Extended-release epidural morphine (DepoDur): review and safety analysis

Extended-release epidural morphine (EREM) provides effective postoperative analgesia for 48 h following injection. It is administered as a single bolus into the lumbar epidural space, and is indicated for lower abdominal and lower extremity surgery associated with moderate-to-severe pain. While its efficacy has been well documented in randomized controlled trials, the safety and clinically appropriate dosing are less well defined. A meta-analysis approach was used to assess the adverse effects of EREM (n = 801) in comparison with intravenous opioids and standard epidural morphine. EREM 15 mg or greater was associated with a trend towards a higher incidence of hypoventilation (odds ratio: 0.48; 95% confidence interval CI]: 0.21-1.09; p = 0.081; number-needed-to-treat NNT] = 14) compared with placebo. The incidence of pruritus was significantly higher for all EREM doses compared with both placebo (p = 0.004) and standard epidural morphine (p = 0.03). Vomiting was also increased with EREM 15 mg or greater compared with placebo (odds ratio: 0.40; 95% CI: 0.18-0.89; p = 0.02; NNT = 5). A multimodal analgesic regime is recommended to permit the use of lower EREM doses, thus reducing the risk for adverse effects including respiratory depression. Prophylactic time-contingent antiemetics are also recommended when EREM is used.