Opioid Analgesia

Question 1

Where are opioid analgesics originated from?

Answer 1

• Derived from morphine
• Provide true analgesia at peripheral and central pain receptors
• Bind to receptor sites on nerve ending, preventing transmission of pain

Question 2

What is the primary receptor site for analgesia?

Answer 2

The mu receptor, with minor effects on kappa receptors

Question 3

What are examples of pure mu agonist and what are they?

Answer 3

They are the most potent pain relievers.

• Fentanyl
• Morphine
• Oxymorphone
• Hydromorphone

Negative side effects:

• dysphoria
• ileus
• vomiting
• nausea
• sedation

Question 4

Why should pain relief not be withheld even with blunted respiratory drive?

Answer 4

Because patients in pain can suffer from a number of stress-induced sequels that includes catecholamine release and hypoventilation. More deleterious respiratory side effects may be seen from withholding opioid pain medication.

Question 5

Buprenorphine

Answer 5

• Partial mu receptor agonist
• Long duration (6-12 hours)
• Not as potent as pure agonists
• Can be given with other pure agonist
• lessen pain relief
• absorbed well transmucosally in cats

Question 6

Butorphanol

Answer 6

• Mixed agonist-antagonist
• Rapid onset of action
• Short duration (2-4hours)
• Poor pain relief
• Fewer side effects
• Useful in patients who already received a pure agonist opioid and is suffering from over sedation or dysphoria
• Reverses above effects while maintaining some level of analgesia

Question 7

Naloxone

Answer 7

• Opioid antagonist
• Completely reverse opioid effects on a dose-dependent basis
• 0.01mg/kg partial reversal
• 0.04mg/kg complete reversal
• Short duration (1-3hours)

Question 8

Tramadol

Answer 8

• Opioid-like
• Centrally acting oral analgesic
• Used in conjunction with other pain management
• Works well with NSAID
• Good for home use