Opioids are a class of compounds that elicit analgesic (pain killing) effects in humans and animals by binding to the μ-opioid receptor within the central nervous system. The following table lists commonly used opioid drugs and their relative potencies. Values for the potencies of opioids listed on this table are given as taken orally unless another route of administration is provided. As such, their bioavailabilities differ, and they may be more potent when taken intravenously.
Analgesic/opioid | Strength [1] (morphine) | Equivalent dose (10 mg morphine) | Bioavailability | Half-life (hours) [active metabolite(s)] |
---|---|---|---|---|
Aspirin (non-opioid) | 1/360 | nil | "total" | 3.1 - 9 |
Diflunisal (NSAID, non-opioid) | 1/160 | 1600 mg | 80-90% | 8-12 |
Dextropropoxyphene[2] | 1/13 to 1/20 | 130-200 mg | ||
Codeine | 1/20 | 200 mg | ≈90% | 2.5-3 [ CG6 1.94[3]; morphine 2-3] |
Tramadol | 1/10 | 100 mg | 68-72% | 5.5-7 [≈9] |
Anileridine[4] | 1/4 | 40 mg | n/a | n/a |
Pethidine | 0.36 | 28 mg | 50-60% | 3-5 |
Hydrocodone | 0.6 | 17 mg | 80%+ | 3.8-6 |
Morphine (oral) | (1) | (10 mg) | ≈25% | 2-3 |
Oxycodone | 1.5–2.0 | 5.0–6.7 mg | up to 87% | 3-4.5 |
Methadone[5] | 3-4 | 2.5-3.33 mg | 40-90% | 15-60 |
Morphine (IV/IM) | 4 | 2.5 mg | 100% | 2-3 |
Diacetylmorphine (heroin; IV/IM)[6] | 1.9–4.3 | 2.3–5.2 mg | 100% | <.6 |
Hydromorphone[7] | 5 | 2 mg | 30-35% | 2-3 |
Oxymorphone | 7 | 1.4 mg | 10% | 7.25-9.43 |
Levorphanol[8] | 8 | 1.3 mg | 70% | 11-16 |
Buprenorphine[9] | 40 | 0.25 mg | 35-40% (sublingual) | 20-70 mean 37 |
Fentanyl | 50–100 | 0.1–0.2 mg | 33% (oral) 92% (transdermal) | .04 (IV); 7 (transdermal) |
Sufentanyl | 500–1,000 | 10–20 μg | n/a | 4.4 |
Etorphine[10] | 1,000–3,000 | 3.3–10 μg | n/a | n/a |
Carfentanil10 | 10,000–100,000 | 0.1–1.0 μg | n/a | 7.7 |