| Morphine | 10 | 30 | 3 | Standard of comparison for opioid analgesics; lower dose for aged and patients with impaired ventilation, bronchial asthma, increased intracranial pressure, liver failure, or renal failure |
| Hydromorphone (Dilaudid ) | 1.5 | 7.5 | 5 | Slightly shorter acting |
| Methadone (Dolophine) | 10 | 20 | 2 | Good oral potency, long plasma half-life; like morphine, may accumulate with repetitive dosing causing excessive sedation |
| Fentanyl (Duragesic) | 100 μg = 4 mg morphine IV | — | — | Short half-life; transdermal and transmucosal preparations available |
| Meperidine (Demerol) | 75 | 300 | 4 | Not recommended in chronic cancer pain due to toxic metabolite, impaired renal function, or if receiving monoamine oxidase inhibitors |
| Levorphanol (Levo-Dromoran) | 2 | 4 | 2 | Like methadone to opioid analgesics |
| Codeine | 130 | 200 | 1.5 | Often used in combination with nonopioid analgesics; biotransformed, in part to morphine |
| Oxycodone (Roxicodone, Tylox) | — | 30 | — | Also in combination with nonopioid analgesics, which limits dose escalation |
| Oxymorphone (Numorphan) | 1 | — | 6 (rectal) | Like methadone; not available orally |
