Opioids

Question 1

Beprenorphine

Answer 1

Class: Analgesic - u-receptor opioid partial agonist (mixed opiate agonist/antagonist)
Apps: moderate - severe pain. Sublingual for opioid dependence.
Mech: u-receptor partial agonist, exhibits ceiling due to pharm. effects. Very slowly dissociates from receptor = longer duration of action than morphine, unpredictability of reversal by antagonist, low dependence.
Effects: similar to other opioids (nausea, drowsiness, dizziness, headache, itch, dry mouth)

Question 2

Codeine

Answer 2

Class: analgesic. moderate u-recetor agonist
Apps: mild to moderate pain. Can be used in combo with acetaminophen, ASA or others. Good oral bioavailability
Mech: analgesic activity due to 15% conversion to morphine.
Effects: opioid effects.

Question 3

Hydromorphone

Answer 3

Class: analgesic. moderate to strong u-receptor opioid agonist (more potent than morphine)
Apps: moderate-severe pain. Low incidence of side effects.
Mech: similar to morphine
Effects: nausea, histamine rxns, mental confusion, miosis, biliary spasms, resp. depression, truncal rigidity

Question 4

Dextromethorphan

Answer 4

Class: Oral, nonprescriptioni antitussive
Apps: cough & cold OTC. Not an expectorant.
Mech: isomer lacks opioid activity except for cough suppression. Has NMDA antagonist properties.
Effects: FDA warning about pure powdered form causing death or brain damage.

Question 5

Diphenoxylate

Answer 5

Class: antidiarrheal
Apps: control & relief of acute diarrhea, and chronic diarrhea from IBD
Mech: inhibit GI motility. no analgesic or opiate-like effects.
Effects: Atropine is added to prevent abuse, so high doses = antimuscarinic effects.

Question 6

Fentanyl

Answer 6

Class: Analgesic. strong u- and k-receptor agonist.
Apps: 100x more potent than morphine, longer half life and action. Administered parenterally, and transmucosal or transdermally.
Mech: similar to morphine, but more lipophilic.
Effects: similar to morphine. Chest wall rigidity with IV administeration

Question 7

Hydrocodone

Answer 7

Class: Analgesic. moderate u-receptor agonist.
Apps: moderate-severe pain. Available combined with acetaminophen, ibuprofen or ASA. Antitussive. Vicodin=hydrocodone+acetaminophin.
Mech: moderate agonist at receptors in CNS.
Effects: similar to other opioids. Formulated with acetaminophen can cause liver toxicity.

Question 8

Loperamide

Answer 8

Class: antidiarrheal. opioid agonist
Apps: acute diarrhea or chronic from IBD.
Mech: interferes with peristalsis by acting on GI muscle walls.
Effects: constipation, dizziness

Question 9

Meperidine

Answer 9

Class: Analgesic. moderate-strong u-receptor opioid agonist.
Apps: moderate-severe acute pain
Mech: opioid receptor agonist
Effects: only for brief courses b/c long term causes seizures. Contraindicated with MAOI’s (serotonin syndrome: tremor, restlessness)

Question 10

Methadone

Answer 10

Class: analgesic. strong u-receptor opioid agonist
Apps: analgesic similar to morphine but better oral bioavailability. Used for medically supervised opiate withdrawal.
Mech: similar to morphine. oral or parenterally, long 1/2 life.
Effects: similar to morphine.

Question 11

Morphine

Answer 11

Class: Analgesic. Strong u-receptor opioid agonist.
Apps: moderate-severe acute and chronic pain, preoperative sedation, supplement to anesthesia. Parenterally, intrathecally, epidurally, rectally, orally
Mech: its metabolite, morphine 6-glucuronide, has analgesic activity and contributes to morphine’s activity
Adverse: constipation, nausea, histamine rxns, confusion, biliary spasm, miosis, respiratory depression, truncal rigidity

Question 12

Naloxone

Answer 12

Class: opioid receptor antagonist (affinity: u>k, d)
Apps: reverse effects of opioid analgesics
Mech: pure antagonist, short half life. Antagonizes toxic & clinical effects. IV, IM or sub-Q. Ineffective orally b/c of 1st pass metabolism.

Question 13

Naltrexone

Answer 13

Opioid receptor antagonist (affinity: u>k,d)
Apps: reverse clinical effects of opioids. For use with drug rehab programs.
Mech: better bioavailability and longer half life than naloxone.
Effects: nausea, headache, dizziness, nervousness, fatigue, insomnia, vomiting

Question 14

Oxycodone

Answer 14

Class: analgesic. moderate-strong u-receptor opioid agonist.
Apps: moderate-severe pain, cancer pain, post-op, postextractional, postpartum and non-pain syndromes (restless leg, Tourette)
Mech: analgesia similar to morphine.
Percocet=oxycodone+acetaminophen
Percodan=oxycodone+aspirin
Effects: less nausea/vomiting than morphine

Question 15

Pentazocine

Answer 15

Class: analgesic. mixed opioid partial agonist/antagonist.
Apps: moderate-severe pain. 1/3rd as potent as morphine. Less respiratory depression than pure agonists. Not commonly used in clinical practice b/c dysphoric rxns & short 1/2 life.
Mech: partial u & k agonist. Effects similar to morphine-like opioids.
Effects: sedation, ceiling effect for respiratory depression. Less effects than other opioids.

Question 16

Propoxyphene (Darvon)

Withdrawn from US market 2010

Answer 16

Class: weak u-receptor opioid agonist in CNS
Apps: mild pain. more effective agents available.
Mech: like codein.
Effects: high doses cause hearth rhythm abnormalities

Question 17

Tramadol (Ultram)

Answer 17

Class: weak opioid agonist at u-receptors (but not opioid derivative)
Apps: effective as adjuvant to NSAID therapy for OA patients with breakthrough pain. For post-op pain, equivalent to codeine but less than acetaminophen. Good for patients who can’t tolerate NSAIDs.
Mech: dual mechanism - u-receptor agonist, weak NE and 5HT reuptake inhibitor in CNS, results in inhibition of pain transmission from spinal cord to brain
Effects: similar to other opiate agonists