Table 3.
Opioid | Receptor binding | Routes of administration | Metabolic pathway | Ceiling dose | Onset of effect | Duration of effect |
---|---|---|---|---|---|---|
Morphine | μ, κ (weak) | Oral tablet, oral liquid, intramuscular or subcutaneous, epidural or intrathecal, intravenous, rectal | Glucuronidation | None | NA | ER or IR |
Hydrocodone | μ, κ | Oral | CYP2D6 | Yes for combination products, no for pure hydrocodone | Rapid | ER or IR |
Oxycodone | μ, κ (strong) | Oral, rectal | CYP3A4 CYP2D6 |
Yes for combination product, no for pure oxycodone | Rapid | ER or IR |
Buprenorphine | μ (antagonist), κ (agonist, weak partial) | Transdermal, transmucosal | CYP3A4, glucuronidation | Yes | Slow | Long |
Hydromorphone | μ, κ (weak), δ (weak) | Oral, intramuscular or subcutaneous, intravenous, rectal | Glucuronidation | None | N/A | ER or IR |
Oxymorphone | μ | Oral, intravenous, rectal | Glucuronidation | None | N/A | ER or IR |
Levorphanol | μ, κ, δ | Oral | Glucuronidation | 6–12 mg/d | Rapid | Long |
Tapentadol | μ, 5-HT, NE | Oral | Glucuronidation CYP2C9 (minor) CYP2C19 (minor) |
500 mg/d | Slow | ER or IR |
Fentanyl | μ, κ (weak) | Transdermal, transmucosal, intranasal, intravenous | CYP3A4 | None | Very rapid (transmucosal, intravenous) Very slow (transdermal) |
Very short Very long (transdermal) |
Methadone | μ, κ (weak), δ (strong), NMDA | Oral | CYP3A4 CYP2B6 CYP2C8 CYP2C19 CYP2D6 CYP2C9 |
None | Slow | Long |
Abbreviations: 5-HT, serotonin; CYP, cytochrome P450; d, day; ER, extended release; IR, immediate release; N/A, not applicable; NE, norepinephrine; NMDA, N-methyl-D-aspartate.