DepoDur® (extended-release epidural morphine): a review of an old drug in a new vehicle

The use of epidural opioid can no longer be considered a novel postoperative analgesic, whether used as a one-time bolus or given via an epidural infusion with or without local anesthetic. In this role, epidural opioid is well accepted and efficacious. However, epidurals and other current strategies for treating acute postoperative pain are all limited by side effects and complications. Epidural infusions can provide excellent postoperative analgesia but can also lead to problems and complications related to catheter placement, such as the potential for epidural hematoma with anticoagulation, technical issues with the infusion pumps, and the time and labor necessary to place, adjust, and manage catheters and infusions. Extended-release epidural morphine (EREM, DepoDur®; Endo Pharmaceuticals, Chadds Ford, PA) has been studied and increasingly utilized as a method to improve postoperative analgesia of epidural dosing without the use of infusions. Via a delivery system using liposome encapsulation, EREM provides novel analgesic benefits but also contributes a new set of concerns to the field of pain management: unique onset and duration of opioid adverse effects. These issues have generated controversy in clinical anesthesia. In this review, we provide an overview of the published basic science, background research, and current clinical studies, as well as recent applications and experience with EREM.