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

• Published in: European journal of clinical pharmacology 1999-08, Vol.55 (6), p.425-429
• Main Authors: CURTIS, G. B, JOHNSON, G. H, CLARK, P, TAYLOR, R, BROWN, J, O'CALLAGHAN, R, SHI, M, LACOUTURE, P. G
• Format: Article
• Language: English
• Subjects: Administration, Oral; Adult; Analgesia; Analgesics; Analgesics, Opioid - administration & dosage; Analgesics, Opioid - adverse effects; Analgesics, Opioid - therapeutic use; Analysis of Variance; Biological and medical sciences; Clinical trials; Controlled release; Double-Blind Method; Female; Humans; Hysterectomy; Medical sciences; Morphine; Morphine - administration & dosage; Morphine - adverse effects; Morphine - therapeutic use; Narcotics; Neuropharmacology; Opioids; oxycodone; Oxycodone - administration & dosage; Oxycodone - adverse effects; Oxycodone - therapeutic use; Pain management; Pain perception; Pain, Postoperative - drug therapy; Pharmacology. Drug treatments; Side effects
• ISSN: 0031-6970; 1432-1041
• DOI: 10.1007/s002280050651

The relative analgesic potency of single doses of oral controlled-release oxycodone and oral controlled-release morphine were compared in a randomized, double-blind trial using a postoperative pain model. Women (n = 169) with moderate to severe pain following abdominal hysterectomy received single oral doses of controlled-release oxycodone, 20 mg or 40 mg, or controlled-release morphine, 45 mg or 90 mg. Assessments were made at 30 min, 60 min, then hourly after dosing for 12 h or until remedication. The most precise estimates of relative potency showed that controlled-release oxycodone was 1.8 times more potent than controlled-release morphine for total effect (95% confidence limits 1.09-2.42; lambda 0.44) and 2.2 times more potent for peak effect (95% confidence limits 0.96-4.59; lambda 0.71). Controlled-release oxycodone at doses of 20 mg or 40 mg was comparable with controlled-release morphine at doses of 45 mg or 90 mg, respectively, for total and peak analgesic effects. For the two higher doses, time to peak relief was approximately 1 h shorter with controlled-release oxycodone than with controlled-release morphine. Most patients reported onset of analgesia within 1 h with all doses. Side effects were similar with the two opioids. 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.