. Rotation therapy.

Question 13

euphoria

Answer 13

Mediated by Mu. Does not occur with Codeine or Pentazocine. Improves life quality and compliance.

Question 14

sedation

Answer 14

More so in the elderly. Greater in Phenanthrene derivatives than synthetic agents. Drowsiness, mental clouding, no amnesia.

Question 15

antitussance

Answer 15

No correlation with analgesia or respiratory depression. Most potent with Codeine or Pholcodine. Dextromethorphan is preferred.

Question 16

2 opioid receptor antagonists

Answer 16

Naloxone, Naltrexone

Question 17

3 partial and mixed agonists

Answer 17

Butorphanol, Buprenorphine, Nalbuphine

Question 18

7 synthetic opioids

Answer 18

Methadone, Meperidine, Fentanyl, Sufentanyl, Alfentanil, Ramifentanil, Diphenoxylate

Question 19

5 naturally occuring opioids

Answer 19

Codeine, Morphine, and derivatives (hydromorphone, hydrocodone, oxycodone). Most widely used fo pain control (epidural, trauma, surgery)

Question 20

Morphine

Answer 20

Naturally occuring. Hepatic metabolism - M3G to M6G (analgesic).

Question 21

Hydromorphone

Answer 21

Widely used more potent Morphine derivative.

Question 22

Codeine

Answer 22

antitussant, no euphoria, naturally occuring. Useful for mild to moderate pain. Hepatic deamination to Morphine by CYP2D6. Genetic alteration of CYP 2D6 and 3A4 voids analgesic effect.

Question 23

Oxycodone

Answer 23

effective mild analogue of codiene.

Question 24

Hydrocodone

Answer 24

effective mild analogue of codiene.

Question 25

Pholcodine

Answer 25

potent antitussant

Question 26

Dextromethorphan

Answer 26

Preferred to Codeine and Pholcodine bc - Low adverse effects, neuroprotective, useful in neuropathic pain.

Question 27

Pentazocine

Answer 27

no associated euphoria

Question 28

Methadone

Answer 28

Long plasma T1/2 - lipophilic and plasma protein binding. Chronic pain and terminally ill cancer patients. High risk of respiratory depression and QT prolongation - torsades de pointes.

Question 29

Meperidine

Answer 29

poor oral bioavailability. Metabolites cause seizures. Similar efficacy to Morphine, but less potent. Causes mydriasis (contrast to other opioids)

Question 30

Fentanyl

Answer 30

short acting, 100x more potent than morphine, highly lipophilic. Available in transdermal patch for slow delivery. Sufentanil, Alfentanil, and Ramifentanil.

Question 31

Butorphanol

Answer 31

K agonist, Mu partial agonist yields analgesia with a milder euphoria. Opioid addiction Tx, and maintenance in balance anesthesia, labor pain.

Question 32

Buprenorphine

Answer 32

K antagonist, Mu partial agonist. Moderate-severe long-term chronic pain management.

Question 33

Nalbuphine

Answer 33

K agonist, Mu antagonist. High psychological dysphoria. Moderate-severe pain, pre and post-op, obstetrical analgesia.

Question 34

Naloxone

Answer 34

Competetive antagonist ant Mu and K. Shorter T1/2 than Morphine. Parenteral administration. Opioid antidote whether known or suspected.

Question 35

Naltrexone

Answer 35

Opioid antagonist. Oral admin. Outpatient settings. Tx - dependence, relapse, following detox, and prophylaxis. Alcohol withdrawal.

Question 36

opioid respiratory depression

Answer 36

decrease sensitivity of chemosensitive neurons to PCO2. occurs at therapeutic doses. Most common cause of death in acute poisoning.

Question 37

GI Disturbances

Answer 37

epigastric distress and biliary colic (confused with angina). Increse pyloric sphincter tone, enhance and decrease frequency of peristalsis - constipation.

Question 38

miosis

Answer 38

diagnostic tool. Mu and K mediated. Involves edinger westphal nucleus.

Question 39

N/V

Answer 39

involving area postrema

Question 40

Hypotension and Bradycardia

Answer 40

impaired sympathetic response - orthostatic hypotension (morphine). Rapid IV admin of large dose causes non-specific mast cell degranulation. Synthetics and short-acting opioids generally do not evoke histamine release.

Question 41

NSAIDs and Acetominophen

Answer 41

decrease prostaglandin synthesis and therefore pain sensation.

Question 42

Antidepressants

Answer 42

Amitriptyline, Nortriptyline, and Imipramine - Tx of chronic pain that in not responsive to opioids. Venlafaxine and Duloxetine - used for neuropathic pain.

Question 43

NMDA receptor antagonists

Answer 43

Ketamine and Dexamethorphan - chronic pain syndrome and post-op pain. Ketamine - acute severe pain, strong psychomimetic effects.

Question 44

Adrenergic agonists

Answer 44

Clonidine - acute and chronic pain state. As well as withdrawal.

Question 45

Gabapentin

Answer 45

synthetic GABA analog - inhibits voltage-gated Ca channels. Chronic pain and post-op pain state. Erratic oral bioavailability - has to be monitored.

Question 46

Pregabalin

Answer 46

GABA analog - inhibits voltage gated Ca2+ channels in the CNS. Faster onset, more potent, and predictable bioavailability than Gabapentin. Neuropathic pain, fibromyalgia, spinal chord injury.

Question 47

Lamotrigine

Answer 47

Na+ channel blocker. Tx - neuropathic pain, trigeminal neuralgia. Skin reaction - steven/johnsons.

Question 48

Carbamazepine

Answer 48

Na+ channel blocker. Tx - trigeminal neuralgia. May cause Hypotension.