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Analgesic and adverse effects of a fixed-ratio morphine-oxycodone combination (MoxDuo®) in the treatment of postoperative pain

Patricia Richards, MD, PhD, Dennis Riff, MD, Robin Kelen, RN, Warren Stern, PhD


Objective: To compare efficacy and safety profiles of an immediate-release morphine and oxycodone Dual-Opioid® combination (MoxDuo®) versus its individual components and versus its morphine-equivalent doses in moderate to severe postoperative pain patients.
Design: Randomized, double-blind, 48-hour, parallel-treatment, multicenter, six-arm study of MoxDuo.
Setting: Six US centers.
Patients: Within 6 hours after bunionectomy surgery, patients were eligible if they reported pain intensity 2 on the 4-point Likert scale and 4 on an 11-point Numerical Pain Rating Scale (197 randomly assigned; 175 completers).
Interventions: MoxDuo 12 mg/8 mg, MoxDuo 6 mg/4 mg, morphine 12 mg, oxycodone 8 mg, morphine 6 mg, or oxycodone 4 mg (all administered q6h).
Main outcome measure: Sum of pain intensity differences 0-24 hours after the first dose of study medication (SPID24) and percentage of patients with moderate to severe nausea, emesis, or dizziness.
Results: SPID24 was significantly better in the MoxDuo 12 mg/8 mg group when compared with its individual components (morphine 12 mg [p = 0.009] and oxycodone 8 mg [p = 0.037]), and when compared with MoxDuo 6 mg/4 mg (p = 0.011; 54.3 vs 28.5, 35.7, and 30.0, respectively). MoxDuo 6 mg/4 mg and its morphine-equivalent doses (morphine 12 mg and oxycodone 8 mg) had comparable analgesic effects. There was a 50-75 percent reduction in moderate to severe adverse events (AEs) commonly associated with opioids (ie, nausea, vomiting, and dizziness) in the MoxDuo 6 mg/4 mg group when compared with its morphineequivalent dose groups.
Conclusions: MoxDuo produced superior analgesic effects when compared with its individual components, but comparable efficacy when compared with its morphine-equivalent doses. Common AEs were reduced at least 50 percent with MoxDuo when compared with its morphine-equivalent doses. MoxDuo may be an improved intervention in the management of moderate to severe acute pain.


pain, dual opioid, opioid, MoxDuo, morphine, oxycodone, bunionectomy, analgesia, morphine-equivalent dose, adverse events, nausea, emesis, dizziness

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