Background
- Class of analgesic medications that act primarily on the μ-opioid receptor
Morphine Milligram Equivalent Dose
| Drug | MME per mg PO | MME per mg IV/SC |
|---|---|---|
| Meperidine | 0.1 | — |
| Codeine | 0.15 | — |
| Morphine | 1 | 2 |
| Oxycodone | 1.5 | — |
| Methadone | 3 | — |
| Hydromorphone | 5 | 10 |
| Fentanyl | 200 MME per 50 mcg/h transdermal | |
Fentanyl
| Fentanyl mcg/h | MME |
|---|---|
| 25 | 60-134 |
| 37 | 135-179 |
| 50 | 180-224 |
| 62 | 225-269 |
| 75 | 270-314 |
| 87 | 315-359 |
| 100 | 360-404 |
- IV is essentially twice as strong as PO
Safety
Adverse Events
| Common | Occasional | Rare | |
|---|---|---|---|
| Gastrointestinal | nausea, vomiting, constipation | delayed gastric emptying | biliary coli |
| Neurological | sedation, drowsiness, cognitive dysfunction | hallucinations, mood disturbance, anxiety, myoclonus | delirium, seizure, addiction |
| Respiratory | inhibition of cough reflex | dry mouth, bronchospasm | respiratory depression, non-cardiac pulmonary edema |
| Others | miosis | pruritus, muscle rigidity | hyperalgesia, allodynia, tolerance, physical dependence |
