New morphine injection cleared for postop pain management

Approximately 40 million inpatient surgical procedures take place in the United States annually. Optimizing postoperative pain management for hospitalized patients continues to be a challenge for healthcare providers. Current approaches to treating postoperative pain include the administration of analgesics via an epidural catheter or intravenous patient-controlled analgesia (PCA).

While these techniques have proven beneficial in managing postoperative pain, some difficulties also exist. Both epidural and IV catheters are associated with an increased risk of infection and can interfere with patient mobility. "Another concern with epidural catheters is the inadvertent administration of an epidural solution into the IV space or of an IV solution's being administered into the epidural space," said Leslie N. Schechter, Pharm.D., clinical pharmacy specialist at Thomas Jefferson University Hospital in Philadelphia.

The introduction of a less invasive therapy may help enhance patient safety and satisfaction. One such option may be DepoDur, a morphine sulfate sustained-release liposome injection with a novel delivery system, DepoFoam, made of lipid vesicles that consistently release morphine to provide pain relief for up to 48 hours following a single dose.

DepoDur has been shown to be useful in providing postoperative pain relief to patients undergoing hip or knee arthoplasty, abdominal surgery, and cesarean section. In a study presented by Craig Hartrick, M.D., William Beaumont Hospital, at the 2004 Joint Meeting of the American Pain Society and the Canadian Pain Society, the safety and efficacy of DepoDur were evaluated in 168 knee arthoplasty patients.

Patients were randomized to receive single epidural doses of DepoDur at 20 mg or 30 mg or IV PCA morphine. The study found that, up to 30 hours after drug administration, the mean time-weighted pain intensity recall scores were significantly lower in both DepoDur groups than in the IV PCA morphine group. DepoDur administration also eliminated the need for supplemental opioids in some patients. The overall adverse-event profile of DepoDur was similar to that of the epidural opioids and opioids in general.

In another clinical trial presented at the joint meeting, patients who had abdominal surgery were randomized to receive either a single epidural dose of DepoDur or standard unencapsulated morphine sulfate. About 15% of all patients taking 10-25 mg of DepoDur received no postoperative IV fentanyl at 48 hours postdose, compared with only 2% of patients taking standard morphine sulfate (p < 0.02).

The study authors also stated that perioperative administration of epidural DepoDur prior to the initiation of prophylactic anticoagulation therapy would avoid the risk of epidural hematomas, while still providing pain relief. On the other hand, epidural catheters are contraindicated in patients requiring anticoagulation therapy to reduce the risk of deep vein thrombosis in the postoperative period, because of the risk of epidural hematomas and neurological injury.

The manufacturer of DepoDur, SkyePharma, has licensed the drug to Endo Pharmaceuticals for commercialization in North America. Endo Pharmaceuticals anticipates that DepoDur will be available for commercial use by the end of 2004.

Pharmacists can play a crucial role in improving postoperative pain management by ensuring that analgesics are utilized appropriately within their institution. Some barriers to adequate postoperative analgesia include clinicians' misconceptions regarding analgesic medication doses and duration of effect. The Joint Commission on Accreditation of Healthcare Organizations 2004 pain management standards advocate that analgesics be administered around-the-clock for patients with continuous pain, instead of on an as-needed (p.r.n.) basis. A short-acting, rapid-onset p.r.n. analgesic, however, can be used to manage breakthrough pain.

With the advent of these JCAHO standards, many hospitals have instituted multidisciplinary committees to address pain management issues. "All pharmacists at my institution participate in a pain management education program and complete a competency test, which includes calculating analgesic medication dosages and dosage conversions," stated Schechter. "Pharmacists here, in collaboration with other healthcare professionals, have also developed a pain management guideline booklet in an effort to enhance clinician knowledge of appropriate pain management. Pharmacists are also uniquely qualified to provide patient education. Providing thorough information to patients before surgery may help reduce preoperative anxiety and postoperative pain," she noted.