Table 2.

Critical pharmacological properties in postmortem toxicology, volume of distributon (Vd), protein bining and potency relative to morphine, of selected natural, semi-synthetic and synthetic opioids.

Group	Analyte	Vd (L/kg)	Protein binding (%)	Potency relative to morphine	References
Natural and semi-synthetic opioids	Morphine	1–6	30–40	1	Baselt, 2017
	Codeine	2.5–3.5	7–25	0.3	Baselt, 2017
	Hydrocodone	3.3–4.7	19–45	0.5–1	Patanwala et al., 2007; Baselt, 2017
	Hydromorphone	2.9	20	5–10	Bruera et al., 1996; Patanwala et al., 2007; Baselt, 2017
	Oxycodone	2.6	45	1	Patanwala et al., 2007; Al-Asmari et al., 2009
	Oxymorphone	3	10–12	10	Patanwala et al., 2007; Smith, 2009
	Buprenorphine	3–5	96	40	Dahan et al., 2005
Synthetic opioids	Fentanyl	3–8	80–85	224	Jumbelic, 2010
	Methadone	1–8	85–90	3–5	Patanwala et al., 2007; Baselt, 2017
	Tramadol	3	20	0.1	Christoph et al., 2007; Oertel et al., 2011
Synthetic opioids-Fentanyl derivatives	Acetylfentanyl	NA	NA	15	Higashikawa and Suzuki, 2008
	Acrylfentanil	NA	NA	170	Ujváry et al., 2017
	Alfentanil	0.4–1	92	72	Vardanyan and Hruby, 2014
	Butyryl fentanyl; butyr fentanyl	NA	NA	7	Higashikawa and Suzuki, 2008
	Isobutyrylfentanyl	NA	NA	1.3–6.9	Higashikawa and Suzuki, 2008
	Carfentanil	NA	NA	10,000	Van Bever et al., 1976
	Furanyl fentanyl	NA	NA	7	Higashikawa and Suzuki, 2008
	alpha-methylfentanyl	NA	NA	56.9	Higashikawa and Suzuki, 2008
	cis-3-methylfentanyl; 3-MF; mefentanyl	NA	NA	6000	Higashikawa and Suzuki, 2008
	Remifentanil	0.35	70	220	Wax et al., 2003
	Sufentanil	NA	NA	4,520	Niemegeers et al., 1976
Synthetic opioids-Not related to fentanyl	AH-7921	NA	NA	1	Hayes and Tyers, 1983
	U-47700	NA	NA	7.5	Cheney et al., 1985
	MT-45	NA	NA	1	EMCDDA, 2015

NA, not available.