1. Opiod analgesics
9월 흉부외과 인턴 김영재

2. Opioid Analgesics
The μ receptor opioid agonists : morphine, codeine, oxycodone, hydrocodone, fentanyl, hydromorphone, methadone, and meperidine

3. Tramadol Opioid-like drug that has weak opioid analgesic properties
Less constipating and has less risk of abuse than the μ receptor agonists.
Avoided in patients with epilepsy because it rarely can trigger seizures

4. Morphine
Traditional treatment for the pain of myocardial infarction and other acute syndromes
Its slow penetration into the brain may delay the onset of pain relief.

5. Opioid agonist-antagonists
Butorphanol, nalbuphine, and pentazocine
Produce analgesia by binding to κ opioid receptors but antagonize the action of μ receptor agonists.

6. The κ stimulation; psychotomimetic reactions.
Blockade of the μ receptor ; withdrawal symptoms.
Respiratory depression and fewer regulatory controls.
Buprenorphine, a partial agonist at the μ receptor, does not cause psychotomimetic reactions.

7. Routes of administration
Oral (PO); The oral route usually is preferred because of its convenience. for patients who cannot swallow tablets, many opioids are available in suspensions. Peak drug effects occur 1.5 to 2 hours after oral administration.

8. Intramuscular use; discouraged because of painful administration, wide fluctuations in absorption from muscle, a 30- to 60-minute lag to peak effect, and rapid falloff of action compared with oral administration.

9. Intravenous (IV) bolus ; the most rapid onset of effect and clarity of titration.
Time to peak effect- 1 to 5 minutes for fentanyl to 15 to 30 minutes for morphine.
Duration is shorter than after intramuscular administration.
If severe pain persists but side effects are minimal at the time of expected peak effect, another bolus may be given.

10. Opioids with long elimination half-lives, such as methadone and levorphanol, are not recommended for rapid opioid titration because drug levels remain elevated for many hours if too high a dose is given.

11. Transdermal; Fentanyl is available in a transdermal drug delivery system, providing a steady opioid infusion without pumps or needles.
There is a 12- to 24-hour lag to analgesia after initial application of the patch as opioid is transferred to subcutaneous fat

12. Treating opioid side effects
Sedation, constipation, nausea, itching, and respiratory depression
Sedation may be counteracted partly by adding a stimulant such as caffeine, dextroamphetamine (2.5 to 10 mg PO), or methylphenidate (5 to 10 mg PO).

13. Constipation; patients should be given stool softeners and agents to increase bowel motility.
Nausea and vomiting ; may be treated with transdermal scopolamine, hydroxyzine, or a phenothiazine antiemetic.

14. Respiratory depression ; opioid antagonist is required to reverse respiratory depression or coma in a patient on long-term opioids.
Small doses of naloxone (e.g., one twentieth of a 0.4-mg ampule IV every 2 minutes).