Pain medicine : the official journal of the American Academy of Pain Medicine
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Although effective alone, opioids are often used in combination with other drugs for relief of moderate to severe pain. Guidelines for acute perioperative pain recommend the use of multimodal therapy for pain management, although combinations of opioids are not specifically recommended. Mu opioid drugs include morphine, heroin, fentanyl, methadone, and morphine 6β-glucuronide (M6G). ⋯ These differences among the drugs raise the question of whether combinations might result in better pain relief with fewer side effects. This concept has already been demonstrated between two mu opioids in preclinical studies and clinical trials on other combinations are ongoing. This article reviews the current state of knowledge about mu opioid receptor pharmacology, summarizes preclinical evidence for synergy from opioid combinations, and highlights the complex nature of the mu opioid receptor pharmacology.
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Although opioids are widely accepted as standard therapy for treating acute postoperative pain, the frequent occurrence of adverse events (AEs) and the substantial burden on the patient and the costs of care are a barrier to optimal dosing and adherence to prescribed treatment. Coadministration of two opioids is not often recommended as a multimodal treatment option for moderate to severe acute pain because of lack of knowledge about the potential benefit of such combinations and due to potential concerns about side effects and doubts about the added benefits. Study results on the coadministration of two or more opioids demonstrate synergistic analgesia with a similar or lower incidence of opioid-related AEs. One such combination is morphine and oxycodone. ⋯ Thus, the dual-opioid combination product, morphine/oxycodone 3/2, compared with equianalgesic monotherapy doses of oxycodone or morphine may provide effective relief of moderate or severe post-surgical pain, while reducing the impact of AEs on patients and prescribers.