Relative potency of controlled-release oxycodone and controlled-release morphine in a postoperative pain model

Abstract

Oral controlled-release oxycodone was twice as potent as oral controlled-release morphine in this single-dose, relative potency assay. When converting patients from oral morphine to oral oxycodone, an initial oral oxycodone dose of one-half the oral morphine dose is recommended.

Within-subject comparison of the psychopharmacological profiles of oral oxycodone and oral morphine in non-drug-abusing volunteers

“…Relative potency ratios of oral morphine to oral oxycodone that we could find in the peer-reviewed literature were 1:1 (Glare and Walsh 1993), 1.3:1 (Kalso and Vainio 1990), 1.5:1 (Bruera et al 1998), 1.7:1 (Heiskanen et al 2000), 1.8:1 (Curtis et al 1999), 2:1 (Foley 1985, and 2.2:1 (Curtis et al 1999). There appears to be a consensus in the pain management community that oral oxycodone is 1.5 to 2 times as potent as oral morphine (see Levy 1996;Hanks et al 2001).…”

“…However, only one dose of morphine was tested; furthermore, the 30 mg oxycodone dose (and the 20 mg dose) produced a statistically significantly greater degree of miosis than 40 mg morphine, indicating the dosages were not equipotent on a prototypic physiological response to opioids (e.g., Fedder et al 1984;Martin 1984;Benziger et al 1997). The comparison of 40 mg of morphine to 30 mg of oxycodone was based on a morphine/oxycodone analgesic potency ratio of 1.3:1 reported in a study on cancer-pain patients in severe pain (Kalso and Vainio 1990), but there are other reported analgesic potency ratios (e.g., Foley 1985; Curtis et al 1999). This leaves open the possibility that morphine would generate a similar profile of psychopharmacological effects to that of oxycodone if higher morphine doses were tested (that were equipotent to oxycodone on some objective measure).…”

Quantitative Contribution of Cyp2d6 and Cyp3a to Oxycodone Metabolism in Human Liver and Intestinal Microsomes

“…Oxycodone (4,5-epoxy-14-hydroxy-3-methoxy-17-methylmorphinan-6-one; 14-dihydrohydroxycodeinone) is an opioid analgesic widely used for the treatment of postoperative pain (Nuutinen et al, 1986;Silvasti et al, 1998;Curtis et al, 1999) and pain associated with cancer (De Conno et al, 1991;Glare and Walsh, 1993;Parris et al, 1998). It has also been suggested for the management of nonmalignant chronic pain (Watson and Babul, 1998;Sindrup and Jensen, 1999).…”

Molecular Aspects of Opioid Receptors and Opioid Receptor Painkillers

“…(Volpe, Tobin et al 2011) Some potency comparisons with morphine worth mentioning include the following: fentanyl when administered intramuscularly is about 100 fold more potent; hydromorphone is 6-8 fold more potent; (Inturrisi 2002) and oral oxycodone is about 1.8 times more potent. (Curtis, Johnson et al 1999) Though a partial agonist buprenorphine is reported to be 25-40 times more potent than morphine. (Blakeney, Reid et al 2007) …”