Opioids

Question 1

What is th MOA of opioids?

Answer 1

• Close voltage-gated Ca2+ channels on presyaptic nerve terminals
• Open K+ channels on postsynaptic neurons

Overall will inhibit the ascending pain transmission and activate descending pain-inhibitory circuits

Question 2

What are the opioid agonist, mixed agonist-antagonist, and antagonist?

Answer 2

Agonist:

• Morphine/Hydromoprhone/Oxymorhpone, Heroin, Fentanyl, Meperidine, Methadone, Levorphanol, Codeine/Oxycodone/Hydrocodone

Mixed Agonist-antagonist:

• Pentazocine, Butorphanol, Nalbuphine, Buprenorphine

Antagonist:

• Naloxone, Naltrexone

Question 3

What are the CNS and PNS effects of opioids?

Answer 3

CNS:

• Analgesia, euphoria, sedation/drowsiness, respiratory depression, cough suppression, miosis, truncal rigidity, N/V

PNS:

• Hypotension, constipation, contraction of biliary smooth muscle, pruritis

Question 4

Which opioid can cause seizures and why?

Answer 4

• Meperidine
• converted to normeperidine in pts with decreased renal function and in high concentrations can cause seizures
• Only used for short term Tx of acute pain

Question 5

What are the uses, AE, CI of opioid analgesics?

Answer 5

Uses:

• Analgesia: Tx moderate to severe pain
• Acute pulmonary edema
• Cough
• Diarrhea
• Applications in anesthesia

AE: N/V, sedation itching, constipation, urinary retention, hypotension, respiratory depression

CI: use of pure agonist w/ partial agonist can induce withdrawal, head injuries, pregnancy, impaired pulmonary/hepatic/renal function

Question 6

Morphine/Hydromorphone/Oxymorphone MOA, Uses

Answer 6

MOA: high affinity u with lower affinity delta, and kappa

Morphine is DOC for severe pain

Question 7

Heroin MOA

Answer 7

MOA: rapidly hydrolyzed to 6-MAM which are both more liposoluble than morphine to enter the brain

Question 8

Fentanyl MOA, Uses

Answer 8

MOA: u agonist with rapid onset 15-30minutes and 100 times more potent than morphien

Uses: severe pain

Question 9

Methadone MOA, uses, AE

Answer 9

MOA: u agonist, NDMA antagonist, 5-HT/NE reuptake inhibitor

Uses: managing opioid withdrawal be cause of long half life and less profound sedation and euphoria

AE: QT prolongation, torsades de pointes, and death

Question 10

Levorphanol MOA, Uses

Answer 10

MOA: u/d/k agonist, 5-HT/NE uptake inhibitor, NDMA antagonist

Uses: severe pain

Question 11

Oxycodone & Hydrocodone uses

Answer 11

• Oxycodone: moderate-severe pain alone or in combination
• Hydrocodone: moderate-severe pain only in combination with acetaminophen/NSAID

Question 12

Codeine MOA, uses

Answer 12

MOA: converted to morphine by CYP2D6

Uses: mild-moderate pain

Question 13

Pentazocine, Butorphanol, Nalbuphine MOA, uses

Answer 13

MOA: k agonist and u antagonist

Uses: not recommended because of ceiling effect, can cause withdrawal, and psychotomimetic effects (k)

Question 14

Buprenorphine MOA, Uses

Answer 14

MOA: weak u agonist, k antagonist

Uses: management of opioid addiction

Question 15

Tramadol MOA, Uses, AE

Answer 15

MOA: weak u agonist, 5-HT/NE reuptake inhibitor

Uses: moderate pain, neuropathic pain

AE: increased risk of seizures in pts with seizure disorder

Question 16

Naloxone & Naltrexone MOA, uses

Answer 16

MOA: u/d/k antagonist

Uses:

• Naloxone: tx acute opioid overdose
• Naltrexone: opioid and alcohol addiction

Question 17

What are the high, moderate-high, moderate, and low efficacy opioids?

Answer 17

High: Morphine/Hydromorphone/Oxymorphone, Methadone, Merperidine, Fentanyl, Levorphanol, Nalbuphine, Buprenorphine, Butorphanol

Moderate-High: Oxycodone

Moderate: Hydrocodone, Pentazocine

Low: Codeine

Question 18

Antitussives opioids?

Answer 18

• Dextrometorphan
• Codeine

Question 19

Antimotility opioids?

Answer 19

• Diphenoxylate
• Loperamide