Table 1.

Pharmacological properties of oxycodone, morphine, fentanyl, sufentanil, pethidine, and hydromorphone

	Oxycodone [21, 22, 53–58]	Morphine [59–61]	Fentanyl [59, 61–63]	Sufentanil [64–67]	Pethidine [61, 68–70]	Hydromorphone [71, 72]
Absorption
T max	6–25 min	19 min	4 min	6 min	1.2 min	20 min
Distribution
Plasma protein binding	45%	35–36%	84%	~ 90%	~ 58%	8–19%
VD	2–3 l/kg	1–4.7 l/kg	4 l/kg	1.7–5.2 l/kg	3–5 l/kg	302.9 l
Metabolism
Major metabolites	Noroxycodone, oxymorphone	Morphine-3-glucuronide	Norfentanyl	Norfentanyl	Norpethidine	Hydromorphone-3-glucuronide
Excretion
Cl	1.10 l/min	0.9–1.2 l/kg/h	0.8–1.0 ml/min/kg	57.6 l/h	20.5 l/h	1.96 l/min
T1/2	2–3.5 h	1.5–4.5 h	3.7 h	2.7 h	2–5 h	2.3 h
Opioid receptor action
μ	+++	+++	+++	+++	+++	+++
κ	++	+	+	+	+	Nil
δ	++	+	Nil	+	+	+

Cl, clearance; T_max, time to maximum plasma concentration; T_1/2, half-life; V_D, volume of distribution; μ, mu-opioid receptor; κ, kappa-opioid receptor; δ, delta-opioid receptor